JP7529971B2 - tire - Google Patents

Description

The present invention relates to a tire that has lug grooves on the tread surface of the shoulder area and that has a well-balanced improvement in dry handling stability (hereinafter sometimes referred to as "dry handling stability") and wet handling stability (hereinafter sometimes referred to as "wet handling stability").

In order to improve the wet handling of tires, lug grooves may be placed on the tread surface of the shoulder area of the tire.

In this regard, the pneumatic tire disclosed in Patent Document 1 includes a main groove extending along the tire circumferential direction on the tread surface of the shoulder portion, a shoulder land portion defined and formed on the outermost side in the tire width direction of the main groove, a plurality of lug grooves arranged in the tire circumferential direction on the tread surface of the shoulder land portion so as to intersect with the tire circumferential direction, one end side of which terminates within the shoulder land portion and the other end side of which passes through the ground contact edge, and a cutout portion formed by cutting out the opening edge of the lug groove from the tread surface to the tire radially inward, the lug groove being formed with a groove width decreasing from one end side to the other end side, the end position being located within a range of 5% to 35% from the main groove with respect to the tire width direction dimension from the main groove to the ground contact edge, and the maximum groove width position being located within a range of 40% or less from the main groove with respect to the tire width direction dimension from the main groove to the ground contact edge, and the cutout portion being formed with a cutout width increasing from one end side of the lug groove to the other end side.

JP 2018-134979 A

In tires having lug grooves on the tread surface of the shoulder portion as disclosed in Patent Document 1, cutouts, i.e., chamfered portions, may be formed from the viewpoint of further improving drainage. However, the present inventors have found that forming chamfered portions in the areas where the lug grooves are formed may reduce the block rigidity of the land portion, resulting in poor dry handling stability.

The present invention aims to provide a tire that has a good balance between dry and wet handling stability, based on the premise that the tire has lug grooves on the tread surface of the shoulder area.

The present inventors have found that the above object can be achieved by the following means:
A tire in which at least three land portions are defined by at least two circumferential main grooves, and a lug groove including a ground contact edge is formed in at least one of the outermost land portions in the tire width direction including the ground contact edge, and a chamfer is provided around at least a portion of the lug groove,
In plan view of the tire,
The innermost portion of the lug groove in the tire width direction is located within the outermost portion in the tire width direction, and the chamfered portion includes a portion whose width increases from the ground contact edge toward the inner side in the tire width direction.
tire.

According to the present invention, by providing chamfers around at least a portion of the lug grooves, drainage is improved, while the width of the chamfer is reduced toward the contact edge to increase the block rigidity at the contact edge, providing a tire with a good balance between dry and wet handling stability.

FIG. 1 is a meridian cross-sectional view of a tire according to a basic embodiment of the present invention. FIG. 2 is a plan view showing the outermost land portion in the tire width direction where lug grooves are formed in a tire according to the basic embodiment of the present invention. FIG. 3 is a cross-sectional view taken along the width direction of a lug groove 41 at the outermost land portion in the tire width direction of a tire according to additional embodiment 4 of the present invention. FIG. 4 is a cross-sectional view taken along the width direction of a lug groove 21 at the outermost portion in the tire width direction of a tire according to additional embodiment 5 of the present invention.

Below, embodiments of the tire according to the present invention (basic form and additional forms 1 to 6 shown below) are explained in detail with reference to the drawings. Note that these embodiments and drawings do not limit the present invention. Furthermore, the components of the embodiments include those that are easily replaceable by a person skilled in the art, or those that are substantially the same. Furthermore, the various forms included in the embodiments can be arbitrarily combined within the scope of what is obvious to a person skilled in the art.

In the following description, "tire radial direction" refers to the direction perpendicular to the tire's rotation axis, "tire radial inner side" refers to the side facing the tire's rotation axis in the tire radial direction, and "tire radial outer side" refers to the side facing away from the tire's rotation axis in the tire radial direction.

In addition, "tire circumferential direction" refers to the direction around the above-mentioned rotation axis as the central axis, and when the tire rotation direction is specified, the "incoming side" in relation to the tire circumferential direction refers to the side where the land part of the tire first comes into contact with the ground when running, and the "kicking side" refers to the side where the land part of the tire last leaves the ground when running.

Furthermore, "tire width direction" refers to the direction parallel to the rotation axis, "inner side in the tire width direction" refers to the side toward the tire equatorial plane (tire equator line) in the tire width direction, and "outer side in the tire width direction" refers to the side away from the tire equatorial plane in the tire width direction. Note that the "tire equatorial plane" is a plane that is perpendicular to the tire rotation axis and passes through the center of the tire width.

<Basic Form>
A basic embodiment of a tire according to the present invention will be described below. Note that the tire described below is an example of a pneumatic tire.

Figure 1 is a tire meridian cross section showing a tire 100 according to the basic embodiment of the invention. As shown in Figure 1, the tire 100 according to the basic embodiment of the invention has at least three (five in the figure) land portions (the outermost land portion 2 in the tire width direction, the intermediate land portion 3 in the tire width direction, and the innermost land portion 4 in the tire width direction) defined by at least two (four in the figure) circumferential main grooves 1a-1d, and a lug groove 21 including the ground contact end 25 is formed in at least one of the outermost land portions 2 in the tire width direction including the ground contact end 25. Note that, although lug grooves, etc. are not shown in Figure 1 in the intermediate land portion 3 in the tire width direction and the innermost land portion 4 in the tire width direction, lug grooves, etc. may also be formed in these land portions 3 and 4 as appropriate in a tire meridian cross section different from that in Figure 1 in the tire circumferential direction.

Figure 2 is a plan view showing an area including the tire widthwise outermost land portion 2 located on the right side of Figure 1 for a tire according to the basic embodiment of the present invention shown in Figure 1. As shown in Figure 2, in a tire plan view of the tire according to the basic embodiment of the present invention, the tire widthwise outermost land portion 2 and the tire widthwise intermediate land portion 3 are defined by the circumferential main groove 1a. Lug grooves 21 are formed in the tire widthwise outermost land portion 2. Here, the innermost part of the lug groove 21 in the tire width direction is within the tire widthwise outermost land portion 2, and the chamfered portion 23 formed to surround the lug groove 21 from the inner side in the tire width direction includes a portion whose width increases from the ground contact edge 25 toward the inner side in the tire width direction.

In the embodiment shown in FIG. 2, the lug groove 21 extends from the inner side in the tire width direction toward the outer side in the tire width direction, beyond the ground contact edge 25 in the tire width direction. In the embodiment shown in the figure, the chamfered portion 23 is formed from the outer end of the lug groove 21 in the tire width direction to the periphery of the inner end in the tire width direction, and the width increases from the outer end in the tire width direction toward the inner end in the tire width direction.

In this specification, the contact width is defined as follows. That is, if the tire of this embodiment is a pneumatic tire, the contact width is the maximum length in the tire width direction of the contact surface that occurs when the tire is mounted on a specified rim, a specified internal pressure is applied, and a specified load is applied. In contrast, if the tire of this embodiment is an airless tire, the contact width means the maximum length in the tire width direction of the contact surface that occurs when the tire is mounted on a vehicle and a specified load is applied. In addition, the contact edge means the end of the contact surface in the tire width direction.

Here, the specified rim refers to the "applicable rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. Additionally, the specified internal pressure refers to the "maximum air pressure" specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" specified by TRA, or the "inflation pressures" specified by ETRTO. Furthermore, the specified load refers to the "maximum load capacity" specified by JATMA, the maximum value listed in the "tire load limits at various cold inflation pressures" specified by TRA, or the "load capacity" specified by ETRTO.

In addition, in a tire according to the basic embodiment of the present invention, the depth of the lug groove 21, i.e., the radial depth from the tire surface profile to the innermost position of the lug groove in the tire radial direction in a tire meridian cross section in the case where the lug groove 21 and the chamfered portion 23 are not present, can be 5.6 mm or more and 7.0 mm or less. In addition, in a pneumatic tire according to the basic embodiment of the present invention, the width of the lug groove 21 can be 7.0 mm or more and 10.0 mm or less.

In addition, in a tire according to the basic embodiment of the present invention, the depth of the chamfered portion 23, i.e., the radial depth from the tire surface profile to the innermost position of the chamfered portion 23 in the tire radial direction in a tire meridian cross section in the absence of the lug grooves 21 and the chamfered portion 23, can be 0.5 mm or more and 2.5 mm or less. In a pneumatic tire according to the basic embodiment of the present invention, the width of the chamfered portion 23 can be 0.5 mm or more and 1.5 mm or less.

(Action, etc.)
In conventional technology, when drainage was improved by forming chamfered portions around the lug grooves, there was a problem in that the volume of the land area around the area where the lug grooves were formed was reduced, reducing the block rigidity, resulting in a decrease in dry handling stability.

In contrast, in a tire according to the basic embodiment of the present invention, the chamfered portion 23 is provided at least in a portion around the lug groove 21 to improve drainage, while the chamfered portion 23 is formed so that the chamfer width becomes smaller toward the ground edge. In a tire according to the basic embodiment of the present invention, the chamfer width is wider on the inner side of the chamfered portion 23 in the tire width direction, so that more water can be taken in by the chamfered portion 23 in addition to the lug groove 21 and discharged to the outer side of the lug groove 21 in the tire width direction. This achieves high drainage, thereby improving wet handling stability. In addition, in a tire according to the basic embodiment of the present invention, the width of the chamfered portion 23 is narrowed especially on the ground edge side of the lug groove 21 where the ground pressure is high and the block rigidity of the land portion has a large effect on dry handling stability. Therefore, the reduction in the volume of the land portion around that portion is suppressed, and the block rigidity is maintained, thereby improving dry handling stability.

As a result, tires according to the basic form of the present invention provide a good balance between dry and wet handling stability.

When the tire according to the basic embodiment shown above is a pneumatic tire, it has a meridian cross-sectional shape similar to that of a conventional pneumatic tire, although not shown. Here, the meridian cross-sectional shape of the tire refers to the cross-sectional shape of the tire that appears on a plane perpendicular to the tire equatorial plane CL. The pneumatic tire according to the basic embodiment has, from the inner side to the outer side in the tire radial direction in the tire meridian cross-sectional view, a bead portion, a sidewall portion, a shoulder portion, and a tread portion. The pneumatic tire has, for example, a carcass layer that extends from the tread portion to the bead portions on both sides in the tire meridian cross-sectional view and is wound around a pair of bead cores, and a belt layer and a belt reinforcing layer that are formed in sequence on the outer side of the carcass layer in the tire radial direction.

The pneumatic tire according to the basic form shown above can be obtained through the usual manufacturing processes, i.e., a tire material mixing process, a tire material processing process, a green tire molding process, a vulcanization process, and a post-vulcanization inspection process. When manufacturing a pneumatic tire of the basic form, for example, a protrusion corresponding to the groove shown in FIG. 1 is formed on the inner wall of a vulcanization mold, and vulcanization can be performed using this mold.

Additional Forms 1 to 6
Next, additional embodiments 1 to 6 that can be optionally implemented in relation to a tire according to the basic embodiment of the present invention will be described.

<Additional Form 1>
In a tire according to the basic embodiment of the present invention, it is preferable that the combined width of the lug groove 21 and the chamfered portion 23 includes a portion where the combined width increases from the ground contact edge 25 toward the inside in the tire width direction (additional embodiment 1).

The combined width of the lug groove 21 and the chamfered portion 23 increases from the ground edge 25 toward the inner side in the tire width direction, so that the volume of the concave portion of the lug groove 21 and the chamfered portion 23 is large on the inner side in the tire width direction of the outermost land portion 2 in the tire width direction and small around the ground edge 25. Therefore, on the inner side of the lug groove 21 in the tire width direction, the concave portion of the lug groove 21 and the chamfered portion 23 can take in more water and discharge it to the outer side of the lug groove in the tire width direction, so that high drainage is achieved and wet handling stability can be improved. In addition, the concave portion of the lug groove 21 and the chamfered portion 23 is narrowed on the ground edge 25 side of the lug groove, where the ground pressure is particularly high and the block rigidity of the land portion has a large effect on dry handling stability, so that the reduction in the volume of the land portion around that portion is suppressed and the block rigidity is maintained, thereby improving dry handling stability.

<Additional Form 2>
In the basic form or the form obtained by adding Additional Form 1 to the basic form, it is preferable that, when viewed in meridian section of the tire, the radial depth from the tire surface profile in the absence of the lug grooves 21 to the radially innermost position of the chamfered portion 23 is 0.5 mm or more and 3.0 mm or less (Additional Form 2).

By making the radial depth of the chamfered portion 23 to the innermost position in the tire radial direction 0.5 mm or more, the volume of the chamfered portion 23 becomes sufficiently large, and high drainage can be achieved, i.e., high wet handling stability can be achieved. By making the radial depth of the chamfered portion 23 to the innermost position in the tire radial direction 3.0 mm or less, the volume of the land area around the chamfered portion 23 does not become too small, and the decrease in block rigidity can be further suppressed, i.e., high dry handling stability can be achieved.

The radial depth of the tire is measured under unloaded conditions with the specified internal pressure.

<Additional Form 3>
In the basic form or a form in which additional form 1 or 2 is added to the basic form, when the length in the tire width direction from the inner end in the tire width direction of the outermost portion 2 in the tire width direction to the ground contact edge 25 is taken as 100%, it is preferable that the chamfered portion 23 has an outer terminal end in the tire width direction at a position that is 90% or more and 110% or less in length from the inner end in the tire width direction (additional form 3).

By positioning the outer end of the chamfered portion 23 at a length of 90% or more from the inner end in the tire width direction, the chamfered portion 23 does not terminate at a point far away from the tire ground edge in the tire width direction inward, so that water captured in the concave portion formed by the lug groove 21 and the chamfered portion 23 can be efficiently drained outward in the tire width direction from the ground edge 25, thereby achieving high drainage, i.e., high wet handling stability. In addition, by positioning the outer end of the chamfered portion 23 at a length of 110% or less from the inner end in the tire width direction, the chamfered portion 23 does not terminate at a point far away from the tire ground edge 25 in the tire width direction outward, so that the volume of the land portion around the tire ground edge can be increased, which can further suppress the decrease in block rigidity, i.e., high dry handling stability can be achieved.

<Additional Form 4>
In the basic form or a form obtained by adding at least one of Additional Forms 1 to 3 to the basic form, it is preferable that the rotation direction of the tire is specified, and when the width of the leading-in side chamfer provided on the leading side of the lug groove 21 is _Ds and the width of the trailing-out side chamfer provided on the trailing-out side is _Dk , _Ds < _Dk < _3Ds (Additional Form 4).

Figure 3 is a cross-sectional view along the width direction of a lug groove 21 in the outermost portion 2 in the tire width direction of a tire according to additional embodiment 4 of the present invention.

In a tire according to additional embodiment 4 of the present invention shown in FIG. 3, in the portion of the outermost land portion 2 in the tire width direction where the lug groove 21 is formed, the outermost land portion 2 in the tire width direction is divided into a land portion 2a on the left side of the lug groove 21 and a land portion 2b on the right side of the lug groove 21.

Here, because the lug grooves 21 are formed in the outermost land portion 2 in the tire width direction, the portion of the land portion 2a on the left side of the lug groove 21 that is on the lug groove 21 side is the last to leave the ground of the land portion 2a on the left side of the lug groove 21 during driving, and therefore is the kick-off side of the land portion 2a on the left side of the lug groove 21. Similarly, the portion of the land portion 2b on the right side of the lug groove 21 that is on the lug groove 21 side is the first to come into contact with the ground of the land portion 2b on the left side of the lug groove 21 during driving, and therefore is the step-in side of the land portion 2b on the right side of the lug groove 21.

3, a trailing side chamfer 23k is formed in the land portion 2a on the left side of the lug groove 21, and a leading side chamfer 23s is formed in the land portion 2b on the right side of the lug groove 21. Although not shown, the width _Dk of the trailing side chamfer 23k and the width _Ds of the leading side chamfer 23s satisfy _Ds < _Dk < _3Ds .

In general, from the perspective of improving drainage on the trailing side, it is considered to increase the volume of the lug grooves on the trailing side. However, increasing the volume of the lug grooves on the trailing side reduces the volume of the land portion on the trailing side, which leads to a decrease in the block rigidity of that portion, and ultimately to a decrease in dry handling stability.

In this regard, in the tire according to additional embodiment 4 of the present invention shown in FIG. 3, the width of the trailing side chamfer 23k in the land portion 2a on the left side of the lug groove 21 is greater than the width of the step-in side chamfer 23s, improving the drainage on the trailing side. On the other hand, in the tire according to additional embodiment 4 of the present invention, the width of the trailing side chamfer 23k in the land portion 2a on the left side of the lug groove 21 is less than three times the width of the step-in side chamfer 23s, preventing the volume of the land portion on the trailing side from decreasing too much, thereby preventing a decrease in block rigidity.

As a result, a tire according to additional embodiment 4 of the present invention shown in FIG. 3 can achieve high wet handling stability as well as high dry handling stability.

<Additional Form 5>
In the basic form or a form obtained by adding at least one of Additional Forms 1 to 4 to the basic form, it is preferable that the rotation direction of the tire is specified, and when viewed in a cross section along the width direction of the lug groove, the angle between the groove wall on the leading side of the lug groove and the tire radial direction is θ _s and the angle between the groove wall on the trailing side of the lug groove and the tire radial direction is θ _k , θ _s < θ _k (Additional Form 5).

Figure 4 is a cross-sectional view along the width direction of a lug groove 21 at the outermost portion in the tire width direction of a tire according to additional embodiment 5 of the present invention.

As shown in FIG. 4, in a tire according to additional embodiment 5 of the present invention, in the portion of the outermost land portion 2 in the tire width direction where the lug groove 21 is formed, the outermost land portion 2 in the tire width direction is divided into a land portion 2a on the left side of the lug groove 21 and a land portion 2b on the right side of the lug groove 21.

Here, because the lug grooves 21 are formed in the outermost land portion 2 in the tire width direction, the portion of the land portion 2a on the left side of the lug groove 21 that is on the lug groove 21 side is the last to leave the ground of the land portion 2a on the left side of the lug groove 21 during driving, and therefore is the kick-out side of the land portion 2a on the left side of the lug groove 21. Similarly, the portion of the land portion 2b on the right side of the lug groove 21 that is on the lug groove 21 side is the first to come into contact with the ground of the land portion 2b on the left side of the lug groove 21 during driving, and therefore is the step-in side of the land portion 2b on the right side of the lug groove 21.

As shown in Fig. 4, the angle between the straight line _L4 in the tire radial direction and the extension line _L3 from the groove wall 21s on the leading side of the lug groove 21, i.e., the angle between the leading side groove wall 21s of the lug groove 21 and the tire radial direction, is defined as _θs . Also, as shown in Fig. 4, the angle between the straight line _L6 in the tire radial direction and the extension line _L5 from the groove wall 21s on the trailing side of the lug groove 21, i.e., the angle between the trailing side groove wall 21k of the lug groove 21 and the tire radial direction, is defined as _θk . In a tire according to additional embodiment 5 of the present invention, the angle _θs and the angle _θk satisfy the relationship _θs < _θk .

Here, the area of the part surrounded by the straight line _L1 in the tire radial direction passing through the leading-side end of the lug groove 21, the extension line _L8 along the bottom surface of the lug groove, and the leading-side groove wall 21s of the lug groove 21 is defined as S _k1 . Also, the area of the part surrounded by the straight line _L2 in the tire radial direction passing through the trailing-side end of the lug groove 21, the extension line _L8 along the bottom surface of the lug groove, and the trailing-side groove wall 21k of the lug groove is defined as S _s1 . As shown in FIG. 4, when the angle θ _s and the angle θ _k satisfy the above relationship, S _k1 is larger than S _s1 . That is, therefore, the volume of the land portion 2a on the left side of the lug groove 21 is larger than the volume of the land portion 2b on the right side of the lug groove 21.

This increases the block rigidity of the trailing edge of the land portion 2a on the left side of the lug groove 21, improving dry handling stability.

Furthermore, the area of the part surrounded by the straight line _L2 in the tire radial direction passing through the leading end of the lug groove 21, the extension line _L8 along the bottom surface of the lug groove 21, the groove wall 21s on the leading side of the lug groove 21, the tire surface profile _L7 in the case where the lug groove 21 and the chamfered portion 23 are not present, and the straight line _L9 in the tire radial direction passing through the center portion of the lug groove 21 is defined as _Ss2 . Also, the area of the part surrounded by the straight line _L1 in the tire radial direction passing through the trailing end of the lug groove 21, the extension line _L8 along the bottom surface of the lug groove 21, the groove wall 21k on the trailing side of the lug groove 21, the tire surface profile _L7 in the case where the lug groove 21 and the chamfered portion 23 are not present, and the straight line _L9 in the tire radial direction passing through the center portion of the lug groove 21 is defined as _Sk2 . As shown in FIG. 4, when the angle _θs and the angle _θk satisfy the above relationship, _Ss1 is larger than _Sk2 . Therefore, the volume of the leading side of the right side of the lug groove 21, i.e., the land portion 2b on the right side of the lug groove 21, is larger than the volume of the leading side of the left side of the lug groove 21, i.e., the land portion 2a on the left side of the lug groove 21.

This improves drainage on the leading edge of the land portion 2a on the right side of the lug groove 21, improving wet handling.

<Additional Form 6>
In Additional Form 5, it is preferable that the angle θ _s and the angle θ _k satisfy the relationship 2°<θ _k −θ _s <10° (Additional Form 6).

When θ _k -θ _s is greater than 2°, S _k1 can be made sufficiently large relative to S _s1 , and therefore the volume of the land portion 2a on the left side of the lug groove 21 can be made sufficiently large compared to the volume of the land portion 2b on the right side of the lug groove 21. This allows the block rigidity of the trailing side of the land portion 2a on the left side of the lug groove 21 to be kept moderate. On the other hand, S _s1 can be made sufficiently large relative to S _k1 , and therefore the volume of the leading side of the land portion 2b on the right side of the lug groove 21, i.e., the volume of the leading side of the land portion 2a on the left side of the lug groove 21, can be made sufficiently large compared to the volume of the leading side of the land portion 2a on the left side of the lug groove 21, i.e., the volume of the leading side of the land portion 2a on the left side of the lug groove 21. This allows the drainage on the leading side of the land portion 2a on the right side of the lug groove 21 to be kept moderate. Therefore, in a tire according to Additional Mode 6 of the present invention, it is possible to improve wet handling stability while improving dry handling stability.

The pneumatic tires of Examples 1 to 7 and Conventional Example 1 were manufactured with a tire size of 255/45R17 (specified by JATMA), with three land areas defined by multiple circumferential main grooves on the tread surface, lug grooves including the ground contact edge formed in the outermost land area in the tire width direction including the ground contact edge, and chamfered portions provided around at least a portion of the lug groove. The detailed conditions of these pneumatic tires are as shown in Table 1 below.

The pneumatic tires of Examples 1 to 7 and Conventional Example 1 were evaluated for dry handling and wet handling in the following manner.

(Evaluation of dry handling and stability)
The tires of each example were mounted on a rim wheel having a JATMA standard rim with a rim size of 17×7.0J, the air pressure was adjusted to 240 kPa, and the tires were mounted on all wheels of a FR vehicle equipped with a 2.0L engine as a test vehicle.

The test vehicle then traveled on a dry test course with a flat circular track at speeds between 10km/h and 180km/h, and the test driver performed a sensory evaluation of the steering during lane changes and cornering, and the stability during straight driving. Dry handling stability was expressed as a score based on a conventional example being 100, with the higher the score, the better. The results are also shown in Table 1.

(Evaluation of wet road handling)
The tires of each example were mounted on a rim wheel having a JATMA standard rim with a rim size of 17×7.0J, the air pressure was adjusted to 240 kPa, and the tires were mounted on all wheels of a FR vehicle equipped with a 2.0L engine as a test vehicle.

The test vehicle was then driven on a wet test course with a flat circular track, decelerating from 180 km/h until it came to a stop, and the reciprocal of the distance traveled was calculated. Wet handling stability was expressed as a score based on a conventional example being 100, with a higher score indicating superiority. The results are also shown in Table 1.

Table 1 shows that the pneumatic tires of Example 1 to Example 7, which fall within the technical scope of the present invention (i.e., improvements have been made to the chamfered portion), all achieve a well-balanced improvement in dry handling stability and wet handling stability compared to the pneumatic tire of Conventional Example 1, which does not fall within the technical scope of the present invention.

1a to 1d Circumferential main groove 2 Outermost land portion in tire width direction 21 Lug groove 23 Chamfered portion 25 Ground contact edge 3 Intermediate land portion in tire width direction

Claims (7)

A tire in which at least three land portions are defined by at least two circumferential main grooves, and a lug groove including a ground contact edge is formed in at least one of the outermost land portions in the tire width direction including the ground contact edge, and a chamfer is provided around at least a portion of the lug groove,
In plan view of the tire,
The innermost portion of the lug groove in the tire width direction is within the outermost portion in the tire width direction, and the chamfered portion includes a portion whose width increases from the ground contact edge toward the inner side in the tire width direction,
The width of the chamfered portion increases without decreasing from the ground contact edge to the inner end in the tire width direction, the chamfered portion is formed on both sides of the lug groove in the tire circumferential direction, and the chamfered portion surrounds the inner end of the lug groove in the tire width direction.
Characterized in that
tire. The tire according to claim 1, characterized in that the combined width of the lug groove and the chamfered portion includes a portion in which the combined width increases from the ground contact edge toward the inner side in the tire width direction. The tire according to claim 1 or 2, wherein the tire radial depth from the tire surface profile in the absence of the lug groove to the tire radially innermost position of the chamfered portion is 0.5 mm or more and 3.0 mm or less in a tire meridian cross section. The tire according to any one of claims 1 to 3, wherein the chamfered portion has an outer end in the tire width direction at a position that is 90% to 110% of the length from the inner end in the tire width direction of the outermost land portion in the tire width direction, when the length in the tire width direction from the inner end in the tire width direction to the ground edge is 100%. 5. The tire according to claim 1, wherein a rotation direction is specified, and when a width of a leading-in side chamfer portion provided on a leading-out side of the lug groove is _Ds and a width of a trailing-out side chamfer portion provided on a trailing-out side of the lug groove is _Dk , _Ds < _Dk < _3Ds . 6. The tire according to claim 5, wherein a rotation direction is specified, and when viewed in a cross section along the width direction of the lug groove, an angle between the groove wall of the lug groove on the leading side and the tire radial direction is _θs , and an angle between the groove wall of the lug groove on the trailing side and the tire radial direction is _θk , _θs < _θk . The angle θ _s and the angle θ _k are
The tire according to claim 6, which satisfies the relationship: 2°<θ _k - _{θ s} <10°.

Images