tire

Abstract

To provide a tire enhanced in overturning resistance while maintaining wear resistance.SOLUTION: A tire has a shoulder land portion 3. The shoulder land portion 3 includes a plurality of shoulder lateral grooves 6 and a circumferential sipe 7 connecting the shoulder lateral grooves 6. A chamfer 11 is formed on each shoulder lateral groove 6. The circumferential sipe 7 is disposed at a distance of 30% to 100% of the width Ws of the shoulder land portion 3 in the tire axial direction from the inner end 3i of the shoulder land portion 3 in the tire axial direction. The depth of the circumferential sipe 7 is equal to or larger than the groove depth of the shoulder lateral groove 6.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The following Patent Document 1 describes a pneumatic tire in which blocks are formed by providing longitudinal main grooves and lateral main grooves. The blocks are formed with chamfered portions by cutting out the block wall surface facing the longitudinal main groove. The chamfered portions have an upper chamfered edge that intersects with the block surface and a lower chamfered edge that intersects with the block wall surface. The chamfer width between the upper chamfered edge and the lower chamfered edge increases from both ends in the tire circumferential direction toward the center in the circumferential direction. Such a pneumatic tire is said to be able to suppress an increase in cornering power while maintaining high block rigidity, and to improve rollover limit performance while ensuring excellent wear resistance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-172916 A Summary of the Invention [Problem to be solved by the invention]

[0004] Thus, in recent years, there has been a demand for improving fall resistance while maintaining wear resistance.

[0005] The present invention has been devised in view of the above circumstances, and has as its main object to provide a tire that has improved rollover resistance while maintaining wear resistance. [Means for solving the problem]

[0006] The present invention is a tire having a tread portion, the tread portion having a shoulder land portion including a tread edge, the shoulder land portion being provided with a plurality of shoulder lateral grooves and a circumferential sipe connecting the plurality of shoulder lateral grooves, the shoulder lateral grooves being chamfered, the circumferential sipes being arranged at a distance of 30% to 100% of the axial width of the shoulder land portion from the axial inner end of the shoulder land portion, and the depth of the circumferential sipes being the same as or greater than the groove depth of the shoulder lateral grooves.

[0007] In the tire according to the present invention, it is preferable that the width of the circumferential sipe is less than 1.0 mm.

[0008] In the tire according to the present invention, it is preferable that the tread portion includes a shoulder main groove that defines the inner end of the shoulder land portion and extends in the tire circumferential direction, and that, on the contact surface of the tread portion in a meridian cross section of the tire in a normal state where the tire is mounted on a normal rim with normal internal pressure and is unloaded, the radial distance A of the tire between the tire equator and the axial inner end of the shoulder main groove is smaller than the radial distance B of the tire between the inner end of the shoulder land portion and the tread edge.

[0009] In the tire according to the present invention, it is desirable that the distance A is 25% or more of the distance B.

[0010] In the tire according to the present invention, the distance A is preferably 1.0 to 8.0 mm.

[0011] In the tire according to the present invention, it is preferable that the shoulder land portion is provided with an axial sipe having an angle of 30 degrees or less with respect to the tire axial direction.

[0012] In the tire according to the present invention, it is preferable that the axial sipes intersect with the circumferential sipes.

[0013] In the tire according to the present invention, it is preferable that the axial sipes are arranged axially inward of the tread ends.

[0014] In the tire according to the present invention, it is preferable that the angle of the axial sipes is 20 degrees or more.

[0015] In the tire according to the present invention, in a tire meridian cross section in a normal state in which the tire is mounted on a normal rim with normal internal pressure and is unloaded, it is preferable that the profile of the shoulder land portion is an arc shape that is convex outward in the radial direction of the tire from the inner end of the shoulder land portion toward the outside in the tire axial direction.

[0016] In the tire of the present invention, it is preferable that the tread portion has a middle land portion adjacent to the axially inner side of the shoulder main groove, and in a tire meridian cross section in a normal state where the tire is mounted on a normal rim with normal internal pressure and no load, the profile of the middle land portion is an arc shape that convex outward in the radial direction of the tire from the axially inner end of the shoulder main groove toward the axially inner side. Effect of the Invention

[0017] By employing the above-mentioned configuration, the tire of the present invention can improve rollover resistance while maintaining wear resistance. [Brief description of the drawings]

[0018] [Figure 1] 1 is a development view of a tread portion of a pneumatic tire according to the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line DD in FIG. [Diagram 3] 2 is a cross-sectional view taken along line EE in FIG. 1. [Figure 4] FIG. 2 is an enlarged view of a shoulder land portion in FIG. [Diagram 5] FIG. 2 is an enlarged view of a middle land portion and a crown land portion of FIG. [Figure 6] FIG. 2 is a cross-sectional view of the right half of the tread portion of FIG. 1. [Figure 7] FIG. 11 is a development view of a tread portion of another embodiment. [Figure 8] 8 is a cross-sectional view taken along the line FF in FIG. 7. [Figure 9] 8 is an enlarged view of a middle land portion and a crown land portion of FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a development view of a tread portion 2 of a tire 1 of this embodiment. Fig. 1 shows the tread portion 2 of a pneumatic tire for, for example, an SUV. However, the present invention may also be applied to tires for heavy loads or light trucks, or non-pneumatic tires that are not filled with pressurized air inside.

[0020] The tread portion 2 of this embodiment has a shoulder land portion 3 including a tread end Te. In the case of a pneumatic tire, the tread end Te is the axially outermost ground contact position when the tire 1 in a normal state is loaded with a normal load and grounded on a flat surface with a camber angle of 0°. The normal state refers to a state in which the tire 1 is mounted on a normal rim, filled to a normal internal pressure, and no load is applied. In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured in the normal state. The axial distance between both tread ends Te is the tread width TW.

[0021] A "genuine rim" is a rim that is defined for each tire by the standard system that includes the standard on which the tire is based. For example, in the case of JATMA, it is called a "standard rim," in the case of TRA, it is called a "Design Rim," and in the case of ETRTO, it is called a "Measuring Rim."

[0022] "Normal internal pressure" is the air pressure set for each tire by each standard in the standard system on which the tire is based. In the case of JATMA, it is the "maximum air pressure." In the case of TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." In the case of ETRTO, it is the "INFLATION PRESSURE."

[0023] "Normal load" is the load that each standard specifies for each tire in the system of standards on which the tire is based. For JATMA, it is "maximum load capacity." For TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." For ETRTO, it is "LOAD CAPACITY."

[0024] The shoulder land portion 3 is provided with a plurality of shoulder lateral grooves 6 and circumferential sipes 7 connecting the plurality of shoulder lateral grooves 6. In this specification, a sipe is a notch-like body having a width of 1.5 mm or less, and is clearly distinguished from a groove-like body having a groove width of more than 1.5 mm.

[0025] FIG. 2 is a cross-sectional view taken along line DD in FIG. 1. As shown in FIG. 2, the shoulder lateral groove 6 is formed with a chamfer 11. The chamfer 11 uniformizes the ground pressure acting on the shoulder land portion 3, thereby improving the wear resistance. The chamfer 11 is formed, for example, by cutting the groove wall of the shoulder lateral groove 6 diagonally from the tread surface 3a of the shoulder land portion 3. In this embodiment, the chamfer 11 includes an equal width portion 11a (shown in FIG. 1) that extends with the same width w1 in the longitudinal direction of the shoulder lateral groove 6. The width w1 of the chamfer 11 is the length in the direction perpendicular to the groove width center line 6c of the shoulder lateral groove 6. In this embodiment, the equal width portion 11a extends from the inner end 6i of the shoulder lateral groove 6 in the tire axial direction beyond the tread edge Te. The chamfer 11 and the equal width portion 11a are provided, for example, on both sides of the shoulder lateral groove 6 in the groove width direction.

[0026] As shown in FIG. 1, the circumferential sipes 7 are arranged at a distance La of 30% to 100% of the axial width Ws of the shoulder land portion 3 from the inner end 3i of the shoulder land portion 3. This prevents the rigidity of the shoulder land portion 3 from being excessively reduced, so that the wear resistance is maintained at a high level. The circumferential sipes 7 also reduce the torsional rigidity of the shoulder land portion 3 and reduce the cornering force. Furthermore, the circumferential sipes 7 divide the shoulder land portion 3 in the axial direction of the tire, reducing the frictional force in the axial direction of the tire, thereby reducing the cornering force. This maintains the rollover prevention performance. To effectively exert such an effect, the distance La is preferably 30% or more of the width Ws of the shoulder land portion 3, more preferably 50% or more, more preferably 100% or less, and even more preferably 90% or less.

[0027] Fig. 3 is a cross-sectional view taken along line EE in Fig. 1. Fig. 3 is a cross-section taken along the meridian of a tire in a normal state. As shown in Fig. 3, the depth d1 of the circumferential sipes 7 is equal to or greater than the groove depth d2 of the shoulder lateral grooves 6. This allows the shoulder land portion 3 to move more easily during running, reducing the cornering force, and thus further improving rollover prevention performance. Although not particularly limited, the depth d1 of the circumferential sipes 7 is preferably 1.8 times or less, more preferably 1.3 times or less, of the groove depth d2 of the shoulder lateral grooves 6.

[0028] As shown in FIG. 1, the tread portion 2 includes, for example, a pair of shoulder land portions 3, 3, a pair of middle land portions 4, 4 arranged on the axially inner side of each shoulder land portion 3, and a crown land portion 5 arranged between each middle land portion 4. The tread portion 2 also includes a pair of shoulder main grooves 13, 13 arranged between the shoulder land portion 3 and the middle land portion 4, and a pair of crown main grooves 14, 14 arranged between the middle land portion 4 and the crown land portion 5. The shoulder main grooves 13 and the crown main groove 14 extend, for example, in the tire circumferential direction. The tread portion 2 of this embodiment is formed as a point-symmetric pattern centered on an arbitrary point on the tire equator C. The tread portion 2 is not limited to a point-symmetric pattern.

[0029] Although not particularly limited, the width Ws of the shoulder land portion 3 is preferably larger than the axial width Wm of the middle land portion 4. The width Wm of the middle land portion 4 is preferably larger than the axial width Wc of the crown land portion 5.

[0030] Each shoulder main groove 13 includes an outer groove edge 13t that defines the axial inner end 3i of the shoulder land portion 3, and an inner groove edge 13s that defines the axial outer end 4e of the middle land portion 4. Each crown main groove 14 includes an outer groove edge 14t that defines the axial inner end 4i of the middle land portion 4, and an inner groove edge 14s that defines the axial end 5e of the crown land portion 5.

[0031] In this embodiment, the outer groove edge 13t of the shoulder main groove 13 and the outer groove edge 14t of the crown main groove 14 extend linearly along the tire circumferential direction. In this embodiment, each of the outer groove edges 13t, 14t is formed in a single straight line. The inner groove edge 13s of the shoulder main groove 13 and the inner groove edge 14s of the crown main groove 14 extend in a crank shape in the tire circumferential direction. In this embodiment, each of the inner groove edges 13s, 14s includes a first portion a1, a second portion a2, and a third portion a3. The first portion a1 extends linearly in the tire circumferential direction. The second portion a2 is disposed axially inward of the first portion a1 and extends linearly in the tire circumferential direction. The third portion a3 extends axially from the first portion a1 to the second portion a2. In this embodiment, each of the third portions a3 may be connected to a lateral groove, described later, disposed in the crown land portion 5 or the middle land portion 4.

[0032] Fig. 4 is an enlarged view of the shoulder land portion 3. As shown in Fig. 4, the shoulder lateral groove 6 crosses the shoulder land portion 3. The shoulder lateral groove 6 extends, for example, from the shoulder main groove 13 to the outside in the tire axial direction beyond the tread end Te.

[0033] The shoulder lateral groove 6 includes a narrow portion 6A having a narrow groove width, a wide portion 6B having a wide groove width, and a width-changing portion 6C where the groove width changes continuously between the narrow portion 6A and the wide portion 6B. The narrow portion 6A is connected to the shoulder main groove 13. The wide portion 6B is connected to the tread edge Te. The groove width W1b of the wide portion 6B is preferably 105% or more of the groove width W1a of the narrow portion 6A, more preferably 110% or more, more preferably 135% or less, and more preferably 130% or less. The groove width W1a of the narrow portion 6A is preferably 10% or more of the width Ws of the shoulder land portion 3, more preferably 13% or more, more preferably 25% or less, and more preferably 22% or less.

[0034] The shoulder lateral groove 6 extends in an arc shape protruding toward one side in the tire circumferential direction (downward in FIG. 4). A protruding portion 6t of the shoulder lateral groove 6 that protrudes most toward one side in the tire circumferential direction is formed in the large width portion 6B.

[0035] The shoulder lateral groove 6 is provided with a tie bar 15 having a raised groove bottom 6s. In this embodiment, the tie bar 15 is formed in the narrow width portion 6A. For example, the tie bar 15 is not formed in the width changing portion 6C and the large width portion 6B. The raised height h1 (shown in FIG. 3) of the tie bar 15 from the groove bottom 6s is preferably 20% or more of the groove depth d2 of the shoulder lateral groove 6, more preferably 25% or more, more preferably 40% or less, and even more preferably 35% or less.

[0036] The circumferential sipes 7 extend, for example, linearly. In this embodiment, the circumferential sipes 7 extend along the tire circumferential direction. The circumferential sipes 7 may extend, for example, in a zigzag or wavy shape.

[0037] The circumferential sipes 7 connect the large width portions 6B of the shoulder lateral grooves 6. For example, the circumferential sipes 7 are connected to the shoulder lateral grooves 6 at a position adjacent to the width changing portion 6C rather than the protruding portion 6t. Such circumferential sipes 7 appropriately reduce the torsional rigidity of the shoulder land portion 3, thereby maintaining high rollover prevention performance.

[0038] The width W2 of the circumferential sipe 7 is preferably 1.0 mm or less, so that an excessive decrease in the rigidity of the shoulder land portion 3 is suppressed.

[0039] The shoulder land portion 3 is provided with axial sipes 8 having an angle θ1 of 30 degrees or less with respect to the tire axial direction. The shoulder land portion 3 is also provided with shoulder narrow lateral grooves 9 having a groove width W3 smaller than that of the shoulder lateral grooves 6. The angle θ1 of the axial sipes 8 is preferably 20 degrees or more.

[0040] The axial sipes 8 intersect with the circumferential sipes 7. In this embodiment, the circumferential sipes 7 intersect with a central portion 8c in the tire axial direction of the axial sipes 8. In this specification, the central portion 8c refers to a range separated by 10% of the axial length L1 of the axial sipes 8 from the axial middle position of the axial sipes 8 on both sides in the tire axial direction.

[0041] The axial sipes 8 extend from, for example, the shoulder main groove 13. In this embodiment, the axial sipes 8 terminate axially inward of the tread end Te. The axial length L1 of the axial sipes 8 is preferably 55% or more of the width Ws of the shoulder land portion 3, more preferably 60% or more, and more preferably 75% or less, and even more preferably 70% or less. Such axial sipes 8 improve rollover prevention performance and wear resistance in a well-balanced manner.

[0042] In this embodiment, a plurality of axial sipes 8 are provided between the shoulder lateral grooves 6, 6 adjacent in the tire circumferential direction. For example, two or more axial sipes 8 are provided between the shoulder lateral grooves. In this embodiment, the axial sipes 8, 8 adjacent in the tire circumferential direction extend parallel to each other. This makes the rigidity of the shoulder land portion 3 uniform, and greatly improves the wear resistance.

[0043] The shoulder narrow lateral grooves 9 are disposed outward of the axially outer ends 8e of the axial sipes 8. The axially inner ends 9i of the shoulder narrow lateral grooves 9 are positioned outward of the axially outer ends 8e of the axial sipes 8. This prevents the stiffness of the shoulder land portion 3 from being locally reduced. The shoulder narrow lateral grooves 9 extend, for example, axially outward of the tread ends Te.

[0044] The axial distance L2 between the inner end 9i of the shoulder narrow lateral groove 9 and the outer end 8e of the axial sipe 8 is preferably smaller than the axial distance L3 between the inner end 9i of the shoulder narrow lateral groove 9 and the tread end Te. This appropriately reduces the torsional rigidity of the shoulder land portion 3, improving rollover prevention performance. Although not particularly limited, the distance L2 is preferably 10% or more of the distance L3, more preferably 15% or more, more preferably 30% or less, and even more preferably 25% or less.

[0045] For example, one shoulder narrow lateral groove 9 is provided between circumferentially adjacent shoulder lateral grooves 6, 6. For example, the shoulder narrow lateral groove 9 is disposed in a central portion 10 of a circumferential distance Ls between circumferentially adjacent shoulder lateral grooves 6, 6. The central portion 10 refers to a range within 10% of the distance Ls from the middle position of the distance Ls to both sides in the circumferential direction of the tire.

[0046] The groove width W3 of the shoulder narrow lateral groove 9 is preferably 25% or more of the groove width W1a of the narrow portion 6A of the shoulder lateral groove 6, more preferably 30% or more, and is preferably 50% or less, and even more preferably 45% or less.

[0047] Fig. 5 is an enlarged view of the middle land portion 4 and the crown land portion 5 in Fig. 1. As shown in Fig. 5, the middle land portion 4 of the present embodiment includes a first middle lateral groove 17, a second middle lateral groove 18, a third middle lateral groove 19, a first middle sipe 20, and a second middle sipe 21.

[0048] The first middle lateral groove 17 of this embodiment crosses the middle land portion 4. The first middle lateral groove 17 includes, for example, a first inclined portion 17A, a second inclined portion 17B, and a third inclined portion 17C. The first inclined portion 17A extends inclined to one side with respect to the tire axial direction and is connected to the shoulder main groove 13. The second inclined portion 17B is inclined at the same angle as the first inclined portion 17A and is connected to the crown main groove 14. The third inclined portion 17C is inclined at an angle larger than the first inclined portion 17A and connects the first inclined portion 17A and the second inclined portion 17B. The third inclined portion 17C is inclined in the same direction as the first inclined portion 17A.

[0049] The groove width W4 of the first middle lateral groove 17 is smaller than the groove width W1a of the narrow portion 6A. The groove width W4 of the first middle lateral groove 17 is preferably 35% or more of the groove width W1a of the narrow portion 6A, more preferably 40% or more, and more preferably 55% or less, and even more preferably 50% or less.

[0050] The second middle lateral groove 18 of this embodiment extends axially inward from the shoulder main groove 13 and has an inner end 18i terminated within the middle land portion 4. The third middle lateral groove 19 of this embodiment extends axially outward from the crown main groove 14 and has an outer end 19e terminated within the middle land portion 4. The first middle sipe 20 of this embodiment connects the crown main groove 14 and the inner end 18i of the second middle lateral groove 18. The second middle sipe 21 of this embodiment connects the shoulder main groove 13 and the outer end 19e of the third middle lateral groove 19.

[0051] The second middle lateral groove 18 and the third middle lateral groove 19 are inclined in the same direction as the first inclined portion 17A. The second middle lateral groove 18 and the third middle lateral groove 19 extend linearly. The length L5 of the second middle lateral groove 18 and the length L6 of the third middle lateral groove 19 in the tire axial direction are formed to be smaller than the length L4 of the first inclined portion 17A of the first middle lateral groove 17. The lengths L5 and L6 are preferably 50% or more of the length L4, more preferably 55% or more, more preferably 70% or less, and even more preferably 65% ​​or less.

[0052] The groove width W5 of the second middle lateral groove 18 and the groove width W6 of the third middle lateral groove 19 are formed smaller than the groove width W4 of the first middle lateral groove 17. The groove width W5 and the groove width W6 are preferably 65% ​​or more of the groove width W4, more preferably 70% or more, and more preferably 85% or less, and even more preferably 80% or less.

[0053] The first middle sipes 20 and the second middle sipes 21 are inclined in the same direction as the first inclined portion 17A of the first middle lateral groove 17. The absolute value |θ2-θ3| of the difference between the angle θ2 of the first middle sipe 20 relative to the tire axial direction and the angle θ3 of the second middle sipe 21 relative to the tire axial direction is preferably 30 degrees or less, more preferably 15 degrees or less. In this embodiment, the absolute value |θ2-θ3| of the difference is 0 degrees. The absolute value |θ2-θ4| of the difference between the angle θ2 of the first middle sipe 20 and the angle θ4 of the first inclined portion 17A is preferably 30 degrees or less, more preferably 15 degrees or less. In this embodiment, the absolute value |θ2-θ4| of the difference is 0 degrees.

[0054] The middle land portion 4 may be provided with a third middle sipe 22 connecting the second middle lateral groove 18 and the third middle lateral groove 19. The second middle lateral groove 18, the third middle lateral groove 19, and the third middle sipe 22 extend to form a single straight line.

[0055] The crown land portion 5 includes a first crown lateral groove 24, a second crown lateral groove 25, and a crown sipe 26. In this embodiment, the first crown lateral groove 24, the second crown lateral groove 25, and the crown sipe 26 each extend linearly. The first crown lateral groove 24, the second crown lateral groove 25, and the crown sipe 26 are inclined in the same direction with respect to the tire axial direction, for example.

[0056] The first crown lateral groove 24 of this embodiment extends from one crown main groove 14A (right side in FIG. 5) toward the other crown main groove 14B (left side in FIG. 5) and terminates without reaching the tire equator C. The second crown lateral groove 25 of this embodiment extends from the other crown main groove 14B toward one crown main groove 14A and terminates without reaching the tire equator C. The first crown lateral groove 24 is disposed, for example, on a virtual line K1 extending from the groove center line 25c of the second crown lateral groove 25. The second crown lateral groove 25 is disposed, for example, on a virtual line K2 extending from the groove center line 24c of the first crown lateral groove 24. In this embodiment, the first crown lateral groove 24 has a virtual line K1 running longitudinally. In this embodiment, the second crown lateral groove 25 has a virtual line K2 running longitudinally.

[0057] In this embodiment, the crown sipes 26 traverse the crown land portion 5. A plurality of crown sipes 26 in this embodiment (two in this embodiment) are provided between the first crown lateral grooves 24, 24 adjacent in the tire circumferential direction.

[0058] As shown in Fig. 3, on the contact surface 2a of the tread portion 2, distance A in the tire radial direction is formed to be smaller than distance B in the tire radial direction. Distance A is the distance in the tire radial direction between the tire equator C and the axially inner end 13i of the shoulder main groove 13. Distance B is the distance in the tire radial direction between the inner end 3i of the shoulder land portion 3 and the tread end Te. This makes the ground contact pressure on the contact surface 2a of the tread portion 2 uniform, and further maintains high wear resistance.

[0059] In order to more effectively exert the above-mentioned effect, the distance A is preferably 55% or less, and more preferably 50% or less, of the distance B. In order to improve the tipping limit performance while ensuring excellent abrasion resistance, the distance A is preferably 25% or more, and more preferably 30% or more, of the distance B.

[0060] Distance A is preferably 1.0 to 8.0 mm. In particular, in a tire 1 having an outer diameter of 750 mm or more, by setting distance A to 8.0 mm or less, it is possible to achieve uniformity of the ground contact pressure.

[0061] FIG. 6 is a cross-sectional view of the right half of the tread portion 2. As shown in FIG. 6, the profile p1 of the shoulder land portion 3 is preferably, for example, an arc shape that is convex outward in the tire radial direction from the inner end 3i of the shoulder land portion 3 toward the outer side in the tire axial direction. The profile p2 of the middle land portion 4 is preferably, for example, an arc shape that is convex outward in the tire radial direction from the inner end 13i of the shoulder main groove 13 toward the inner side in the tire axial direction. Such an embodiment is useful for equalizing the ground pressure. Specifically, the profile p1 is preferably an arc shape that is convex outward in the tire radial direction from the first hypothetical profile pa that connects the inner end 13i of the shoulder main groove 13, the inner end 3i of the shoulder land portion 3, and the tread edge Te with an arc of the same curvature radius. The profile p2 is preferably an arc shape that is more convex outward in the tire radial direction than a second imaginary profile pb that connects the inner end 13i of the shoulder main groove 13, the inner end 3i of the shoulder land portion 3, and the inner end 4i in the tire axial direction of the middle land portion 4 with an arc of the same radius of curvature. The radius of curvature r1 of the profile p1 of the shoulder land portion 3 is preferably the same as the radius of curvature of the profile p2 of the middle land portion 4.

[0062] 7 is a development view of the tread portion 2 of another embodiment. The same components as those of the tread portion 2 of this embodiment are denoted by the same reference numerals, and detailed description thereof may be omitted.

[0063] 7, the tread portion 2 of this embodiment includes a pair of shoulder land portions 3, 3, a pair of middle land portions 4, 4, and a crown land portion 5. The tread portion 2 also includes a pair of shoulder main grooves 13, 13 arranged between the shoulder land portions 3 and the middle land portion 4, and a pair of crown main grooves 14, 14 arranged between the middle land portion 4 and the crown land portion 5.

[0064] In this embodiment, the shoulder main groove 13 and the crown main groove 14 extend in a zigzag pattern. The shoulder main groove 13 and the crown main groove 14 each include, for example, a first portion 30 inclined toward one side with respect to the tire circumferential direction and a second portion 31 inclined in the opposite direction to the first portion 30, and the first portion 30 and the second portion 31 are arranged alternately. The average pitch of the zigzag of the shoulder main groove 13 is larger than the average pitch of the zigzag of the crown main groove 14.

[0065] The shoulder land portion 3 includes an inside corner portion 3A recessed toward the outside in the tire axial direction at the intersection of the first portion 30 and the second portion 31 of the shoulder main groove 13, and an outside corner portion 3B protruding toward the inside in the tire axial direction at the intersection of the first portion 30 and the second portion 31 of the shoulder main groove 13. In this embodiment, the inside corner portions 3A and the outside corner portions 3B are arranged alternately in the tire circumferential direction.

[0066] The shoulder land portion 3 of this embodiment includes shoulder lateral grooves 6 , circumferential sipes 7 and axial sipes 8 .

[0067] The shoulder lateral groove 6 extends from the shoulder main groove 13 to the axially outer side of the tread edge Te. The shoulder lateral groove 6 includes a narrow portion 6A connected to the shoulder main groove 13, a wide portion 6B connected to the tread edge Te, and a width-changing portion 6C connecting the wide portion 6B and the narrow portion 6A. The narrow portion 6A in this embodiment is connected to the inside corner portion 3A.

[0068] A chamfer 11 is formed in the shoulder lateral groove 6. The chamfer 11 is formed on both sides in the groove width direction of the shoulder lateral groove 6. The chamfer 11 includes a constant width portion 11a. The constant width portion 11a extends from an axially inner end 6i of the shoulder lateral groove 6 to a tread edge Te.

[0069] Fig. 8 is a cross-sectional view taken along line FF in Fig. 7. As shown in Fig. 7 and Fig. 8, the shoulder lateral groove 6 is provided with a tie bar 15 having a raised groove bottom 6s. The tie bar 15 is disposed, for example, in the narrow width portion 6A. The tie bar 15 is provided with a groove bottom sipe 32 extending in the longitudinal direction of the narrow width portion 6A. The axial length L6 of the groove bottom sipe 32 is, for example, 90% or more and less than 100% of the axial length L7 of the narrow width portion 6A.

[0070] In this embodiment, the circumferential sipes 7 are continuous with the large width portion 6 B. The circumferential sipes 7 intersect with the axial sipes 8 at the center portions 8 c in the tire axial direction, for example.

[0071] In this embodiment, the axial sipes 8 extend in a zigzag shape. Such axial sipes 8 reduce the rigidity of the shoulder land portion 3, and maintain high rollover prevention performance.

[0072] 9 is a development view of the middle land portion 4 and the crown land portion 5 of another embodiment. In this embodiment, the middle land portion 4 is provided with middle lateral grooves 35 and middle sipes 36.

[0073] The middle lateral groove 35 crosses, for example, the middle land portion 4. The middle lateral groove 35 extends, for example, in a convex arc shape toward one side in the tire circumferential direction. In the middle lateral groove 35 of the present embodiment, a tie bar 37 connected to the crown main groove 14 and a groove bottom sipe 38 formed on the tie bar 37 are formed.

[0074] The middle sipes 36 include a middle cross sipe 36A that crosses the middle land portion 4 and a middle terminal sipe 36B that terminates within the middle land portion 4. The middle cross sipe 36A extends in a bent shape having at least one bent portion 40. In this embodiment, the middle cross sipe 36A includes a first cross sipe 41A having one bent portion 40, a second cross sipe 41B having two bent portions 40, and a third cross sipe 41C having three bent portions 40. In this embodiment, the middle terminal sipe 36B includes a first terminal sipe 42A that extends linearly and a second terminal sipe 42B having one bent portion 40.

[0075] The crown land portion 5 includes a crown lateral groove 45, a first crown sipe 46, a second crown sipe 47, and a third crown sipe 48. The crown lateral groove 45 crosses the crown land portion 5 and extends linearly. The first crown sipe 46 crosses the crown land portion 5. The first crown sipe 46 includes a pair of outer portions 46a inclined to one side with respect to the tire axial direction, and a central portion 46b inclined at an angle different from that of the outer portions 46a and connecting the pair of outer portions 46a. The central portion 46b is disposed, for example, on the tire equator C. In this embodiment, the central portion 46b is inclined at a smaller angle with respect to the tire axial direction than the outer portions 46a.

[0076] The second crown sipes 47 extend from one crown main groove 14A toward the other crown main groove 14B and terminate within the crown land portion 5. The third crown sipes 48 extend from the other crown main groove 14B toward one crown main groove 14A and terminate within the crown land portion 5. The second crown sipes 47 extend in a generally V-shape protruding in one direction in the tire circumferential direction. The third crown sipes 48 extend in a generally V-shape protruding in the opposite direction to the second crown sipes 47 in the tire circumferential direction.

[0077] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment and can be modified and carried out in various forms. EXAMPLES

[0078] Pneumatic tires for passenger cars with a size of 255 / 60R18 and the basic pattern shown in Figure 1 were prototyped based on the specifications in Table 1. Tests were then conducted on the rollover prevention performance and wear resistance performance of each prototype tire. The common specifications and test methods for each prototype tire are as follows: Rim used: 18×7.5J Internal pressure: 230kPa d1:6mm |d1-d2|: 2 mm (Comparative Example 2, Example 2)

[0079] <Fall prevention performance> A test driver got into the following test vehicle, drove it on a dry asphalt road surface, and evaluated the limit steering stability during cornering by sensory evaluation. The results are shown as a score based on Comparative Example 1 being 100. The higher the score, the better the performance. Test vehicle: 3500cc (engine displacement) SUV passenger car

[0080] <Wear resistance> A GPS bench wear energy analyzer was used to measure the wear energy during braking, driving, and turning. The results are expressed as an index with Comparative Example 1 being 100. The higher the value, the better the result. The test results are shown in Table 1.

[0081] [Table 1]

[0082] As shown in the table, the tires of the examples are excellent in rollover resistance while maintaining wear resistance. [Explanation of symbols]

[0083] 1 Tire 3 Shoulder Land Section 3i Inner end of shoulder land 6 Shoulder groove 7 Circumferential sipes 11 Chamfering Ws Shoulder width

Claims

1. A tire having a tread portion, The tread portion has a shoulder land portion including a tread end, The shoulder land portion is provided with a plurality of shoulder lateral grooves and a circumferential sipe connecting the plurality of shoulder lateral grooves, The shoulder lateral groove is formed with a chamfer, The circumferential sipes are arranged at a distance of 30% to 100% of the axial width of the shoulder land portion from an axial inner end of the shoulder land portion, The depth of the circumferential sipe is equal to or greater than the groove depth of the shoulder lateral groove, The chamfer extends from an axially inner end of the shoulder lateral groove beyond a tread end. tire.

2. A tire as described in claim 1, wherein the chamfer is provided on both sides of the shoulder lateral groove in the groove width direction.

3. the tread portion includes a shoulder main groove that defines the inner end of the shoulder land portion and extends in a tire circumferential direction, In a tire meridian cross section in a normal state where the tire is mounted on a normal rim with normal internal pressure and no load, 3. The tire according to claim 1, wherein a distance A in the tire radial direction between a tire equator and an axially inner end of the shoulder main groove is smaller than a distance B in the tire radial direction between the inner end of the shoulder land portion and a tread edge.

4. The tire according to claim 3 , wherein the distance A is equal to or greater than 25% of the distance B.

5. The tire according to claim 3 or 4, wherein the distance A is 1.0 to 8.0 mm.

6. The tire according to claim 1 , wherein the shoulder land portion is provided with an axial sipe having an angle of 30 degrees or less with respect to the tire axial direction.

7. The tire of claim 6 wherein said axial sipes intersect said circumferential sipes.

8. The tire according to claim 6 or 7, wherein the axial sipes are arranged axially inward of a tread end.

9. The shoulder land portion is provided with a shoulder narrow lateral groove, The tire according to claim 6 , wherein an inner end in the tire axial direction of the shoulder narrow lateral groove is positioned outside an outer end in the tire axial direction of the axial sipe.

10. In the meridian cross section of a tire in a normal state with normal internal pressure, mounted on a normal rim, and no load, The tire according to claim 1 , wherein the shoulder land portion has a profile that is an arc convex outward in the tire radial direction from the inner end of the shoulder land portion toward the outside in the tire axial direction.

11. The tread portion has a shoulder main groove and a middle land portion adjacent to the axially inner side of the shoulder main groove, In the meridian cross section of a tire in a normal state with normal internal pressure, mounted on a normal rim, and no load, 11. The tire according to claim 1, wherein the middle land portion has a profile that is an arc convex radially outward from an axially inner end of the shoulder main groove toward an axially inner side.

12. A tire having a tread portion, The tread portion has a shoulder land portion including a tread end, The shoulder land portion is provided with a plurality of shoulder lateral grooves and a circumferential sipe connecting the plurality of shoulder lateral grooves, The shoulder lateral groove is formed with a chamfer, The circumferential sipes are arranged at a distance of 30% to 100% of the axial width of the shoulder land portion from an axial inner end of the shoulder land portion, The depth of the circumferential sipe is equal to or greater than the groove depth of the shoulder lateral groove, The chamfer is provided on both sides of the shoulder lateral groove in a groove width direction. tire.

13. A tire having a tread portion, The tread portion has a shoulder land portion including a tread end, The shoulder land portion is provided with a plurality of shoulder lateral grooves and a circumferential sipe connecting the plurality of shoulder lateral grooves, The shoulder lateral groove is formed with a chamfer, The circumferential sipes are arranged at a distance of 30% to 100% of the axial width of the shoulder land portion from an axial inner end of the shoulder land portion, The depth of the circumferential sipe is equal to or greater than the groove depth of the shoulder lateral groove, The shoulder land portion is provided with an axial sipe and a shoulder narrow lateral groove, An inner end of the shoulder narrow lateral groove in the tire axial direction is located outside an outer end of the axial sipe in the tire axial direction. tire.

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