tire

Abstract

To provide a tire capable of improving dry performance, on-ice performance and on-snow performance in a good balance.SOLUTION: A tire 1 includes a tread part 2. The tread part 2 includes a plurality of circumferential grooves 3 extending continuously in a tire circumferential direction, land parts 4 partitioned into the circumferential grooves 3, and a plurality of lateral grooves 5 crossing the land parts 4. At least one of the lateral grooves 5 has a first edge part 7 on one side of the tire circumferential direction, and a second edge part 8 on the other side of the tire circumferential direction. The first edge part 7 linearly extends. The second edge part 8 comprises a first portion 8a extending in parallel to the first edge part 7, and a second portion 8b extending so as to gradually increase a groove width from the first portion 8a.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a tire having a tread portion. [Background technology]

[0002] Conventionally, there is known a tire in which a land portion divided by a plurality of circumferential grooves provided in a tread portion includes blocks divided by a plurality of lateral grooves. For example, the tire disclosed in the following Patent Document 1 proposes a tire in which a slot is provided in a middle block to improve performance on snow while maintaining steering stability. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2018-134960 Summary of the Invention [Problem to be solved by the invention]

[0004] However, providing slots in the blocks to improve performance on snow tends to reduce the rigidity around the slots, resulting in reduced performance on ice and on dry surfaces, so further improvements were desired even in the tire of Patent Document 1.

[0005] The present invention has been devised in view of the above circumstances, and has as its main object to provide a tire that can improve dry performance, performance on ice, and performance on snow in a well-balanced manner. [Means for solving the problem]

[0006] The present invention is a tire having a tread portion, the tread portion including a plurality of circumferential grooves extending continuously in a tire circumferential direction, a land portion divided into the circumferential grooves, and a plurality of lateral grooves crossing the land portions, at least one of the lateral grooves having a first groove edge portion on one side in the tire circumferential direction and a second groove edge portion on the other side in the tire circumferential direction, the first groove edge portion extending in a straight line, and the second groove edge portion consisting of a first portion extending parallel to the first groove edge portion and a second portion extending from the first portion so that the groove width gradually increases.

[0007] In the tire of the present invention, the axial length of the second portion is desirably 50% to 200% of the axial length of the first portion.

[0008] In the tire of the present invention, it is preferable that the groove depth of the lateral groove in the region having the second portion is 60% to 100% of the groove depth of the circumferential groove.

[0009] In the tire of the present invention, it is preferable that the tread portion has an asymmetric tread pattern with a specified orientation when mounted on a vehicle, and the second portion is located on the outer side of the vehicle of the first portion when mounted on the vehicle.

[0010] In the tire of the present invention, it is preferable that the land portion has a circumferential narrow groove extending in the tire circumferential direction, and the circumferential narrow groove communicates with the first portion.

[0011] In the tire of the present invention, it is preferable that the land portion includes a crown land portion disposed on the tire equator, and the second portion is disposed at a position straddling the tire equator.

[0012] In the tire of the present invention, the tread portion has an asymmetric tread pattern in which the orientation of mounting on a vehicle is specified, and the crown land portion is divided into an outer crown circumferential groove arranged on the outer side of the vehicle when mounted on the vehicle and an inner crown circumferential groove arranged on the inner side of the vehicle, and it is preferable that the groove width of the inner crown circumferential groove is larger than the groove width of the outer crown circumferential groove.

[0013] In the tire of the present invention, it is desirable that the land portion includes a first land portion separated by a pair of the circumferential grooves and a second land portion adjacent to the first land portion, the lateral groove includes a first lateral groove crossing the first land portion and a second lateral groove crossing the second land portion, the first lateral groove has the first groove edge portion and the second groove edge portion, and the second lateral groove has a constant groove width.

[0014] In the tire of the present invention, it is preferable that the first lateral groove includes an opening portion that opens into the circumferential groove on the second portion side, and the second lateral groove opens into the circumferential groove at a position opposite to the opening portion with the circumferential groove interposed therebetween.

[0015] In the tire of the present invention, it is preferable that the groove width of the first lateral groove in the region having the first portion is 30% to 50% of the groove width of the second lateral groove. Effect of the Invention

[0016] In the tire of the present invention, at least one of the lateral grooves has a first groove edge portion on one side in the tire circumferential direction and a second groove edge portion on the other side in the tire circumferential direction, the first groove edge portion extending in a straight line, and the second groove edge portion consisting of a first portion extending parallel to the first groove edge portion and a second portion extending from the first portion so that the groove width gradually increases.

[0017] By varying the groove width, such lateral grooves can improve traction on snowy roads and improve the tire's snow performance. In addition, since the lateral grooves do not add other slots or grooves to the land portions crossed by the lateral grooves, the ratio and rigidity of the land portions can be prevented from decreasing, and the tire's dry performance and on-ice performance can be improved. Therefore, the tire of the present invention can improve the dry performance, on-ice performance, and on-snow performance in a well-balanced manner. [Brief description of the drawings]

[0018] [Figure 1] 1 is a development view showing one embodiment of a tread portion of a tire of the present invention. [Diagram 2]2 is an enlarged view of a first land portion and a second land portion of FIG. 1. [Diagram 3] FIG. 2 is an enlarged view of a fourth land portion in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a development view showing a tread portion 2 of a tire 1 of this embodiment. As shown in Fig. 1, the tire 1 of this embodiment has a tread portion 2 that comes into contact with the road surface during driving. The tire 1 can be suitably adopted, for example, as a pneumatic tire for passenger cars used in winter. The tire 1 is not limited to such an embodiment, and can be adopted, for example, as a heavy load tire, a tire for two-wheeled vehicles, a non-pneumatic tire that is not filled with pressurized air inside, and the like.

[0020] The tread portion 2 of this embodiment includes a plurality of circumferential grooves 3 extending continuously in the tire circumferential direction, a land portion 4 divided into the circumferential grooves 3, and a plurality of lateral grooves 5 crossing the land portion 4 in the tire axial direction. Such a tread portion 2 can generate snow column shear force by the circumferential grooves 3 and the lateral grooves 5, and the circumferential grooves 3 and the lateral grooves 5 can exert an edge effect, which helps to improve the steering stability performance of the tire 1 when it is running on snowy roads (hereinafter referred to as "on-snow performance") and the steering stability performance when it is running on icy roads (hereinafter referred to as "on-ice performance").

[0021] The land portion 4 includes, for example, a first land portion 4A partitioned between a pair of circumferential grooves 3. The lateral groove 5 includes, for example, a first lateral groove 5A provided in the first land portion 4A. The first land portion 4A in this embodiment includes a plurality of first blocks 6 partitioned by a plurality of first lateral grooves 5A that cross the first land portion 4A in the tire axial direction.

[0022] 2 is an enlarged view of the first land portion 4A in FIG. 1 and the second land portion 4B described later. As shown in FIG. 2, at least one of the lateral grooves 5, the first lateral groove 5A in this embodiment, has a first groove edge 7 on one side in the tire circumferential direction and a second groove edge 8 on the other side in the tire circumferential direction. The first groove edge 7 in this embodiment extends linearly. On the other hand, the second groove edge 8 is preferably composed of a first portion 8a extending parallel to the first groove edge 7 and a second portion 8b extending from the first portion 8a so that the groove width gradually increases.

[0023] By varying the groove width, such lateral grooves 5 can improve traction on snowy road surfaces and improve the on-snow performance of the tire 1. Furthermore, since the lateral grooves 5 do not add other slots or grooves to the land portions 4 that the lateral grooves 5 cross, it is possible to suppress a decrease in the ratio and rigidity of the land portions 4, and it is possible to improve the steering stability performance (hereinafter referred to as "dry performance") of the tire 1 when traveling on dry roads and the performance on ice. Therefore, the tire 1 of this embodiment can improve the dry performance, the performance on ice, and the performance on snow in a well-balanced manner.

[0024] In a more preferred embodiment, the first groove edge 7 extends in a direction inclined relative to the tire axial direction. Such a first groove edge 7 can exert an edge effect in the tire circumferential direction and the tire axial direction, thereby improving the on-ice performance of the tire 1.

[0025] It is desirable that the first portion 8a and the second portion 8b of the second groove edge 8 extend linearly. Such a second groove edge 8 prevents the rigidity of the first block 6 from decreasing, and helps to improve the dry performance and on-ice performance of the tire 1.

[0026] The axial length L2 of the second portion 8b is preferably 50% to 200% of the axial length L1 of the first portion 8a. Such a second groove edge 8 has an excellent balance between the first portion 8a and the second portion 8b, and helps to improve the dry performance, ice performance, and snow performance of the tire 1 in a well-balanced manner.

[0027] The groove depth of the lateral groove 5 in the region R2 having the second portion 8b is preferably the same as or smaller than the groove depth of the lateral groove 5 in the region R1 having the first portion 8a. Such a lateral groove 5 can strongly compact snow in the region R2 having the second portion 8b to generate a large snow column shear force, and can compact more snow in the region R1 having the first portion 8a. Therefore, the tire 1 of this embodiment can further improve the on-snow performance.

[0028] The groove depth of the lateral grooves 5 in the region R2 having the second portion 8b is preferably 60% to 100%, more preferably 60% to 90%, of the groove depth of the lateral grooves 5 in the region R1 having the first portion 8a. Such lateral grooves 5 can more reliably improve the on-snow performance of the tire 1.

[0029] The groove depth of the lateral grooves 5 in the region R1 having the first portions 8a is preferably 60% to 100%, and more preferably 70% to 100%, of the groove depth of the circumferential grooves 3. Such lateral grooves 5 suppress a decrease in the rigidity of the first blocks 6 and are useful for improving the dry performance and on-ice performance of the tire 1.

[0030] The groove depth of the lateral grooves 5 in the region R2 having the second portions 8b is preferably 60% to 100%, and more preferably 60% to 90%, of the groove depth of the circumferential grooves 3. Such lateral grooves 5 suppress a decrease in the rigidity of the first blocks 6 and are useful for improving the dry performance and on-ice performance of the tire 1.

[0031] The first land portion 4A of this embodiment has a circumferential narrow groove 9 extending in the tire circumferential direction. The circumferential narrow groove 9 has a groove width of, for example, 2 mm or less and extends continuously in a straight line in the tire circumferential direction. The circumferential narrow groove 9 is preferably connected to the first portion 8a. The groove depth of the circumferential narrow groove 9 of this embodiment is smaller than the groove depth of the lateral groove 5 in the region R1 having the first portion 8a. Such a circumferential narrow groove 9 can exhibit an edge effect while maintaining the high rigidity of the first land portion 4A, and can further improve the on-ice performance of the tire 1.

[0032] The first block 6 of this embodiment has a plurality of lateral sipes 10 extending in the tire axial direction. In this specification, a sipe is a cut having a width of 2 mm or less perpendicular to the longitudinal direction. In this specification, unless otherwise specified, the dimensions of each part of the tire 1 are values ​​measured in a normal state. In the case where the tire 1 is a pneumatic tire, the "normal state" refers to an unloaded state in which the tire 1 is mounted on a normal rim and adjusted to a normal internal pressure.

[0033] A "genuine rim" is a rim that is determined for each tire by a standard system that includes the standard on which tire 1 is based, such as a "standard rim" for JATMA, a "design rim" for TRA, and a "measuring rim" for ETRTO. A "genuine rim" is a rim that is determined for each tire by the manufacturer, etc., when there is no standard system that includes the standard on which tire 1 is based.

[0034] "Normal internal pressure" is the air pressure set for each tire by each standard in the standard system including the standard on which tire 1 is based, for example, "maximum air pressure" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "INFLATION PRESSURE" for ETRTO. "Normal internal pressure" is the air pressure set for each tire by the manufacturer, etc., when there is no standard system including the standard on which tire 1 is based.

[0035] At least one of the lateral sipes 10 of the first block 6, for example, has at least one end connected to the circumferential groove 3. The lateral sipes 10 of the first block 6 in this embodiment extend in a zigzag shape in a direction inclined in the same direction as the first groove edge portion 7 with respect to the tire axial direction. The lateral sipes 10 of the first block 6, for example, have a discontinuous portion 10a that does not communicate with the circumferential narrow groove 9. That is, the circumferential narrow groove 9 in this embodiment is provided in the discontinuous portion 10a.

[0036] Such a first block 6 can further improve the on-ice performance of the tire 1 due to the edge effect of the lateral sipes 10. Also, since the lateral sipes 10 and the circumferential narrow groove 9 are not connected to the first block 6, high rigidity can be maintained. Note that the lateral sipes 10 of the first block 6 are not limited to this embodiment, and may, for example, terminate without connecting to the circumferential groove 3, extend linearly, or connect to the circumferential narrow groove 9.

[0037] The first lateral groove 5A includes, for example, an opening 5a that opens into the circumferential groove 3 on the second portion 8b side. In this embodiment, the groove width W2 of the first lateral groove 5A at the opening 5a is larger than the groove width W1 of the first lateral groove 5A in the region R1 having the first portion 8a. Here, the groove width W2 of the first lateral groove 5A at the opening 5a is the maximum groove width of the first lateral groove 5A in the region R2 having the second portion 8b.

[0038] The groove width W2 of the first lateral groove 5A at the opening 5a is preferably 160% to 200% of the groove width W1 of the first lateral groove 5A in the region R1 having the first portion 8a. Such a first lateral groove 5A can take in a large amount of snow from the opening 5a and generate a large snow column shear force, thereby improving the on-snow performance of the tire 1.

[0039] 1, the land portion 4 desirably includes a second land portion 4B adjacent to the first land portion 4A, and a third land portion 4C adjacent to the second land portion 4B on the opposite side to the first land portion 4A. The land portion 4 may further include, for example, a fourth land portion 4D adjacent to the first land portion 4A on the opposite side to the second land portion 4B, and a fifth land portion 4E adjacent to the fourth land portion 4D on the opposite side to the first land portion 4A.

[0040] The lateral grooves 5 include, for example, a second lateral groove 5B provided in the second land portion 4B, a third lateral groove 5C provided in the third land portion 4C, a fourth lateral groove 5D provided in the fourth land portion 4D, and a fifth lateral groove 5E provided in the fifth land portion 4E.

[0041] The second land portion 4B is preferably divided by a pair of circumferential grooves 3. In this embodiment, the second land portion 4B includes a plurality of second blocks 11 divided by a plurality of second lateral grooves 5B that cross the second land portion 4B in the tire axial direction. The second lateral grooves 5B in this embodiment extend linearly in a direction inclined in the opposite direction to the first lateral grooves 5A.

[0042] The second lateral grooves 5B of this embodiment have a constant groove width W3. The linear shape of the second lateral grooves 5B helps maintain high rigidity of the second blocks 11, and the inclined shape provides an edge effect in the tire circumferential direction and the tire axial direction. The second lateral grooves 5B are not limited to this form, and may extend in a curved shape or have a variable groove width W3.

[0043] The second lateral groove 5B in this embodiment opens into the circumferential groove 3 at a position facing the opening 5a of the first lateral groove 5A via the circumferential groove 3. Such first lateral groove 5A and second lateral groove 5B cooperate with each other to generate a large snow column shear force, thereby improving the on-snow performance of the tire 1.

[0044] The groove width W2 of the first lateral groove 5A at the opening 5a is preferably equal to or smaller than the groove width W3 of the second lateral groove 5B. Such a first lateral groove 5A can suppress a decrease in the ratio and rigidity of the first land portion 4A, and can improve the dry performance and on-ice performance of the tire 1.

[0045] The groove width W1 of the first lateral grooves 5A in the region R1 having the first portions 8a is preferably 30% to 50% of the groove width W3 of the second lateral grooves 5B. Such first lateral grooves 5A can suppress a decrease in the ratio and rigidity of the first land portion 4A, and can improve the dry performance and on-ice performance of the tire 1.

[0046] The second block 11 of this embodiment has a plurality of lateral sipes 12 extending in the tire axial direction. For example, at least one end of the lateral sipes 12 of the second block 11 communicates with the circumferential groove 3. The lateral sipes 12 of the second block 11 of this embodiment extend in a zigzag shape in a direction inclined in the opposite direction to the lateral sipes 10 of the first block 6 with respect to the tire axial direction. The lateral sipes 12 of the second block 11 have, for example, an interrupted portion 12a that is interrupted midway in the longitudinal direction.

[0047] Such second blocks 11 can further improve the on-ice performance of the tire 1 due to the edge effect of the lateral sipes 12. Note that the lateral sipes 12 of the second blocks 11 are not limited to this embodiment, and may, for example, terminate without communicating with the circumferential groove 3, extend linearly, or not have the discontinuous portion 12a.

[0048] 1, the second block 11 has a slot 14, for example, at an edge portion 13 on the third land portion 4C side. The slot 14 is preferably provided at a position facing the third lateral groove 5C across the circumferential groove 3. Such a slot 14 can cooperate with the third lateral groove 5C to generate a large snow column shear force, thereby improving the on-snow performance of the tire 1.

[0049] The third land portion 4C of this embodiment includes a plurality of third blocks 15 divided by a plurality of third lateral grooves 5C that cross the third land portion 4C in the tire axial direction. The third blocks 15 of this embodiment have an edge portion 16 on the second land portion 4B side that extends linearly. Such third blocks 15 suppress a decrease in rigidity on the second land portion 4B side, and can further improve the on-ice performance of the tire 1.

[0050] The third lateral groove 5C of this embodiment extends linearly in a direction inclined in the opposite direction to the second lateral groove 5B. The third lateral groove 5C has, for example, a constant groove width W4. The linear shape of the third lateral groove 5C helps maintain high rigidity of the third block 15, and the inclination can provide an edge effect in the tire circumferential direction and the tire axial direction. The third lateral groove 5C is not limited to this form, and may extend in a curved shape or have a variable groove width W4.

[0051] The third block 15 has a slot 17, for example, at an edge portion 16 on the second land portion 4B side. The slot 17 is preferably provided at a position facing the second lateral groove 5B across the circumferential groove 3. Such a slot 17 can generate a large snow column shear force in cooperation with the second lateral groove 5B, thereby improving the on-snow performance of the tire 1.

[0052] The third block 15 of this embodiment has a plurality of lateral sipes 18 extending in the tire axial direction. At least one of the lateral sipes 18 of the third block 15 is connected to the circumferential groove 3, for example. The lateral sipes 18 of the third block 15 of this embodiment extend in a zigzag shape in a direction inclined in the opposite direction to the lateral sipes 12 of the second block 11 with respect to the tire axial direction. The lateral sipes 18 of the third block 15 have, for example, an interrupted portion 18a that is interrupted midway in the longitudinal direction.

[0053] Such a third block 15 can further improve the on-ice performance of the tire 1 due to the edge effect of the lateral sipes 18. Note that the lateral sipes 18 of the third block 15 are not limited to this embodiment, and may, for example, terminate without communicating with the circumferential groove 3, may extend linearly, or may not have the discontinuous portion 18a.

[0054] The fourth land portion 4D is desirably divided by a pair of circumferential grooves 3. The fourth land portion 4D in this embodiment includes a plurality of fourth blocks 19 divided by a plurality of fourth lateral grooves 5D that cross the fourth land portion 4D in the tire axial direction.

[0055] Fig. 3 is an enlarged view of the fourth land portion 4D in Fig. 1. As shown in Fig. 3, the fourth block 19 of this embodiment includes a first edge portion 20 extending linearly on one side in the tire axial direction, and a second edge portion 21 bent so as to be recessed toward the first edge portion 20 on the other side in the tire axial direction. The second edge portion 21 is preferably composed of a pair of gradually increasing portions 21d, 21e that gradually increase the width of the fourth block 19 from a narrowest portion 21a where the axial width W5 of the fourth block 19 is smallest toward both ends 21b, 21c in the tire circumferential direction.

[0056] In such a fourth block 19, the second edge portion 21 forms a slot portion in its entirety, which suppresses local changes in rigidity and improves the dry performance and on-ice performance of the tire 1. Furthermore, the fourth block 19 can generate a large snow column shear force due to the high rigidity of the gradually increasing portions 21d, 21e, thereby improving the on-snow performance of the tire 1. Therefore, the tire 1 of this embodiment can improve the dry performance, on-ice performance, and on-snow performance in a well-balanced manner.

[0057] The recess amount d of the second edge portion 21 is preferably 5% to 20% of the groove width W5 at the narrowest portion 21a of the fourth block 19. Such a fourth block 19 can generate a large snow column shear force while improving the ratio and rigidity of the fourth land portion 4D, and can improve the dry performance, ice performance, and snow performance of the tire 1 in a well-balanced manner.

[0058] In the fourth block 19, preferably, a distance L3 in the tire circumferential direction between the narrowest portion 21a and an end 21b on one side in the tire circumferential direction of the second edge portion 21 is 0.5 to 2.0 times a distance L4 in the tire circumferential direction between the narrowest portion 21a and an end 21c on the other side in the tire circumferential direction of the second edge portion 21. Such a fourth block 19 has an averaged rigidity, and therefore the dry performance of the tire 1 can be further improved.

[0059] Here, when the section from the narrowest portion 21a to the end 21b on one side is defined as a first gradually increasing portion 21d, and the section from the narrowest portion 21a to the end 21c on the other side is defined as a second gradually increasing portion 21e, distance L3 is the length of the first gradually increasing portion 21d in the tire circumferential direction, and distance L4 is the length of the second gradually increasing portion 21e in the tire circumferential direction.

[0060] It is desirable that the first edge portion 20 of the fourth block 19 extends parallel to the tire circumferential direction. Such a fourth block 19 suppresses a decrease in rigidity on the first edge portion 20 side, and can further improve the on-ice performance of the tire 1.

[0061] The fourth lateral groove 5D of this embodiment extends linearly in a direction inclined relative to the tire axial direction. The fourth lateral groove 5D has, for example, a third groove edge 22 on one side in the tire circumferential direction and a fourth groove edge 23 on the other side in the tire circumferential direction. It is preferable that at least one of the third groove edge 22 and the fourth groove edge 23 of the fourth lateral groove 5D extends linearly.

[0062] The fourth lateral grooves 5D are linear, which helps maintain high rigidity of the fourth blocks 19, and are inclined, which provides an edge effect in the tire circumferential and axial directions. Therefore, the tire 1 of this embodiment can improve the dry performance, ice performance, and snow performance in a well-balanced manner.

[0063] The fourth lateral groove 5D of this embodiment includes a deep groove portion 5b having a large groove depth on the first edge 20 side and a shallow groove portion 5c having a small groove depth on the second edge 21 side. Such a fourth lateral groove 5D can increase the rigidity of the second edge 21 side of the fourth block 19, where the rigidity is likely to decrease with bending, and can further improve the on-ice performance of the tire 1. In addition, the fourth lateral groove 5D can strongly compact snow with the shallow groove portion 5c to generate a large snow column shear force, and can improve the on-snow performance of the tire 1.

[0064] In the fourth lateral groove 5D, it is preferable that the groove width W6 of the deep groove portion 5b is larger than the groove width W7 of the shallow groove portion 5c. In the fourth lateral groove 5D of this embodiment, the third groove edge portion 22 extends linearly and the fourth groove edge portion 23 is formed in a stepped shape, so that the groove width W6 of the deep groove portion 5b is larger than the groove width W7 of the shallow groove portion 5c.

[0065] Such fourth lateral grooves 5D can compact more snow in the deep groove portion 5b, improving the on-snow performance of the tire 1. In addition, the fourth lateral grooves 5D are useful for increasing the rigidity of the second edge portion 21 side of the fourth block 19, which is prone to decrease in rigidity due to bending, and can further improve the on-ice performance of the tire 1.

[0066] The fourth block 19 of this embodiment has a plurality of lateral sipes 24 extending in the tire axial direction. For example, at least one of the lateral sipes 24 of the fourth block 19 communicates with the circumferential groove 3. The lateral sipes 24 of the fourth block 19 of this embodiment extend in a zigzag shape in a direction inclined with respect to the tire axial direction.

[0067] Such a fourth block 19 can further improve the on-ice performance of the tire 1 due to the edge effect of the lateral sipes 24. Note that the lateral sipes 24 of the fourth block 19 are not limited to this embodiment, and for example, both ends may terminate within the fourth block 19, or the lateral sipes 24 may extend linearly.

[0068] 1, the fifth land portion 4E of the present embodiment includes a plurality of fifth blocks 25 divided by a plurality of fifth lateral grooves 5E that cross the fifth land portion 4E in the tire axial direction. The fifth blocks 25 of the present embodiment have an edge 26 on the fourth land portion 4D side that extends linearly.

[0069] Such a fifth block 25 can suppress a decrease in rigidity on the fourth land portion 4D side and further improve the on-ice performance of the tire 1. In addition, the circumferential groove 3 between the fourth land portion 4D and the fifth land portion 4E can generate a large snow column shear force by changing the groove width with the bending of the second edge portion 21, and can further improve the on-snow performance of the tire 1.

[0070] The fifth block 25 of this embodiment has a plurality of lateral sipes 27 extending in the tire axial direction. The lateral sipes 27 of the fifth block 25 are connected to, for example, the circumferential groove 3. The lateral sipes 27 of the fifth block 25 of this embodiment extend in a zigzag shape in a direction inclined in the opposite direction to the lateral sipes 24 of the fourth block 19 with respect to the tire axial direction. The lateral sipes 27 of the fifth block 25 have, for example, an interrupted portion 27a that is interrupted midway in the longitudinal direction.

[0071] Such a fifth block 25 can further improve the on-ice performance of the tire 1 due to the edge effect of the lateral sipes 27. Note that the lateral sipes 27 of the fifth block 25 are not limited to this embodiment, and may, for example, terminate without communicating with the circumferential groove 3, extend linearly, or not have the discontinuous portion 27a.

[0072] The fifth lateral groove 5E of this embodiment extends linearly in a direction inclined in the opposite direction to the fourth lateral groove 5D. The fifth lateral groove 5E has, for example, a constant groove width W8. The fifth lateral groove 5E is linear, which helps maintain high rigidity of the fifth block 25, and is inclined, which can provide an edge effect in the tire circumferential direction and the tire axial direction. The fifth lateral groove 5E is not limited to this form, and may extend in a curved shape, or the groove width W8 may vary.

[0073] The fifth lateral groove 5E desirably opens into the circumferential groove 3 at a position facing the narrowest portion 21a of the second edge portion 21 of the fourth block 19 via the circumferential groove 3. Such a fifth lateral groove 5E can cooperate with the second edge portion 21 of the fourth block 19 to generate a large snow column shear force, thereby improving the on-snow performance of the tire 1.

[0074] The tread portion 2 of this embodiment has an asymmetric tread pattern in which the orientation of the tire when mounted on a vehicle is specified. The tread portion 2 includes, for example, an outer tread end To located on the outer side of the vehicle when mounted on the vehicle, and an inner tread end Ti located on the inner side of the vehicle.

[0075] Here, in the case where the tire 1 is a pneumatic tire, the "outer tread end To" and the "inner tread end Ti" refer to the axially outermost ground contact positions when the tire 1 in a normal state is loaded with a normal load and contacts a flat surface with a camber angle of 0°. The tire equator C is the central position in the tire axial direction between the outer tread end To and the inner tread end Ti.

[0076] The "normal load" is the load determined for each tire by each standard in the standard system including the standard on which tire 1 is based, and is the "maximum load capacity" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "LOAD CAPACITY" for ETRTO. When there is no standard system including the standard on which tire 1 is based, the "normal load" is the load determined for each tire by the manufacturer, etc.

[0077] The circumferential grooves 3 of this embodiment include an inner shoulder circumferential groove 3A arranged on the innermost tread edge Ti side when mounted on a vehicle, and an inner crown circumferential groove 3B arranged between the inner shoulder circumferential groove 3A and the tire equator C. It is preferable that the circumferential grooves 3 further include an outer crown circumferential groove 3C adjacent to the inner crown circumferential groove 3B across the tire equator C, and an outer shoulder circumferential groove 3D arranged on the outermost tread edge To side.

[0078] The inner shoulder circumferential groove 3A of this embodiment is a circumferential groove 3 between the second edge portion 21 of the fourth land portion 4D and the edge portion 26 of the fifth land portion 4E. Such an inner shoulder circumferential groove 3A can generate a large snow column shear force by changing the groove width with the bending of the second edge portion 21, and can further improve the on-snow performance of the tire 1.

[0079] The groove width of the inner crown circumferential groove 3B is preferably larger than the groove width of the outer crown circumferential groove 3C. Such a tread portion 2 can compact more snow on the inner side of the vehicle when mounted on the vehicle, thereby improving the on-snow performance of the tire 1.

[0080] The first land portion 4A of the present embodiment is a crown land portion divided by the inner crown circumferential groove 3B and the outer crown circumferential groove 3C and disposed on the tire equator C. The second land portion 4B of the present embodiment is an outer middle land portion divided by the outer crown circumferential groove 3C and the outer shoulder circumferential groove 3D. The third land portion 4C of the present embodiment is an outer shoulder land portion divided between the outer shoulder circumferential groove 3E and the outer tread edge To.

[0081] The fourth land portion 4D of the present embodiment is an inner middle land portion divided by the inner shoulder circumferential groove 3A and the inner crown circumferential groove 3B. The fifth land portion 4E of the present embodiment is an inner shoulder land portion divided between the inner shoulder circumferential groove 3A and the inner tread edge Ti.

[0082] 1 and 2, in the first land portion 4A, the second portion 8b of the second groove edge portion 8 of the first lateral groove 5A of this embodiment is located on the vehicle outer side of the first portion 8a when mounted on the vehicle. Such a first lateral groove 5A can generate a larger snow column shear force on the vehicle outer side, thereby improving the on-snow performance of the tire 1.

[0083] The second portion 8b is desirably disposed at a position straddling the tire equator C. Such first lateral grooves 5A have a groove width that gradually increases at the axial center position of the tread portion 2, so that a larger snow column shear force can be generated, thereby improving the on-snow performance of the tire 1.

[0084] 1 and 3, in the fourth land portion 4D, the deep groove portion 5b of the fourth lateral groove 5D is preferably located on the vehicle outer side of the shallow groove portion 5c when the fourth land portion 4D is mounted on the vehicle. In this embodiment, the deep groove portion 5b of the fourth lateral groove 5D is located closer to the tire equator C than the shallow groove portion 5c. Such a fourth lateral groove 5D can compact more snow on the inner side in the tire axial direction, thereby improving the on-snow performance of the tire 1.

[0085] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment and can be modified in various ways. EXAMPLES

[0086] A tire of the embodiment having the tread pattern of FIG. 1 was prototyped based on the specifications of Table 1. As a comparative example, a tire was prototyped in which the second groove edge of the first lateral groove was made only of the first portion, so that the groove width of the first lateral groove was constant. Using the prototype tire, the dry performance, ice performance, and snow performance were tested. The common specifications and test methods are as follows.

[0087] <Common specifications> Tire size: 195 / 65R15 Rim size: 15×6.0JJ Air pressure: 200kPa Test vehicle: Front-wheel drive mid-size passenger car

[0088] <Dry performance> The test vehicle was fitted with prototype tires on all wheels, and the test driver evaluated the steering stability performance when the vehicle was driven on a test course on dry roads. Similar tests were conducted by multiple test drivers, and the total score was calculated. The results were expressed as an index, with the total score of the comparative example being 100, and the higher the index value, the better the dry performance.

[0089] <Ice performance> A test vehicle fitted with prototype tires was driven on a test course on an icy road surface, and the steering stability performance was evaluated by the test driver through his senses. Similar tests were conducted by multiple test drivers, and the total score was calculated. The results were expressed as an index, with the total score of the comparative example being 100, and the higher the value, the better the performance on ice.

[0090] <Snow performance> The test vehicle was fitted with prototype tires on all wheels, and the test driver evaluated the steering stability performance when the vehicle was driven on a test course on snowy roads. Similar tests were conducted by multiple test drivers, and the total score was calculated. The results were expressed as an index, with the total score of the comparative example being 100, and the higher the index value, the better the performance on snow.

[0091] The test results are shown in Table 1. [Table 1]

[0092] As a result of the tests, it was confirmed that the tires of the examples had better dry performance, ice performance, and snow performance than the comparative examples, and also had excellent overall performance evaluated by the sum of these values, thereby achieving a balanced improvement in dry performance, ice performance, and snow performance. [Explanation of symbols]

[0093] 1 Tire 2 Tread section 3 Circumferential groove 4 Land 5 Yokomizo 7 First groove edge 8 Second groove edge 8a Part 1 8b Part 2

Claims

1. A tire having a tread portion, The tread portion includes a plurality of circumferential grooves extending continuously in a tire circumferential direction, a land portion divided by the circumferential grooves, and a plurality of lateral grooves crossing the land portion, At least one of the lateral grooves has a first groove edge portion on one side in the tire circumferential direction and a second groove edge portion on the other side in the tire circumferential direction, The first groove edge portion extends linearly, the second groove edge portion includes a first portion extending parallel to the first groove edge portion and a second portion extending from the first portion such that the groove width gradually increases, The tread portion has an asymmetric tread pattern with a specified orientation for mounting on a vehicle, The second portion is located on the outer side of the first portion when the vehicle is mounted. tire.

2. A tire having a tread portion, The tread portion includes a plurality of circumferential grooves extending continuously in a tire circumferential direction, a land portion divided by the circumferential grooves, and a plurality of lateral grooves crossing the land portion, At least one of the lateral grooves has a first groove edge portion on one side in the tire circumferential direction and a second groove edge portion on the other side in the tire circumferential direction, The first groove edge portion extends linearly, the second groove edge portion includes a first portion extending parallel to the first groove edge portion and a second portion extending from the first portion such that the groove width gradually increases, The land portion includes a crown land portion disposed on a tire equator, The second portion is disposed at a position straddling the tire equator. tire.

3. The tread portion has an asymmetric tread pattern with a specified orientation for mounting on a vehicle, The crown land portion is divided into an outer crown circumferential groove disposed on an outer side of a vehicle when the tire is mounted on the vehicle and an inner crown circumferential groove disposed on an inner side of the vehicle, The tire of claim 2 , wherein a groove width of the inner crown circumferential groove is greater than a groove width of the outer crown circumferential groove.

4. A tire having a tread portion, The tread portion includes a plurality of circumferential grooves extending continuously in a tire circumferential direction, a land portion divided by the circumferential grooves, and a plurality of lateral grooves crossing the land portion, At least one of the lateral grooves has a first groove edge portion on one side in the tire circumferential direction and a second groove edge portion on the other side in the tire circumferential direction, The first groove edge portion extends linearly, the second groove edge portion includes a first portion extending parallel to the first groove edge portion and a second portion extending from the first portion such that the groove width gradually increases, The land portion includes a first land portion divided by the pair of circumferential grooves and a second land portion adjacent to the first land portion, the lateral grooves include a first lateral groove crossing the first land portion and a second lateral groove crossing the second land portion, The first lateral groove has the first groove edge portion and the second groove edge portion, The second transverse groove has a constant groove width. tire.

5. the first lateral groove includes an opening portion that opens into the circumferential groove on a side of the second portion, The tire according to claim 4 , wherein the second lateral groove opens into the circumferential groove at a position facing the opening portion with the circumferential groove interposed therebetween.

6. The tire according to claim 4 or 5, wherein a groove width of the first lateral groove in a region having the first portion is 30% to 50% of a groove width of the second lateral groove.

7. The tire according to any one of claims 1 to 6, wherein the length of the second portion in the tire axial direction is 50% to 200% of the length of the first portion in the tire axial direction.

8. The tire according to any one of claims 1 to 7, wherein a groove depth of the lateral groove in the region having the second portion is 60% to 100% of a groove depth of the circumferential groove.

9. The land portion has a circumferential narrow groove extending in the tire circumferential direction, The tire according to claim 1 , wherein the circumferential narrow groove communicates with the first portion.

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