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, and land parts 4 partitioned into the circumferential grooves 3. The land parts 4 include a first land part 4A partitioned between the pair of circumferential grooves 3. The first land part 4A includes a plurality of first blocks 6 partitioned by a plurality of first lateral grooves 5A traversing the first land part 4A in a tire axial direction. The first block 6 includes a first edge part 7 extending in the tire circumferential direction on one side of the tire axial direction, and a second edge part 8 bent so as to be recessed to the first edge part 7 side on the other side of the tire axial direction. The second edge part 8 is constituted of a pair of gradually increasing portions 8d, 8e for gradually increasing a width of the first block 6 from the narrowest portion 8a having the smallest width in the tire axial direction of the first block 6 to both ends 8b, 8c in the tire circumferential direction.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 dry and icy performance, and 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 the tire circumferential direction and a land portion divided by the circumferential grooves, the land portion including a first land portion divided between a pair of the circumferential grooves, the first land portion including a plurality of first blocks divided by a plurality of first lateral grooves crossing the first land portion in the tire axial direction, the first blocks including a first edge portion extending in the tire circumferential direction on one side in the tire axial direction and a second edge portion bent so as to be recessed toward the first edge portion on the other side in the tire axial direction, the second edge portion being composed of a pair of gradually increasing portions that gradually increase the width of the first block from a narrowest portion where the axial width of the first block is the smallest toward both ends in the tire circumferential direction.

[0007] In the tire of the present invention, it is preferable that the first edge portion extends linearly.

[0008] In the tire of the present invention, it is desirable that the land portion includes a second land portion adjacent to the second edge side of the first land portion, the second land portion includes a plurality of second blocks divided by a plurality of second lateral grooves that cross the second land portion in the tire axial direction, and the edge of the second blocks on the first land portion side extends in a straight line.

[0009] In the tire of the present invention, it is preferable that the second lateral groove opens into the circumferential groove at a position facing the narrowest portion with the circumferential groove interposed therebetween.

[0010] In the tire of the present invention, it is preferable that each of the first block and the second block has a plurality of lateral sipes extending in the tire axial direction.

[0011] In the tire of the present invention, it is preferable that the first lateral groove has a different groove depth between the first edge side and the second edge side.

[0012] In the tire of the present invention, it is preferable that the first lateral groove includes a deep groove portion having a larger groove depth on the first edge side, and a shallow groove portion having a smaller groove depth on the second edge side.

[0013] In the tire of the present invention, it is preferable that the first lateral groove extends linearly in a direction inclined with respect to the tire axial direction.

[0014] In the tire of the present invention, it is preferable that the distance in the tire circumferential direction between the narrowest portion and the end portion on one side in the tire circumferential direction of the second edge portion of the first block is 0.5 to 2.0 times the distance in the tire circumferential direction between the narrowest portion and the end portion on the other side in the tire circumferential direction of the second edge portion.

[0015] In the tire of the present invention, it is preferable that the first edge portion of the first block extends parallel to the tire circumferential direction.

[0016] In the tire of the present invention, it is preferable that the tread portion has an asymmetric tread pattern in which the orientation of mounting on a vehicle is specified, the circumferential groove includes an inner shoulder circumferential groove arranged on the innermost tread end side when mounted on a vehicle, and an inner crown circumferential groove arranged between the inner shoulder circumferential groove and the tire equator, and the first land portion is an inner middle land portion divided by the inner shoulder circumferential groove and the inner crown circumferential groove. Effect of the Invention

[0017] In the tire of the present invention, the first block includes a first edge portion extending circumferentially on one side in the tire axial direction, and a second edge portion bent so as to be recessed toward the first edge portion on the other side in the tire axial direction, and the second edge portion is composed of a pair of gradually increasing portions that gradually increase the width of the first block from a narrowest portion, where the axial width of the first block is the smallest, toward both ends in the tire circumferential direction.

[0018] In such a first block, the second edge portion forms a slot portion in its entirety, which suppresses local changes in rigidity and improves the tire's dry performance and performance on ice. In addition, the first block can generate a large snow column shear force due to the high rigidity of the gradually increasing portion, thereby improving the tire's performance on snow. Therefore, the tire of the present invention can improve dry performance, performance on ice, and performance on snow in a well-balanced manner. [Brief description of the drawings]

[0019] [Figure 1] 1 is a development view showing one embodiment of a tread portion of a tire of the present invention. [Diagram 2] FIG. 2 is an enlarged view of a first land portion in FIG. [Diagram 3] 2 is an enlarged view of a third land portion and a fourth land portion of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] 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.

[0021] 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").

[0022] 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.

[0023] Fig. 2 is an enlarged view of the first land portion 4A in Fig. 1. As shown in Fig. 2, the first block 6 of this embodiment includes a first edge portion 7 extending in the tire circumferential direction on one side in the tire axial direction, and a second edge portion 8 bent so as to be recessed toward the first edge portion 7 on the other side in the tire axial direction. The second edge portion 8 is preferably composed of a pair of gradually increasing portions 8d, 8e that gradually increase the width of the first block 6 from a narrowest portion 8a, where the axial width W1 of the first block 6 is the smallest, toward both ends 8b, 8c in the tire circumferential direction.

[0024] In such a first block 6, the second edge portion 8 forms a slot portion in its entirety, which suppresses localized changes in rigidity and improves the steering stability performance (hereinafter referred to as "dry performance") of the tire 1 when traveling on dry roads and the performance on ice. In addition, the first block 6 can generate a large snow column shear force due to the high rigidity of the gradually increasing portions 8d, 8e, thereby improving the performance on snow of the tire 1. 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.

[0025] In a more preferred embodiment, the first edge portion 7 extends linearly. Such a first edge portion 7 improves the rigidity of the first block 6 and helps to improve the dry performance, ice performance, and snow performance of the tire 1 in a well-balanced manner.

[0026] The recess amount d of the second edge portion 8 is preferably 5% to 30% of the axial width W1 of the narrowest portion 8a of the first block 6. Such a first block 6 can generate a large snow column shear force while improving the ratio and rigidity of the first land portion 4A, and can improve the dry performance, ice performance, and snow performance of the tire 1 in a well-balanced manner.

[0027] In the first block 6, the distance L1 in the tire circumferential direction between the narrowest portion 8a and an end 8b on one side in the tire circumferential direction of the second edge portion 8 is preferably 0.5 to 2.0 times the distance L2 in the tire circumferential direction between the narrowest portion 8a and an end 8c on the other side in the tire circumferential direction of the second edge portion 8. Since such a first block 6 has an averaged rigidity, the dry performance of the tire 1 can be further improved.

[0028] Here, when the section from the narrowest portion 8a to one end 8b is defined as a first gradually increasing section 8d, and the section from the narrowest portion 8a to the other end 8c is defined as a second gradually increasing section 8e, distance L1 is the length of the first gradually increasing section 8d in the tire circumferential direction, and distance L2 is the length of the second gradually increasing section 8e in the tire circumferential direction.

[0029] It is desirable that the first edge portion 7 of the first block 6 extends parallel to the tire circumferential direction. Such a first block 6 suppresses a decrease in rigidity on the first edge portion 7 side, and can further improve the on-ice performance of the tire 1.

[0030] The first lateral grooves 5A of this embodiment extend linearly in a direction inclined with respect to the tire axial direction. The first lateral grooves 5A have, for example, a first groove edge 9 on one side in the tire circumferential direction and a second groove edge 10 on the other side in the tire circumferential direction. It is preferable that at least one of the first groove edge 9 and the second groove edge 10 of the first lateral grooves 5A extends linearly.

[0031] The first lateral grooves 5A are linear, which helps maintain high rigidity of the first blocks 6, 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.

[0032] It is desirable that the first lateral grooves 5A have different groove depths on the first edge 7 side and the second edge 8 side. The groove depth of such first lateral grooves 5A can be appropriately set according to the rigidity required for the first block 6 and the amount of packed snow required for the first lateral grooves 5A.

[0033] The first lateral groove 5A of this embodiment includes a deep groove portion 5a having a large groove depth on the first edge 7 side and a shallow groove portion 5b having a small groove depth on the second edge 8 side. Such a first lateral groove 5A can increase the rigidity of the second edge 8 side of the first block 6 where the rigidity is likely to decrease due to bending, and can further improve the on-ice performance of the tire 1. In addition, the first lateral groove 5A can strongly compact snow with the shallow groove portion 5b to generate a large snow column shear force, and can improve the on-snow performance of the tire 1.

[0034] In the first transverse groove 5A, it is preferable that the groove width W2 of the deep groove portion 5a is larger than the groove width W3 of the shallow groove portion 5b. In the first transverse groove 5A of this embodiment, the first groove edge portion 9 extends linearly and the second groove edge portion 10 is formed in a stepped shape, so that the groove width W2 of the deep groove portion 5a is larger than the groove width W3 of the shallow groove portion 5b.

[0035] Such first lateral grooves 5A can compact more snow in the deep groove portion 5a, improving the on-snow performance of the tire 1. In addition, the first lateral grooves 5A are useful for increasing the rigidity of the second edge portion 8 side of the first block 6, which is prone to decrease in rigidity due to bending, and can further improve the on-ice performance of the tire 1.

[0036] The first block 6 of this embodiment has a plurality of lateral sipes 11 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.

[0037] 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.

[0038] "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.

[0039] For example, at least one of the lateral sipes 11 of the first block 6 communicates with the circumferential groove 3. In this embodiment, the lateral sipes 11 of the first block 6 extend in a zigzag pattern in a direction inclined to the tire axial direction. 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 11. Note that the lateral sipes 11 of the first block 6 are not limited to this form, and for example, both ends may terminate within the first block 6, or the lateral sipes 11 may extend linearly.

[0040] 1, the land portion 4 desirably includes a second land portion 4B adjacent to the second edge portion 8 side of the first land portion 4A, and a third land portion 4C adjacent to the first edge portion 7 side of the first land portion 4A. The land portion 4 may further include, for example, a fourth land portion 4D adjacent to the third land portion 4C on the side opposite to the first land portion 4A, and a fifth land portion 4E adjacent to the fourth land portion 4D on the side opposite to the third land portion 4C.

[0041] 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.

[0042] The second land portion 4B of this embodiment includes a plurality of second blocks 12 divided by a plurality of second lateral grooves 5B that cross the second land portion 4B in the tire axial direction. The second blocks 12 of this embodiment have an edge portion 13 on the first land portion 4A side that extends linearly. Such second blocks 12 suppress a decrease in rigidity on the first land portion 4A side, and can further improve the on-ice performance of the tire 1.

[0043] In the present embodiment, the circumferential groove 3 between the first land portion 4A and the second land portion 4B has a groove width that changes smoothly due to the second edge portion 8 of the first block 6 and the edge portion 13 of the second block 12. That is, the groove width of this circumferential groove 3 is the largest at the position of the narrowest portion 8a of the first block 6, the groove width gradually decreases due to the gradually increasing portions 8d, 8e of the second edge portion 8, and the groove width is the smallest at the positions of the ends 8b, 8c of the first block 6. Such a circumferential groove 3 can generate a large snow column shear force by changing the groove width with the bending of the second edge portion 8, and can further improve the on-snow performance of the tire 1.

[0044] The second block 12 of this embodiment has a plurality of lateral sipes 14 extending in the tire axial direction. The lateral sipes 14 of the second block 12 are connected to, for example, the circumferential groove 3. The lateral sipes 14 of the second block 12 of this embodiment extend in a zigzag shape in a direction inclined in the opposite direction to the lateral sipes 11 of the first block 6 with respect to the tire axial direction. The lateral sipes 14 of the second block 12 have, for example, an interrupted portion 14a that is interrupted midway in the longitudinal direction.

[0045] Such second blocks 12 can further improve the on-ice performance of the tire 1 due to the edge effect of the lateral sipes 14. Note that the lateral sipes 14 of the second blocks 12 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 14a.

[0046] The second lateral grooves 5B of this embodiment extend linearly in a direction inclined in the opposite direction to the first lateral grooves 5A. The second lateral grooves 5B have, for example, a constant groove width W4. The linear shape of the second lateral grooves 5B helps maintain high rigidity of the second blocks 12, 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 W4.

[0047] The second lateral grooves 5B desirably open into the circumferential groove 3 at a position facing the narrowest portion 8a of the second edge portion 8 of the first block 6 via the circumferential groove 3. Such second lateral grooves 5B can cooperate with the second edge portion 8 of the first block 6 to generate a large snow column shear force, thereby improving the on-snow performance of the tire 1.

[0048] Fig. 3 is an enlarged view of the third land portion 4C and the fourth land portion 4D in Fig. 1. As shown in Fig. 3, the third land portion 4C is preferably divided by a pair of circumferential grooves 3. The third land portion 4C in this embodiment includes a plurality of third blocks 15 divided by a plurality of third lateral grooves 5C crossing the third land portion 4C in the tire axial direction. The third lateral groove 5C has, for example, a third groove edge portion 16 on one side in the tire circumferential direction and a fourth groove edge portion 17 on the other side in the tire circumferential direction.

[0049] In this embodiment, the third groove edge 16 extends linearly. The fourth groove edge 17 preferably includes a first portion 17a extending parallel to the third groove edge 16 and a second portion 17b extending from the first portion 17a so that the groove width gradually increases. Therefore, the fourth groove edge 17 extends while being bent by the first portion 17a and the second portion 17b.

[0050] By varying the groove width, such third lateral grooves 5C can improve traction on snowy road surfaces and improve the on-snow performance of the tire 1. In addition, since the third lateral grooves 5C do not add other slots or grooves to the third land portion 4C that the third lateral grooves 5C cross, it is possible to suppress a decrease in the ratio and rigidity of the third land portion 4C and improve the dry performance and on-ice 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.

[0051] The third groove edge 16 preferably extends in a direction inclined relative to the tire axial direction. In this embodiment, the third groove edge 16 extends in a direction inclined in the opposite direction to the first lateral groove 5A. Such a third groove edge 16 can exert an edge effect in the tire circumferential direction and the tire axial direction, and can improve the on-ice performance of the tire 1.

[0052] It is preferable that the first portion 17a and the second portion 17b of the fourth groove edge 17 extend linearly. Such a fourth groove edge 17 prevents the rigidity of the third block 15 from decreasing, and helps to improve the dry performance and on-ice performance of the tire 1.

[0053] The axial length L4 of the second portion 17b is preferably 50% to 200% of the axial length L3 of the first portion 17a. Such a fourth groove edge portion 17 has an excellent balance between the first portion 17a and the second portion 17b, and helps to improve the dry performance, ice performance, and snow performance of the tire 1 in a well-balanced manner.

[0054] The groove depth of the third lateral groove 5C in the region R2 having the second portion 17b is preferably greater than the groove depth of the third lateral groove 5C in the region R1 having the first portion 17a. Such third lateral groove 5C can compact more snow in the region R2 having the second portion 17b, and can compact snow strongly in the region R1 having the first portion 17a to generate a large snow column shear force. Therefore, the tire 1 of this embodiment can further improve the on-snow performance.

[0055] The groove depth of the third lateral grooves 5C in the region R2 having the second portions 17b is preferably 60% to 100% of the groove depth of the circumferential grooves 3. Such third lateral grooves 5C suppress a decrease in rigidity of the third blocks 15 and are useful for improving the dry performance and on-ice performance of the tire 1.

[0056] The third land portion 4C of the present embodiment has a circumferential narrow groove 18 extending in the tire circumferential direction. The circumferential narrow groove 18 is preferably connected to the first portion 17a. Such a circumferential narrow groove 18 can exert an edge effect while maintaining the high rigidity of the third land portion 4C, and can further improve the on-ice performance of the tire 1.

[0057] The third block 15 of this embodiment has a plurality of lateral sipes 19 extending in the tire axial direction. At least one of the lateral sipes 19 of the third block 15, for example, has at least one end connected to the circumferential groove 3. The lateral sipes 19 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 11 of the first block 6 with respect to the tire axial direction. The lateral sipes 19 of the third block 15 have, for example, a discontinuous portion 19a that is not connected to the circumferential narrow groove 18. That is, the circumferential narrow groove 18 of this embodiment is provided in the discontinuous portion 19a.

[0058] Such third blocks 15 can further improve the on-ice performance of the tire 1 due to the edge effect of the lateral sipes 19. Note that the lateral sipes 19 of the third blocks 15 are not limited to this embodiment, and may, for example, terminate without communicating with the circumferential groove 3, extend linearly, or communicate with the circumferential narrow groove 18.

[0059] The third lateral groove 5C includes, for example, an opening 5c ​​that opens to the circumferential groove 3 on the second portion 17b side. In this embodiment, the groove width W6 of the third lateral groove 5C at the opening 5c ​​is larger than the groove width W5 of the third lateral groove 5C in the region R1 having the first portion 17a. Here, the groove width W6 of the third lateral groove 5C at the opening 5c ​​is the maximum groove width of the third lateral groove 5C in the region R2 having the second portion 17b.

[0060] The fourth land portion 4D is preferably divided by a pair of circumferential grooves 3. The fourth land portion 4D of this embodiment includes a plurality of fourth blocks 20 divided by a plurality of fourth lateral grooves 5D crossing the fourth land portion 4D in the tire axial direction. The fourth lateral grooves 5D of this embodiment extend linearly in a direction inclined in the opposite direction to the third lateral grooves 5C.

[0061] The fourth lateral groove 5D of this embodiment has a constant groove width W7. The fourth lateral groove 5D is linear, which helps maintain high rigidity of the fourth block 20, and is inclined, which provides an edge effect in the tire circumferential direction and the tire axial direction. The fourth lateral groove 5D is not limited to this form, and may extend in a curved shape or have a variable groove width W7.

[0062] The fourth lateral groove 5D of the present embodiment opens into the circumferential groove 3 at a position facing the opening 5c ​​of the third lateral groove 5C via the circumferential groove 3. Such third lateral groove 5C and fourth lateral groove 5D cooperate with each other to generate a large snow column shear force, thereby improving the on-snow performance of the tire 1.

[0063] The groove width W6 of the third lateral groove 5C at the opening 5c ​​is preferably equal to or smaller than the groove width W7 of the fourth lateral groove 5D. Such third lateral groove 5C can suppress a decrease in the ratio and rigidity of the third land portion 4C, and can improve the dry performance and on-ice performance of the tire 1.

[0064] The groove width W5 of the third lateral groove 5C in the region R1 having the first portion 17a is preferably 30% to 50% of the groove width W7 of the fourth lateral groove 5D. Such a third lateral groove 5C can suppress a decrease in the ratio and rigidity of the third land portion 4C, and can improve the dry performance and on-ice performance of the tire 1.

[0065] The fourth block 20 of this embodiment has a plurality of lateral sipes 21 extending in the tire axial direction. For example, at least one end of the lateral sipes 21 of the fourth block 20 communicates with the circumferential groove 3. The lateral sipes 21 of the fourth block 20 of this embodiment extend in a zigzag shape in a direction inclined in the opposite direction to the lateral sipes 19 of the third block 15 with respect to the tire axial direction. The lateral sipes 21 of the fourth block 20 have, for example, an interrupted portion 21a that is interrupted midway in the longitudinal direction.

[0066] Such a fourth block 20 can further improve the on-ice performance of the tire 1 due to the edge effect of the lateral sipes 21. Note that the lateral sipes 21 of the fourth block 20 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 21a.

[0067] 1, the fourth block 20 has a slot 23, for example, in an edge portion 22 on the fifth land portion 4E side. The slot 23 is desirably provided at a position facing the fifth lateral groove 5E across the circumferential groove 3. Such a slot 23 can cooperate with the fifth lateral groove 5E to generate a large snow column shear force, thereby improving the on-snow performance of the tire 1.

[0068] The fifth land portion 4E of this embodiment includes a plurality of fifth blocks 24 divided by a plurality of fifth lateral grooves 5E that cross the fifth land portion 4E in the tire axial direction. The fifth blocks 24 of this embodiment have an edge portion 25 on the fourth land portion 4D side that extends linearly. Such fifth blocks 24 suppress a decrease in rigidity on the fourth land portion 4D side, and can further improve the on-ice performance of the tire 1.

[0069] 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 24, 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.

[0070] The fifth block 24 has a slot 26, for example, at an edge portion 25 on the fourth land portion 4D side. The slot 26 is desirably provided at a position facing the fourth lateral groove 5D across the circumferential groove 3. Such a slot 26 can cooperate with the fourth lateral groove 5D to generate a large snow column shear force, thereby improving the on-snow performance of the tire 1.

[0071] The fifth block 24 of this embodiment has a plurality of lateral sipes 27 extending in the tire axial direction. At least one of the lateral sipes 27 of the fifth block 24, for example, communicates with the circumferential groove 3. The lateral sipes 27 of the fifth block 24 of this embodiment extend in a zigzag shape in a direction inclined in the opposite direction to the lateral sipes 21 of the fourth block 20 with respect to the tire axial direction. The lateral sipes 27 of the fifth block 24 have, for example, an interrupted portion 27a that is interrupted midway in the longitudinal direction.

[0072] Such a fifth block 24 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 24 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 an interrupted portion 27a.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] The inner shoulder circumferential groove 3A of this embodiment is a circumferential groove 3 between the second edge portion 8 of the first land portion 4A and the edge portion 13 of the second land portion 4B. 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 8, and can further improve the on-snow performance of the tire 1.

[0078] 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.

[0079] The first land portion 4A of this embodiment is an inner middle land portion divided by the inner shoulder circumferential groove 3A and the inner crown circumferential groove 3B. The second land portion 4B of this embodiment is an inner shoulder land portion divided between the inner shoulder circumferential groove 3A and the inner tread edge Ti. The third land portion 4C of this 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.

[0080] The fourth land portion 4D 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 fifth land portion 4E 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] 1 and 2, in the first land portion 4A, the deep groove portion 5a of the first lateral groove 5A is preferably located on the vehicle outer side of the shallow groove portion 5b when the tire is mounted on the vehicle. In this embodiment, the deep groove portion 5a of the first lateral groove 5A is located closer to the tire equator C than the shallow groove portion 5b. Such a first lateral groove 5A can compact more snow on the inner side in the tire axial direction, improving the on-snow performance of the tire 1.

[0082] 1 and 3, in the third land portion 4C, the second portion 17b of the fourth groove edge portion 17 of the third lateral groove 5C of this embodiment is located on the vehicle outer side of the first portion 17a when mounted on the vehicle. Such a third lateral groove 5C 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 17b is desirably disposed at a position straddling the tire equator C. Such third lateral grooves 5C have a groove width that gradually increases at the axial center 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] 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

[0085] 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 a conventional partial slot was provided in the center of the first block in the tire circumferential direction. The slot of the comparative example has a slot width in the tire circumferential direction smaller than the slot length in the tire axial direction, and the slot length is equal to the recess amount d of Example 1. Using the prototype tire, the dry performance, ice performance, and snow performance were tested. The common specifications and test methods are as follows.

[0086] <Common specifications> Tire size: 195 / 65R15 Rim size: 15×6.0JJ Air pressure: 200kPa Test vehicle: Front-wheel drive mid-size passenger car

[0087] <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.

[0088] <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.

[0089] <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.

[0090] The test results are shown in Table 1. [Table 1]

[0091] 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 that the overall performance, which is determined by the sum of these values, was also improved, resulting in a well-balanced improvement in dry performance, ice performance, and snow performance. [Explanation of symbols]

[0092] 1 Tire 2 Tread section 3 Circumferential groove 4 Land 4A 1st Land Department 5A First Yokomizo 6 1st Block 7 First groove edge 8 Second groove edge 8a Narrowest part 8b end 8c end 8d Gradual increase 8e Gradual increase

Claims

1. A tire having a tread portion, The tread portion includes a plurality of circumferential grooves extending continuously in a tire circumferential direction and a land portion divided by the circumferential grooves, The land portion includes a first land portion partitioned between the pair of circumferential grooves, The first land portion includes a plurality of first blocks divided by a plurality of first lateral grooves that cross the first land portion in the tire axial direction, The first block includes a first edge portion extending in a tire circumferential direction on one side in the tire axial direction and a second edge portion bent so as to be recessed toward the first edge portion on the other side in the tire axial direction, the second edge portion is composed of a pair of gradually increasing portions that gradually increase the width of the first block from a narrowest portion, where the width of the first block in the tire axial direction is smallest, toward both ends in the tire circumferential direction, the land portion includes a second land portion adjacent to the first land portion on the second edge portion side, The second land portion includes a plurality of second blocks divided by a plurality of second lateral grooves that cross the second land portion in the tire axial direction, The second block has an edge portion on the first land portion side extending linearly, The second lateral groove opens into the circumferential groove at a position facing the narrowest portion with the circumferential groove interposed therebetween. tire.

2. The tire according to claim 1 , wherein the first block and the second block each have a plurality of lateral sipes extending in an axial direction of the tire.

3. A tire having a tread portion, The tread portion includes a plurality of circumferential grooves extending continuously in a tire circumferential direction and a land portion divided by the circumferential grooves, The land portion includes a first land portion partitioned between the pair of circumferential grooves, The first land portion includes a plurality of first blocks divided by a plurality of first lateral grooves that cross the first land portion in the tire axial direction, The first block includes a first edge portion extending in a tire circumferential direction on one side in the tire axial direction and a second edge portion bent so as to be recessed toward the first edge portion on the other side in the tire axial direction, the second edge portion is composed of a pair of gradually increasing portions that gradually increase the width of the first block from a narrowest portion, where the width of the first block in the tire axial direction is smallest, toward both ends in the tire circumferential direction, The first transverse groove has a groove depth different between the first edge side and the second edge side. tire.

4. The tire according to claim 3 , wherein the first lateral groove includes a deep groove portion having a larger groove depth on the first edge side and a shallow groove portion having a smaller groove depth on the second edge side.

5. 5. The tire according to claim 1, wherein the first edge portion extends in a straight line.

6. The tire according to claim 1 , wherein the first lateral groove extends linearly in a direction inclined with respect to the tire axial direction.

7. 7. The tire according to claim 1, wherein the first block has a circumferential distance between the narrowest portion and the end portion on one side in the tire circumferential direction of the second edge portion that is 0.5 to 2.0 times the circumferential distance between the narrowest portion and the end portion on the other side in the tire circumferential direction of the second edge portion.

8. The tire according to claim 1 , wherein the first edge portion of the first block extends parallel to the tire circumferential direction.

9. The tread portion has an asymmetric tread pattern with a specified orientation for mounting on a vehicle, the circumferential groove includes an inner shoulder circumferential groove disposed on an innermost tread end side when mounted on a vehicle, and an inner crown circumferential groove disposed between the inner shoulder circumferential groove and a tire equator, The tire according to claim 1 , wherein the first land portion is an inner middle land portion divided by the inner shoulder circumferential groove and the inner crown circumferential groove.

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