JP7102945B2 - tire - Google Patents

Description

The present invention relates to a tire, and more particularly to a tire that can be suitably implemented as an all-season tire.

All-season tires are required to have basic driving performance not only on dry roads but also on snowy roads. In order to improve the running performance on slippery snowy roads, the tires are required to have a large snow column shearing force and a road surface scratching effect. The snow column shearing force is obtained by compacting the snow on the road surface with a lateral groove and shearing it. Therefore, in order to improve the performance on snow, it is effective to provide a large number of long lateral grooves in the tread portion. In addition, the lateral grooves and edges of the sipe improve traction by scratching the compacted snow-packed road. As a related technique, there is the following Patent Document 1.

Japanese Unexamined Patent Publication No. 2015-013604

The lateral grooves and sipes provided in the tread portion are useful for improving the performance on snow, but tend to reduce the pattern rigidity of the tread portion and, in turn, deteriorate the steering stability on a dry road surface.

The present invention has been devised in view of the above problems, and its main object is to provide a tire capable of improving steering stability and snow performance on a dry road surface.

The present invention is a tire having a tread portion whose mounting direction on a vehicle is specified, and the tread portion has an outer tread end located on the outside of the vehicle when mounted on the vehicle and an inner side located on the inside of the vehicle when mounted on the vehicle. It has a tread end, an outer middle land portion arranged between the outer tread end and the tire equator, and an inner middle land portion arranged between the inner tread end and the tire equator. Each of the land portion and the inner middle land portion has a first vertical edge extending in the tire circumferential direction on the inner tread end side, a second vertical edge extending in the tire circumferential direction on the outer tread end side, and the first vertical edge. The inner middle land portion has a tread between an edge and the second vertical edge, and is provided with an inner middle lateral groove extending from the first vertical edge and interrupted in the inner middle land portion. The land portion is provided with an outer middle lateral groove extending from the first vertical edge and interrupted in the outer middle land portion, and the outer middle land portion is provided from the second vertical edge to the first vertical edge side. A lateral groove that extends and reaches the center position of the outer middle land portion in the tire axial direction is not provided, and the width Wi of the inner middle land portion in the tire axial direction and the length Li of the inner middle lateral groove in the tire axial direction are provided. The ratio Li / Wi to is larger than the ratio Lo / Wo of the width Wo of the outer middle land portion in the tire axial direction and the length Lo of the outer middle lateral groove in the tire axial direction.

In the tire of the present invention, it is desirable that the length Li of the inner middle lateral groove is larger than the length Lo of the outer middle lateral groove.

In the tire of the present invention, it is desirable that the inner middle land portion is provided with a first inner middle sipe extending from a break end of the inner middle lateral groove to the second vertical edge.

In the tire of the present invention, it is desirable that the region extending the first inner middle sipe toward the outer tread end side intersects with the region extending the outer middle lateral groove toward the inner tread end side.

In the tire of the present invention, it is desirable that the outer middle land portion is provided with a first outer middle sipe extending from a break end of the outer middle lateral groove to the second vertical edge.

In the tire of the present invention, the inner middle land portion is not provided with a lateral groove extending from the second vertical edge to the first vertical edge side and reaching the center position of the inner middle land portion in the tire axial direction. Is desirable.

In the tire of the present invention, it is desirable that each of the inner middle lateral groove and the outer middle lateral groove extends with a constant groove width.

The outer middle land portion and the inner middle land portion arranged on the tread portion of the tire of the present invention each extend in the tire circumferential direction on the outer tread end side and the first vertical edge extending in the tire circumferential direction on the inner tread end side. It has a second vertical edge and a tread between the first vertical edge and the second vertical edge.

The inner middle land portion is provided with an inner middle lateral groove extending from the first vertical edge and interrupting within the inner middle land portion. The outer middle land portion is provided with an outer middle lateral groove extending from the first vertical edge and interrupted within the outer middle land portion. Such an inner middle lateral groove and an outer middle lateral groove can provide a snow column shearing force when traveling on snow. Further, the inner middle lateral groove and the outer middle lateral groove prevent a decrease in rigidity on the second vertical edge side of each land portion and suppress deterioration of steering stability. Moreover, the outer middle land portion is not provided with a lateral groove extending from the second vertical edge to the first vertical edge side and reaching the center position of the outer middle land portion in the tire axial direction. In general, this type of groove greatly reduces the rigidity near the second vertical edge of the land area, but by not providing this type of groove, the rigidity of the outer middle land area is further maintained, and excellent steering stability is achieved. Is demonstrated.

The ratio Li / Wi of the width Wi in the tire axial direction of the inner middle land portion and the length Li in the tire axial direction of the inner middle lateral groove is the width Wo in the tire axial direction of the outer middle land portion and the tire of the outer middle lateral groove. The ratio to the axial length Lo is larger than Lo / Wo. As a result, the length of the lateral groove is secured in the inner middle land area where a relatively large ground pressure acts, and excellent on-snow performance is exhibited.

As described above, the tire of the present invention can improve steering stability and snow performance on a dry road surface.

It is a development view of the tread part of the tire of one Embodiment of this invention. It is an enlarged view of the outer middle land part and the inner middle land part of FIG. (A) is a sectional view taken along line AA of FIG. 2, (B) is a sectional view taken along line BB of FIG. 2, and (C) is a sectional view of a second outer middle sipe according to another embodiment. It is a figure. FIG. 2 is a cross-sectional view taken along the line CC of FIG. It is an enlarged view of the outer shoulder land part of FIG. It is an enlarged view of the land part of the inner shoulder of FIG. It is an enlarged view of the outer middle land part and the inner middle land part of the tire of the comparative example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing an embodiment of the present invention. The tire 1 of the present embodiment is configured as, for example, a pneumatic tire. In the present embodiment, as a preferred embodiment, an all-season tire intended to be mounted on a passenger car or an SUV is shown.

As shown in FIG. 1, the tire 1 of the present invention has a tread portion 2 whose mounting direction on a vehicle is specified. The tread portion 2 of the tire 1 of the present embodiment has a left-right asymmetric tread pattern. The tread portion 2 has an outer tread end To located on the outer side of the vehicle when the tire 1 is mounted on the vehicle, and an inner tread end Ti located on the inner side of the vehicle when the tire 1 is mounted on the vehicle. The orientation of mounting on the vehicle is indicated by characters or symbols on the sidewall (not shown), for example.

In the case of a pneumatic tire, the outer tread end To and the inner tread end Ti are the outermost contact positions in the tire axial direction when a normal load is applied to the tire 1 in a normal state and the tire 1 touches a flat surface at a camber angle of 0 °. The normal state is a state in which the tire is rim-assembled on the normal rim, the normal internal pressure is applied, and there is no load. In the present specification, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in the normal state.

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, "standard rim" for JATMA, "Design Rim" for TRA, and ETRTO. If there is, it is "Measuring Rim".

"Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. For JATMA, "maximum air pressure", for TRA, the table "TIRE LOAD LIMITS AT" The maximum value described in "VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

"Regular load" is the load defined for each tire in the standard system including the standard on which the tire is based. For JATMA, "maximum load capacity", for TRA, the table "TIRE LOAD LIMITS" The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO.

The tread portion 2 of the present embodiment is provided with, for example, a plurality of main grooves 3 that continuously extend in the tire circumferential direction. The main groove 3 includes, for example, an outer shoulder main groove 4 arranged on the outermost tread end To side, an inner shoulder main groove 5 arranged on the innermost tread end Ti side, and a crown main groove arranged between them. Includes a groove 6. In the present embodiment, one crown main groove 6 is provided on the tire equator C. As a result, the tread portion 2 is divided into four land portions. In another aspect, the tread portion 2 may be divided into five land portions by, for example, an outer shoulder main groove 4 and an inner shoulder main groove 5, and two crown main grooves 6 sandwiching the tire equator C. ..

The distance L1 in the tire axial direction from the groove center line of the outer shoulder main groove 4 or the inner shoulder main groove 5 to the tire equator C is preferably, for example, 0.15 to 0.25 times the tread width TW. The tread width TW is the distance in the tire axial direction from the outer tread end To to the inner tread end Ti in the normal state.

Each main groove 3 extends linearly, for example. Each main groove 3 may extend in a zigzag shape, for example. The groove width W1 of the main groove 3 is preferably, for example, 4.0% to 7.0% of the tread width TW. The groove depth of the main groove 3 is preferably 5.0 to 12.0 mm, for example. As a result, steering stability on dry roads and performance on snow can be improved in a well-balanced manner.

The tread portion 2 of the present embodiment is divided into an outer middle land portion 7, an inner middle land portion 8, an outer shoulder land portion 9, and an inner shoulder land portion 10. The outer middle land portion 7 is arranged between the tire equator C and the outer tread end To, and specifically, is divided between the crown main groove 6 and the outer shoulder main groove 4. The inner middle land portion 8 is arranged between the tire equator C and the inner tread end Ti, and specifically, is divided between the crown main groove 6 and the inner shoulder main groove 5. The outer shoulder land portion 9 is divided between the outer shoulder main groove 4 and the outer tread end To. The inner shoulder land portion 10 is divided between the inner shoulder main groove 5 and the inner tread end Ti.

FIG. 2 shows an enlarged view of the outer middle land portion 7 and the inner middle land portion 8. As shown in FIG. 2, the outer middle land portion 7 includes a first vertical edge 7a extending in the tire circumferential direction on the inner tread end Ti side and a second vertical edge 7b extending in the tire circumferential direction on the outer tread end To side. It has a tread between the first vertical edge 7a and the second vertical edge 7b. Similarly, the inner middle land portion 8 has a first vertical edge 8a extending in the tire circumferential direction on the inner tread end Ti side, a second vertical edge 8b extending in the tire circumferential direction on the outer tread end To side, and a first vertical edge. It has a tread between the 8a and the second vertical edge 8b.

The outer middle land portion 7 is provided with an outer middle lateral groove 15. The outer middle lateral groove 15 extends from the first vertical edge 7a and is interrupted in the outer middle land portion 7. Further, the outer middle land portion 7 is not provided with a lateral groove extending from the second vertical edge 7b toward the first vertical edge 7a and reaching the center position of the outer middle land portion 7 in the tire axial direction.

The inner middle lateral groove 20 is provided in the inner middle land portion 8. The inner middle lateral groove 20 extends from the first vertical edge 8a and is interrupted in the inner middle land portion 8.

The inner middle lateral groove 20 and the outer middle lateral groove 15 can provide a snow column shearing force when traveling on snow. Further, the inner middle lateral groove 20 and the outer middle lateral groove 15 prevent a decrease in rigidity on the second vertical edge side of each land portion, and suppress deterioration of steering stability. Moreover, the outer middle land portion 7 is not provided with a lateral groove extending from the second vertical edge 7b toward the first vertical edge 7a and reaching the center position of the outer middle land portion 7 in the tire axial direction. In general, this type of groove greatly reduces the rigidity near the second vertical edge 7b of the land portion, but by not providing this type of groove, the rigidity of the outer middle land portion 7 is further maintained, and excellent maneuvering is performed. Stability is demonstrated.

The ratio Li / Wi of the width Wi in the tire axial direction of the inner middle land portion 8 and the length Li in the tire axial direction of the inner middle lateral groove 20 is the width Wo in the tire axial direction of the outer middle land portion 7 and the outer middle. The ratio of the lateral groove 15 to the length Lo in the tire axial direction is larger than Lo / Wo. As a result, the length of the lateral groove is secured in the inner middle land portion 8 on which a relatively large ground pressure acts, and excellent on-snow performance is exhibited.

Further, such an arrangement of the lateral grooves can relatively increase the rigidity of the outer middle land portion 7. As a result, a tire having a large self-aligning torque (hereinafter, may be referred to as "SAT") can be obtained. For example, when tires with a large SAT are mounted on all wheels of an FF passenger car, the cornering power of the front wheels (hereinafter, may be referred to as "CP") is relatively reduced by the SAT, and the CP of the front wheels and the rear wheels are reduced. The CP of the wheel approaches. Therefore, a passenger car equipped with the tires of the present invention on all wheels is excellent because when the front wheels are given a steering angle, it is easy to shift to a steady state in which the cornering force of the front wheels and the cornering force of the rear wheels are substantially balanced. It can demonstrate the steering stability.

Further, the outer middle land portion 7 is provided with the above-mentioned outer middle lateral groove 15, the first outer middle sipe 16, and the second outer middle sipe 17. The first outer middle sipe 16 extends from the break end of the outer middle lateral groove 15 to the second vertical edge 7b. The second outer middle sipe 17 extends from the first vertical edge 7a and is interrupted on the second vertical edge 7b side of the interrupted end of the outer middle lateral groove 15. In the present specification, the “sipe” is a notch having a width of less than 1.5 mm, and in a desirable embodiment, the width of the sipe is, for example, 0.5 to 1.0 mm.

The first outer middle sipe 16 is a notch having a small width, and can easily open the outer middle lateral groove 15 and increase the amount of snow entering the outer middle lateral groove while suppressing an excessive decrease in rigidity of the land portion. The second outer middle sipe 17 maintains the rigidity of the outer middle land portion 7 on the second vertical edge 7b side, and the land portion piece between the outer middle lateral groove 15 and the second outer middle sipe 17 on the first vertical edge 7a side. It is possible to make it moderately easy to move, and by extension, to strongly compact the snow that has entered the outer middle lateral groove 15. As described above, in the present embodiment, the arrangement of the first outer middle sipe 16 and the second outer middle sipe 17 increases the snow column shearing force of the outer middle lateral groove 15, and excellent on-snow performance can be obtained.

In a preferred embodiment, the outer middle land portion 7 is not provided with a lateral groove extending from the second vertical edge 7b and exceeding 0.25 times the width Wo of the outer middle land portion 7. As a more desirable embodiment, in the present embodiment, the outer middle land portion 7 is not provided with a lateral groove extending from the second vertical edge 7b, and only the sipes are connected to the second vertical edge 7b. Further, the second vertical edge 7b is not provided with a chamfered portion in which the corner portion between the tread surface and the side surface of the land portion is recessed. Such an outer middle land portion 7 has higher rigidity in the vicinity of the second vertical edge 7b, and further excellent steering stability can be expected.

The ratio Lo / Wo of the width Wo of the outer middle land portion 7 in the tire axial direction and the length Lo of the outer middle lateral groove 15 in the tire axial direction is preferably 0.40 to 0.60, for example. The outer middle lateral groove 15 of the present embodiment reaches, for example, the center position of the outer middle land portion 7 in the tire axial direction. Such an outer middle lateral groove 15 can improve steering stability on a dry road surface and performance on snow in a well-balanced manner.

It is desirable that the outer middle lateral groove 15 is inclined with respect to the tire axial direction, for example. The angle of the outer middle lateral groove 15 with respect to the tire axial direction is preferably less than 30 °, for example, 15 to 25 °. Such an outer middle lateral groove 15 can be expected to have a large traction on snow.

It is desirable that the outer middle lateral groove 15 extends with a constant groove width, for example. Note that extending with a constant groove width includes a mode in which the difference between the maximum groove width and the minimum groove width of the lateral groove is less than 5% of the maximum groove width. It is desirable that the groove width W2 of the outer middle lateral groove 15 is, for example, 0.25 to 0.40 times the groove width W1 of the main groove 3.

It is desirable that the first outer middle sipe 16 is inclined in the same direction as the outer middle lateral groove 15 with respect to the tire axial direction, for example. Further, the angle of the first outer middle sipe 16 with respect to the tire axial direction is preferably less than 30 °.

FIG. 3A shows a sectional view taken along line AA of the outer middle lateral groove 15 and the first outer middle sipe 16. As shown in FIG. 3A, it is desirable that the depth d2 of the first outer middle sipe 16 is 0.50 to 0.70 times the depth d1 of the outer middle lateral groove 15. Such a first outer middle sipe 16 can improve the performance on snow while preventing the rigidity of the outer middle land portion 7 from being lowered.

As shown in FIG. 2, the second outer middle sipe 17 is interrupted, for example, on the second vertical edge 7b side of the center position of the outer middle land portion 7 in the tire axial direction. The length L2 of the second outer middle sipe 17 in the tire axial direction is, for example, 0.65 to 0.85 times the width Wo of the outer middle land portion 7 in the tire axial direction. Further, it is desirable that the length L2 of the second outer middle sipe 17 is 1.40 to 1.60 times the length Lo of the outer middle lateral groove 15 in the tire axial direction. As a result, the land piece between the outer middle lateral groove 15 and the second outer middle sipe 17 becomes easier to move, and when traveling on snow, the snow in the outer middle lateral groove 15 is strongly compacted, and a larger snow column shearing force is obtained. Be done.

The second outer middle sipe 17 is inclined in the same direction as the outer middle lateral groove 15 with respect to the tire axial direction, for example. The angle of the second outer middle sipe 17 with respect to the tire axial direction is, for example, 10 to 30 °.

FIG. 3B shows a sectional view taken along line BB of the second outer middle sipe 17. As shown in FIG. 3B, the second outer middle sipe 17 is formed at, for example, a shallow bottom portion 17a having a raised groove bottom at an end on the first vertical edge 7a side and a break on the second vertical edge 7b side. It has a tapering portion 17b whose depth gradually decreases toward it. The depth d4 of the shallow bottom portion 17a is 0.70 to 0.90 times the maximum depth d3 of the second outer middle sipe 17. Since the second outer middle sipe 17 having the shallow bottom portion 17a and the tapering portion 17b is suppressed from being excessively opened, it is possible to prevent the steering stability on the dry road surface from being lowered.

FIG. 3C shows a cross-sectional view of another embodiment of the second outer middle sipe 17. As shown in FIG. 3C, the depth of the second outer middle sipe 17 of this embodiment gradually decreases from the end on the first vertical edge 7a side toward the break end. The ratio d5 / d3 of the maximum depth d3 and the minimum depth d5 of the second outer middle sipe 17 is, for example, 0.20 to 0.40. In the outer middle land portion 7 on which the second outer middle sipe 17 is arranged, the rigidity in the tire circumferential direction gradually increases toward the second vertical edge 7b side, so that the steering response during turning can be made linear. can.

As shown in FIG. 2, the outer middle land portion 7 is provided with a chamfered portion 18 having a concave corner portion between the tread surface and the side surface of the land portion on the first vertical edge 7a side. The chamfered portion 18 of the present embodiment is connected to, for example, the outer middle lateral groove 15. Such a chamfered portion 18 suppresses uneven wear of the outer middle land portion 7. Further, the chamfered portion 18 is useful for integrating the snow in the outer middle lateral groove 15 and the snow in the crown main groove 6 when traveling on snow, and can prevent the snow from being clogged in the outer middle lateral groove 15.

The ratio Li / Wi of the width Wi of the inner middle land portion 8 in the tire axial direction and the length Li of the inner middle lateral groove 20 in the tire axial direction is more preferably 0.70 to 0.90, for example. Further, it is desirable that the length Li of the inner middle lateral groove 20 is larger than the length Lo of the outer middle lateral groove 15. This further enhances the performance on snow.

The inner middle land portion 8 is not provided with a lateral groove extending from the second vertical edge 8b toward the first vertical edge 8a and reaching the center position of the inner middle land portion 8 in the tire axial direction. In a preferred embodiment, the inner middle land portion 8 is not provided with a transverse groove extending from the second vertical edge 8b and exceeding 0.25 times the width Wo of the inner middle land portion 8. As a more desirable embodiment, in the present embodiment, the inner middle land portion 8 is not provided with a lateral groove extending from the second vertical edge 8b, and only the sipes are connected to the second vertical edge 8b. Further, the second vertical edge 8b is not provided with a chamfered portion in which the corner portion between the tread surface and the side surface of the land portion is recessed. Such an inner middle land portion 8 can further improve steering stability on a dry road surface.

It is desirable that the inner middle lateral groove 20 is inclined in the same direction as the outer middle lateral groove 15, for example. The angle of the inner middle lateral groove 20 with respect to the tire axial direction is preferably less than 30 °, for example, 15 to 25 °. Such an inner middle lateral groove 20 can improve traction on snow and turning performance in a well-balanced manner.

It is desirable that the inner middle lateral groove 20 extends with a constant groove width. It is desirable that the groove width W3 of the inner middle lateral groove 20 is, for example, 0.25 to 0.40 times the groove width W1 of the main groove 3.

The inner middle land portion 8 is provided with a first inner middle sipe 21 and a second inner middle sipe 22.

The first inner middle sipe 21 extends from, for example, a break in the inner middle lateral groove 20 to the second vertical edge 8b. It is desirable that the first inner middle sipe 21 is inclined in the same direction as the inner middle lateral groove 20 with respect to the tire axial direction, for example. The angle of the first inner middle sipe 21 with respect to the tire axial direction is preferably less than, for example, 30 °.

It is desirable that the region extending the first inner middle sipe 21 toward the outer tread end To side intersects the region extending the outer middle lateral groove 15 toward the inner tread end Ti side within the crown main groove 6. Such arrangement of the lateral grooves and sipes makes it easy to open each lateral groove appropriately and helps to improve the performance on snow.

The second inner middle sipe 22 extends from, for example, the first vertical edge 8a to the second vertical edge 8b. Such a second inner middle sipe 22 can enhance traction on snow.

It is desirable that the second inner middle sipe 22 is inclined in the same direction as the inner middle lateral groove 20 with respect to the tire axial direction, for example. The angle of the second inner middle sipe 22 with respect to the tire axial direction is, for example, 10 to 30 °.

FIG. 4 shows a sectional view taken along line CC of the second inner middle sipe 22. As shown in FIG. 4, it is desirable that the second inner middle sipe 22 has shallow bottom portions 22a at both ends in the tire axial direction. The depth d7 of the shallow bottom portion 22a is, for example, 0.70 to 0.90 times the maximum depth d6 of the second inner middle sipe 22. Such a second inner middle sipe 22 can improve the performance on snow while suppressing a decrease in steering stability.

As shown in FIG. 2, the inner middle land portion 8 is provided with a chamfered portion 23 having a concave corner portion between the tread surface and the side surface of the land portion on the first vertical edge 8a side. The chamfered portion 23 of the present embodiment is connected to, for example, the inner middle lateral groove 20. Such a chamfered portion 23 can suppress uneven wear of the inner middle land portion 8. Further, the length of the chamfered portion 23 provided on the inner middle land portion 8 in the tire circumferential direction is larger than the length of the chamfered portion 18 provided on the outer middle land portion 7 in the tire circumferential direction. As a result, the difference in the progress of wear between the inner middle land portion 8 and the outer middle land portion 7 due to the difference in ground pressure becomes smaller.

FIG. 5 shows an enlarged view of the outer shoulder land portion 9. As shown in FIG. 5, the outer shoulder land portion 9 is provided with an outer shoulder lateral groove 25, a first outer shoulder sipe 26, and a second outer shoulder sipe 27.

The outer shoulder lateral groove 25 extends from, for example, the outer shoulder main groove 4 to the outer tread end To. The outer shoulder lateral groove 25 is inclined in the same direction as the outer middle lateral groove 15 with respect to the tire axial direction, for example. The angle of the outer shoulder lateral groove 25 with respect to the tire axial direction is preferably, for example, 10 to 30 °.

The outer shoulder lateral groove 25 of the present embodiment is connected to the first groove portion 25a extending from the outer shoulder main groove 4 and the first groove portion 25a, and extends to the outer tread end To with a groove width larger than that of the first groove portion 25a. And include. In a more desirable embodiment, one edge of the first groove 25a and one edge of the second groove 25b are smoothly continuous.

It is desirable that the groove width W4 of the first groove portion 25a is smaller than, for example, the groove width W2 (shown in FIG. 2) of the outer middle lateral groove 15. It is desirable that the groove width W5 of the second groove portion 25b is larger than, for example, the groove width W2 of the outer middle lateral groove 15. It is desirable that the groove width W5 of the second groove portion 25b is, for example, 1.70 to 2.00 times the groove width W4 of the first groove portion 25a. Such an outer shoulder lateral groove 25 can improve steering stability on a dry road surface and performance on snow in a well-balanced manner.

The length L3 of the first groove portion 25a in the tire axial direction is, for example, 0.35 to 0.55 times the width W6 of the outer shoulder land portion 9 in the tire axial direction. Further, it is desirable that the length L3 of the first groove portion 25a in the tire axial direction is larger than the length Lo of the outer middle lateral groove 15 in the tire axial direction (shown in FIG. 2).

It is desirable that the second groove portion 25b has a depth larger than that of the first groove portion 25a, for example. It is desirable that the depth of the second groove portion 25b is, for example, 1.5 to 2.0 times the depth of the first groove portion 25a. Such an outer shoulder lateral groove 25 exhibits excellent on-snow performance due to the second groove portion 25b while preventing the rigidity of the land portion from being lowered by the first groove portion 25a.

The first outer shoulder sipe 26 is, for example, a closed sipe whose both ends are interrupted in the outer shoulder land portion 9. In the present embodiment, two first outer shoulder sipes 26 are provided between the two outer shoulder lateral grooves 25 adjacent to each other in the tire circumferential direction.

It is desirable that the length of the first outer shoulder sipe 26 in the tire axial direction is larger than, for example, the length of the first groove portion 25a of the outer shoulder lateral groove 25 in the tire axial direction.

The second outer shoulder sipe 27 extends from the outer tread end To to the tire equator C side and is interrupted in the outer shoulder land portion 9. In the present embodiment, two second outer shoulder sipes 27 are provided between the two outer shoulder lateral grooves 25 adjacent to each other in the tire circumferential direction. In a preferred embodiment, the second outer shoulder sipe 27 and the first outer shoulder sipe 26 do not overlap in the tire axial direction. Such a second outer shoulder sipe 27 is useful for improving the wandering performance on snow while maintaining the rigidity of the land portion.

The outer shoulder land portion 9 is provided with a chamfered portion 28 having a concave corner portion between the tread surface and the side surface of the outer shoulder portion 4 on the outer shoulder main groove 4 side. The chamfered portion 28 of the present embodiment is connected to, for example, the outer shoulder lateral groove 25. Such a chamfered portion 28 can form a large snow column together with the outer shoulder lateral groove 25 to improve the performance on snow.

As shown in FIG. 1, it is desirable that the region where the chamfered portion 28 provided on the outer shoulder land portion 9 extends along the tire axial direction intersects with the second outer middle sipe 17. Such an arrangement of the chamfered portion 28 is useful for suppressing uneven wear of the outer shoulder land portion 9.

FIG. 6 shows an enlarged view of the inner shoulder land portion 10. As shown in FIG. 6, the inner shoulder land portion 10 is provided with an inner shoulder lateral groove 30, a first inner shoulder sipe 31, and a second inner shoulder sipe 32.

The inner shoulder lateral groove 30 extends from, for example, the inner shoulder main groove 5 to the inner tread end Ti. The inner shoulder lateral groove 30 is inclined in the same direction as the inner middle lateral groove 20 with respect to the tire axial direction, for example. The angle of the inner shoulder lateral groove 30 with respect to the tire axial direction is preferably, for example, 10 to 30 °.

It is desirable that the groove width W7 of the inner shoulder lateral groove 30 is at least larger than the groove width W4 (shown in FIG. 5) of the first groove portion 25a of the outer shoulder lateral groove 25. In a more preferred embodiment, the groove width W7 of the inner shoulder lateral groove 30 is larger than either the groove width W2 of the outer middle lateral groove 15 (shown in FIG. 2) and the groove width W3 of the inner middle lateral groove 20 (shown in FIG. 2). Such an inner shoulder lateral groove 30 is useful for exhibiting excellent on-snow performance.

It is desirable that the inner shoulder lateral groove 30 has a shallow bottom portion in which the groove bottom is raised, for example, at the end portion on the inner shoulder main groove 5 side. It is desirable that the length of the shallow bottom portion in the tire axial direction is smaller than the length of the first groove portion 25a (shown in FIG. 5) of the outer shoulder lateral groove 25 in the tire axial direction. Further, the depth of the shallow bottom portion is, for example, 0.55 to 0.70 times the maximum depth of the inner shoulder lateral groove 30.

The first inner shoulder sipe 31 extends from, for example, the inner shoulder main groove 5 toward the inner tread end Ti side, and is interrupted in the inner shoulder land portion 10. In the present embodiment, two first inner shoulder sipes 31 are provided between the two inner shoulder lateral grooves 30 adjacent to each other in the tire circumferential direction. The length L4 of the first inner shoulder sipe 31 in the tire axial direction is, for example, 0.75 to 0.90 times the width W8 of the inner shoulder land portion 10 in the tire axial direction.

The second inner shoulder sipe 32 extends from the inner tread end Ti toward the tire equator C side and is interrupted in the inner shoulder land portion 10. In the present embodiment, two second inner shoulder sipes 32 are provided between the two inner shoulder lateral grooves 30 adjacent to each other in the tire circumferential direction. In a preferred embodiment, the second inner shoulder sipe 32 and the first inner shoulder sipe 31 do not overlap in the tire axial direction. Such a second inner shoulder sipe 32 can improve the wandering performance on snow while maintaining the rigidity of the inner shoulder land portion 10.

The inner shoulder land portion 10 is provided with a chamfered portion 33 in which a corner portion between the tread surface and the side surface of the land portion is recessed on the inner shoulder main groove 5 side. The chamfered portion 33 of the present embodiment is connected to, for example, the inner shoulder lateral groove 30 and the first inner shoulder sipe 31. Such a chamfered portion 33 can suppress uneven wear of the inner shoulder land portion 10.

Although the preferred embodiment of the tire of the present invention has been described in detail above, the present invention is not limited to the specific embodiment described above, and may be modified to various embodiments.

A size 185 / 65R15 tire having the basic pattern shown in FIG. 1 was prototyped. As a comparative example, as shown in FIG. 7, the ratio Lo / Wo of the width Wo of the outer middle land portion a in the tire axial direction and the length Lo of the outer middle lateral groove c in the tire axial direction is the inner middle land portion b. A tire having the same ratio of the width Wi in the tire axial direction and the length Li in the tire axial direction of the outer middle lateral groove d as Li / Wi was prototyped. The tires of the comparative examples have substantially the same tread pattern as that shown in FIG. 1, except for the above configuration. The steering stability and snow performance of each test tire on dry roads were tested. The common specifications and test methods for each test tire are as follows.
Mounting rim: 15 x 6.0J
Tire internal pressure: 220kPa for front wheels, 210kPa for rear wheels
Test vehicle: Displacement 1300cc, front-wheel drive vehicle Tire mounting position: All wheels

<Maneuvering stability on dry roads>
The steering stability of the test vehicle when traveling on a dry road surface was evaluated by the driver's sensuality. The result is a score of 100 in the comparative example, and the larger the value, the better the steering stability on the dry road surface.

<Performance on snow>
The performance of the test vehicle equipped with each test tire when traveling on a snowy road was evaluated by the driver's sensuality. The result is a score with a comparative example of 100, and the larger the value, the better the performance on snow.
The test results are shown in Table 1.

As a result of the test, it was confirmed that the tires of the examples had improved steering stability and snow performance on dry road surfaces as compared with the tires of the comparative examples.

2 Tread 7 Outer middle land 8 Inner middle land 15 Outer middle lateral groove 20 Inner middle lateral groove To Outer tread end Ti Inner tread end Wi Inner middle land tire axial width Wo Outer middle land tire axial width Width Li Inner middle lateral groove tire axial length Lo Lo Outer middle lateral groove tire axial length

Claims (7)

A tire with a tread that is oriented to be mounted on a vehicle.
The tread portion includes an outer tread end located on the outer side of the vehicle when mounted on the vehicle, an inner tread end located on the inner side of the vehicle when mounted on the vehicle, and an outer middle land portion arranged between the outer tread end and the tire equatorial line. Has an inner middle land portion arranged between the inner tread end and the tire equatorial line.
The outer middle land portion and the inner middle land portion each have a first vertical edge extending in the tire circumferential direction on the inner tread end side, a second vertical edge extending in the tire circumferential direction on the outer tread end side, and the above. It has a tread between the first vertical edge and the second vertical edge,
The inner middle land portion is provided with an inner middle lateral groove extending from the first vertical edge and interrupted within the inner middle land portion.
The outer middle land portion is provided with an outer middle lateral groove extending from the first vertical edge and interrupting within the outer middle land portion, and the outer middle land portion is provided with the first vertical groove from the second vertical edge. There is no lateral groove extending to the edge side,
The ratio Li / Wi of the width Wi in the tire axial direction of the inner middle land portion and the length Li in the tire axial direction of the inner middle lateral groove is the width Wo in the tire axial direction of the outer middle land portion and the outer side. The ratio of the middle lateral groove to the length Lo in the tire axial direction is larger than Lo / Wo,
tire. A tire with a tread that is oriented to be mounted on a vehicle.
The tread portion includes an outer tread end located on the outer side of the vehicle when mounted on the vehicle, an inner tread end located on the inner side of the vehicle when mounted on the vehicle, and an outer middle land portion arranged between the outer tread end and the tire equatorial line. Has an inner middle land portion arranged between the inner tread end and the tire equatorial line.
The outer middle land portion and the inner middle land portion each have a first vertical edge extending in the tire circumferential direction on the inner tread end side, a second vertical edge extending in the tire circumferential direction on the outer tread end side, and the above. It has a tread between the first vertical edge and the second vertical edge,
The inner middle land portion is provided with an inner middle lateral groove extending from the first vertical edge and interrupted within the inner middle land portion.
The outer middle land portion is provided with an outer middle lateral groove extending from the first vertical edge and interrupted in the outer middle land portion, and the outer middle land portion is provided with the first vertical groove from the second vertical edge. There is no lateral groove extending to the edge side and reaching the center position in the tire axial direction of the outer middle land portion.
The ratio Li / Wi of the width Wi in the tire axial direction of the inner middle land portion and the length Li in the tire axial direction of the inner middle lateral groove is the width Wo in the tire axial direction of the outer middle land portion and the outer side. The length of the middle lateral groove in the tire axial direction is larger than the ratio Lo / Wo to Lo,
The outer middle land portion is provided with a first outer middle sipe extending from a break in the outer middle lateral groove to the second vertical edge.
tire. A tire with a tread that is oriented to be mounted on a vehicle.
The tread portion includes an outer tread end located on the outer side of the vehicle when mounted on the vehicle, an inner tread end located on the inner side of the vehicle when mounted on the vehicle, and an outer middle land portion arranged between the outer tread end and the tire equatorial line. Has an inner middle land portion located between the inner tread end and the tire equator.
Each of the outer middle land portion and the inner middle land portion has a first vertical edge extending in the tire circumferential direction on the inner tread end side, a second vertical edge extending in the tire circumferential direction on the outer tread end side, and the above. It has a tread between the first vertical edge and the second vertical edge,
The inner middle land portion is provided with an inner middle lateral groove extending from the first vertical edge and interrupted within the inner middle land portion.
The outer middle land portion is provided with an outer middle lateral groove extending from the first vertical edge and interrupted in the outer middle land portion, and the outer middle land portion is provided with the first vertical groove from the second vertical edge. There is no lateral groove extending to the edge side and reaching the center position in the tire axial direction of the outer middle land portion.
The ratio Li / Wi of the width Wi in the tire axial direction of the inner middle land portion and the length Li in the tire axial direction of the inner middle lateral groove is the width Wo in the tire axial direction of the outer middle land portion and the outer side. The length of the middle lateral groove in the tire axial direction is larger than the ratio Lo / Wo to Lo,
The inner middle land portion is provided with a first inner middle sipe extending from a break in the inner middle lateral groove to the second vertical edge.
tire. The tire according to claim 3 , wherein the region extending the first inner middle sipe toward the outer tread end side intersects the region extending the outer middle lateral groove toward the inner tread end side. The tire according to any one of claims 1 to 4, wherein the length Li of the inner middle lateral groove is larger than the length Lo of the outer middle lateral groove. The inner middle land portion is not provided with a lateral groove extending from the second vertical edge toward the first vertical edge side and reaching the center position of the inner middle land portion in the tire axial direction, according to claims 1 to 5. Tires listed in either. The tire according to any one of claims 1 to 6, wherein each of the inner middle lateral groove and the outer middle lateral groove extends with a constant groove width.

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