Tire

Abstract

The present application further improves dry road performance, wet road performance, and resistance to uneven wear. The present application is a tire (1) provided with a first land portion (3) in a tread portion (2). A plurality of first sipes (7) extending in a circular arc shape are provided in the first land portion (3). The first sipes (7) are arranged so as not to communicate with a lateral groove extending in the tire axial direction in the first land portion 3. When the tread is viewed in plan, both ends (7e) of the first sipes (7) have an angle (θ1) of 10 degrees or less with respect to the tire circumferential direction with a notional sipe reference line (n1) connecting the both ends in a straight line.

Description

TECHNICAL FIELD

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

[0002] Patent Document 1 describes a pneumatic tire having an outer side region that is located outward of a tire equator when mounted on a vehicle. An intermediate land portion and a shoulder land portion are provided in the outer side region. An outer side intermediate sipe that extends across the intermediate land portion is provided in the intermediate land portion, and an outer side shoulder sipe that extends across 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, wet road performance, and wear resistance. SUMMARY

[0005] The present application was made in view of the above-described actual circumstances, and its main object is to provide a tire that further improves dry road performance, wet road performance, and wear resistance.

[0006] The present application provides a tire having a tread portion, the tread portion having a first land portion, a plurality of first sipes being provided in the first land portion, the plurality of first sipes each extending in a circular arc shape, the plurality of first sipes each being configured not to communicate with a sipe that extends in a tire axial direction in the first land portion, and an imaginary sipe reference line that connects both ends of each of the plurality of first sipes in a straight line has an angle of 10 degrees or less with respect to a tire circumferential direction when the tread portion is viewed from above.

[0007] The tire according to the present application preferably has a plurality of first sipes that protrude outward in a tire axial direction when the tread portion is viewed from above.

[0008] The tire according to the present application preferably has a first land portion that includes a tread end.

[0009] The tire according to the present application preferably has a shoulder circumferential groove that defines the first land portion provided in the tread portion, and a plurality of transverse sipes that connect each of the plurality of first sipes and the shoulder circumferential groove provided in the first land portion.

[0010] The tire according to the present application preferably has a plurality of first transverse grooves that extend inward in a tire axial direction from the tread end provided in the first land portion, and a length of each of the plurality of first transverse grooves in the tire axial direction is 75% to 85% of a width of the first land portion in the tire axial direction.

[0011] The tire according to the present application preferably has a plurality of second sipes connected to the inner ends in the tire axial direction of the respective first sipes in the first land portion.

[0012] The tire according to the present application preferably has the plurality of second sipes extending in the tire circumferential direction.

[0013] The tire according to the present application preferably has, in each of the second sipes, an imaginary sipe reference line connecting the two ends of the second sipe in a straight line having an angle of 10 degrees or less with respect to the tire circumferential direction when the tread is viewed in plan view.

[0014] The tire according to the present application preferably has each of the second sipes being in a circular arc shape projecting toward the inner side in the tire axial direction.

[0015] The tire according to the present application preferably has each of the second sipes disposed at a position inside in the tire axial direction than the first sipe.

[0016] The tire according to the present application can exhibit excellent dry road performance, wet road performance, and wear resistance by adopting the above-described structure. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a plan view of a first land portion of a tread portion of an embodiment of the tire according to the present application.

[0018] Figure 2 (a) of is an enlarged view of a first sipe, and (b) is an enlarged view of a second sipe.

[0019] Figure 3 is a plan view of the entire tread portion.

[0020] Figure 4 is a plan view of the first land portion.

[0021] Figure 5 is a plan view of a second land portion.

[0022] EXPLANATION OF REFERENCE NUMERALS

[0023] 1...tire; 2...tread portion; 3...first land portion; 7...first sipe; 7e...two ends of the first sipe; nl...imaginary sipe reference line. DETAILED DESCRIPTION

[0024] Hereinafter, an embodiment of the present application will be described based on the drawings.

[0025] Figure 1is an enlarged plan view of the tread portion 2 of the tire 1 of the present embodiment. The present application is suitable for use in, for example, pneumatic tires for passenger cars. In addition, the present application can also be applied to, for example, pneumatic tires for heavy loads, light trucks, and the like, and non-pneumatic tires that are not filled with compressed air.

[0026] As shown in Figure 1 , the tread portion 2 of the present embodiment is provided with a first land portion 3. A plurality of first sipes 7 are provided in the first land portion 3. In the present specification, a "sipe" means a slit-like body having a width of less than 1.5 mm.

[0027] The plurality of first sipes 7 each extend in a circular arc shape. Such a first sipe 7 has a relatively large length compared to a linear sipe (omitted from the drawing). Thus, the effect of discharging a water film between the road surface and the tread surface 3a of the first land portion 3 using the first sipe 7 can be improved, and thus the wet road performance is improved. The "circular arc shape" naturally includes a shape in which the angle of the sipe with respect to the tire axial direction continuously changes, and also includes a shape having at least two inflection portions in which the above-mentioned angle changes by an angle of 5 degrees or less with respect to an arbitrary point on the sipe.

[0028] The plurality of first sipes 7 are each arranged so as not to communicate with a cross groove extending in the tire axial direction in the first land portion 3. In other words, the first sipes 7 do not communicate with a groove arranged in the first land portion 3 and a groove extending in the tire circumferential direction (circumferential groove). Such a first sipe 7 suppresses a local decrease in the rigidity of the first land portion 3, and thus maintains a high uneven wear resistance. In addition, the first sipe 7 maintains a high dry road performance. In the present specification, the above-mentioned groove, including the above-mentioned cross groove, a later-described cross sipe groove, and the circumferential groove, means a groove-like body having a width of 1.5 mm or more.

[0029] Figure 2 (a) of FIG. 1 is an enlarged view of the first sipe 7. As shown in (a) of FIG. 1, in the first sipe 7 when the tread is viewed in plan, a notional 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 a first sipe 7 suppresses an excessive decrease in the rigidity of the first land portion 3 in the tire circumferential direction, and improves the road contact with the road surface, and thus improves the dry road performance and the wet road performance. Figure 2

[0030] ​To improve the dry road performance, for example, it is effective to increase the equivalent cornering power (Equivalent CP) of the tire. The Equivalent CP is the cornering power (CP) divided by the self-aligning torque power (SATP). The CP generally becomes large by increasing the rigidity of the tread portion 2. The SATP is the self-aligning torque (SAT) when a 1-degree slip angle is imparted to the tire 1 in running. The SAT is indicated by the sum of the braking force and the driving force on the tire circumferential line of the tread portion 2 (shown by the arrow). Therefore, an increase in the rigidity of the tread portion 2 in the tire circumferential direction results in an increase in the SATP, and the Equivalent CP cannot be increased. Figure 3

[0031] Therefore, to improve the dry road performance, it is effective to suppress the decrease in the CP and to maintain the SATP small, that is, to suppress the increase in the rigidity of the tread portion 2 in the tire circumferential direction. It is particularly desirable to suppress the increase in the rigidity in the tire circumferential direction on the tread end Te (shown by the arrow) where the SAT becomes the largest. Figure 3

[0032] The tread end Te is the tire axial outermost ground contact position when the tire 1 in the normal state assembled to the normal rim (not shown) and filled with the normal internal pressure and without load is loaded with the normal load and grounded at 0° of the camber angle on a flat surface. 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 ends Te on both sides of the tire axial direction is the tread width TW (shown by the arrow). Figure 3

[0033] The above "normal rim" is the rim prescribed for each tire in the specification system including the specification to which the tire is subjected, for example, "Standard Rim" if JATMA, "Design Rim" if TRA, and "Measuring Rim" if ETRTO.

[0034] The above "normal internal pressure" is the air pressure prescribed for each specification in the specification system including the specification to which the tire is subjected, for example, "Maximum Air Pressure" if JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" if TRA, and "INFLATION PRESSURE" if ETRTO.

[0035] ​​​The "normal load" is a load determined for each tire in a 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.

[0036] Figure 3 is a plan view of the tread portion 2. As shown in Figure 3 In the present embodiment, the first land portion 3 is demarcated by the tread end Te and the shoulder circumferential groove 5A. In addition, the second land portion 4 is provided in the tread portion 2 so as to adjoin the shoulder circumferential groove 5A on the inner side in the tire axial direction. In the present embodiment, the second land portion 4 is demarcated by the shoulder circumferential groove 5A and the crown circumferential groove 5B. The second land portion 4 of the present embodiment is provided on both sides of the tire equator C.

[0037] In the present embodiment, the first land portion 3 is demarcated by the tread end Te and the shoulder circumferential groove 5A. In addition, the second land portion 4 is provided in the tread portion 2 so as to adjoin the shoulder circumferential groove 5A on the inner side in the tire axial direction. In the present embodiment, the second land portion 4 is demarcated by the shoulder circumferential groove 5A and the crown circumferential groove 5B. The second land portion 4 of the present embodiment is provided on both sides of the tire equator C.

[0038] In the present embodiment, the shoulder circumferential groove 5A and the crown circumferential groove 5B extend in a straight line shape along the tire circumferential direction. The shoulder circumferential groove 5A and the crown circumferential groove 5B may, for example, also extend in a wavy shape or a zigzag shape.

[0039] 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, since the water film on the tread surface 4a of the second land portion 4, which is difficult to drain, can be effectively drained, the wet road performance is 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 preferably, for example, about 3% to 10% of the tread width TW. In addition, the groove depth (not shown) of the shoulder circumferential groove 5A is preferably, for example, 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.

[0040] The first land portion 3 includes the tread end Te. Thus, the first land portion 3 is positioned on the outermost side of the tire axial direction and is the land portion that experiences a large lateral force during cornering. The first land portion 3 is provided with a first sipe 7, thereby particularly improving dry and wet road performance during cornering.

[0041] like Figure 1 As shown, when viewed from above, the radius of curvature R1 of the first groove 7 is... Figure 2 (a) As shown, the first sipe 7 is preferably 100% or more, more preferably 150% or more, more preferably 250% or less, and more preferably 200% or less, of the tire axial width Ws of the first land portion 3. Since the radius of curvature R1 of the first sipe 7 is 100% or more of the width Ws of the first land portion 3, excessive reduction in the rigidity of the first land portion 3 is suppressed. Since it is 250% or less of the width Ws of the first land portion 3, the length of the first sipe 7 can be ensured to be large. The radius of curvature R1 of the first sipe 7 is preferably greater than the tire axial width Ws of the first land portion 3. In this specification, the radius of curvature is the radius of a single arc passing through the two ends of the sipe and its center.

[0042] The tire circumferential length L1 of the first sipe 7 is preferably 40% or more, more preferably 45% or more, more preferably 70% or less, and more preferably 65% ​​or less, of the pitch P1 of the first sipe 7 adjacent to it in the tire circumferential direction. This suppresses excessive reduction in the rigidity of the first land portion 3 and maintains the improved wet road performance resulting from the scraping force of the first sipe 7.

[0043] The depth of the first groove 7 (illustration omitted) is preferably 50% or more of the groove depth of the shoulder circumferential groove 5A, more preferably 75% or more, more preferably 100% or less, and more preferably 85% or less. The depth of the first groove 7 is preferably less than the groove depth of the shoulder circumferential groove 5A.

[0044] A transverse sipe 8 is provided on the first land portion 3, connecting the first sipe 7 to the tire shoulder circumferential groove 5A. In other words, the inner end 8i of the transverse sipe 8 along the tire axial direction is connected to the tire shoulder circumferential groove 5A, and the outer end 8e of the transverse sipe 8 along the tire axial direction is connected to the first sipe 7. This improves the contact with the road surface at the connection points between the transverse sipe 8 and the first sipe 7, and between the transverse sipe 8 and the tire shoulder circumferential groove 5A, thereby further improving road performance.

[0045] For example, a plurality of lateral sipes 8 communicate with one first sipe 7. In the present embodiment, two lateral sipes 8 communicate with one first sipe 7. Thereby, the grounding property at the connection portion K is further improved. Further, such lateral sipes 8 appropriately reduce the rigidity in the tire circumferential direction of the first land portion 3, and lower the SATP. The pitch P2 in the tire circumferential direction of the lateral sipes 8 communicating with one first sipe 7 is, for example, preferably 40% or more, more preferably 45% or more, and preferably 60% or less, more preferably 55% or less, of the length LI in the tire circumferential direction of the first sipe 7.

[0046] The lateral sipes 8 are, for example, continuously inclined toward one side in the tire axial direction (in the drawing, the lower left). Further, the lateral sipes 8 are formed in a circular arc shape projecting toward one side in the tire circumferential direction (in the drawing, the lower side). Such lateral sipes 8 have a relatively large length compared to linear sipes, and improve the wet performance. The lateral sipes 8 are not limited to such a shape, and various shapes can be adopted.

[0047] Although not particularly limited, the length Wl in the tire axial direction of the lateral sipes 8 is preferably 25% or more, more preferably 30% or more, and preferably 55% or less, more preferably 50% or less, of the width Ws of the first land portion 3. Further, the depth (omitted from the drawing) of the lateral sipes 8 is preferably 80% or more, more preferably 90% or more, and preferably 120% or less, more preferably 110% or less, of the depth of the first sipe 7.

[0048] The first land portion 3 in the present embodiment is provided with a plurality of first lateral grooves 9 extending from the tread end Te toward the inner side in the tire axial direction. Such first lateral grooves 9 reduce the rigidity in the tire circumferential direction on the tread end Te of the first land portion 3, and lower the SATP, and thus improve the equivalent CP. Thereby, the dry performance is improved. Further, the first lateral grooves 9 smoothly discharge the water film on the tread surface 3a of the first land portion 3 from the tread end Te, and thus improve the wet performance.

[0049] The first lateral grooves 9 are, for example, disposed between the first sipes 7 adjacent in the tire circumferential direction. For example, one first lateral groove 9 is disposed between the first sipes 7. Thereby, the first land portion 3 suppresses excessive reduction in rigidity, and balances the wet performance and the dry performance.

[0050] The first lateral grooves 9 are, for example, continuously inclined toward one side in the tire axial direction (in the drawing, the lower left). In this way, the first lateral grooves 9 are inclined in the same direction as the lateral sipes 8. Further, the first lateral grooves 9 are formed in a circular arc shape projecting toward one side in the tire circumferential direction (in the drawing, the lower side). In this way, the first lateral grooves 9 are formed in a circular arc shape projecting in the same direction as the lateral sipes 8. Thereby, the length in the tire circumferential direction between the first lateral grooves 9 and the lateral sipes 8 is secured, and thus the local reduction in rigidity of the first land portion 3 is suppressed, and the uneven wear performance is maintained high.

[0051] The first transverse groove 9 overlaps the transverse sipe 8 in the tire axial direction, for example. In other words, an overlap region J in which the first transverse groove 9 overlaps the transverse sipe 8 in the tire axial direction is formed in the first land portion 3 in a manner extending in the tire circumferential direction. Such an overlap region J appropriately reduces the rigidity of the first land portion 3 in the tire circumferential direction, and thus further enables reduction of the SATP.

[0052] Although not particularly limited, the width Wj of the overlap region J in the tire axial direction is preferably 5% or more, more preferably 10% or more, and preferably 35% or less, more preferably 30% or less, of the width Ws of the first land portion 3.

[0053] Figure 4 is a plan view of the first land portion 3. As shown in Figure 4 the angle Θ2 of the first transverse groove 9 with respect to the tire axial direction is preferably smaller than the angle Θ1 of the transverse sipe 8 with respect to the tire axial direction. Thereby, the rigidity of the tire axial direction on the tire shoulder Te side of the first land portion 3, on which a large lateral force acts, is maintained high, and the cornering wear resistance is improved. In the present specification, the angle Θ2 of the first transverse groove 9 is the slope of an imaginary straight line m2 connecting both ends 9d, 9d of the center line 9c of the first transverse groove 9. The angle Θ1 of the transverse sipe 8 is the slope of an imaginary straight line ml connecting both ends thereof.

[0054] Although not particularly limited, in order to improve the dry road performance and the cornering wear resistance, the difference (Θ1 - Θ2) between the angle Θ1 of the transverse sipe 8 and the angle Θ2 of the first transverse groove 9 is preferably 5 degrees or more, more preferably 7 degrees or more, and preferably 15 degrees or less, more preferably 13 degrees or less. In addition, the angle Θ2 of the first transverse groove 9 is preferably 20 degrees or more, more preferably 25 degrees or more, and preferably 40 degrees or less, more preferably 35 degrees or less.

[0055] The length L2 of the first transverse groove 9 in the tire axial direction is preferably 75% or more, more preferably 77% or more, and preferably 85% or less, more preferably 83% or less, of the width Ws of the first land portion 3. Since the length L2 of the first transverse groove 9 is 75% or more of the width Ws of the first land portion 3, the wet road performance is improved. Since the length L2 of the first transverse groove 9 is 85% or less of the width Ws of the first land portion 3, the cornering wear resistance is improved by suppressing excessive reduction of the rigidity.

[0056] Although not particularly limited, the groove width W2 of the first transverse groove 9 is preferably 65% or more, more preferably 70% or more, and preferably 85% or less, more 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 transverse groove 9 is preferably 60% or more, more preferably 70% or more, and preferably 100% or less, more preferably 90% or less, of the groove depth of the shoulder circumferential groove 5A.

[0057] The first land portion 3 in the present embodiment is provided with a second sipe 10 that is connected to the inner end 9i of the tire axial direction of the first sipe 9. Such a second sipe 10 appropriately lowers the rigidity of the tire axial direction in the vicinity of the inner end 9i of the first sipe 9, and contributes to the reduction of SATP.

[0058] The second sipe 10 extends, for example, in the tire circumferential direction. Thereby, the ground adhesion of the tread surface 3a of the first land portion 3 is improved, and thus the dry road performance and the wet road performance are improved.

[0059] Figure 2 (b) is an enlarged view of the second sipe 10. As shown in (b) of FIG. 6, in the second sipe 10 when the tread is observed in plan view, the two ends 10e of the second sipe 10 are connected by a notional sipe reference line n2 that is a straight line, and the notional sipe reference line n2 has an angle a2 of 10 degrees or less with respect to the tire circumferential direction. Thereby, the above-described effects are effectively exerted. Figure 2 As shown in (b) of FIG. 6, in the second sipe 10 when the tread is observed in plan view, the two ends 10e of the second sipe 10 are connected by a notional sipe reference line n2 that is a straight line, and the notional sipe reference line n2 has an angle a2 of 10 degrees or less with respect to the tire circumferential direction. Thereby, the above-described effects are effectively exerted.

[0060] Figure 4 As shown in (b) of FIG. 6, in the second sipe 10 when the tread is observed in plan view, the two ends 10e of the second sipe 10 are connected by a notional sipe reference line n2 that is a straight line, and the notional sipe reference line n2 has an angle a2 of 10 degrees or less with respect to the tire circumferential direction. Thereby, the above-described effects are effectively exerted.

[0061] The second sipe 10 is disposed at a position that is on the inner side of the tire axial direction than the first sipe 7. Thereby, in the first land portion 3 of the present embodiment, the concave side portion 10a of the second sipe 10 is formed in an opposed manner to the concave side portion 7a of the first sipe 7. Such a configuration of the first sipe 7 and the second sipe 10 improves the steering operability (transition characteristics) at the time of cornering. In addition, the one side end of the tire circumferential direction of the first sipe 7 is disposed in close proximity to the other side end of the tire circumferential direction of the second sipe 10. Thereby, it is possible to easily cause the water film that is not completely absorbed by one sipe 8 or 10 to be absorbed by the other sipe 8 or 10, and thus the wet road performance is improved. In addition, such a configuration of the first sipe 7 and the second sipe 10 improves the wet road performance because they are formed in close proximity to one undulating sipe shape, and the flow of water within each sipe 7, 10 is smooth.

[0062] ​The second sipe 10 is formed of, for example, a first portion 10A connected to a first end 9a of the first cross groove 9 in the tire circumferential direction, a second portion 10B connected to a second end 9b opposite 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 cross groove 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.

[0063] The depths of the first portion 10A and the second portion 10B are preferably below the groove depth of the first cross groove 9. In addition, the depth (omitted from the drawing) of the third portion 10C is preferably above the depth of the first portion 10A. Also, the depth (omitted from the drawing) of the third portion 10C is preferably above the groove depth of the first cross groove 9.

[0064] The second sipe 10 is connected only to the first cross groove 9. In other words, in the present embodiment, the second sipe 10 is not connected to the first sipe 7 or the cross sipe 8. Thereby, excessive reduction in the rigidity of the first land portion 3 is suppressed.

[0065] 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 cross groove 15 extending in the tire axial direction is provided. The second cross groove 15 of the present embodiment is connected to the crown circumferential groove 5B. Such a second cross groove 15 extending in the tire axial direction also contributes to reduction in SATP. In addition, the second cross groove 15 causes water in the groove to be discharged to the crown circumferential groove 5B having a relatively large groove width, and thus improves wet performance.

[0066] The second cross groove 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 an angle θ4 with respect to the tire axial direction, the angle θ4 being larger than the angle of the first groove portion 15A with respect to the tire axial direction. The first groove portion 15A is, for example, inclined with respect to the tire axial direction.

[0067] The length L3 of the second cross groove 15 in the tire axial direction is preferably 50% or more, more preferably 55% or more, and preferably 85% or less, more preferably 80% or less, of the width Wc of the second land portion 4 in the tire axial direction.

[0068] 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 between the second transverse groove 15 and the crown circumferential groove 5B becomes smooth, and a high wet performance is exerted. Since the angle a3 is 60 degrees or less, the decrease in rigidity at the intersection between the second transverse groove 15 and the crown circumferential groove 5B is suppressed, and the generation of cornering power uneven wear is suppressed. Therefore, the angle a is preferably 35 degrees or more, and more preferably 55 degrees or less. In the present specification, the angle a3 is the angle between one groove edge 15i of the second transverse groove 15 and the groove edge 5i of the crown circumferential groove 5B connected to the one groove edge 15i.

[0069] The second land portion 4 is provided with a transverse sipe 16 extending from the crown circumferential groove 5B to the outside in the tire axial direction and forming a terminal end 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 an angle θ6 with respect to the tire axial direction, the angle θ6 being larger than the angle of 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.

[0070] The second land portion 4 is provided with a transverse sipe 16 extending from the crown circumferential groove 5B to the outside in the tire axial direction and forming a terminal end 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 an angle θ6 with respect to the tire axial direction, the angle θ6 being larger than the angle of 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.

[0071] The first flex point 19 connecting the first groove portion 15A and the second groove portion 15B, the second flex point 20 connecting the first sipe portion 16A and the second sipe portion 16B, and the third flex point 21 connecting the third sipe portion 17A and the fourth sipe portion 17B are respectively disposed at the same position in the tire axial direction. Thereby, the rigidity of the tire circumferential line of the second land portion 4 provided with the first flex point 19 can be decreased, and the SATP can be reduced. The above-mentioned same position means in the present specification that each of the flex points 19 to 21 is separated by a maximum separation distance L4 at which the separation is the largest, within 10% of the width Wc of the second land portion 4 in the tire axial direction. In addition, the tire axial distance L5 between the first flex point 19 and the inner end 4i of the second land portion 4 in the tire axial direction is preferably a position disposed at 45% to 55% of the width Wc of the second land portion 4. Thereby, the excessive decrease in the rigidity of the second land portion 4 is suppressed.

[0072] 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, at straight running, the decrease in rigidity of the second land portion 4 having a large ground contact pressure is suppressed. The above-mentioned "same" means that the absolute value of each difference between the angle θ3 of the first groove portion 15A and the angles θ5, θ7 of the sipe portions 16A, 17A is 5 degrees or less in the present specification. The angle θ3 of the first groove portion 15A is preferably 30 degrees or more, more preferably 35 degrees or more, and preferably 60 degrees or less, more preferably 55 degrees or less, for example.

[0073] According to the same view, 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 preferably 55 degrees or less, more preferably 50 degrees or less, for example.

[0074] 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" 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 in the present specification.

[0075] The depth (not shown) of the second lateral groove 15 is preferably greater than the depth (not shown) of the lateral sipe 16. Thereby, the effects of suppressing the decrease in rigidity of the block and improving the water drainage property are exerted.

[0076] According to the same view, the depth (not shown) of the second lateral groove 15 is preferably greater than the depth (not shown) of the lateral sipe 17.

[0077] Although not particularly limited, the depth of the second lateral 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.

[0078] Although the tire according to the embodiment of the present application has been described in detail above, the present application is not limited to the above-described specific embodiment, and can be implemented in various modes.

[0079] Example

[0080] A tire having a basic pattern of Figure 3 was trial-produced. Furthermore, the dry road performance, wet road performance, and cornering wear resistance of each trial-produced tire were tested. The general specifications of each trial-produced tire and the test methods are as follows.

[0081] Dry road performance, wet road performance, and uneven wear resistance

[0082] 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 respective stabilities and operabilities when the test vehicle was driven on a test course of a dry asphalt pavement and a wet asphalt pavement by the sense of sight. In addition, the test driver evaluated the uneven wear resistance based on the uneven wear generated by driving on the test course by the sense of sight. The results were expressed in scores with Comparative Example 1 being 100. The larger the value, the more excellent.

[0083] "A" of "the shape of the first sipe" of Table 1 is a shape communicating with the cross groove, and "B" is a shape not communicating with the cross groove.

[0084] Tire size: 205 / 65R16

[0085] Rim: 16 x 6.5J

[0086] Internal pressure (kPa): 390 (front wheels) / 420 (rear wheels)

[0087] Vehicle: sedan with a displacement of 2000 cc

[0088] The results of the test are shown in Table 1.

[0089] Table 1

[0090]

[0091] The results of the test confirmed that the tires of the examples had excellent dry road performance, wet road performance, and uneven wear resistance.

Claims

1. A tire having a tread portion, wherein a first land portion is provided in the tread portion, a plurality of first sipes are provided in the first land portion, the plurality of first sipes each extend in a circular arc shape, the plurality of first sipes are each arranged so as not to communicate with a cross groove extending in a tire axial direction in the first land portion, in each of the first sipes, an imaginary sipe reference line connecting both ends of the first sipe in a straight line has an angle of 10 degrees or less with respect to a tire circumferential direction when the tread portion is viewed in plan, the first land portion includes a tread end, a plurality of first cross grooves extending from the tread end toward an inner side in the tire axial direction are provided in the first land portion, a second sipe is provided in the first land portion so as to be connected to one of the plurality of first cross grooves at an inner end in the tire axial direction of each of the first cross grooves, in each of the second sipes, an imaginary sipe reference line connecting both ends of the second sipe in a straight line has an angle of 10 degrees or less with respect to the tire circumferential direction when the tread portion is viewed in plan, each of the second sipes is in a circular arc shape that protrudes toward the inner side in the tire axial direction when the tread portion is viewed in plan.

2. The tire according to claim 1, wherein the plurality of first sipes protrude toward an outer side in the tire axial direction when the tread portion is viewed in plan.

3. The tire according to claim 1 or 2, wherein a shoulder circumferential groove demarcating the first land portion is provided in the tread portion, a transverse sipe connecting the plurality of first sipes to the shoulder circumferential groove is provided in the first land portion, each of the first sipes is connected to the shoulder circumferential groove via a plurality of the transverse sipes.

4. The tire according to claim 1 or 2, wherein a length in the tire axial direction of each of the first cross 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, wherein the second sipe extends in the tire circumferential direction.

6. The tire according to claim 1 or 2, wherein each of the second sipes is arranged at a position that is more toward an inner side in the tire axial direction than the first sipes.

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