tire

Abstract

To provide a tire excellent in wet grip performance, dry grip performance, control performance and abrasion resistance performance.SOLUTION: A tread of a tire has (1) a first major groove 38 located to a back side from an equatorial plane CL of a tire, extending along a circumferential direction, and having a zigzag shape, (2) a second major groove 40 located to the back side from the equatorial plane and to a front side from the first major groove 38, extending along the circumferential direction, and having a zigzag shape, and (3) a plurality of first lateral grooves 48, each of which is inclined in a negative direction to an axial direction of the tire, and is separated from the first major groove 38 and the second major groove 40, and (4) a plurality of second lateral grooves 50, each of which is inclined in a positive direction to the axial direction, and is separated from the first major groove 38 and the second major groove 40.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a tire, and more particularly to an improvement in a tire tread pattern. [Background technology]

[0002] Tires are mounted on vehicles that run on both dry and wet road surfaces, and therefore tires are required to have both dry and wet grip performance.

[0003] JP 2020-200018 A discloses a tire having a tread pattern in which grooves are arranged asymmetrically. This tread pattern can contribute to dry grip performance and wet grip performance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication 2020-200018 Summary of the Invention [Problem to be solved by the invention]

[0005] A tread with a large contact area with the ground has a high coefficient of friction. A tire with this tread has excellent dry grip performance. Grooves contribute to drainage on wet roads. A tire with many grooves has excellent wet grip performance. However, the contact area of ​​a tread with grooves with the ground is small. Grooves can impede dry grip performance. Dry grip performance and wet grip performance are contradictory.

[0006] When a tire is in motion, the zone of the tread surface where a large load is applied frequently shifts. This shift causes fluctuations in grip performance. In particular, the fluctuations in grip performance are large in tires with tread grooves. The fluctuations in grip performance impair control performance.

[0007] The grooves cause uneven tread stiffness, which is one of the causes of uneven wear.

[0008] An object of the present invention is to provide a tire which is excellent overall in wet grip performance, dry grip performance, control performance and wear resistance. [Means for solving the problem]

[0009] The tire according to the present invention includes a tread having a tread surface. (1) a first main groove located behind the equatorial plane of the tire, extending along the circumferential direction, and having a zigzag shape; (2) a second main groove located behind the equatorial plane and on the front side of the first main groove, extending along the circumferential direction and having a zigzag shape; (3) a plurality of first lateral grooves, each of which is inclined in a negative direction with respect to the axial direction of the tire and spaced apart from the first main groove and the second main groove; and (4) a plurality of second transverse grooves, each of which is inclined in a positive direction relative to the axial direction and spaced apart from the first main groove and the second main groove; The first transverse grooves and the second transverse grooves are alternately arranged in the circumferential direction on the back side of the first main groove. The first transverse grooves and the second transverse grooves are alternately arranged in the circumferential direction on the front side of the second main groove.

[0010] Preferably, the land ratio Pb of the tread surface on the rear side of the equatorial plane is smaller than the land ratio Pf of the tread surface on the front side of the equatorial plane.

[0011] Preferably, the number of main grooves in the tread is two.

[0012] Preferably, the first main groove has a plurality of negative elements each inclined in a negative direction with respect to the circumferential direction and a plurality of positive elements each inclined in a positive direction with respect to the circumferential direction. These negative elements and positive elements are arranged alternately along the circumferential direction. Preferably, the second main groove has a plurality of negative elements each inclined in a negative direction with respect to the circumferential direction and a plurality of positive elements each inclined in a positive direction with respect to the circumferential direction. These negative elements and positive elements are arranged alternately along the circumferential direction.

[0013] Preferably, in the first main groove, the absolute value of the angle of the negative elements relative to the circumferential direction is 10° to 20°, and the absolute value of the angle of the positive elements relative to the circumferential direction is 10° to 20°. Preferably, in the second main groove, the absolute value of the angle of the negative elements relative to the circumferential direction is 10° to 20°, and the absolute value of the angle of the positive elements relative to the circumferential direction is 10° to 20°.

[0014] Preferably, the second lateral groove is located on the back side of the negative element of the first main groove, and the first lateral groove is located on the back side of the positive element of the first main groove. Preferably, the second lateral groove is located on the front side of the negative element of the second main groove, and the first lateral groove is located on the front side of the positive element of the second main groove.

[0015] Preferably, the absolute value of the angle of the first transverse groove with respect to the axial direction is equal to or greater than 10° and equal to or less than 40°. Preferably, the absolute value of the angle of the second transverse groove with respect to the axial direction is equal to or greater than 10° and equal to or less than 40°.

[0016] Preferably, on the front side of the equatorial plane, (1) A row of multiple second lateral grooves aligned in the circumferential direction and (2) A row of first transverse grooves arranged in the circumferential direction exists.

[0017] Preferably, the width of the first main groove is greater than the width of the first transverse groove and the width of the second transverse groove. Preferably, the width of the second main groove is greater than the width of the first transverse groove and the width of the second transverse groove.

[0018] The tire may further include a plurality of sipes. Preferably, each sipe is sandwiched between the first main groove and the second main groove. Effect of the Invention

[0019] The tire according to the present invention is excellent overall in wet grip performance, dry grip performance, control performance and wear resistance. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a front view showing a tire according to an embodiment of the present invention together with a vehicle. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a portion of the tire of FIG. [Diagram 3] FIG. 3 is a development view showing a part of the tread pattern of the tire of FIG. [Figure 4] FIG. 4 is an enlarged cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 5 is an enlarged cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is an enlarged cross-sectional view taken along the line VI-VI in FIG. [Figure 7] FIG. 7 is an enlarged view showing a part of the first main groove of the tread pattern of FIG. [Figure 8] FIG. 8 is an enlarged view showing the first lateral groove of the tread pattern of FIG. [Figure 9] FIG. 9 is an enlarged view showing the second lateral groove of the tread pattern of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the drawings as appropriate.

[0022] In FIG. 1, a tire 2 is shown together with a vehicle 4. The vehicle 4 has a body 6 and an axle 8. The tire 2 is connected to the axle 8 via a wheel and a hub, neither of which are shown. The right side in FIG. 1 is the face side of the tire 2. This face side is also the outer side in the width direction of the vehicle 4. The left side in FIG. 1 is the back side of the tire 2. This back side is also the inner side in the width direction of the vehicle 4.

[0023] Fig. 2 shows a part of a cross section of the tire 2 taken along a plane including the rotation axis of the tire 2 in Fig. 1. In Fig. 2, the up-down direction is the radial direction of the tire 2, the left-right direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. In Fig. 2, a dashed dotted line CL represents the equatorial plane of the tire 2. Except for the tread pattern described below, the shape of the tire 2 is mirror symmetrical with respect to the equatorial plane CL. This dashed dotted line CL is also the center line of the tire 2 in the axial direction.

[0024] The tire 2 has a tread 10, a pair of sidewalls 12, a pair of beads 14, a carcass 16, a belt 18, a band 20, and an inner liner 22. The tire 2 may have various other components. The tire 2 is a tubeless type. The tire 2 is typically mounted on a four-wheeled vehicle.

[0025] The tread 10 has a shape that is convex outward in the radial direction. The tread 10 has a tread surface 24 that contacts the road surface. The material of the tread 10 is a crosslinked rubber composition. The tread 10 may have a base and a cap that covers the base. The tread 10 may have three or more layers. The tread 10 has a tread pattern that will be described in detail later.

[0026] Each sidewall 12 extends substantially radially inward from the tread 10. A portion of the sidewall 12 is joined to the tread 10. The sidewall 12 is made of crosslinked rubber that has excellent cut resistance and weather resistance. The sidewall 12 prevents damage to the carcass 16.

[0027] Each bead 14 is located axially inward of the sidewall 12. The bead 14 has a core 26 and an apex 28 extending radially outward from the core 26. The core 26 is ring-shaped and includes a wound inelastic wire. The wire is typically made of steel. The apex 28 tapers radially outward. The apex 28 is made of high-hardness crosslinked rubber.

[0028] The carcass 16 is laid between the beads 14 on both sides and extends along the tread 10 and the sidewall 12. The carcass 16 has a large number of cords arranged in parallel and a topping rubber. The absolute value of the angle that each cord makes with respect to the equatorial plane CL is 75° to 90°. In other words, the carcass 16 has a radial structure. The cords are made of organic fibers. Preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

[0029] The belt 18 is located on the radially inner side of the tread 10. The belt 18 is laminated with the carcass 16. The belt 18 reinforces the carcass 16. The belt 18 has an inner layer 30 and an outer layer 32. Each of the inner layer 30 and the outer layer 32 has a large number of cords arranged in parallel and a topping rubber. Each cord is inclined with respect to the equatorial plane CL. The general absolute value of the inclination angle is 10° or more and 35° or less. The inclination direction of the cord of the inner layer 30 with respect to the equatorial plane CL is opposite to the inclination direction of the cord of the outer layer 32 with respect to the equatorial plane CL. The preferred material of the cord is steel. Organic fibers may be used for the cord. Examples of organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

[0030] The band 20 is located radially outward of the belt 18. The band 20 has a cord and a topping rubber. The cord is wound in a spiral shape. The band 20 has a so-called jointless structure. The cord extends substantially in the circumferential direction. The angle of the cord with respect to the circumferential direction is 5° or less, and further 2° or less. The cord is made of organic fiber. Examples of preferred organic fibers include nylon fiber, polyester fiber, rayon fiber, polyethylene naphthalate fiber, and aramid fiber.

[0031] FIG. 3 is a development view showing a portion of the tread pattern of the tire 2 in FIG. 1. In FIG. 3, the up-down direction is the circumferential direction, and the left-right direction is the axial direction. The up direction is also the traveling direction of the tire 2 (i.e., the front side). In FIG. 3, the right side is the front side, and the left side is the back side. In FIG. 3, the clockwise direction is the positive direction of rotation. The tread surface 24 is divided into a back half 34 and a front half 36 by an equatorial plane CL. The back half 34 is located behind the equatorial plane CL. The front half 36 is located on the front side of the equatorial plane CL.

[0032] This tread pattern has a first main groove 38 and a second main groove 40. The first main groove 38 is located on the rear side of the equatorial plane CL. The second main groove 40 is located on the rear side of the equatorial plane CL. The second main groove 40 is located on the front side of the first main groove 38. The tread pattern of this embodiment does not have a main groove on the front side of the equatorial plane CL. This tread pattern is not symmetrical with respect to the equatorial plane CL.

[0033] The first main groove 38 and the second main groove 40 divide the tread surface 24 into three ribs. Specifically, the tread surface 24 has a first rib 42, a second rib 44, and a third rib 46. The first rib 42 is located on the back side of the first main groove 38. The second rib 44 is sandwiched between the first main groove 38 and the second main groove 40. The third rib 46 is located on the front side of the second main groove 40. In FIG. 3, the symbol TW represents the width of the tread 10.

[0034] The tread pattern has a plurality of first lateral grooves 48 and a plurality of second lateral grooves 50. These lateral grooves 48, 50 are distributed in the first rib 42 and the third rib 46, respectively. These lateral grooves form a first row R1, a second row R2, a third row R3, and a fourth row R4. The first row R1 is located on the back side of the first main groove 38. The second row R2 is located on the front side of the second main groove 40. The third row R3 is located on the front side of the second row R2. The fourth row R4 is located on the front side of the third row R3. In this embodiment, the second rib 44 does not have any lateral grooves.

[0035] The tread pattern has a plurality of sipes 52. Each sipe 52 is present in the second rib 44. In other words, the sipe 52 is sandwiched between the first main groove 38 and the second main groove 40. The sipe 52 extends in the axial direction. The zones on the surface of the tread 10 other than the grooves 38, 40, 48, 50 and the sipes 52 are lands.

[0036] In this tread pattern, the pattern of units 54 shown in Figure 3 is repeated in the circumferential direction. Thus, the groove pitch is constant. The tread pattern may have variations in the groove pitch.

[0037] FIG. 4 is an enlarged cross-sectional view taken along line IV-IV in FIG. 3. FIG. 4 shows the vicinity of the first main groove 38. The first main groove 38 is recessed from the tread surface 24. The first main groove 38 has a pair of slopes 56. Each slope 56 is formed by chamfering. The slopes 56 can contribute to the wear resistance of the tread 10. The angle of the slopes 56 with respect to the radial direction is preferably 45° or more and 70° or less. Although not shown, the second main groove 40 is also recessed from the tread surface 24, similar to the first main groove 38. The second main groove 40 also has a slope 56 formed by chamfering.

[0038] FIG. 5 is an enlarged cross-sectional view taken along line VV in FIG. 3. FIG. 5 shows the vicinity of the first lateral groove 48. The first lateral groove 48 is recessed from the tread surface 24. The first lateral groove 48 has a slope 58 formed by chamfering. As is clear from FIG. 3, the slope 58 is annular. This slope 58 can contribute to the wear resistance of the tread 10. The angle of the slope 58 with respect to the radial direction is preferably 45° or more and 70° or less. Although not shown, the second lateral groove 50 is also recessed from the tread surface 24, similar to the first lateral groove 48. The second lateral groove 50 also has a slope 58 formed by chamfering.

[0039] Fig. 6 is an enlarged cross-sectional view taken along line VI-VI in Fig. 3. Fig. 6 shows the vicinity of the sipe 52. The sipe 52 is recessed from the tread surface 24.

[0040] FIG. 7 is an enlarged view showing a part of the first main groove 38. In FIG. 7, the up-down direction is the circumferential direction, and the left-right direction is the axial direction. The first main groove 38 generally extends in the circumferential direction. The first main groove 38 has a zigzag shape. The first main groove 38 has a plurality of negative elements 60 and a plurality of positive elements 62. Each of the negative elements 60 is inclined in the negative direction (counterclockwise direction) with respect to the circumferential direction. Each of the positive elements 62 is inclined in the positive direction (clockwise direction) with respect to the circumferential direction. These negative elements 60 and positive elements 62 are alternately arranged along the circumferential direction. The negative elements 60 are continuous with the positive elements 62 at one end and with another positive element 62 at the other end. The positive elements 62 are continuous with the negative elements 60 at one end and with another negative element 60 at the other end. Therefore, in the first main groove 38, the number of positive elements 62 is the same as the number of negative elements 60. In one first main groove 38, the number of negative elements 60 is preferably 10 or more and 20 or less, and the number of positive elements 62 is preferably 10 or more and 20 or less.

[0041] In this embodiment, all the negative elements 60 have the same shape and size. The negative elements 60 may have variations in shape. The negative elements 60 may have variations in size.

[0042] In this embodiment, all the positive elements 62 have the same shape and size. The positive elements 62 may have variations in shape. The positive elements 62 may have variations in size.

[0043] As is clear from Fig. 3, in this embodiment, the shape of the second main groove 40 is the same as the shape of the first main groove 38. Therefore, the second main groove 40 also has a plurality of negative elements 60 and a plurality of positive elements 62 shown in Fig. 7. As is clear from Fig. 3, in this embodiment, the phases of the negative elements 60 and the positive elements 62 in the second main groove 40 match those in the first main groove 38.

[0044] FIG. 8 is an enlarged view showing the first transverse groove 48. In FIG. 8, the up-down direction is the circumferential direction, and the left-right direction is the axial direction. The contour of the first transverse groove 48 is generally horizontally elongated. In this embodiment, the contour of the first transverse groove 48 is an oval. The first transverse groove 48 may have another contour shape. The first transverse groove 48 is inclined in the negative direction with respect to the axial direction. The contour of the first transverse groove 48 is closed. Therefore, the first transverse groove 48 is separated from the first main groove 38 (see FIG. 3) and also from the second main groove 40. The first transverse groove 48 does not communicate with the main groove. In this embodiment, all the first transverse grooves 48 have the same shape and size. These first transverse grooves 48 may have variations in shape. These first transverse grooves 48 may have variations in size.

[0045] FIG. 9 is an enlarged view showing the second transverse groove 50. In FIG. 9, the up-down direction is the circumferential direction, and the left-right direction is the axial direction. The contour of the second transverse groove 50 is generally horizontally elongated. In this embodiment, the contour of the second transverse groove 50 is an ellipse. The second transverse groove 50 may have other contour shapes. The second transverse groove 50 is inclined in the positive direction with respect to the axial direction. The contour of the second transverse groove 50 is closed. Therefore, the second transverse groove 50 is separated from the first main groove 38 and also from the second main groove 40. The second transverse groove 50 does not communicate with the main groove. In this embodiment, the shape and size of all the second transverse grooves 50 are uniform. These second transverse grooves 50 may have variations in shape. These second transverse grooves 50 may have variations in size.

[0046] As described above, the first row R1 is located behind the first main groove 38. As shown in FIG. 3, the first row R1 includes a plurality of first lateral grooves 48 and a plurality of second lateral grooves 50. These first lateral grooves 48 and second lateral grooves 50 are alternately arranged along the circumferential direction. The number of the first lateral grooves 48 in the first row R1 is preferably 10 or more and 20 or less. The number of the second lateral grooves 50 in the first row R1 is preferably 10 or more and 20 or less. The total number N1 of the lateral grooves in the first row R1 is preferably 20 or more and 40 or less.

[0047] As described above, the second row R2 is located on the front side of the second main groove 40. As shown in FIG. 3, the second row R2 includes a plurality of first transverse grooves 48 and a plurality of second transverse grooves 50. These first transverse grooves 48 and second transverse grooves 50 are alternately arranged along the circumferential direction. Each of the first transverse grooves 48 straddles the equatorial plane CL. The axial center point of the first transverse groove 48 is located on the front side of the equatorial plane CL. Each of the second transverse grooves 50 straddles the equatorial plane CL. The axial center point of the second transverse groove 50 is located on the front side of the equatorial plane CL. The number of the first transverse grooves 48 in the second row R2 is preferably 10 or more and 20 or less. The number of the second transverse grooves 50 in the second row R2 is preferably 10 or more and 20 or less. The total number N2 of the transverse grooves 48, 50 in the second row R2 is preferably 20 or more and 40 or less.

[0048] As described above, the third row R3 is located on the front side of the second row R2. As shown in FIG. 3, the third row R3 includes a plurality of second transverse grooves 50. These second transverse grooves 50 are arranged along the circumferential direction. In this embodiment, these second transverse grooves 50 are arranged at equal pitches. Each of the second transverse grooves 50 is located on the front side of the equatorial plane CL. The number of the second transverse grooves 50 in the third row R3 is preferably 20 to 40. In this embodiment, the third row R3 does not include the first transverse groove 48. The third row R3 may include the first transverse groove 48. The total number N3 of transverse grooves in the third row R3 is preferably 20 to 40.

[0049] As described above, the fourth row R4 is located on the front side of the third row R3. As shown in FIG. 3, the fourth row R4 includes a plurality of first transverse grooves 48. These first transverse grooves 48 are arranged along the circumferential direction. In the present embodiment, these first transverse grooves 48 are arranged at equal pitches. Each of the first transverse grooves 48 is located on the front side of the equatorial plane CL. The number of the first transverse grooves 48 in the fourth row R4 is preferably 20 or more and 40 or less. In the present embodiment, the fourth row R4 does not include a second transverse groove 50. The fourth row R4 may include a second transverse groove 50. The total number N4 of transverse grooves in the fourth row R4 is preferably 20 or more and 40 or less.

[0050] 3, the sipe 52 is located in a zone between a corner where the first main groove 38 protrudes toward the rear side and a corner where the second main groove 40 protrudes toward the rear side. The sipe 52 can suppress the stiffness of the tread 10 in this zone. The sipe 52 is spaced apart from the first main groove 38 and also from the second main groove 40. The sipe 52 does not promote uneven wear.

[0051] When the tire 2 mounted on the vehicle 4 runs straight with a negative camber, the back half 34 of the tread surface 24 mainly comes into contact with the ground. In this tire 2, when running straight on a wet road surface, the first main groove 38 and the second main groove 40 contribute to drainage. This tire 2 has excellent wet grip performance.

[0052] When the vehicle 4 turns, the outer half 36 of the tread surface 24 also comes into contact with the ground under strong pressure. There are no main grooves in this zone. Therefore, in this tire 2, when turning on a dry road surface, a wide area of ​​the tread surface 24 comes into contact with the road surface. Furthermore, the rigidity of the tread 10 in this zone is high. This tire 2 has excellent dry grip performance.

[0053] As described above, each of the first main groove 38 and the second main groove 40 has a zigzag shape. In other words, the tread surface 24 has many edges. These edges suppress slippage of the tire 2 with the road surface. The first main groove 38 and the second main groove 40 can contribute to both dry grip performance and wet grip performance.

[0054] Since the first main groove 38 and the second main groove 40 each have a zigzag shape, the distribution of stiffness is suppressed on the tread surface 24. Even if the zone on the tread surface 24 to which a large load is applied shifts due to a slight slippage or the like during driving, the grip performance does not fluctuate significantly. This tire 2 has excellent controllability.

[0055] As described above, each of the first lateral groove 48 and the second lateral groove 50 is spaced apart from the first main groove 38 and also from the second main groove 40. The rigidity of the tread 10 is appropriate. This rigidity contributes to dry grip performance and controllability. Furthermore, in the tread 10, uneven wear can be suppressed. The tire 2 has excellent wear resistance.

[0056] From the viewpoint of wet grip performance, the number of main grooves located in the back half 34 of the tread surface 24 is preferably 1 or more, and more preferably 2 or more. From the viewpoint of suppressing uneven wear, the number of main grooves located in this back half 34 is preferably 3 or less, and more preferably 2 or less. The ideal number of main grooves located in this back half 34 is 2. From the viewpoint of dry grip performance during cornering, the number of main grooves located in the front half 36 of the tread surface 24 is preferably zero. Therefore, the number of main grooves in the entire tread surface 24 is preferably 1 to 3, and more preferably 2. A main groove that straddles the equatorial plane CL and has an area belonging to the back half 34 that is larger than the area belonging to the front half 36 is a "main groove located in the back half 34". A main groove that straddles the equatorial plane CL and has an area belonging to the front half 36 that is larger than the area belonging to the back half 34 is a "main groove located in the front half 36".

[0057] 3, arrow L1 indicates the distance from the back end of the first main groove 38 to the equatorial plane CL, and arrow L2 indicates the distance from the back end of the second main groove 40 to the equatorial plane CL. From the viewpoint of achieving both drainage performance during straight running and drainage performance during cornering, the ratio of the distance L1 to the width TW of the tread 10 is preferably 20% or more and 40% or less, and the ratio of the distance L2 to the width TW of the tread 10 is preferably 10% or more and 20% or less.

[0058] From the viewpoint of wet grip performance, it is preferable that the land ratio Pb of the tread surface 24 on the back side is smaller than that of the equatorial plane CL. From the viewpoint of dry grip performance during cornering, it is preferable that the land ratio Pf of the tread surface 24 on the front side is larger than that of the equatorial plane CL. From the viewpoint of achieving both wet grip performance and dry grip performance, the ratio (Pb / Pf) is preferably 48 / 52 or less, more preferably 47 / 53 or less, and particularly preferably 46 / 54 or less. This ratio (Pb / Pf) is preferably 40 / 60 or more. The land ratio Pt of the entire tread 10 is 70% or more and 85% or less. below Each land ratio is the ratio of the area of ​​the land present in that zone to the area of ​​that zone face if the grooves and sipes 52 were not present.

[0059] In FIG. 7, the arrow α is the angle of the negative element 60 with respect to the circumferential direction. The absolute value of the angle α is preferably 10° or more and 20° or less. The negative element 60 with an absolute value of 10° or more can contribute to grip performance due to the edge effect. The negative element 60 with an absolute value of 10° or more can also contribute to suppressing the stiffness distribution. From these viewpoints, the absolute value is more preferably 12° or more, and particularly preferably 13° or more. The negative element 60 with an absolute value of 20° or less can contribute to drainage. From this viewpoint, the absolute value is more preferably 18° or less, and particularly preferably 17° or less. Although not shown, the angle of the negative element 60 of the second main groove 40 with respect to the circumferential direction is the same as this angle α.

[0060] In FIG. 7, the arrow β indicates the angle of the positive element 62 with respect to the circumferential direction. The absolute value of the angle β is preferably 10° or more and 20° or less. The positive element 62 with an absolute value of 10° or more can contribute to grip performance due to the edge effect. The positive element 62 with an absolute value of 10° or more can also contribute to suppressing stiffness distribution. From these viewpoints, the absolute value is more preferably 12° or more, and particularly preferably 13° or more. The positive element 62 with an absolute value of 20° or less can contribute to drainage. From this viewpoint, the absolute value is more preferably 18° or less, and particularly preferably 17° or less. Although not shown, the angle of the positive element 62 of the second main groove 40 with respect to the circumferential direction is the same as this angle β.

[0061] In FIG. 8, the arrow θ1 indicates the angle of the first lateral groove 48 with respect to the axial direction. The absolute value of the angle θ1 is preferably 10° or more and 40° or less. The first lateral groove 48 having an absolute value of 10° or more can suppress the rigidity distribution and contribute to the control performance. From this viewpoint, the absolute value is more preferably 13° or more, and particularly preferably 15° or more. The tread 10 having an absolute value of 40° or less has excellent axial rigidity. The tread 10 has excellent steering stability during cornering and excellent wear resistance. From these viewpoints, the absolute value is preferably 30° or less, and particularly preferably 25° or less.

[0062] In FIG. 9, the arrow θ2 indicates the angle of the second lateral groove 50 with respect to the axial direction. The absolute value of the angle θ2 is preferably 10° or more and 40° or less. The second lateral groove 50 having an absolute value of 10° or more can suppress the rigidity distribution and contribute to the control performance. From this viewpoint, the absolute value is more preferably 13° or more, and particularly preferably 15° or more. The tread 10 having an absolute value of 40° or less is excellent in the rigidity in the axial direction. The tread 10 is excellent in the steering stability performance during cornering and the wear resistance. From these viewpoints, the absolute value is preferably 30° or less, and particularly preferably 25° or less.

[0063] As shown in FIG. 3, the first lateral groove 48 belonging to the first row R1 is located behind the positive element 62 of the first main groove 38. The second lateral groove 50 belonging to the first row R1 is located behind the negative element 60 of the first main groove 38. As described above, the first lateral groove 48 is inclined in the negative direction with respect to the axial direction. In other words, the first lateral groove 48 is inclined in the positive direction with respect to the circumferential direction. As described above, the second lateral groove 50 is inclined in the positive direction with respect to the axial direction. In other words, the second lateral groove 50 is inclined in the negative direction with respect to the circumferential direction.

[0064] In this way, the first lateral grooves 48 belonging to the first row R1 and the positive elements 62 of the first main groove 38 are inclined in the positive direction with respect to the circumferential direction. The second lateral grooves 50 belonging to the first row R1 and the negative elements 60 of the first main groove 38 are inclined in the negative direction with respect to the circumferential direction. The phase of the lateral grooves belonging to the first row R1 matches the phase of the first main groove 38. The lateral grooves belonging to the first row R1 suppress the stiffness distribution of the first rib 42 caused by the first main groove 38. These lateral grooves can contribute to control performance.

[0065] As shown in FIG. 3 , the first lateral groove 48 belonging to the second row R2 is located on the front side of the positive element 62 of the second main groove 40. The second lateral groove 50 belonging to the second row R2 is located on the front side of the negative element 60 of the second main groove 40. As described above, the first lateral groove 48 is inclined in the negative direction with respect to the axial direction. In other words, the first lateral groove 48 is inclined in the positive direction with respect to the circumferential direction. As described above, the second lateral groove 50 is inclined in the positive direction with respect to the axial direction. In other words, the second lateral groove 50 is inclined in the negative direction with respect to the circumferential direction.

[0066] In this way, the first lateral grooves 48 belonging to the second row R2 and the positive elements 62 of the second main groove 40 are inclined in the positive direction with respect to the circumferential direction. The second lateral grooves 50 belonging to the second row R2 and the negative elements 60 of the second main groove 40 are inclined in the negative direction with respect to the circumferential direction. The phase of the lateral grooves belonging to the second row R2 is consistent with the phase of the second main groove 40. The lateral grooves belonging to the second row R2 suppress the stiffness distribution of the third rib 46 caused by the second main groove 40. These lateral grooves can contribute to control performance.

[0067] As described above, the third row R3 includes the second transverse grooves 50, and the fourth row R4 includes the first transverse grooves 48. Therefore, the inclination direction of the grooves in the fourth row R4 is opposite to that of the grooves in the third row R3. The number of the first transverse grooves 48 in the fourth row R4 is equal to the number of the second transverse grooves 50 in the third row R3. The circumferential positions of the first transverse grooves 48 in the fourth row R4 are offset from the circumferential positions of the second transverse grooves 50 in the third row R3. In other words, the second transverse grooves 50 and the first transverse grooves 48 are arranged in a zigzag pattern. The third row R3 and the fourth row R4 suppress the rigidity distribution of the third rib 46.

[0068] In Fig. 4, the arrow Wm represents the width of the first main groove 38 (or the second main groove 40). The width Wm is preferably 2.0 mm or more and 8.0 mm or less. The ratio of the width Wm to the width TW of the tread 10 is preferably 3% or more and 8% or less. In Fig. 4, the arrow Dm represents the depth of the first main groove 38 (or the second main groove 40). The depth Dm is preferably 3.0 mm or more and 10.0 mm or less.

[0069] In Fig. 5, an arrow Wt represents the width of the first lateral groove 48 (or the second lateral groove 50). The width Wt is preferably 1.5 mm or more and 7.0 mm or less. The ratio of the width Wt to ​​the width TW of the tread 10 is preferably 2% or more and 7% or less. In Fig. 5, an arrow Dt represents the depth of the first lateral groove 48 (or the second lateral groove 50). The depth Dt is preferably 3.0 mm or more and 10.0 mm or less.

[0070] In this embodiment, the width Wm is greater than the width Wt. In this tire 2, the first main groove 38 and the second main groove 40 contribute to drainage. In this tire 2, the first lateral groove 48 and the second lateral groove 50 do not impair rigidity. The ratio (Wm / Wt) of the width Wm to the width Wt is preferably 1.1 or more, more preferably 1.2 or more, and particularly preferably 1.3 or more. This ratio (Wm / Wt) is preferably 2.5 or less.

[0071] In Fig. 6, an arrow Ws represents the width of the sipe 52. The width Wt is preferably 0.3 mm or greater and 2.0 mm or less. In Fig. 6, an arrow Ds represents the depth of the sipe 52. The depth Ds is preferably 3.0 mm or greater and 10.0 mm or less.

[0072] 8 (or 9), an arrow Lt indicates the axial length of the first lateral groove 48 (or the second lateral groove 50). The length Lt is preferably 10% or more and 20% or less of the width Wt of the tread 10.

[0073] From the viewpoint of grip performance, steering stability and abrasion resistance, the hardness of the tread 10 is preferably 40 or more and 60 or less. The hardness is measured by a type A durometer in accordance with the provisions of "JIS K6253". The temperature during measurement is 23°C.

[0074] In the present invention, the dimensions and angles of each component of the tire 2 are measured in a state where the tire 2 is mounted on a regular rim and filled with air so as to have a regular internal pressure. No load is applied to the tire 2 during measurement. In this specification, regular rim means a rim defined in the standard on which the tire 2 is based. The "standard rim" in the JATMA standard, the "design rim" in the TRA standard, and the "measuring rim" in the ETRTO standard are regular rims. In this specification, regular internal pressure means an internal pressure defined in the standard on which the tire 2 is based. The "maximum air pressure" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITSAT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "INFLATION PRESSURE" in the ETRTO standard are regular internal pressures. EXAMPLES

[0075] The effects of the present invention will be clarified by the following examples, but the present invention should not be construed as being limited based on the description of these examples.

[0076] [Example 1] A pneumatic tire shown in Figure 1-9 was manufactured. The size of this tire was 225 / 45R17. The specifications of the tread pattern of this tire are as follows: Number of main grooves on the back half: 2 Number of main grooves on the outer half: 0 Lateral groove: Separated from main groove Main groove angle α and angle β: 15° Lateral groove angle θ1 and angle θ2: 20° Phase of the first lateral groove / phase of the first main groove: same Phase of the second row of lateral grooves / phase of the second main groove: coincident Inclination of the 3rd row grooves / inclination of the 4th row grooves: Reverse First and second transverse grooves of the first row: alternate The first and second transverse grooves of the second row: alternate Second rib groove: None Main groove width Wm: greater than lateral groove width Wt Tread surface land ratio Pt: 75% Land rate ratio (Pb / Pf): 45 / 55 Number of grooves in each row: 30 Main groove depth Dm: 5.0mm Depth of lateral groove Dt: 5.0mm Sipe position: The main groove is convex on the back side Shape of main and lateral grooves: chamfered

[0077] [Example 2] A tire of Example 2 was obtained in the same manner as Example 1, except that the width Wt of the lateral groove was made larger than the width Wm of the main groove, and the land ratio Pb of the rear half was made larger than the land ratio Pf of the front half.

[0078] [Example 3] A tire of Example 3 was obtained in the same manner as Example 1, except that another main groove was provided between the first main groove and the second main groove.

[0079] [Example 4] A tire of Example 4 was obtained in the same manner as Example 1, except that the angles α and β of the main grooves were set to 30°.

[0080] [Example 5] A tire of Example 5 was obtained in the same manner as Example 1, except that main grooves were provided in the front half as well.

[0081] [Example 6] A tire of Example 6 was obtained in the same manner as Example 1, except that the lateral groove angles θ1 and θ2 were set to 60°.

[0082] [Example 7] A tire of Example 7 was obtained in the same manner as in Example 1, except that the phase of the first row was reversed to that of the first main groove and the phase of the second row was reversed to that of the second main groove.

[0083] [Example 8] A tire of Example 8 was obtained in the same manner as in Example 1, except that 30 first lateral grooves were provided in the third row.

[0084] [Example 9] A tire of Example 9 was obtained in the same manner as in Example 1, except that lateral grooves were provided in the second rib.

[0085] [Example 10] A tire of Example 10 was obtained in the same manner as Example 1, except that the width Wt of the lateral groove was made larger than the width Wm of the main groove.

[0086] [Example 11] A tire of Example 11 was obtained in the same manner as Example 1, except that the main groove width Wm and the lateral groove width Wt were made small and the land ratio Pt was made large.

[0087] [Example 12] A tire of Example 12 was obtained in the same manner as in Example 1, except that the number of lateral grooves in each row was 60.

[0088] [Example 13] A tire of Example 13 was obtained in the same manner as Example 1, except that the main groove depth Dm was 8.0 mm and the lateral groove depth Dt was 8.0 mm.

[0089] [Example 14] A tire of Example 14 was obtained in the same manner as Example 1, except that the sipes were provided in the main grooves at positions that protruded toward the front side.

[0090] [Example 15] A tire of Example 15 was obtained in the same manner as in Example 1, except that non-chamfered main grooves and lateral grooves were provided.

[0091] [Comparative Example 1] A tire of Comparative Example 1 was obtained in the same manner as in Example 1, except that a pattern mirror-symmetrical with respect to the equatorial plane was provided.

[0092] [Comparative Example 2] A tire of Comparative Example 2 was obtained in the same manner as in Example 1, except that 30 lateral grooves were provided instead of the second main groove.

[0093] [Comparative Example 3] A tire of Comparative Example 3 was obtained in the same manner as in Example 1, except that a main groove having a straight shape was provided.

[0094] [Comparative Example 4] A tire of Comparative Example 4 was obtained in the same manner as in Example 1, except that a pattern in which the pattern shown in FIG.

[0095] [Comparative Example 5] A tire of Comparative Example 5 was obtained in the same manner as in Example 1, except that a pattern was provided in which the first row of lateral grooves communicated with the first main groove, and the second row of lateral grooves communicated with the second main groove.

[0096] [Comparative Example 6] A tire of Comparative Example 6 was obtained in the same manner as in Example 1, except that the lateral groove angles θ1 and θ2 were set to 0°.

[0097] [Comparative Example 7] A tire of Comparative Example 7 was obtained in the same manner as in Example 1, except that 30 first lateral grooves were provided in the first row and 30 second lateral grooves were provided in the second row.

[0098] [Dry grip performance] The tire was mounted on a rim with a size of "17 x 8.5J". The tire was filled with air so that the internal pressure was 180 kPa. The rim was mounted on a rear-wheel drive vehicle with an engine displacement of 2000 cc. The vehicle was driven on a circuit course with a dry road surface, and the driver was asked to evaluate the grip performance. The results are shown in Tables 1-4 below, with Example 1 being assigned an index of 100. Tires with a higher index have better dry grip performance.

[0099] [Wet grip performance] The vehicle was driven on a road surface having a puddle 5 mm deep, and the driver was asked to evaluate the grip performance. The results are shown in Table 1-4 below, with Example 1 being assigned an index of 100. Tires with a higher index value have better wet grip performance.

[0100] [Control performance] In the above-mentioned dry grip performance test, the driver was asked to evaluate the control performance (stability of grip performance). The results are shown in Table 1-4 below as an index, with Example 1 being assigned a score of 100. Tires with a higher index value have better control performance.

[0101] [Wear resistance] The vehicle was run on a circuit course with a dry road surface. When the running distance reached 20 km, the tread surface was visually observed and the degree of uneven wear was evaluated. The results are shown in Table 1-4 below as an index, with Example 1 being assigned an index of 100. Tires with a higher index value have better wear resistance.

[0102] [Table 1]

[0103] [Table 2]

[0104] [Table 3]

[0105] [Table 4]

[0106] As shown in Tables 1 to 4, the total score of the tires of the respective examples is large. From these evaluation results, the superiority of the present invention is clear. [Industrial Applicability]

[0107] The tire according to the present invention can be mounted on various vehicles. [Explanation of symbols]

[0108] 2. Tires 4. Vehicle 6. Body 8...Axle 10. Tread 24 Tread surface 34 Back half 36 Front half 38...First main groove 40...Second main groove 42 First rib 44 Second rib 46 Third rib 48. First side groove 50. Second lateral groove 52···Siped 54... units 56 Slope 58 Slope 60 Negative element 62 Positive element

Claims

1. A tire having a tread having a tread surface, The above tread is (1) a first main groove located behind an equatorial plane of the tire, extending along a circumferential direction, and having a zigzag shape; (2) a second main groove located behind the equatorial plane and on the front side of the first main groove, extending along the circumferential direction and having a zigzag shape; (3) A plurality of first lateral grooves each inclined in a direction from the back side to the front side in the traveling direction of the tire and spaced apart from the first main groove and the second main groove; and (4) A plurality of second transverse grooves, each of which is inclined in a direction from the front side to the back side in the traveling direction and is spaced apart from the first main groove and the second main groove. It has The first lateral groove and the second lateral groove are alternately arranged in a circumferential direction on a rear side of the first main groove, The tire has the first lateral grooves and the second lateral grooves arranged alternately along the circumferential direction on a front side of the second main groove.

2. The tire according to claim 1, wherein a land ratio Pb of the tread surface on the rear side of the equatorial plane is smaller than a land ratio Pf of the tread surface on the front side of the equatorial plane.

3. 3. A tire according to claim 1, wherein the number of main grooves in the tread is two.

4. the first main groove has a plurality of negative elements each inclined in a direction from the front side to the back side in the traveling direction, and a plurality of positive elements each inclined in a direction from the back side to the front side in the traveling direction, and these negative elements and positive elements are alternately arranged along the circumferential direction, 4. The tire according to claim 1, wherein the second main groove has a plurality of negative elements each inclined in a direction from the front side to the back side in the traveling direction and a plurality of positive elements each inclined in a direction from the back side to the front side in the traveling direction, and the negative elements and the positive elements are arranged alternately in the circumferential direction.

5. 5. The tire according to claim 4, wherein, in the first main groove, an absolute value of an angle of the negative elements with respect to the circumferential direction is 10° or greater and 20° or less, and an absolute value of an angle of the positive elements with respect to the circumferential direction is 10° or greater and 20° or less.

6. 6. The tire according to claim 4, wherein, in the second main groove, an absolute value of an angle of the negative elements with respect to the circumferential direction is 10° or greater and 20° or less, and an absolute value of an angle of the positive elements with respect to the circumferential direction is 10° or greater and 20° or less.

7. The second lateral groove is located on the back side of the negative element of the first main groove, The tire according to claim 4 , wherein the first lateral groove is located on a back side of the positive element of the first main groove.

8. The second lateral groove is located on the front side of the negative element of the second main groove, The tire according to claim 4 , wherein the first lateral groove is located on a front side of the positive element of the second main groove.

9. 9. The tire according to claim 1, wherein an absolute value of an angle of the first lateral groove with respect to the axial direction is greater than or equal to 10° and less than or equal to 40°, and an absolute value of an angle of the second lateral groove with respect to the axial direction is greater than or equal to 10° and less than or equal to 40°.

10. On the front side of the equatorial plane, (1) A row of second transverse grooves arranged in a circumferential direction and (2) A row of a plurality of first transverse grooves arranged along the circumferential direction 10. A tire according to claim 1, wherein

11. 11. The tire according to claim 1, wherein a width of the first main groove is larger than a width of the first lateral groove and a width of the second lateral groove, and a width of the second main groove is larger than a width of the first lateral groove and a width of the second lateral groove.

12. It also has multiple sipes, The tire according to any one of claims 1 to 11, wherein each sipe is sandwiched between the first main groove and the second main groove.

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