Tire

Abstract

The tire of the present invention has excellent dry road performance. The tire (1) is provided with a first land portion (3) divided by a shoulder circumferential groove (5A) and a tread end (Te) in a tread portion (2). A first sipe (7) extending in the tire circumferential direction, a plurality of transverse sipes (8), and a first transverse groove (9) extending from the tread end (Te) are provided in the first land portion (3). The first sipe (7) does not communicate with the first transverse groove (9). An inner end (8i) of the transverse sipe (8) is connected to the shoulder circumferential groove (5A). An outer end (8e) of the transverse sipe (8) is connected to the first sipe (7).

Description

TECHNICAL FIELD

[0001] The present application relates to a tire. BACKGROUND

[0002] A pneumatic tire having an outer side region which is located further outside a vehicle than a tire equator when mounted to a vehicle is described in Patent Document 1. An intermediate land portion and a shoulder land portion are provided in the outer side region. An outer side intermediate sipe which traverses the intermediate land portion is provided in the intermediate land portion, and an outer side shoulder sipe which traverses the shoulder land portion is provided in the shoulder land portion. Patent Document 1 improves dry road performance, wet road performance, and wear resistance by defining the inclination direction and inclination angle of the outer side intermediate sipe and the outer side shoulder sipe.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-196286

[0004] In recent years, it is desired to further improve dry road performance. In order to improve dry road performance, for example, it is required to increase the equivalent side stiffness (equivalent CP) of a tire.

[0005] The equivalent CP is obtained by dividing the tire side stiffness (CP) by the self-aligning torque stiffness (SATP). The CP generally becomes larger by increasing the rigidity of a tread portion. The SATP is the self-aligning torque (SAT) when a slip angle of 1 degree is imparted to a tire during running. The SAT is expressed by the sum of the braking force and the driving force on the tire circumferential line of the tread ground surface. Therefore, an increase in the rigidity of the tread portion in the tire circumferential direction results in an increase in the SATP, and thus the equivalent CP cannot be increased.

[0006] Therefore, in order to improve dry road performance, it is effective to suppress a decrease in the CP and to maintain the SATP small, that is, to suppress an increase in the rigidity of the tread portion in the tire circumferential direction. In particular, it is desirable to suppress an increase in the rigidity of the tire circumferential direction on the tread end where the SAT is largest. SUMMARY

[0007] The present application has been made in view of the above-described circumstances, and a main object thereof is to provide a tire which further improves dry road performance.

[0008] The tire of the present application has a tread portion, wherein a shoulder circumferential sipe which extends in the tire circumferential direction on the most tread end side is provided in the tread portion, and a first land portion which is divided by the shoulder circumferential sipe and the tread end is provided in the tread portion, a plurality of first sipes which extend in the tire circumferential direction, a plurality of transverse sipes, and a plurality of first transverse grooves which extend from the tread end toward the inside in the tire axial direction are provided in the first land portion, the first sipes are not communicated with the first transverse grooves, the inner end in the tire axial direction of each of the transverse sipes is connected to the shoulder circumferential sipe, and the outer end in the tire axial direction of each of the transverse sipes is connected to any one of the first sipes.

[0009] The tire of the present application preferably has a plurality of second sipes connecting the plurality of first sipes.

[0010] The tire of the present application preferably has a plurality of second sipes connecting the plurality of first sipes.

[0011] The tire of the present application preferably has a plurality of second sipes connecting the plurality of first sipes.

[0012] The tire of the present application preferably has a plurality of second sipes connecting the plurality of first sipes.

[0013] The tire of the present application preferably has a plurality of second sipes connecting the plurality of first sipes.

[0014] The tire of the present application preferably has a plurality of second sipes connecting the plurality of first sipes.

[0015] The tire of the present application preferably has a plurality of second sipes connecting the plurality of first sipes.

[0016] The tire of the present application preferably has a plurality of second sipes connecting the plurality of first sipes.

[0017] The tire of the present application preferably has a plurality of second sipes connecting the plurality of first sipes.

[0018] The tire of the present application preferably has a plurality of second sipes connecting the plurality of first sipes.

[0019] The tire of the present application preferably has a plurality of second sipes connecting the plurality of first sipes.

[0020] The tire of the present application preferably has a plurality of second sipes connecting the plurality of first sipes.

[0021] The tire of the present application preferably has a plurality of second sipes connecting the plurality of first sipes. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1is a plan view of a first land portion of a tread portion of one embodiment of the tire of the present application.

[0023] Figure 2 (a) is an enlarged view of the first sipe, and (b) is an enlarged view of the second sipe.

[0024] Figure 3 is an overall plan view of the tread portion.

[0025] Figure 4 is a plan view of the first land portion.

[0026] Figure 5 is a plan view of the second land portion.

[0027] BRIEF DESCRIPTION OF DRAWINGS 1 … tire; 2 … tread portion; 3 … first land portion; 7 … first sipe; 8 … transverse sipe; 8i … inner end of the transverse sipe; 8e … outer end of the transverse sipe; 9 … first lateral groove; Te … tread edge. DETAILED DESCRIPTION

[0028] Hereinafter, one embodiment of the present application will be described with reference to the drawings.

[0029] Figure 1 is an enlarged plan view showing the tread portion 2 of the tire 1 of the present embodiment. The tire 1 of the present embodiment is suitable for use in a pneumatic tire for a passenger car, for example. However, the present application can be used in a pneumatic tire for heavy load, a light truck, and the like, a non-pneumatic tire that is not filled with compressed air, for example.

[0030] As shown in Figure 1 , the tread portion 2 of the present embodiment is provided with a circumferential groove 5 that extends continuously in the tire circumferential direction. In the present embodiment, the circumferential groove 5 includes a shoulder circumferential groove 5A disposed on the most tread edge Te side. The tread portion 2 is provided with a first land portion 3 divided by the shoulder circumferential groove 5A and the tread edge Te, for example.

[0031] The tread edge Te is the outermost ground contact position in the tire axial direction when the tire 1 in the normal state in which the tire is assembled to a normal rim (not shown) and filled with a normal internal pressure, and no load is applied, is applied with a normal load and grounded to a flat surface at a camber angle of 0°. Unless otherwise specified, the dimensions and the like of each portion of the tire are values measured in the above normal state. In addition, the distance in the tire axial direction between the tread edges Te on both sides in the tire axial direction is the tread width TW (shown in Figure 3 ).

[0032] The "normal rim" is the rim prescribed for each tire in the specification system including the specification to which the tire adheres, and is the "standard rim" if JATMA, the "design rim" if TRA, and the "measuring rim" if ETRTO.

[0033] The "normal inflation pressure" is the air pressure prescribed for each tire in the specification system including the specification to which the tire adheres, and is the "maximum air pressure" if JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" if TRA, and the "inflation pressure" if ETRTO.

[0034] The "normal load" is the load prescribed for each tire in the specification system including the specification to which the tire adheres, and is the "maximum load capacity" if JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" if TRA, and the "load capacity" if ETRTO.

[0035] The first land portion 3 is provided with a plurality of first sipes 7 extending in the tire circumferential direction, a plurality of transverse sipes 8, and a first transverse groove 9 extending from the tread end Te toward the inner side in the tire axial direction. The first transverse groove 9 extending from the tread end Te reduces the rigidity in the tire circumferential direction on the tread end Te of the first land portion 3, thereby reducing the SATP and improving the equivalent CP. Thus, the dry road performance is improved. In addition, the first transverse groove 9 smoothly discharges a water film on the tread surface 3a of the first land portion 3 from the tread end Te, thereby improving the wet road performance. In the present specification, the "sipe" refers to a cut groove-shaped body having a width of less than 1.5 mm. In addition, the "groove" of the transverse groove and the circumferential groove refers to a groove-shaped body having a groove width of 1.5 mm or more in the present specification.

[0036] The first sipes 7 are not communicated with the first transverse groove 9. Such first sipes 7 suppress a local reduction in the rigidity of the first land portion 3, and thus the dry road performance can be maintained at a high level. In addition, such first sipes 7 improve the uneven wear resistance. In the present embodiment, the first sipes 7 are not communicated with all the grooves and the shoulder circumferential groove 5A provided in the first land portion 3.

[0037] The inner end 8i of the transverse sipe 8 in the tire axial direction is connected to the shoulder circumferential groove 5A. In addition, the outer end 8e of the transverse sipe 8 in the tire axial direction is connected to any one of the first sipes 7. Thus, in the connection portions of the transverse sipe 8 and the first sipes 7 and the connection portions of the transverse sipe 8 and the shoulder circumferential groove 5A, the SATP is reduced to improve the road surface contact, and thus the dry road performance is further improved.

[0038] Figure 3 is a plan view of the tread portion 2. As shown in Figure 3 the present embodiment, the circumferential groove 5 includes a pair of shoulder circumferential grooves 5A, 5A, and a crown circumferential groove 5B disposed between the shoulder circumferential grooves 5A, 5A. In the present embodiment, the crown circumferential groove 5B is disposed on the tire equator C. In the present embodiment, the tread portion 2 is a point-symmetrical pattern with respect to any point on the tire equator C.

[0039] In addition, the second land portion 4 is provided in the tread portion 2 adjacent to the shoulder circumferential groove 5A on the inner side in the tire axial direction. In the present embodiment, the second land portion 4 is divided by the shoulder circumferential groove 5A and the crown circumferential groove 5B. The second land portion 4 of the present embodiment is disposed on both sides of the tire equator C.

[0040] In the present embodiment, the shoulder circumferential groove 5A and the crown circumferential groove 5B extend in a straight line along the tire circumferential direction. The shoulder circumferential groove 5A and the crown circumferential groove 5B may, for example, extend in a wavy or zigzag shape.

[0041] The groove width Wb of the crown circumferential groove 5B is preferably greater than the groove width Wa of the shoulder circumferential groove 5A. Thus, the water film on the tread surface 4a of the second land portion 4, which is difficult to drain, can be effectively drained, and thus the wet road performance can be improved. From the viewpoint of balancing the dry road performance and the wet road performance, the groove width Wb of the crown circumferential groove 5B is preferably about 110% to 140% of the groove width Wa of the shoulder circumferential groove 5A. The groove width Wa of the shoulder circumferential groove 5A is, for example, preferably about 3% to 10% of the tread width TW. In addition, the groove depth (not shown) of the shoulder circumferential groove 5A is, for example, preferably 8.5 to 11.5 mm. Furthermore, the groove depth (not shown) of the crown circumferential groove 5B is preferably 85% to 115% of the groove depth of the shoulder circumferential groove 5A.

[0042] Thus, the first land portion 3 includes the tread end Te and is disposed on the outermost side in the tire axial direction, and thus is a land portion on which a large lateral force acts when cornering. The first sipes 7 are provided in this first land portion 3, and thus the dry road performance and the wet road performance when cornering can be particularly improved.

[0043] As shown in Figure 1As shown, the plurality of first sipes 7 each extend in a circular arc shape. In comparison with linear sipes (not shown), such first sipes 7 are relatively longer in length. As a result, the effect of expelling the water film between the road surface and the tread surface 3a of the first land portion 3 by the wiping force of the first sipes 7 is improved, and thus the wet road performance is improved. The "circular arc shape" is a state in which the angle of the sipe with respect to the tire axial direction continuously changes, and of course includes a state in which at least two curved portions having the above-described angle changing by 5 degrees or less are provided with respect to an arbitrary point on the sipe.

[0044] Figure 2 (a) is an enlarged view of the first sipe 7. As shown in (a) of FIG. 1, Figure 2 As shown in (a) of FIG. 1, in the first sipe 7 in the tread plan view, an imaginary sipe reference line nl connecting both ends 7e, 7e of the first sipe 7 with a straight line has an angle al of 10 degrees or less with respect to the tire circumferential direction. Such first sipe 7 suppresses excessive reduction in the rigidity of the first land portion 3 in the tire circumferential direction, and improves the road surface contactability, and thus improves the dry road performance and the wet road performance.

[0045] As shown in (a) of FIG. 1, in the first sipe 7 in the tread plan view, an imaginary sipe reference line nl connecting both ends 7e, 7e of the first sipe 7 with a straight line has an angle al of 10 degrees or less with respect to the tire circumferential direction. Such first sipe 7 suppresses excessive reduction in the rigidity of the first land portion 3 in the tire circumferential direction, and improves the road surface contactability, and thus improves the dry road performance and the wet road performance. Figure 1 As shown in (a) of FIG. 1, in the first sipe 7 in the tread plan view, an imaginary sipe reference line nl connecting both ends 7e, 7e of the first sipe 7 with a straight line has an angle al of 10 degrees or less with respect to the tire circumferential direction. Such first sipe 7 suppresses excessive reduction in the rigidity of the first land portion 3 in the tire circumferential direction, and improves the road surface contactability, and thus improves the dry road performance and the wet road performance. Figure 2 As shown in (a) of FIG. 1, in the first sipe 7 in the tread plan view, an imaginary sipe reference line nl connecting both ends 7e, 7e of the first sipe 7 with a straight line has an angle al of 10 degrees or less with respect to the tire circumferential direction. Such first sipe 7 suppresses excessive reduction in the rigidity of the first land portion 3 in the tire circumferential direction, and improves the road surface contactability, and thus improves the dry road performance and the wet road performance.

[0046] The length LI of the first sipe 7 in the tire circumferential direction is, for example, preferably 40% or more, further preferably 45% or more, and preferably 70% or less, further preferably 65% or less, of the pitch PI of the first sipes 7 adjacent in the tire circumferential direction. As a result, it is possible to suppress excessive reduction in the rigidity of the first land portion 3 and to maintain the improvement in the wet road performance by the wiping force of the first sipes 7.

[0047] The depth (not shown) of the first sipe 7 is, for example, preferably 50% or more, more preferably 75% or more, and preferably 100% or less, more preferably 85% or less, of the groove depth of the shoulder circumferential groove 5A. The depth of the first sipe 7 is preferably less than the groove depth of the shoulder circumferential groove 5A.

[0048] One first sipe 7 is connected to, for example, a plurality of transverse sipes 8. In the present embodiment, one first sipe 7 is connected to two transverse sipes 8. Thereby, the grounding property at the joint portion is further improved. In addition, such a transverse sipe 8 appropriately reduces the rigidity of the first land portion 3 in the tire circumferential direction, and lowers the SATP. The pitch P2 of the transverse sipes 8 in the tire circumferential direction connected to one first sipe 7 is, for example, preferably 40% or more, further preferably 45% or more, and preferably 60% or less, further preferably 55% or less, of the length LI of the first sipe 7 in the tire circumferential direction.

[0049] The transverse sipe 8 is, for example, continuously inclined to one side in the tire circumferential direction with respect to the tire axial direction (inclined to the lower left in the drawing). In addition, the transverse sipe 8 is formed in a circular arc shape that protrudes to one side in the tire circumferential direction (the lower side in the drawing). Such a transverse sipe 8 has a relatively long length compared to a linear sipe, and thereby improves the wet performance. The transverse sipe 8 is not limited to such an embodiment, and various shapes can be adopted.

[0050] Although not particularly limited, the length Wl of the transverse sipe 8 in the tire axial direction is preferably 25% or more, further preferably 30% or more, and preferably 55% or less, further preferably 50% or less, of the width Ws of the first land portion 3. In addition, the depth (omitted from the drawing) of the transverse sipe 8 is preferably 80% or more, further preferably 90% or more, and preferably 120% or less, further preferably 110% or less, of the depth of the first sipe 7.

[0051] The first transverse groove 9 is, for example, disposed between the first sipes 7 adjacent in the tire circumferential direction. For example, one first transverse groove 9 is disposed between the first sipes 7. Thereby, the first land portion 3 suppresses excessive reduction in rigidity, and thereby balances the wet performance and the dry performance.

[0052] The first transverse groove 9 is, for example, continuously inclined to one side in the tire circumferential direction with respect to the tire axial direction (inclined to the lower left in the drawing). In this way, the first transverse groove 9 is inclined in the same direction as the transverse sipe 8. In addition, the first transverse groove 9 is formed in a circular arc shape that protrudes to one side in the tire circumferential direction (the lower side in the drawing). In this way, the first transverse groove 9 is formed in a circular arc shape that protrudes in the same direction as the transverse sipe 8. Thereby, the length in the tire circumferential direction between the first transverse groove 9 and the transverse sipe 8 is secured, and thus it is possible to suppress local reduction in rigidity of the first land portion 3, and the uneven wear resistance performance is maintained at a high level.

[0053] The first transverse groove 9 is, for example, overlapped with the transverse sipe 8 in the tire axial direction. In other words, an overlapping region J in which the first transverse groove 9 and the transverse sipe 8 are overlapped in the tire axial direction is formed in the first land portion 3 in a manner extending in the tire circumferential direction. Such an overlapping region J moderately reduces the rigidity of the first land portion 3 in the tire circumferential direction, and thus it is possible to further achieve reduction in the SATP.

[0054] Although not particularly limited, the width Ws in the tire axial direction of the overlap region J is preferably 5% or more, further preferably 10% or more, and is preferably 35% or less, further preferably 30% or less, of the width Wj of the first land portion 3.

[0055] Figure 4 is a plan view of the first land portion 3. As shown in Figure 4 the angle Θ2 of the first sipe 9 with respect to the tire axial direction is preferably smaller than the angle Θ1 of the transverse groove 8 with respect to the tire axial direction. Thereby, the rigidity of the tire axial direction of the first land portion 3 on the tire face end Te side where a larger transverse force acts is maintained higher, and the uneven wear resistance is improved. In the present specification, the angle Θ2 of the first sipe 9 is the slope of an imaginary straight line m2 connecting both ends 9d, 9d of the center line 9c of the first sipe 9. The angle Θ1 of the transverse groove 8 is the slope of an imaginary straight line m1 connecting both ends thereof.

[0056] Although not particularly limited, in order to improve the dry road performance and the uneven wear resistance, the difference (Θ1-Θ2) between the angle Θ1 of the transverse groove 8 and the angle Θ2 of the first sipe 9 is preferably 5 degrees or more, further preferably 7 degrees or more, and is preferably 15 degrees or less, further preferably 13 degrees or less. In addition, the angle Θ2 of the first sipe 9 is preferably 20 degrees or more, further preferably 25 degrees or more, and is preferably 40 degrees or less, further preferably 35 degrees or less.

[0057] The length L2 in the tire axial direction of the first sipe 9 is preferably 75% or more, further preferably 77% or more, and is preferably 85% or less, further preferably 83% or less, of the width Ws of the first land portion 3. The length L2 of the first sipe 9 is 75% or more of the width Ws of the first land portion 3, and thus the wet road performance can be improved. The length L2 of the first sipe 9 is 85% or less of the width Ws of the first land portion 3, and thus excessive reduction in rigidity can be suppressed, and the uneven wear resistance can be improved.

[0058] Although not particularly limited, the groove width W2 of the first sipe 9 is preferably 65% or more, further preferably 70% or more, and is preferably 85% or less, further preferably 80% or less, of the groove width Wa of the shoulder circumferential groove 5A. In addition, the groove depth (not shown) of the first sipe 9 is preferably 60% or more, further preferably 70% or more, and is preferably 100% or less, further preferably 90% or less, of the groove depth of the shoulder circumferential groove 5A.

[0059] In this embodiment, the first land portion 3 is provided with a second groove 10 that connects to the inner end 9i of the first lateral groove 9 in the tire axial direction. Such a second groove 10 moderately reduces the axial stiffness of the tire near the inner end 9i of the first lateral groove 9, thereby helping to reduce SATP.

[0060] The second groove 10 extends, for example, along the tire circumference. This improves the ground contact of the tread 3a of the first land section 3, thereby improving dry road performance and wet road performance.

[0061] Figure 2 (b) is an enlarged view of the second tool groove 10. For example... Figure 2 As shown in (b), in the second sipe 10 of the top view of the tread, the imaginary sipe reference line n2, which connects the two ends 10e of the second sipe 10 with a straight line, has an angle α2 of less than 10 degrees relative to the tire circumference. This effectively achieves the aforementioned function.

[0062] like Figure 4 As shown, in the top view of the tread, the second sipe 10 is an arc-shaped protrusion extending inward toward the tire axial direction. Thus, in this embodiment, the second sipe 10 is an arc-shaped protrusion protruding in the opposite direction to the first sipe 7. In other words, in the top view of the tread, the first sipe 7 is an arc-shaped protrusion extending outward toward the tire axial direction. Therefore, in this embodiment, the first land portion 3 is alternately provided with a first sipe 7 protruding outward toward the tire axial direction and a second sipe 10 protruding inward toward the tire axial direction along the tire circumference. This mitigates the localized reduction in rigidity of the first land portion 3 caused by the first sipe 7 and the second sipe 10, thereby maintaining higher resistance to uneven wear.

[0063] The second sipe 10 is positioned inside the tire axial direction of the first sipe 7. Therefore, in the first land section 3 of this embodiment, the concave side 10a of the second sipe 10 and the concave side 7a of the first sipe 7 are formed opposite each other. This arrangement of the first sipe 7 and the second sipe 10 improves steering wheel operability (transition characteristics) during cornering. Furthermore, the end of the first sipe 7 on one side of the tire circumferential direction and the end of the second sipe 10 on the other side of the tire circumferential direction are positioned close together. This allows water film not absorbed by one sipe 8 or 10 to be easily absorbed by the other sipe 8 or 10, thus improving wet road performance. Additionally, this arrangement of the first sipe 7 and the second sipe 10 forms a shape close to a wavy sipe, thus ensuring smooth water flow within each sipe 7, 10, thereby improving wet road performance.

[0064] The second sipe 10 is formed of, for example, a first portion 10A connected to a first end 9a of the tire circumferential direction of the first sipe 9, a second portion 10B connected to a second end 9b opposite to the first end 9a, and a third portion 10C connecting the first portion 10A and the second portion 10B. The third portion 10C extends, for example, in the same manner as the first sipe 9. The depth (omitted from the drawing) of the first portion 10A is, for example, the same as the depth (omitted from the drawing) of the second portion 10B.

[0065] The depths of the first portion 10A and the second portion 10B are preferably below the depth of the groove of the first sipe 9. In addition, the depth (omitted from the drawing) of the third portion 10C is preferably above the depth of the first portion 10A. Furthermore, the depth (omitted from the drawing) of the third portion 10C is preferably above the depth of the groove of the first sipe 9.

[0066] The second sipe 10 is connected only to the first sipe 9. In other words, in the present embodiment, the second sipe 10 is not connected to the first sipe 7 and the transverse sipe 8. Thereby, it is possible to suppress excessive reduction of the rigidity of the first land portion 3.

[0067] Figure 5 is a plan view of the second land portion 4. As shown in Figure 5 In the second land portion 4 of the present embodiment, a second transverse sipe 15 extending in the tire axial direction is provided. The second transverse sipe 15 of the present embodiment is connected to the crown circumferential groove 5B. Such a second transverse sipe 15 extending in the tire axial direction also contributes to reduction of the SATP. In addition, the second transverse sipe 15 discharges water in the groove to the crown circumferential groove 5B having a relatively large groove width, and thus improves wet performance.

[0068] The second transverse sipe 15 includes a first groove portion 15A extending from the crown circumferential groove 5B, and a second groove portion 15B connected to the first groove portion 15A and inclined at a larger angle θ4 than the first groove portion 15A with respect to the tire axial direction. The first groove portion 15A is inclined, for example, with respect to the tire axial direction.

[0069] The length L3 of the second transverse sipe 15 in the tire axial direction is preferably 50% or more, further preferably 55% or more, and is preferably 85% or less, further preferably 80% or less, of the width Wc of the second land portion 4 in the tire axial direction.

[0070] The angle a3 between the second transverse groove 15 and the crown circumferential groove 5B is preferably 30 to 60 degrees. Since the angle a3 is 30 degrees or more, the flow of water becomes smooth between the second transverse groove 15 and the crown circumferential groove 5B, and a higher wet performance can be exhibited. Since the angle a3 is 60 degrees or less, the rigidity at the intersection of the second transverse groove 15 and the crown circumferential groove 5B can be suppressed from decreasing, and the generation of uneven wear can be suppressed. Therefore, the angle a3 is further preferably 35 degrees or more, and further preferably 55 degrees or less. In the present specification, the angle a3 is the angle between the groove edge 15i of one of the second transverse grooves 15 and the groove edge 5i of the crown circumferential groove 5B connected to the groove edge 15i of one of the second transverse grooves 15.

[0071] The second land portion 4 is provided with a transverse sipe 16 extending from the crown circumferential groove 5B to the outer side in the tire axial direction and ending within the second land portion 4, for example. The transverse sipe 16 includes a first sipe portion 16A extending from the crown circumferential groove 5B, and a second sipe portion 16B connected to the first sipe portion 16A and inclined at a larger angle θ6 than the first sipe portion 16A with respect to the tire axial direction. The first sipe portion 16A of the present embodiment is inclined with respect to the tire axial direction.

[0072] The second land portion 4 is provided with a transverse sipe 16 extending from the crown circumferential groove 5B to the outer side in the tire axial direction and ending within the second land portion 4, for example. The transverse sipe 16 includes a first sipe portion 16A extending from the crown circumferential groove 5B, and a second sipe portion 16B connected to the first sipe portion 16A and inclined at a larger angle θ6 than the first sipe portion 16A with respect to the tire axial direction. The first sipe portion 16A of the present embodiment is inclined with respect to the tire axial direction.

[0073] The first bend point 19 at which the first groove portion 15A and the second groove portion 15B are connected, the second bend point 20 at which the first sipe portion 16A and the second sipe portion 16B are connected, and the third bend point 21 at which the third sipe portion 17A and the fourth sipe portion 17B are connected are each disposed at the same position in the tire axial direction. Thus, the rigidity of the tire circumferential direction of the second land portion 4 in the tire circumferential line where the first bend point 19 is provided decreases, and the SATP can be reduced. In the present specification, the above-mentioned same position means that the maximum distance L4 at which each of the bend points 19 to 21 is farthest from the tire axial direction is within 10% of the width Wc of the second land portion 4. In addition, the tire axial distance L5 between the first bend point 19 and the inner end 4i of the second land portion 4 in the tire axial direction is preferably disposed at a position of 45% to 55% of the width Wc of the second land portion 4. Thus, excessive decrease in the rigidity of the second land portion 4 can be suppressed.

[0074] The angle θ3 of the first groove portion 15A with respect to the tire axial direction, the angle θ5 of the first sipe portion 16A with respect to the tire axial direction, and the angle θ7 of the third sipe portion 17A with respect to the tire axial direction are preferably the same. Thereby, during straight-ahead running, excessive reduction in rigidity of the second land portion 4 subjected to a large ground contact pressure can be suppressed. The "same" in the present specification means that the absolute value of the difference between the angle θ3 of the first groove portion 15A and each of the angles θ5 and θ7 of the sipe portions 16A and 17A is 5 degrees or less. The angle θ3 of the first groove portion 15A is preferably 30 degrees or more, more preferably 35 degrees or more, and is preferably 60 degrees or less, more preferably 55 degrees or less, for example.

[0075] From the same viewpoint, the angle θ4 of the second groove portion 15B, the angle θ6 of the second sipe portion 16B, and the angle θ8 of the fourth sipe portion 17B are preferably the same. The angle θ4 of the second groove portion 15B is preferably 35 degrees or more, more preferably 40 degrees or more, and is preferably 55 degrees or less, more preferably 50 degrees or less, for example.

[0076] The length L6 of the second groove portion 15B in the tire axial direction is preferably the same as the length L7 of the second sipe portion 16B in the tire axial direction. The "same" in the present specification means that the absolute value of the difference between the length L6 of the second groove portion 15B and the length L7 of the second sipe portion 16B is 10% or less of the width Wc of the second land portion 4.

[0077] The depth of the second cross groove 15 (not shown) is preferably greater than the depth of the cross sipe 17 (not shown). Thereby, the effects of suppressing reduction in rigidity of the block and improving drainability can be exerted.

[0078] From the same viewpoint, the depth of the second cross groove 15 (not shown) is preferably greater than the depth of the cross sipe 17 (not shown).

[0079] Although not particularly limited, the depth of the second cross groove 15 is preferably 30% or more, more preferably 40% or more, of the depth of the crown circumferential groove 5B, and is preferably 100% or less, more preferably 90% or less.

[0080] Although the tire according to one embodiment of the present application has been described in detail above, the present application is not limited to the above-described specific embodiment, but can be modified into various embodiments.

[0081] [Example]

[0082] A tire having a basic pattern of Figure 3 was trial-manufactured. Then, the dry road performance, wet road performance, and uneven wear resistance of each of the trial tires were tested. The common specifications of the trial tires and the test methods are as follows.

[0083] Dry road performance, wet road performance, and uneven wear resistance

[0084] Each of the test tires was mounted on the following test vehicle. A test driver evaluated the dry road performance and the wet road performance based on the stability and the operability of each of the test tires when the test vehicle was driven on a test course of a dry asphalt road and a wet asphalt road by the sense of sight. In addition, the test driver evaluated the uneven wear resistance based on the uneven wear generated when the test vehicle was driven on the test course by the sense of sight. The results were expressed as scores with Comparative Example 1 being 100. The larger the value, the more excellent.

[0085] Tire size: 205 / 65R16

[0086] Rim: 16 x 6.5J

[0087] Internal pressure (kPa): 390 (front wheels) / 420 (rear wheels)

[0088] Vehicle: passenger car with a displacement of 2000 cc

[0089] The results of the test are shown in Table 1.

[0090] [Table 1]

[0091]

[0092] [Table 2]

[0093]

[0094] The results of the test confirmed that the tires of the examples had excellent dry road performance. In addition, the tires of the examples had excellent wet road performance and uneven wear resistance.

Claims

1. A tire having a tread portion, characterized by in the tread portion, a shoulder circumferential groove extending in a tire circumferential direction at a most tread end side, and a first land portion divided by the shoulder circumferential groove and the tread end, in the first land portion, a plurality of first sipes and a plurality of second sipes extending in the tire circumferential direction, a plurality of transverse sipes, and a plurality of first transverse grooves extending from the tread end to an inner side in a tire axial direction, the first sipes not communicating with the first transverse grooves, the second sipes each being connected to an inner end in the tire axial direction of any one of the plurality of first transverse grooves, inner ends in the tire axial direction of the transverse sipes each being connected to the shoulder circumferential groove, outer ends in the tire axial direction of the transverse sipes each being connected to any one of the first sipes, in the second sipes in a plan view of the tread portion, an imaginary sipe reference line connecting both ends of the second sipes with straight lines has an angle of 10 degrees or less with respect to the tire circumferential direction.

2. The tire according to claim 1, characterized by in at least one of the plurality of first sipes, a plurality of the transverse sipes are connected.

3. The tire according to claim 1, characterized by the plurality of second sipes are connected only to the plurality of first transverse grooves.

4. The tire according to claim 1 or 2, characterized by a length in the tire axial direction of the first transverse grooves is 75% to 85% of a width in the tire axial direction of the first land portion.

5. The tire according to claim 1 or 2, characterized by an angle with respect to the tire axial direction of the first transverse grooves is 20 to 45 degrees.

6. The tire according to claim 1 or 2, characterized by in the tread portion, a second land portion adjacent to the shoulder circumferential groove on an inner side in the tire axial direction is provided, in the second land portion, a second transverse groove extending in the tire axial direction is provided.

7. The tire according to claim 6, characterized by a length in the tire axial direction of the second transverse groove is 50% to 85% of a width in the tire axial direction of the second land portion.

8. The tire according to claim 6, characterized by in the tread portion, a crown circumferential groove dividing the second land portion on the inner side in the tire axial direction is provided, the second transverse groove is connected to the crown circumferential groove.

9. The tire according to claim 8, characterized by an angle between the second transverse groove and the crown circumferential groove is 30 to 60 degrees.

10. The tire according to claim 8 or 9, characterized by in the second land portion, a transverse sipe extending from the crown circumferential groove to an outer side in the tire axial direction and terminating within the second land portion is provided.

11. The tire according to claim 6, characterized by in the second land portion, a traverse sipe traversing the second land portion is provided.

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