WO2025176666A1 - Tyre comprising a wear-resistant complex tread - Google Patents

Abstract

The invention relates to a tyre (10) comprising a tread that comprises a tread layer (52) which comprises an axially central portion (P0c) and an axially lateral portion (P1c, P2c). The axially central portion (P0c) and the axially lateral portion (P1c, P2c) of the tread layer (52) respectively comprise a central material (M0) and a lateral material (M1, M2) respectively having a dynamic shear modulus G*C, G*1 such that G*1<G*C. The crown reinforcement (60) comprises a radially outermost layer (72) comprising reinforcing elements embedded in a polymer matrix. The mean radial distance E1m in a central portion of the tread (14) between the surface passing through the radially innermost point and the radially outer surface passing through the radially outermost points of the radially outermost reinforcing elements is such that E1m ≤ 2.00 mm.

Description

Tire with a complex wear-resistant tread

[001] The present invention relates to a tire, in particular for a passenger vehicle. By tire is meant a bandage intended to form a cavity by cooperating with a support element, for example a rim, this cavity being capable of being pressurized to a pressure higher than atmospheric pressure. A tire according to the invention has a structure of substantially toroidal shape of revolution around a main axis of the tire.

[002] Known from the state of the art are tires comprising a tread comprising a tread layer comprising an axially central portion of the tread layer and first and second axially lateral portions of the tread layer arranged axially outside and on either side of the axially central portion of the tread layer. In order to optimize certain performances of the tire, for example the rolling resistance and/or the drift rigidity of the tire, the axially central portion of the tread layer and each first and second axially lateral portion of the tread layer respectively comprise a central material and first and second lateral materials respectively having a dynamic shear modulus at 23°C G*C, G*1, G*2 such that G*1<G*C and G*2<G*C.

[003] It was noted that this tire reached the maximum wear level on each first and second axially lateral portion of the tread layer before reaching it on the axially central portion of the tread layer. Thus, a user of the tire is led to change this tire while there is still a significant thickness of tread layer to wear in the axially central portion of the tread layer.

[004] The invention aims to delay the wear of the tread layer in at least one of the first and second axially lateral portions of the tread layer in order to delay the replacement of the tire.

[005] For this purpose, the subject of the invention is a tire comprising a crown comprising a tread carrying a tread surface and a crown reinforcement arranged radially inside the tread, the tread comprising a tread layer comprising an axially central portion of the tread layer and an axially lateral portion of the tread layer arranged axially outside the axially central portion of the tread layer, the axially central portion and the axially lateral portion of the tread layer respectively comprise a central material and a lateral material respectively having a dynamic shear modulus G*C, G*1 such that G*1<G*C, each dynamic shear modulus G*C, G*1 being measured at 23°C at 10% strain and at a frequency of 10 Hz according to ASTM D 5992-96, the tread comprising an axially central portion of the tread and first and second axially lateral portions of the tread arranged axially outside and on either side of the axially central portion of the tread, the tread comprises main circumferential cutouts having a depth greater than or equal to 50% of the tread height comprising first and second axially outer main circumferential cutouts arranged axially on either side of the median plane of the tire, the first and second axially outer main circumferential cutouts being the axially outermost portions of the tread, each first and second axially lateral portion of the tread being arranged axially outside respectively each first and second axially outer main circumferential cutout and the axially central portion of the tread extending from the first axially lateral portion of the tread to the second axially lateral portion of the tread, the axially central portion of the tread layer being at least partly arranged in the axially central portion of the tread, the axially lateral portion of the tread layer being at least partly arranged in one of the first and second axially lateral portions of the tread, the crown reinforcement comprising a radially outermost layer and comprising reinforcing elements embedded in a polymer matrix, the average radial distance E1 m in the axially central portion of the tread between:

- the surface passing through the radially innermost point of the deepest cutout made in the axially central portion of the tread and substantially parallel to the tread surface, and

- the radially outer surface passing through the radially outermost points of the radially outermost reinforcing elements among the reinforcing elements of the radially outermost layer arranged directly above the axially central portion of the tread, is such that E1 m < 2.00 mm. [006] The tire according to the invention makes it possible to obtain axially more uniform wear of the tread layer and to extend the distance that the tire can travel before it needs to be replaced. In addition, the tire also has relatively low rolling resistance.

[007] Indeed, the inventors behind the invention understood that the wear of a tire resulted from two different phenomena, one at the local level of the tread layer and the other at the global level of the tread. Indeed, the inventors understood that local wear responded to a rule according to which a portion of the tread layer having a relatively high rigidity compared to its neighboring portions wore out more quickly than a portion of the tread layer having a relatively low rigidity compared to its neighboring portions. The inventors also understood that global wear, unlike local wear, responded to a rule according to which the lower the rigidity of the tread, the more quickly the tread wore out.

[008] Once these two rules have been discovered, the inventors explain the more homogeneous wear of the tire according to the invention in the following way. By using a lateral material having a relatively low dynamic shear modulus (in other words low rigidity), the local rigidity of the axially lateral portion of the tread layer is reduced, which has the effect of reducing the wear of the axially lateral portion of the tread layer. However, the use of this lateral material having a relatively low dynamic shear modulus results in a reduction in the overall rigidity of the tread, thereby increasing the wear rate of the tread. To compensate for this faster overall wear, the inventors had the idea of using a reduced average radial distance E1 m to globally stiffen the tread and therefore reduce the overall wear rate.

[009] The complex shear modulus G* is a dynamic property well known to those skilled in the art and is measured on a Metravib VA4000 or DMA+450 type viscoanalyzer using specimens comprising a cured composition extracted from the tire. The response of the specimen subjected to alternating simple sinusoidal shear stress is recorded at a frequency of 10 Hz under determined temperature conditions (here 23°C) according to the ASTM D1349-99 standard. A strain amplitude sweep is carried out from 0.1% cc to 100% cc (forward cycle), then from 100% cc to 0.1% cc (return cycle), cc meaning peak-peak. The test piece is of cylindrical section as described in ASTM D 5992-96 (version reapproved in 2011, originally approved in 1996) in Figure X2.1 (circular embodiment) and has a diameter of 10 mm [0 to + 0.04 mm] and a thickness of 2 mm [1.83-2.33]. The dynamic complex shear modulus G* is defined as the square root of the sum of the square of G' and the square of G” where G' represents the elastic modulus and G” represents the viscous modulus. The complex shear modulus G* is measured at 10% cc strain on the return cycle.

[010] The determination of the average radial distance E1 m is carried out in the axially central portion of the tread by measuring, between the surfaces, several radial distances axially distributed over the axial width of the axially central portion of the tread. For example, a distance will be measured every centimeter in the axial direction starting from the first and second axial edges of the axially central portion of the tread. Obviously, if the radially outermost point of the most radially outer reinforcing element among the reinforcing elements is radially outside the surface passing through the radially innermost point of the or each deepest cutout and substantially parallel to the tread surface, the measured radial distance is considered negative. Conversely, and in the vast majority of cases, if the radially outermost point of the most radially outer reinforcing element among the reinforcing elements is radially inside the surface passing through the radially innermost point of the or each deepest cutout and substantially parallel to the rolling surface, the measured radial distance is considered positive.

[011] These measurements will be carried out in several meridian cutting planes equally distributed around the circumference of the tire, for example in four meridian cutting planes. The radial distances thus measured will then be averaged in order to obtain the average radial distance E1 m.

[012] By radial distance between two surfaces, we mean the straight distance between a point on one of the surfaces and its projection on the other of the surfaces in the radial direction of the tire.

[013] By vertically above the axially central portion of the tread, we mean the radially outer surface resulting from the projection in the radial direction of said axially central portion of the tread onto the radially outer surface passing through the radially outermost points of the radially outermost reinforcing elements among the reinforcing elements of the radially outermost layer.

[014] The axially central portion of the tread layer comprises the median plane of the tire.

[015] Preferably, the axially central portion of the wearing course has an axial width strictly greater than the axial width of the or each portion axially lateral.

[016] The wearing course is intended to come into contact with the ground when the tire is in new condition and at least until a predetermined wear threshold is reached, for example a regulatory wear threshold. Such a regulatory wear threshold is indicated in particular by the presence of wear indicators in the tread. A layer which would come into contact with the ground when the tire has a level of wear greater than the regulatory wear threshold is not a wearing course.

[017] Conventionally, the tread surface is delimited axially by first and second axial edges which coincide respectively with the first and second axial edges of the tread. The first and second axial edges are determined on a tire mounted on a nominal rim and inflated to the nominal pressure within the meaning of the ETRTO 2023 standard manual. The first and second axial edges are arranged on either side of the median plane of the tire and formed by lines substantially parallel to the circumferential direction of the tire. In the case of an obvious boundary between the tread surface and the rest of the tire, the first and second axial edges are determined simply. In the case where the tread surface is continuous with the outer surfaces of the tire sidewalls, the first and second axial edges are usually determined by loading the tire to 80% of its load capacity according to the ETRTO 2023 standard manual and the first and second axial edges are identified as the axial limits of the tread in contact with the ground.

[018] A matrix is said to be polymeric because it is based on a polymeric composition, this polymeric composition being able to comprise one or more polymers, for example chosen from thermoplastic polymers, thermosetting polymers, elastomers, thermoplastic elastomers, but also fillers and other components usually used in the field of compositions for tires, in particular compositions for embedding reinforcing elements.

[019] Preferably, the polymer matrix is an elastomeric matrix. By elastomeric matrix is meant a matrix exhibiting, in the crosslinked state, elastomeric behavior. Such a matrix is advantageously obtained by crosslinking a composition comprising at least one elastomer and at least one other component. Preferably, the composition comprising at least one elastomer and at least one other component comprises an elastomer, a crosslinking system and a filler. The compositions used for these layers are conventional compositions for calendering reinforcements, typically based on natural rubber or other elastomer. diene, a reinforcing filler such as carbon black, a vulcanization system and the usual additives. The adhesion between the wire reinforcement elements and the matrix in which they are embedded is ensured for example by a usual adhesive composition, for example an RFL type glue or equivalent glue such as for example described in WO2013017421 or W02017168109.

[020] By reinforcing element is meant an element allowing the mechanical reinforcement of the polymer matrix in which this reinforcing element is intended to be embedded. Preferably, each reinforcing element is wire-like, that is to say that each reinforcing element has a length at least 10 times greater than the largest dimension of its section regardless of the shape of the latter: circular, elliptical, oblong, polygonal, in particular rectangular or square or oval. In the case of a rectangular section, the wire-like reinforcing element has the shape of a strip. [021] A cutout or a portion of a cutout has two main characteristic dimensions: a width and a curvilinear length such that the curvilinear length is at least equal to twice the width. A cutout or a portion of a cutout is therefore delimited by at least two main lateral faces determining its curvilinear length and connected by a base, the two main lateral faces being distant from each other by a non-zero distance, called the width of the cutout or of the portion of the cutout.

[022] The principal direction of a cutout is the direction along which the curve equidistant from each of the edges of the cutout to the radial dimension of the rolling surface passes. The curvilinear length is the length measured along this curve equidistant from each of the edges of the cutout to the radial dimension of the rolling surface, and this between each end of the cutout. The mean direction is the shortest curve joining the two ends of the cutout.

[023] The width of a cutout or a portion of a cutout is, in the case where the cutout or the portion of a cutout does not include a chamfer, on a new tire, the distance between the two main lateral faces measured over the entire depth of the cutout or the portion. The width of a cutout or a portion of a cutout is, in the case where the cutout or the portion of a cutout includes a chamfer, on a new tire, the distance between the two main lateral faces measured over the entire depth of the cutout or the portion radially inside the chamfer. The width is measured substantially perpendicular to the main lateral faces. The minimum width of a cutout or a portion is the smallest width of the cutout or the portion concerned.

[024] The depth of a cutout or portion of a cutout is, on a new tire, the radial distance between the bottom of the cut or portion and its projection onto the ground when the tire is rolling. The maximum depth of a cut or portion is the greatest of the depths of the cut or portion concerned.

[025] The maximum value of the depths of the cutouts is called the tread height. Preferably, the maximum value of the depths of the main circumferential cutouts is called the tread height. Thus, preferably, the deepest cutout provided in the axially central portion of the tread is a main circumferential cutout.

[026] A cutout or portion of a cutout may be transverse or circumferential.

[027] A cutout or a transverse portion is such that the cutout extends in a mean direction forming an angle strictly greater than 30°, preferably greater than or equal to 45° with the circumferential direction of the tire, i.e. forming an angle less than or equal to 60°, preferably strictly less than 45° with the axial direction of the tire. A cutout or a transverse portion may be continuous, i.e. not interrupted by a tread block or another cutout so that the two main lateral faces determining its length are uninterrupted over the length of the transverse cutout or portion. A cutout or a transverse portion may also be discontinuous, i.e. interrupted by one or more tread blocks and/or one or more cutouts so that the two main lateral faces determining its length are interrupted by one or more tread blocks and/or one or more cutouts.

[028] A circumferential cutout or portion is such that the cutout or portion extends in a mean direction forming an angle less than or equal to 30°, preferably less than or equal to 10° with the circumferential direction of the tire, i.e. forming an angle strictly greater than 60°, preferably strictly greater than 80° with the axial direction of the tire. In the case of a continuous circumferential cutout, the two ends coincide with each other and are joined by a curve making a complete turn of the tire. A circumferential cutout or portion may be continuous, i.e. not be interrupted by a tread block or another cutout so that the two main lateral faces determining its length are uninterrupted over the entire turn of the tire. A circumferential cutout may also be discontinuous, i.e. interrupted by one or more sculpture blocks and/or one or more cutouts so that the two main lateral faces determining its length are interrupted by one or more tread blocks and/or one or more cutouts over the entire length of the tire.

[029] The tire according to the invention has a substantially toric shape around an axis of revolution substantially coincident with the axis of rotation of the tire. This axis of revolution defines three directions conventionally used by those skilled in the art: an axial direction, a circumferential direction and a radial direction.

[030] By axial direction is meant the direction substantially parallel to the axis of revolution of the tire, that is to say the axis of rotation of the tire.

[031] By circumferential direction is meant the direction which is substantially perpendicular to both the axial direction and a radius of the tire (in other words, tangent to a circle whose center is on the axis of rotation of the tire).

[032] By radial direction is meant the direction along a radius of the tire, that is to say any direction intersecting the axis of rotation of the tire and substantially perpendicular to this axis.

[033] By median plane of the tire (noted M), we mean the plane perpendicular to the axis of rotation of the tire which is located at the axial mid-distance of the two beads and passes through the axial middle of the crown reinforcement.

[034] By equatorial circumferential plane of the tire is meant, in a meridian section plane, the plane passing through the equator of the tire, perpendicular to the median plane and to the radial direction. The equator of the tire is, in a meridian section plane (plane perpendicular to the circumferential direction and parallel to the radial and axial directions) the axis parallel to the axis of rotation of the tire and located equidistant between the radially outermost point of the tread intended to be in contact with the ground and the radially innermost point of the tire intended to be in contact with a support, for example a rim.

[035] By meridian plane is meant a plane parallel to and containing the axis of rotation of the tire and perpendicular to the circumferential direction.

[036] By radially inner, respectively radially outer, is meant closer to the axis of rotation of the tire, respectively further from the axis of rotation of the tire. By axially inner, respectively axially outer, is meant closer to the median plane of the tire, respectively further from the median plane of the tire.

[037] By bead is meant the portion of the tire intended to allow the tire to be attached to a mounting support, for example a wheel comprising a rim. Thus, each bead is in particular intended to be in contact with a hook on the rim allowing it to be attached. [038] Any interval of values designated by the expression "between a and b" represents the domain of values from more than a to less than b (i.e., excluding the limits a and b), while any interval of values designated by the expression "from a to b" means the domain of values from a to b (i.e., including the strict limits a and b).

[039] Any angle made between two directions is the smallest of the angles made by these two directions with each other.

[040] The tires are, in preferred embodiments of the invention, intended for passenger vehicles as defined within the meaning of the standard of the European Tyre and Rim Technical Organisation or “ETRTO”, 2023. Such a tire has a section in a meridian cutting plane characterized by a section height H and a nominal section width or flange thickness S within the meaning of the standard of the European Tyre and Rim Technical Organisation or “ETRTO”, 2023 such that the ratio H/S, expressed as a percentage, is at most equal to 90 and is at least equal to 20, and the nominal section width S is at least equal to 115 mm and at most equal to 385 mm. In addition, the hook diameter D, defining the diameter of the rim on which the tire is mounted, is at least equal to 12 inches and at most equal to 30 inches.

[041] The tires are, in preferred embodiments of the invention, so-called summer tires. By summer, we mean tires which are neither so-called 4-season or all-season tires, nor so-called winter tires.

[042] Winter tires are identified in particular by an M+S marking (M+S being the acronym for “Mud + Snow”) and/or 3PMSF (3PMSF being the acronym for “3 Peak Mountain Snow Flake”). 4-season or all-season tires, due to their performance on snow, also have the M+S and/or 3PMSF markings. Thus, a summer tire does not have an M+S marking or a 3PMSF marking.

[043] In advantageous and optional embodiments, the wearing course comprises first and second axially lateral portions of the wearing course arranged axially outside and on either side of the axially central portion of the wearing course, each first and second axially lateral portion of the wearing course respectively comprises a first and second lateral material having respectively a dynamic shear modulus G*1, G*2 such that G*1<G*C and G*2<G*C, the dynamic shear modulus G*2 being measured at 23°C at 10% deformation and at a frequency of 10 Hz according to the ASTM D 5992-96 standard, each first and second axially lateral portion of the wearing course being at least partly arranged respectively in each first and second axially lateral portion of the tread. [044] Thus, the technical effect of the invention can be obtained on each first and second axially lateral portion of the wearing course.

[045] In some variants, the first side material is identical to the second side material, and in particular G*1=G*2. In other variants, the first and second side materials are different, and in particular G*1 >G*2 or G*1<G*2.

[046] In advantageous and optional embodiments, E1 m < 1.80 mm, preferably E1 m < 1.50 mm, more preferably E1 m < 1.40 mm and even more preferably E1 m < 1.20 mm.

[047] By further reducing the value of the average radial distance E1 m, the tread is further stiffened overall and the overall wear rate of the tire is reduced.

[048] In advantageous and optional embodiments:

- in the case where the tire comprises an axially lateral portion of the tread layer, G*1/G*C < 85%, preferably G*1/G*C < 80%,

- in the case where the tire comprises first and second axially lateral portions of the tread layer, G*1/G*C < 85% and/or G*2/G*C < 85%, preferably G*1/G*C < 80% and/or G*2/G*C < 80%.

[049] The difference in intrinsic rigidities between the central material and the lateral material or each first and second lateral material is increased. Thus, the rolling resistance of the tire is further reduced while benefiting from the effect of the invention.

[050] In advantageous and optional embodiments:

- in the case where the tire includes an axially lateral portion of the tread layer, G*1/G*C > 40%,

- in the case where the tire comprises first and second axially lateral portions of the tread layer, G*1/G*C > 40% and/or G*2/G*C > 40%.

[051] By differentiating too much between the intrinsic rigidities of the central material and the lateral material or of each first and second lateral material, there is a risk of excessively promoting wear of the central portion.

[052] In an embodiment making it possible to reduce the rolling resistance of the tire:

- in the case where the tire comprises an axially lateral portion of the tread layer, 40% <G*1/G*C < 70%, preferably 40% <G*1/G*C < 60%,

- in the case where the tire comprises first and second portions axially lateral of the wearing course, 40% <G*1/G*C < 70% and/or 40%

< G*2/G*C < 70%, preferably 40% <G*1/G*C < 60% and 40% < G*2/G*C < 60%.

[053] In a first variant of this embodiment making it possible to reduce rolling resistance while maintaining drift rigidity:

- in the case where the tire comprises an axially lateral portion of the tread layer, the lateral material has a maximum dynamic loss tanDMAX23-1 such that tanDMAX23-1 < 0.20, preferably tanDMAX23-1 < 0.15 and the central material has a maximum dynamic loss tanDMAX23-0 such that 0.40 < tanDMAX23-0 < 0.50.

- in the case where the tire comprises first and second axially lateral portions of the tread layer, each first and second lateral material respectively has a maximum dynamic loss tanDMAX23-1, tanDMAX23-2, such that tanDMAX23-1 < 0.20 and/or tanDMAX23-2

< 0.20, preferably tanDMAX23-1 < 0.15 and/or tanDMAX23-2 < 0.15 and the core material has a maximum dynamic loss tanDMAX23-0 such that 0.40 < tanDMAX23-0 < 0.50.

[054] In a second variant of this embodiment making it possible to maximize the reduction in rolling resistance:

- in the case where the tire comprises an axially lateral portion of the tread layer, the lateral material has a maximum dynamic loss tanDMAX23-1 such that tanDMAX23-1 < 0.20, preferably tanDMAX23-1 < 0.15 and the central material has a maximum dynamic loss tanDMAX23-0 such that tanDMAX23-0 < 0.40, preferably tanDMAX23-0 < 0.35,

- in the case where the tire comprises first and second axially lateral portions of the tread layer, each first and second lateral material respectively has a maximum dynamic loss tanDMAX23-1, tanDMAX23-2, such that tanDMAX23-1 < 0.20 and/or tanDMAX23-2

< 0.20, preferably tanDMAX23-1 < 0.15 and/or tanDMAX23-2 < 0.15 and the core material has a maximum dynamic loss tanDMAX23-0 such that tanDMAX23-0 < 0.40, preferably tanDMAX23-0 < 0.35.

[055] In an embodiment making it possible to increase the drift rigidity of the tire and therefore to improve its behavior:

- in the case where the tire comprises an axially lateral portion of the tread layer, 50% < G*1/G*C < 85%, preferably 65% < G*1/G*C < 85% and more preferably 70% < G*1/G*C < 85%. Even more preferably, 50% < G*1/G*C < 80%, preferably 65% < G*1/G*C < 80% and more preferably 70% < G*1/G*C < 80%,

- in the case where the tire comprises first and second axially lateral portions of the tread layer, 50% < G*1/G*C < 85% and/or 50% < G*2/G*C < 85%, preferably 65% < G*1/G*C < 85% and 65% < G*2/G*C < 85% and more preferably 70% < G*1/G*C < 85% and 70% < G*2/G*C < 85%. Even more preferably, 50% < G*1/G*C < 80% and/or 50% < G*2/G*C < 80%, preferably 65% < G*1/G*C < 80% and 65% < G*2/G*C < 80% and more preferably 70% < G*1/G*C < 80% and 70% < G*2/G*C < 80%.

[056] In this embodiment making it possible to increase the drift rigidity, the drift rigidity is favored to the detriment of rolling resistance in a variant in which:

- in the case where the tire comprises an axially lateral portion of the tread layer, the lateral material has a maximum dynamic loss tanDMAX23-1 such that 0.30 < tanDMAX23-1 and the central material has a maximum dynamic loss tanDMAX23-0 such that 0.50 < tanDMAX23-0,

- in the case where the tire comprises first and second axially lateral portions of the tread layer, each first and second lateral material respectively has a maximum dynamic loss tanDMAX23-1, tanDMAX23-2, such that 0.30 < tanDMAX23-1 and/or 0.30 < tanDMAX23-2 and the central material has a maximum dynamic loss tanDMAX23-0 such that 0.50 < tanDMAX23-0.

[057] Each dynamic loss tanDMAX23 is yet another dynamic property well known to those skilled in the art and is measured on the same viscoanalyzer of the Metravib VA4000 or DMA+450 type using specimens comprising a cured composition extracted from the tire. The response of the specimen subjected to alternating simple sinusoidal shear stress is recorded at a frequency of 10 Hz under determined temperature conditions (here 23°C) according to the ASTM D1349-99 standard. A strain amplitude sweep is carried out from 0.1% cc to 100% cc (forward cycle), then from 100% cc to 0.1% cc (return cycle), cc meaning peak-peak. The specimen is of cylindrical section as described in ASTM D 5992 - 96 (version reapproved in 2011, initially approved in 1996) in Figure X2.1 (circular embodiment) and has a diameter of 10 mm [0 to + 0.04 mm] and a thickness of 2 mm [1.83-2.33]. The tangent tanD of the phase angle D between the force exerted on the specimen and its displacement reflects a dynamic loss and is equal to the ratio G”/G'. The maximum value tanDMAX of the tangent tanD of the phase angle D observed on the deformation return cycle is recorded. [058] In preferred embodiments, the tread height is in the range of 5.0 mm to 10.0 mm, preferably 6.0 mm to 8.0 mm.

[059] In embodiments in which the main circumferential cutouts are relatively deep, each main circumferential cutout has a depth ranging from 4.0 mm to the tread height, preferably from 5.0 mm to the tread height, and more preferably from 5.5 mm to the tread height.

[060] In embodiments in which the main circumferential cutouts are relatively deep, each main circumferential cutout has a depth greater than or equal to 75% of the tread height, preferably 90% of the tread height.

[061] In embodiments in which the major circumferential cutouts are relatively wide major circumferential grooves, each major circumferential cutout has a minimum width greater than or equal to 3.0 mm, preferably greater than or equal to 5.0 mm and more preferably ranging from 5.0 mm to 20.0 mm.

[062] In advantageous and optional embodiments:

- in the case where the tire comprises an axially lateral portion of the tread layer, the axially central portion of the tread layer is in contact with the axially lateral portion of the tread layer via an interface arranged in the axially central portion of the tread or in the axially lateral portion of the tread,

- in the case where the tire comprises first and second axially lateral portions of the tread layer, the axially central portion of the tread layer is in contact with each first and second axially lateral portion of the tread layer respectively by means of a first and a second interface arranged respectively in each first and second axially lateral portion of the tread.

[063] In the case where the tire comprises an axially lateral portion of the tread layer, the arrangement of the interface in the axially central portion of the tread makes it possible to more distinctly functionalize the side of the tire carrying the axially lateral portion of the tread layer relative to the other side carrying the axially central portion. For this purpose, preferably, the axially lateral portion of the tread layer is arranged on the same side of the median plane of the tire as the outer side of the tire and the axially central portion is arranged on the same side of the tire's median plane as the inner side of the tire. By inner and outer sides, we mean that the tire is designed so that one of its sides is arranged on the inner side and the other of its sides is arranged on the outer side. This orientation imposed by the tire manufacturer ensures that the tire has the expected operation. Indeed, mounting a tire with an orientation different from that imposed by the manufacturer can lead to suboptimal behavior of the vehicle. By outer side, we mean the side of the tire that is fully visible from the outside of the vehicle when the tire is mounted on the vehicle. By inner side, we mean the side of the tire facing the wheel arch of the vehicle on which it is mounted. Generally, the tire has a marking indicating the inner side and the outer side.

[064] Still in the case where the tire comprises an axially lateral portion of the tread layer, if it is desired to functionalize less distinctly the side of the tire carrying the axially lateral portion, the interface is arranged in the axially lateral portion of the tread.

[065] In the case where the tire comprises first and second axially lateral portions of the tread layer, the compromise between reduction of rolling resistance, drift stiffness and wet grip is optimized. Indeed, too high a proportion of lateral material or of the first and second lateral materials leads to a reduction in drift stiffness and wet grip. Conversely, too high a proportion of the central material reduces the gain in rolling resistance.

[066] Optionally:

- in the case where the tire comprises an axially lateral portion of the tread layer, the axially central portion of the tread layer extends axially from a first axial edge of the tread surface arranged on the opposite side relative to the median plane of the axially lateral portion to the interface,

- in the case where the tire comprises first and second axially lateral portions of the tread layer, the axially central portion of the tread layer extends axially from the first interface to the second interface.

[067] Optionally:

- in the case where the tire comprises an axially lateral portion of the tread layer, the axially lateral portion extends axially from a second axial edge of the running surface arranged on the same side of the median plane as the axially lateral portion of the running course up to the interface,

- in the case where the tire comprises first and second axially lateral portions of the tread layer, the first axially lateral portion of the tread layer extends axially from a first axial edge of the tread surface arranged on the same side of the median plane as the first axially lateral portion of the tread layer to the first interface and the second axially lateral portion of the tread layer extends axially from a second axial edge of the tread surface arranged on the same side of the median plane as the second axially lateral portion of the tread layer to the second interface.

[068] The invention is particularly advantageous in advantageous and optional embodiments in which:

- in the case where the tire includes an axially lateral portion of the tread layer, the average thickness of the axially central portion of the tread layer is strictly greater than the average thickness of the axially lateral portion of the tread layer,

- in the case where the tire comprises first and second axially lateral portions of the tread layer, the average thickness of the axially central portion of the tread layer is strictly greater than the average thickness of each first and second axially lateral portion of the tread layer.

[069] The determination of the average thicknesses is carried out over the axial width of the rolling surface by measuring several thicknesses axially distributed over the axial width of the rolling surface. For example, a thickness will be measured every centimeter in the axial direction starting from the first and second axial edges of the rolling surface. A rolling layer thickness is measured as the distance between a radially inner point of the rolling layer and its projection onto the rolling surface. A radially inner point is, in the case where the rolling layer is directly in contact with the crown reinforcement, a point of the interface between the rolling layer and the crown reinforcement. A radially inner point is, in the case where one or more layers are radially arranged between the rolling layer and the crown reinforcement, a point of the interface between the radially innermost rolling layer and the layer radially adjacent to this radially innermost rolling layer. These measurements will be carried out in several meridian cutting planes equally distributed around the circumference of the tire, for example in four meridian cutting planes. The radial distances thus measured will then be averaged to obtain the average radial thickness.

[070] In first advantageous and optional variants in which the tread comprises a radially inner layer arranged radially inside the tread layer and distinct from the tread layer, the radially inner layer is arranged radially inside:

- the axially lateral portion of the tread layer in the case where the tire comprises an axially lateral portion of the tread layer or each first and second axially lateral portion of the tread layer in the case where the tire comprises first and second axially lateral portions of the tread layer, and

- the axially central portion of the wearing course.

[071] The radially inner layer makes it possible to optimize certain performances of the tire, for example rolling resistance, wet grip, behavior. Thus, by distinct from the rolling layer, it is understood that the radially inner layer is formed in one or more materials different from the lateral material or from the first and second lateral materials.

[072] In a first configuration of these first variants, the radially inner layer may be intended not to come into contact with the ground when the tire is rolling, at least until a regulatory wear threshold is reached. The radially inner layer will be referred to as a support layer. However, occasionally, i.e. over an axial length less than 10% of the axial length of the radially inner layer, the radially inner layer may be brought into contact with the ground, in particular due to the relative control of industrial processes. Preferably, the radially inner layer is in contact with a crown reinforcement of the tire, for example as described below.

[073] In a second configuration of these first variants, the radially inner layer may be intended to come into contact with the ground when the tire is rolling before the tire reaches the regulatory wear threshold. The radially inner layer will be referred to as the worn tread layer as opposed to the new tread layer, which is the radially outermost tread layer and which is intended to be in contact with the ground when the tire is in the new condition.

[074] In second advantageous and optional variants, the tread comprises at least one radially inner layer, the or each layer radially inner layer is formed in the lateral material in the case where the tire comprises an axially lateral portion of the tread layer or in the first and/or in the second lateral material of the tread layer in the case where the tire comprises first and second axially lateral portions of the tread layer, the radially inner layer being arranged radially inside the axially central portion of the tread layer.

[075] Thus, compared to the first variants, the number of materials of the tread is reduced. Preferably, the first lateral material is identical to the second lateral material.

[076] In still other variants, the tread does not comprise a radially inner layer. Thus, the tread layer is directly in contact with the crown reinforcement of the tire, for example as described below.

[077] Conventionally, the tire comprises a crown, two sidewalls, two beads, each sidewall connecting each bead to the crown. The tire also comprises a carcass reinforcement anchored in each bead and extending radially in each sidewall and axially in the crown radially inward to the crown reinforcement.

[078] In embodiments allowing the performance of so-called radial tires to be obtained, for example as defined by the ETRTO, the carcass reinforcement comprises at least one carcass layer, the or each carcass layer comprising carcass wire reinforcement elements, each carcass wire reinforcement element extending substantially in a main direction forming with the circumferential direction of the tire, an angle, in absolute value, ranging from 80° to 90°. As a variant, it will be possible to have a variable angle ranging from 80° to 90° in at least a portion of the sidewall and strictly less than 80° in at least a portion of the crown as described for example in US20190152262.

[079] The invention will be better understood on reading the description which follows, given solely by way of non-limiting example and made with reference to the drawings in which:

- figure 1 is a view, in a meridian section plane, of a tire according to a first embodiment of the invention,

- figure 2 is a detailed view of an axially central part of the crown of the tire of figure 1,

- figure 3 is a top view of the tread of the tire of figure 1, - Figure 4 is a detailed view of the tread of the tire of Figures 1 to 3 illustrating certain transverse cutouts, Figure 5 is a detailed view of the tread of the tire of Figures 1 to 3 illustrating other transverse cutouts, Figures 6 and 7 are views similar to that of Figure 1 of tires according to second and third embodiments of the invention, and

- figures 8, 9 and 10 are views similar to those of figures 3, 4 and 5 respectively of a tire according to a fourth embodiment of the invention.

[080] In the figures relating to the tire, a reference X, Y, Z is shown corresponding to the usual axial (Y), radial (Z) and circumferential (X) directions of a tire.

[081] Figures 1 to 5 show a tire according to the invention and designated by the general reference 10. The tire 10 has a substantially toric shape around an axis of revolution substantially parallel to the axial direction Y. The tire 10 is intended for a passenger vehicle and has dimensions 255/40 R20. In the various figures, the tire 10 is shown in new condition, that is to say not yet having been driven. The tire 10 has an inner side INT and an outer side EXT.

[082] The tire 10 comprises a crown 12 comprising a tread 14 carrying a rolling surface 16 intended to come into contact with a ground when the tire 10 is rolling. The rolling surface 16 is delimited axially by first and second axial edges 18, 20. The tread 14 and the rolling surface 16 have an axial width LSR measured as the axial distance from the first axial edge 18 to the second axial edge 20.

[083] The tread 14 comprises an axially central portion POb of the tread 14 and first and second axially lateral portions P1b, P2b of the tread 14 arranged axially outside the axially central portion POb on either side axially of the axially central portion POb of the tread 14.

[084] The tread 14 comprises several main circumferential cutouts, here four main circumferential grooves, comprising first, second, third and fourth main circumferential cutouts respectively designated by the references 22, 24, 26, 28. The first and second main circumferential cutouts 22, 24 are arranged axially on either side of the median plane M of the tire 10 and are the axially outermost main circumferential cutouts of the tread 14 and below called axially external main circumferential cutouts 22, 24.

[085] The first axially lateral portion P1 b and the second axially lateral portion P2b are arranged respectively axially outside the first axially outer main circumferential cutout 22 and the second axially outer main circumferential cutout 24. The first axially lateral portion P1 b extends axially from the first axial edge 18 of the tread surface 16 to the axially outer edge 19 of the first axially outer main circumferential cutout 22. The second axially lateral portion P2b extends axially from the second axial edge 20 of the tread surface 16 to the axially outer edge 21 of the second axially outer main circumferential cutout 24. The axially central portion POb of the tread 14 extends axially from the first axially lateral portion P1b of the tread 14 to the second axially lateral portion P2b of the tread 14.

[086] As illustrated in Figure 2, each main circumferential cutout 22 to 28 has a depth Hr ranging from 4.0 mm to the tread height Hs, preferably ranging from 5.0 mm to the tread height Hs and more preferably ranging from 5.5 mm to the tread height Hs. Each depth Hr is greater than or equal to 50%, preferably 75% and more preferably 90% of the tread height Hs. Here, Hs=6.5 mm, Hr=6.0 mm for each first and second axially outer main circumferential cutout 22, 24 and Hs=Hr=6.5 mm for each main circumferential cutout 26, 28. Each main circumferential cutout 22 to 28 respectively has a minimum width greater than or equal to 3.0 mm, preferably greater than or equal to 5.0 mm and more preferably ranging from 5.0 mm to 20.0 mm.

[087] The axially central portion POb comprises central ribs and here first, second and third central ribs respectively designated by the references 32, 34, 36. Each central rib 32, 34, 36 is arranged axially between two of the adjacent main circumferential cutouts 22 to 28. Each central rib 32, 34, 36 comprises transverse cutouts 38, 38', 40, 40', 42 formed in the central ribs 32, 34, 36.

[088] Each transverse cutout 38, 38’, 40, 40’, 42 extends between its first and second ends in a mean direction forming an angle respectively denoted A38, A38’, A40, A40’, A42 with the axial direction Y of the tire 10 such that A38=A38’=A40=A40’=A42=10°.

[089] With reference to Figures 3 to 5, each transverse cutout 38 comprises two portions 381, 382 respectively having a depth H81, H82 such that H81=4.9 mm and H82=1.4 mm. Each transverse cutout 38' comprises a portion 381' having a depth H81'=4.9 mm. Each transverse cutout 40 comprises two portions 401, 402 respectively having a depth H01, H02 such that 1-101=1.4 mm and H02=4.9 mm. Each transverse cutout 40' comprises a portion 402' having a depth H02'=4.9 mm. Each transverse cutout 42 comprises two portions 421, 422 respectively having a depth H21, H22 such that 1-121=1.4 mm and H22=4.9 mm. Each portion 381, 382, 381', 401, 402, 402', 421, 422 has a minimum width less than or equal to 1.5 mm, preferably ranging from 0.2 mm to 1.5 mm and here equal to 0.4 mm.

[090] Each first and second axially lateral portion P1b, P2b respectively comprises a first and a second lateral rib respectively designated by the reference 44, 46. The tread 14 comprises first and second transverse cutouts 48’, 48”, 50’, 50” formed at least in part in each first and second axially lateral portion P1b, P2b. The first transverse cutouts 48’, 48” are arranged on the inner side INT of the tire 10. The second transverse cutouts 50’, 50” are arranged on the outer side EXT of the tire 10.

[091] Each first transverse cutout 48’ extends in a mean direction forming an angle A48’ equal to 10° with the axial direction Y and comprises a portion 48T having a maximum depth H481’=4.7 mm. Each first transverse cutout 48’ also comprises a portion widened axially outside the portion formed in the first axially lateral portion P1b and having a width equal to 4.0 mm. Each first transverse cutout 48” extends in a mean direction forming an angle A48” equal to 10° with the axial direction Y and comprises two portions 481”, 482” having respectively a maximum depth H481”=4.7 mm and H482”=1.4 mm.

[092] Each second transverse cutout 50’, 50” extends in a mean direction forming an angle A50’, A50” equal to 0° with the axial direction Y and comprises a portion 50T, 501” having a depth H50T, H501” equal to 4.7 mm. Each second transverse cutout 50’, 50” also comprises a portion 502’, 502” having a depth H502’, H502” equal to 1.4 mm. Each second transverse cutout 50’ also comprises a portion widened axially outside the portion formed in the second axially lateral portion P2b and having a width equal to 3.0 mm.

[093] Each first and second transverse cutout 48', 48” has a minimum width less than or equal to 1.5 mm, preferably ranging from 0.2 mm to 1.5 mm and here equal to 0.4 mm. Each first and second transverse cutout 50', 50” has a minimum width greater than or equal to 1.5 mm, preferably ranging from 1.5 mm to 6.0 mm and here equal to 4.5 mm.

[094] All the transverse cutouts described above, whether inclined or not, are provided with chamfers which are not shown.

[095] Due to the presence of the various transverse cutouts previously described, the tread 14 has a volumetric notch rate equal to 25%, which gives it a good compromise between the external noise generated by the tire and grip on wet ground.

[096] The tread 14 comprises a tread layer 52 and a radially inner layer 54 arranged radially inside the tread layer 52 and distinct from the tread layer 52.

[097] The tread layer 52 comprises an axially central portion POc of the tread layer 52 and first and second axially lateral portions P1c, P2c of the tread layer 52 arranged axially outside and on either side of the axially central portion POc of the tread layer 52. The axially central portion POc of the tread layer 52 is at least partly arranged in the axially central portion POb of the tread 14. Each first and second axially lateral portion P1c, P2c of the tread layer 52 is at least partly arranged respectively in each first and second axially lateral portion P1b, P2b of the tread 14.

[098] The radially inner layer 54 is arranged radially inside each first and second axially lateral portion P1c, P2c of the wearing course 52 and the axially central portion POc of the wearing course 52. The axially central portion POc of the wearing course 52 comprises the median plane M.

[099] The axially central portion POc is in contact with each first and second axially lateral portion P1c, P2c respectively via a first and second interface 56, 58 arranged respectively in each first and second axially lateral portion P1b, P2b of the tread 14.

[0100] The axially central portion POc of the wearing course 52 extends axially from the first interface 56 to the second interface 58. The first axially lateral portion P1c of the wearing course 54 extends axially from the first axial edge 18 to the first interface 56 arranged on the same side of the median plane M as the first axially lateral portion P1c of the wearing course 52. The second axially lateral portion P2c extends axially from the second axial edge 20 arranged on the same side of the median plane M as the second axially lateral portion P2c of the wearing course 52 to the second interface 58.

[0101] The axially central portion POc has an axial width strictly greater than the axial width of each first and second axially lateral portion P1c, P2c.

[0102] The average thickness EOcm of the thicknesses EOc of the axially central portion POc is strictly greater than the average thickness E1cm, E2cm of the thicknesses E1c, E2c respectively of each first and second axially lateral portion P1c, P2c as can be seen in Figures 1 and 2.

[0103] The axially central portion POc comprises a central material MO having a dynamic shear modulus G*C measured at 23°C at 10% deformation and at a frequency of 10 Hz according to the ASTM D 5992-96 standard. Each first and second axially lateral portion P1c, P2c respectively comprises a first and second lateral material M1, M2 having respectively a dynamic shear modulus G*1, G*2 measured at 23°C at 10% deformation and at a frequency of 10 Hz according to the ASTM D 5992-96 standard. In the embodiment described here, rolling resistance is favored over drift stiffness. The first and second lateral materials M1, M2 are identical here.

[0104] The dynamic shear moduli G*C, G*1, G*2 satisfy G*1<G*C and G*2<G*C. Furthermore, G*1/G*C < 85% and G*2/G*C < 85%, preferably G*1/G*C < 80% and G*2/G*C < 80%. Also, G*1/G*C > 40% and G*2/G*C > 40%. Here, 40% <G*1/G*C < 70% and/or 40% < G*2/G*C < 70%, preferably 40% <G*1/G*C < 60% and 40% < G*2/G*C < 60%. In this embodiment, G*1=G*2=1.35 MPa, G*C=2.66 MPa and G*1/G*C=G*2/G*C=51%. The Shore hardness of each first and second lateral material M1, M2 is equal to 53 and the Shore hardness of the central material MO is equal to 67. The Shore hardness is for example measured according to the JIS K6253 standard at 23°C using a type A durometer. The dynamic shear modulus G*’1, G*’2 of each first and second lateral material M1, M2 measured not at 10% deformation and at an imposed temperature of 23°C but at 60°C and at an imposed stress (0.7 MPa) is equal to 0.95 MPa and the dynamic shear modulus G*’0 of the central material MO measured not at 10% deformation and at an imposed temperature of 23°C but at 60°C and at an imposed stress (0.7 MPa) is equal to 1.14 MPa.

[0105] The complex shear modulus G*' at imposed stress is determined using a viscoanalyzer of the Metravib VA4000 or DMA+450 type using specimens comprising a cured composition extracted from the tire. The response of the specimens subjected to a sinusoidal stress in alternating simple shear, at a frequency of 10 Hz under a force equal to 55 N. A temperature scan is carried out between -80°C and 80°C at a speed of 1.5°C/min, having previously accommodated the specimens at 100% peak-peak strain at a temperature less than or equal to 40°C, for example 23°C. The specimen has a cylindrical section as described in the standard ASTM D 5992 - 96 (version reapproved in 2011, initially approved in 1996) in figure X2.1 (circular embodiment) and has a diameter of 10 mm [0 to + 0.04 mm] and a thickness of 2 mm [1.83-2.33]. It should be noted that the force of 55 N is equivalent, in the case of a specimen with a diameter of 10.00 mm, to a stress of an amplitude equal to 0.7 MPa peak-peak. The complex shear modulus G*' is measured at 60°C.

[0106] Each first and second lateral material M1, M2 respectively has a maximum dynamic loss tanDMAX23-1, tanDMAX23-2, such that tanDMAX23-1 < 0.20 and tanDMAX23-2 < 0.20, preferably tanDMAX23-1 < 0.15 and tanDMAX23-2 < 0.15 and the central material MO has a maximum dynamic loss tanDMAX23-0 such that 0.40 < tanDMAX23-0 < 0.50. Here, tanDMAX23-1=tanDMAX23-2=0.14 and tanDMAX23-0=0.46.

[0107] The glass transition temperature Tg of each first and second lateral material M1, M2 is equal to -24°C and the glass transition temperature Tg of the central material MO is equal to -10°C. Each glass transition temperature Tg is determined using a viscoanalyzer of the Metravib VA4000 or DMA+450 type using test pieces comprising a cured composition extracted from the tire. The response of the test pieces subjected to alternating simple sinusoidal shear stress is recorded at a frequency of 10 Hz under a force equal to 55 N. A temperature scan is carried out between -80°C and 80°C at a speed of 1.5°C/min. The test piece is of cylindrical section as described in ASTM D 5992 - 96 (version reapproved in 2011, initially approved in 1996) in figure X2.1 (circular embodiment) and has a diameter of 10 mm [0 to + 0.04 mm] and a thickness of 2 mm [1.83-2.33]. It will be noted that the force of 55 N is equivalent, in the case of a test piece with a diameter equal to 10.00 mm, to a stress of an amplitude equal to 0.7 MPa peak-peak. The glass transition temperature Tg is taken equal to the temperature for which the value of the tangent of the phase angle tanD is maximum. The tangent tanD of the phase angle D between the force exerted on the sample and its displacement reflects a dynamic loss and is equal to the ratio G”/G’.

[0108] Table 1 below lists the compositions from which the following were manufactured in a conventional manner known to those skilled in the art: first and second lateral materials M1, M2 and central MO. Values are given in pce.

[0109] [Table 1]

[0110] (1) - Styrene-Butadiene Elastomer described as polymer B on page 34 of WO2018115722; (2) - Styrene-Butadiene Elastomer described as polymer E on page 34 of WO2018115722; (3) - Styrene-Butadiene Elastomer described as polymer C on page 34 of WO2018115722; (4) - Styrene-Butadiene Elastomer described as control polymer A on page 39 of WO2022162292; (5) - Carbon black grade 234 according to ASTM D-1765; (6) - Silica 160MP from Solvay; (7) - "Si75" from Evonik; (8) - "Si69" from Evonik; (9) - N-tert-butyl-2-benzothiazyl sulfenamide (marketed by the company Flexsys; (10) - The other additives are conventionally known to those skilled in the art and here include in particular a protective wax, N-1,3-dimethylbutyl-N-phenylparaphenylenediamine, N-cyclohexyl-benzothiazyl sulfenamide, diphenylguanidine, sulfur, stearic acid, zinc oxide, oleic sunflower oil and an AMO70 processing agent.

[0111] The radially inner layer 54 comprises an MS material having a dynamic shear modulus G*S measured at 23°C at 10% strain and at a frequency of 10 Hz according to ASTM D 5992-96 such that G*S=1.67 MPa and a maximum dynamic loss tanDMAX23-S=0.13. The MS material is manufactured from a composition conventionally comprising at least one diene elastomer and here comprising a styrene-butadiene elastomer, a butadiene elastomer and a natural rubber, at least one filler and here comprising a carbon black, for example a carbon black N234, and a silica, a coupling agent for example a silane “Si69” or “Si75” from the company Evonik, a resin, for example a resin Hydrogenated DCPD marketed under the reference PR-383 by the Exxon company or a C5-C9 hydrocarbon cut marketed under the reference ECR-373 by the Exxon company, as well as various additives such as those described previously for materials MO, M1 and M2.

[0112] With reference to Figures 1 and 2, the crown 12 comprises a crown reinforcement 60 extending in the crown 12 in the circumferential direction X. The tire 10 also comprises a sealing layer 62 to an inflation gas being intended to delimit an internal cavity closed with a mounting support of the tire 10 once the tire 10 is mounted on the mounting support, for example a rim. The crown reinforcement 60 comprises a working reinforcement 64 and a hooping reinforcement 66.

[0113] The working reinforcement 64 comprises two working layers 68, 70. The radially outer working layer 70 is arranged radially outside the radially inner working layer 68.

[0114] The hoop reinforcement 66 comprises at least one hoop layer and here comprises a hoop layer 72.

[0115] The crown reinforcement 60 is arranged radially inside the tread 14. The hoop reinforcement 66, here the hoop layer 72, is arranged radially outside the working reinforcement 64 and radially inside the tread 14. The hoop reinforcement 66 is therefore radially interposed between the working reinforcement 64 and the tread 14. The hoop layer 72 is therefore the radially outermost layer of the crown reinforcement 60.

[0116] The tire 10 comprises two sidewalls 74 extending the crown 12 radially inwards. The tire 10 further comprises two beads 76 radially inwards to the sidewalls 74. Each sidewall 74 connects each bead 76 to the crown 12.

[0117] The tire 10 comprises a carcass reinforcement 78 anchored in each bead 76, in this case is wound around two bead wires 80. The carcass reinforcement 78 extends radially in each sidewall 74 and axially in the crown 12 radially inside the crown reinforcement 60. The crown reinforcement 60 is arranged radially between the tread 14 and the carcass reinforcement 78. The carcass reinforcement 78 comprises at least one carcass layer and here comprises a single carcass layer 82.

[0118] With reference to FIG. 2, each working layer 68, 70, hooping layer 72 and carcass layer 82 comprises a polymer matrix, here an elastomeric matrix in which one or more wire reinforcement elements of the corresponding layer are embedded. Thus, each working layer 68, 70 respectively comprises working wire reinforcement elements 680, 700, the hoop layer 72 comprises hoop wire reinforcement elements 720 and the carcass layer 82 comprises carcass wire reinforcement elements 820. The angles of the wire reinforcement elements as well as the materials of the wire reinforcement elements are for example described in WO2021250331. [0119] The interfaces between two adjacent layers are represented by dashed lines. In Figure 2, there are shown:

- the surface 100 passing through the radially innermost point of the deepest cutout made in the axially central portion POb of the tread 14 and substantially parallel to the tread surface, here passing through the innermost point of the main circumferential cutouts 26, 28 and substantially parallel to the tread surface 16,

- the radially outer surface 102 passing through the radially outermost points of the radially outermost hooping wire reinforcement elements 720 among the hooping wire reinforcement elements 720 of the radially outermost layer 72 arranged directly above the axially central portion POb of the tread 14.

[0120] In the axially central portion POb of the tread 14, the average radial distance E1 m of the distances E1 between the surface 100 and the radially outer surface 102 is such that E1 m < 2.00 mm, preferably E1 m < 1.80 mm. Furthermore, E1 m > 0.50 mm, preferably E1 m > 1.00 mm. In this case, E1 = 1.70 mm. Alternatively, one could envisage E1 m < 1.50 mm, very preferably E1 m < 1.40 mm and even more preferably E1 m < 1.20 mm.

[0121] Tires according to second, third and fourth embodiments will now be described with reference to FIGS. 6 to 10. Elements similar to those described with reference to the first embodiment are designated by identical references.

[0122] Unlike the tire according to the first embodiment, the tire according to the second embodiment of FIG. 6 does not comprise a second axially lateral portion of the tread layer but an axially central portion POc of the tread layer 52 and an axially lateral portion Pic arranged axially outside the axially central portion POc. The axially central portion POc of the tread layer 52 extends axially from the first axial edge 18 of the tread surface 16 arranged on the opposite side relative to the median plane M of the axially lateral portion Pic to a contact interface 57 between the axially central portion POc and the axially lateral portion Pic. The portion axially lateral portion Pic of the rolling layer 52 extends axially from the second axial edge 20 of the rolling surface 16 arranged on the same side of the median plane M as the axially lateral portion Pic to the interface 57. The axially lateral portion Pic comprises the first material M1 and the axially central portion POc comprises the material MO described previously.

[0123] Furthermore, the axially central portion POc is in contact with the axially lateral portion Pic via the interface 57 which is arranged in the axially central portion POb of the tread 14, and here in the central rib 36 which is the rib adjacent to the axially outer main circumferential cutout 24 and arranged axially inside the axially outer main circumferential cutout 24.

[0124] The axially lateral portion Pic is arranged on the same side of the median plane M as the outer side EXT of the tire 10 and the axially central portion POc is arranged on the same side of the median plane M as the inner side INT of the tire 10. The axially central portion POc has an axial width strictly greater than the axial width of the axially lateral portion Pic.

[0125] Unlike the tire according to the first embodiment, the tire according to the third embodiment of FIG. 7 comprises a radially inner layer 54 formed in each first and second lateral material M1, M2 (the first and second lateral materials are identical). The radially inner layer 54 is integral with each first and second lateral material M1, M2 of the tread layer 52. The radially inner layer 54 is arranged radially inside the axially central portion POc of the tread layer 52.

[0126] Unlike the tire according to the first embodiment, the tire 10 according to the fourth embodiment of FIGS. 8 to 10 comprises a tread 14 in which each transverse cutout 38, 38', 40, 40', 42 extends between its first and second ends in a mean direction forming an angle respectively denoted A38, A38', A40, A40', A42 with the axial direction Y of the tire 10 such that A38=A38'=10° and A40=A40'=A42=40°.

[0127] With reference to Figures 8 to 10, each transverse cutout 38 comprises three portions 381, 382, 383 respectively having a depth H81, H82, H83 such that H82=4.7 mm and H81=H83=1.4 mm. Each transverse cutout 38' comprises two portions 38T, 382' respectively having a depth H81'=1.4 mm and H82'=4.7 mm. Each transverse cutout 40 comprises two portions 401, 402 respectively having a depth H01, H02 such that 1-101 =1.4 mm and 1-102=4.9 mm. Each transverse cutout 40' comprises a portion 402' having a depth H02'=4.9 mm. Each transverse cutout 42 comprises two portions 421, 422 respectively having a depth H21, H22 such that 1-121=1.4 mm and H22=4.9 mm. Each portion 381, 382, 383, 381', 382', 401, 402, 402', 421, 422 has a minimum width less than or equal to 1.5 mm, preferably ranging from 0.2 mm to 1.5 mm and here equal to 0.4 mm.

[0128] Each first and second axially lateral portion P1b, P2b respectively comprises a first and a second lateral rib respectively designated by the reference 44, 46. The tread 14 comprises first and second transverse cutouts 48’, 48”, 50’, 50” formed at least in part in each first and second axially lateral portion P1b, P2b. The first transverse cutouts 48’, 48” are arranged on the inner side INT of the tire 10. The second transverse cutouts 50’, 50” are arranged on the outer side EXT of the tire 10.

[0129] Each first transverse cutout 48’ extends in a mean direction forming an angle A48’ equal to 10° with the axial direction Y and comprises a portion 48T having a maximum depth H481’=4.7 mm. Each first transverse cutout 48’ also comprises a portion widened axially outside the portion formed in the first axially lateral portion P1b and having a width equal to 4.0 mm. Each first transverse cutout 48” extends in a mean direction forming an angle A48” equal to 10° with the axial direction Y and comprises two portions 481”, 482” having respectively a maximum depth H481”=4.7 mm and a maximum depth H482”=1.4 mm.

[0130] Each second transverse cutout 50’, 50” extends in a mean direction forming an angle A50’, A50” equal to 10° with the axial direction Y and comprises a portion 50T, 501” having a depth H50T, H501” equal to 4.7 mm. Each second transverse cutout 50’, 50” also comprises a portion 502’, 502” having a depth H502’, H502” equal to 1.4 mm. Each second transverse cutout 50’ also comprises a portion axially widened outside the portion formed in the second axially lateral portion P2b and having a width equal to 3.0 mm.

[0131] Each first and second transverse cutout 48’, 48”, 50’, 50” has a minimum width less than or equal to 1.5 mm, preferably ranging from 0.2 mm to 1.5 mm and here equal to 0.4 mm.

[0132] All the transverse cutouts described above, whether inclined or not, are provided with chamfers which are not shown. [0133] Due to the presence of the various transverse cutouts previously described, in particular due to the presence of the second transverse cutouts 50', 50” having widths smaller than those of the second transverse cutouts 50', 50” of the tire according to the first embodiment, the tread 14 has a volumetric notch rate equal to 22% which allows it to generate an external noise lower than that of the tire according to the first embodiment in return for slightly degraded wet grip.

[0134] In a first variant of materials MO, M1, M2 of the tire according to the fourth embodiment making it possible to promote drift rigidity, the dynamic shear moduli G*C, G*1, G*2 verify 50% < G*1/G*C < 85% and/or 50% < G*2/G*C < 85%, preferably 65% < G*1/G*C < 85% and 65% < G*2/G*C < 85% and more preferably 70% < G*1/G*C < 85% and 70% < G*2/G*C < 85% and even more preferably, 50% < G*1/G*C < 80% and/or 50% < G*2/G*C < 80%, preferably 65% < G*1/G*C < 80% and 65% < G*2/G*C < 80% and more preferably 70% < G*1/G*C < 80% and 70% < G*2/G*C < 80%. In this first variant of the MO, M1 and M2 materials, G*1=G*2=2.56 MPa, G*C=3.40 MPa and G*1/G*C=G*2/G*C=75%.

[0135] In this first variant embodiment of the materials MO, M1 and M2, the Shore hardness of each first and second lateral material M1, M2 is equal to 66 and the Shore hardness of the central material MO is equal to 74. The dynamic shear modulus of each first and second lateral material M1, M2 measured not at 23°C but at 60°C and at imposed stress (0.7 MPa) is equal to 1.38 MPa and the dynamic shear modulus of the central material MO measured not at 23°C but at 60°C and at imposed stress (0.7 MPa) is equal to 1.40 MPa.

[0136] In this first variant embodiment of the materials MO, M1 and M2, each first and second lateral material M1, M2 respectively has a maximum dynamic loss tanDMAX23-1, tanDMAX23-2, such that 0.30 < tanDMAX23-1 and 0.30 < tanDMAX23-2 and the central material MO has a maximum dynamic loss tanDMAX23-0 such that 0.50 < tanDMAX23-0 and here tanDMAX23-1=tanDMAX23-2=0.32 and tanDMAX23-0=0.54.

[0137] In this first variant embodiment of the materials MO, M1 and M2, the glass transition temperature Tg of each first and second lateral material M1, M2 is equal to -10°C and the glass transition temperature Tg of the central material MO is equal to -4°C.

[0138] Table 2 below lists the compositions from which the following were manufactured in a conventional manner known to those skilled in the art: first and second lateral materials M1, M2 and the central material MO of this first variant of the materials MO, M1 and M2 described just above. The values are given in pce. The constituents are identical to those in table 1.

[0139] [Table 2]

[0140] Still in this first variant embodiment of the materials MO, M1 and M2, the material MS of the radially inner layer 54 has a dynamic shear modulus G*S measured at 23°C at 10% deformation and at a frequency of 10 Hz according to the standard ASTM D 5992-96 such that G*S=1.88 MPa and a maximum dynamic loss tanDMAX23-S=0.12. The material MS is manufactured from a composition as described previously using a carbon black N550 instead of carbon black N234 and the proportions of which will be known to those skilled in the art in order to obtain the dynamic properties described above.

[0141] In a second variant of materials MO, M1, M2 of the tire according to the fourth embodiment making it possible to promote the reduction of rolling resistance, the dynamic shear moduli G*C, G*1, G*2 verify 40% <G*1/G*C < 70% and/or 40% < G*2/G*C < 70%, preferably 40% <G*1/G*C < 60% and 40% < G*2/G*C < 60%. In this second variant of embodiment of the materials MO, M1 and M2, G*1=G*2=1.35 MPa, G*C=2.56 MPa and G*1/G*C=G*2/G*C=53%.

[0142] In this second variant embodiment of the materials MO, M1 and M2, the Shore hardness of each first and second lateral material M1, M2 is equal to 53 and the Shore hardness of the central material MO is equal to 66. The dynamic shear modulus of each first and second lateral material M1, M2 measured not at 23°C but at 60°C and at imposed stress (0.7 MPa) is equal to 0.95 MPa and the dynamic shear modulus of the central material MO measured not at 23°C but at 60°C and at imposed stress imposed (0.7 MPa) is equal to 1.38 MPa.

[0143] In this second embodiment of the materials MO, M1 and M2, each first and second lateral material M1, M2 respectively has a maximum dynamic loss tanDMAX23-1, tanDMAX23-2, such that tanDMAX23-1 < 0.20 and tanDMAX23-2 < 0.20, preferably tanDMAX23-1 < 0.15 and tanDMAX23-2 < 0.15 and the central material MO has a maximum dynamic loss tanDMAX23-0 such that tanDMAX23-0 < 0.40. Here, tanDMAX23-1=tanDMAX23-2=0.14 and tanDMAX23-0=0.32.

[0144] In this second variant embodiment of the materials MO, M1 and M2, the glass transition temperature Tg of each first and second lateral material M1, M2 is equal to -24°C and the glass transition temperature Tg of the central material MO is equal to -10°C.

[0145] Still in this second variant embodiment of the materials MO, M1 and M2, the material MS of the radially inner layer 54 is identical to that of the tire according to the first embodiment.

[0146] Table 3 below lists the compositions from which the first and second lateral materials M1, M2 and the central material MO of this second variant embodiment of the materials MO, M1 and M2 described just above were manufactured in a conventional manner known to those skilled in the art. The values are given in pce. The constituents are identical to those in Table 1.

[0147] [Table 3]

[0148] COMPARATIVE TEST

[0149] The tire 10 according to the first embodiment was compared with a control tire T. Unlike the tire 10, the control tire T is such that E1 m > 2.0 mm and such that G*1 =G*2=1.70 MPa, G*C=2.69 MPa. [0150] 10 and T tires were driven each time on the same TESLA Model Y vehicle in a predominantly rear-wheel drive driving mode. The wear of the tires mounted at the rear of the vehicle was recorded as a function of mileage over approximately 15,000 km. Then, in order to shorten the test, the wear was extrapolated until one of the portions of the tread reached the maximum wear indicated by a regulatory wear indicator.

[0151] We thus gathered the maximum mileage reached by each tire (which reflects the tire's lifespan) as well as the tire's dead point, i.e. the point on the tread that has reached maximum wear. The results are gathered in table 4 below using tire T as the base 100.

[0152] [Table 4]

[0153] Unlike the control tire T for which the service life is determined by the early achievement of a regulatory wear indicator on one of the axially lateral portions, the service life of the tire 10 is determined by the later achievement of a regulatory wear indicator on the axially lateral portion and the earlier achievement of a regulatory wear indicator on the axially central portion. In addition, the service life of the tire 10 according to the invention is 9 points longer than that of the control tire.

[0154] Thus, the invention has made it possible, on the one hand, to delay the wear of the tread layer in each first and second axially lateral portion of the tread layer and, on the other hand, to extend the service life of the tire.

[0155] The invention is not limited to the embodiments described above. Indeed, it will be possible without any difficulty and depending on the desired performance compromise, to combine the treads of the tires according to each first, second, third embodiment with the first or second variant of the materials MO, M1 and M2 of the fourth embodiment described above.

[0156] It may also be provided that the tread comprises noise reduction devices, in particular Helmoltz resonators as described for example in EP0989000, EP2011671, EP2240335, EP2627524.

[0157] It may also be provided that the tire includes a noise reduction device as described in WO2022/069822 or as described in EP1219944, EP1253025, EP1184207, EP1110763, EP1876038.

Claims

1. A tire (10) comprising a crown (12) comprising a tread (14) carrying a tread surface (16) and a crown reinforcement (60) arranged radially inside the tread (14), the tread (14) comprising a tread layer (52) comprising an axially central portion (POc) of the tread layer (52) and an axially lateral portion (P1c, P2c; Pic) of the tread layer (52) arranged axially outside the axially central portion (POc) of the tread layer (52), the axially central portion (POc) and the axially lateral portion (P1c, P2c; Pic) of the tread layer (52) respectively comprise a central material (MO) and a lateral material (M1, M2) respectively having a dynamic shear modulus G*C, G*1 such that G*1 <G*C, each dynamic shear modulus G*C, G*1 being measured at 23°C at 10% deformation and at a frequency of 10 Hz according to ASTM D 5992 - 96, the tread comprising an axially central portion (POb) of the tread (14) and first and second axially lateral portions (P1 b, P2b) of the tread (14) arranged axially outside and on either side of the axially central portion (POb) of the tread, the tread (14) comprises main circumferential cutouts (22, 24, 26, 28) having a depth greater than or equal to 50% of the tread height comprising first and second axially outer main circumferential cutouts (22, 24) arranged axially on either side of the median plane (M) of the tire (10), the first and second axially outer main circumferential cutouts (22, 24) being the axially outermost main circumferential cutouts of the tread (14), each first and second axially lateral portion (P1 b, P2b) of the tread (14) being arranged axially outside respectively each first and second axially outer main circumferential cutout (22, 24) and the axially central portion (POb) of the tread (14) extending from the first axially lateral portion (P1 b) of the tread (14) to the second axially lateral portion (P2b) of the tread (14), the axially central portion (POc) of the tread layer (52) being at least partly arranged in the axially central portion (POb) of the tread (14), the axially lateral portion (P1 c, P2c; Pic) of the tread layer (52) being at least partly arranged in one of the first and second portions axially lateral (P1 b, P2b) of the tread (14), the crown reinforcement (60) comprising a radially outermost layer (72) and comprising reinforcing elements (720) embedded in a polymer matrix, the average radial distance E1 m in the axially central portion (POb) of the tread (14) between: - the surface (100) passing through the radially innermost point of the deepest cutout (26, 28) made in the axially central portion (POb) of the tread (14) and substantially parallel to the tread surface (16), and - the radially outer surface (102) passing through the radially outermost points of the radially outermost reinforcing elements (720) among the reinforcing elements (720) of the radially outermost layer (72) arranged directly above the axially central portion (POb) of the tread (14), is such that E1 m < 2.00 mm. 2. A tire (10) according to the preceding claim, wherein the tread layer comprises first and second axially lateral portions (P1c, P2c) of the tread layer (52) arranged axially outside and on either side of the axially central portion (POc) of the tread layer (52), each first and second axially lateral portion (P1c, P2c; Pic) of the tread layer (52) respectively comprises a first and second lateral material (M1, M2) respectively having a dynamic shear modulus G*1, G*2 such that G*1<G*C and G*2<G*C, the dynamic shear modulus G*2 being measured at 23°C at 10% deformation and at a frequency of 10 Hz according to standard ASTM D 5992-96, each first and second axially lateral portion (P1c, P2c; Pic) of the tread layer (52) being at least partly arranged respectively in each first and second axially lateral portion (P1b, P2b) of the tread (14). 3. Tire (10) according to any one of the preceding claims, in which E1 m < 1.80 mm, preferably E1 m < 1.50 mm, more preferably E1 m < 1.40 mm and even more preferably E1 m < 1.20 mm. 4. A tire (10) according to any one of the preceding claims, wherein: - in the case where the tire (10) comprises an axially lateral portion (Pic) of the tread layer (52), G*1/G*C < 85%, preferably G*1/G*C < 80%, - in the case where the tire (10) comprises first and second axially lateral portions (P1c, P2c) of the tread layer (52), G*1/G*C < 85% and/or G*2/G*C < 85%, preferably G*1/G*C < 80% and/or G*2/G*C < 80%. 5. A tire (10) according to any preceding claim, wherein: - in the case where the tire (10) comprises an axially lateral portion (Pic) of the tread layer (52), G*1/G*C > 40%, - in the case where the tire (10) comprises first and second axially lateral portions (P1c, P2c) of the tread layer (52), G*1/G*C > 40% and/or G*2/G*C > 40%. 6. A tire (10) according to any one of the preceding claims, wherein: - in the case where the tire (10) comprises an axially lateral portion (Pic) of the tread layer (52), the axially central portion (POc) of the tread layer (52) is in contact with the axially lateral portion (Pic) of the tread layer (52) via an interface (56) arranged in the axially central portion (POb) of the tread (14), - in the case where the tire (10) comprises first and second axially lateral portions (P1c, P2c) of the tread layer (52), the axially central portion (POc) of the tread layer (52) is in contact with each first and second axially lateral portion (P1c, P2c) of the tread layer (52) respectively via a first and a second interface (56, 58) arranged respectively in each first and second axially lateral portion (P1b, P2b) of the tread (14). 7. Tire (10) according to the preceding claim, in which: - in the case where the tire (10) comprises an axially lateral portion (Pic) of the tread layer (52), the axially central portion (POc) of the tread layer (52) extends axially from a first axial edge (18) of the tread surface (16) arranged on the opposite side relative to the median plane (M) of the axially lateral portion (Pic) to the interface (56), - in the case where the tire (10) comprises first and second axially lateral portions (P1c, P2c) of the tread layer (52), the axially central portion (POc) of the tread layer (52) extends axially from the first interface (56) to the second interface (58). 8. A tire (10) according to claim 6 or 7, wherein: - in the case where the tire (10) comprises an axially lateral portion (Pic) of the tread layer (52), the axially lateral portion (Pic) extends axially from a second axial edge (20) of the tread surface (16) arranged on the same side of the median plane (M) as the axially lateral portion (Pic) of the tread layer (52) to the interface (56), - in the case where the tire (10) comprises first and second axially lateral portions (P1c, P2c) of the tread layer (52), the first axially lateral portion (P1c) of the tread layer (52) extends axially from a first axial edge (18) of the tread surface (16) arranged on the same side of the median plane (M) as the first axially lateral portion (P1c) of the tread layer (52) to the first interface (56) and the second axially lateral portion (P2c) of the tread layer (52) extends axially from a second axial edge (20) of the tread surface (16) arranged on the same side of the median plane (M) as the second axially lateral portion (P2c) of the tread layer (52) to the second interface (58). 9. A tire (10) according to any one of the preceding claims, wherein: - in the case where the tire (10) comprises an axially lateral portion (Pic) of the tread layer (52), the average thickness (EOc) of the axially central portion (POc) of the tread layer (52) is strictly greater than the average thickness (E1c) of the axially lateral portion (Pic) of the tread layer (52), - in the case where the tire (10) comprises first and second axially lateral portions (P1c, P2c) of the tread layer (52), the average thickness (EOc) of the axially central portion (POc) of the tread layer (52) is strictly greater than the average thickness (E1c, E2c) of each first and second axially lateral portion (P1c, P2c) of the tread layer (52). 10. A tire (10) according to any one of claims 1 to 9, wherein the tread (14) comprises a radially inner layer (54) arranged radially inside the tread layer (52) and separate from the tread layer (52), the radially inner layer (54) is arranged radially inside: - the axially lateral portion (Pic) of the tread layer (52) in the case where the tire (10) comprises an axially lateral portion (Pic) of the tread layer (52) or of each first and second axially lateral portion (P1c, P2c) of the tread layer (52) in the case where the tire (10) comprises first and second axially lateral portions (P1c, P2c) of the tread layer (52), and - the axially central portion (POc) of the wearing course (52). 11. Tire (10) according to any one of claims 1 to 9, wherein the tread (14) comprises at least one radially inner layer (54), the or each radially inner layer (54) is formed in the lateral material (M1) in the case where the tire (10) comprises an axially lateral portion (Pic) of the layer of rolling (52) or in the first and/or in the second lateral material (M1, M2) of the rolling layer (52) in the case where the tire (10) comprises first and second axially lateral portions (P1c, P2c; Pic) of the rolling layer (52), the radially inner layer (54) being arranged radially inside the axially central portion (POc) of the rolling layer (52).