tire

Abstract

The present invention provides a tire having comprehensive advantages in wet road grip performance, dry road grip performance, control performance and wear resistance. The tire tread comprises: a first main groove (38) located on the back side of the tire's equatorial plane (CL) and extending in the circumferential direction and having a zigzag shape; a second main groove (40) located on the back side of the equatorial plane (CL) and on the front side of the first main groove (38) and extending in the circumferential direction and having a zigzag shape; a plurality of first lateral grooves (48) each inclined in the negative direction relative to the axial direction of the tire and separated from the first main groove (38) and the second main groove (40); and a plurality of second lateral grooves (50) each inclined in the positive direction relative to the axial direction and separated from the first main groove (38) and the second main groove (40).

Description

Technical Field

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

[0002] Tires are mounted on vehicles. Vehicles travel on both dry and wet roads. Therefore, tires are required to have both dry and wet grip performance.

[0003] Japanese Patent Application Laid-Open No. 2020-200018 discloses a tire having a tread pattern in which grooves are arranged asymmetrically. This tread pattern contributes to both dry and wet grip performance.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-200018

[0005] A tread with a large contact area with the road has a high coefficient of friction. Tires with such treads have excellent dry-road grip. Grooves contribute to wet road drainage. Tires with numerous grooves have excellent wet-road grip. However, treads with grooves have a small contact area with the road. Grooves hinder dry-road grip, leading to a conflict between dry-road grip and wet-road grip.

[0006] During driving, areas of the tire's tread surface subject to heavy loads frequently shift. This shift causes fluctuations in grip performance. Tires with grooves in their treads experience particularly large fluctuations in grip performance, hindering control.

[0007] Grooves cause uneven tread rigidity, which is a factor in uneven wear. Summary of the Invention

[0008] An object of the present invention is to provide a tire that is comprehensively excellent in wet grip performance, dry grip performance, controllability, and wear resistance.

[0009] The tire of the present invention includes a tread having a tread surface. The tread has:

[0010] a first main groove located on the back side of the tire's equatorial plane, extending in the circumferential direction, and having a zigzag shape;

[0011] a second main groove located on the dorsal side of the equatorial plane and on the surface side of the first main groove, extending in the circumferential direction and having a zigzag shape;

[0012] a plurality of first lateral grooves, each of which is inclined in a negative direction relative to the axial direction of the tire and is separated from the first main groove and the second main groove; and

[0013] The plurality of second lateral grooves are each inclined in a positive direction relative to the axial direction and separated from the first main groove and the second main groove.

[0014] The first lateral grooves and the second lateral grooves are alternately arranged along the circumferential direction at a position further back than the first main grooves. The first lateral grooves and the second lateral grooves are alternately arranged along the circumferential direction at a position further front than the second main grooves.

[0015] It is preferable that the land ratio Pb of the tread surface on the back side relative to the equatorial plane is smaller than the land ratio Pf of the tread surface on the front side relative to the equatorial plane.

[0016] Preferably, the number of main grooves in the tread is two.

[0017] Preferably, the first main groove has a plurality of negative elements each inclined in the negative direction relative to the circumferential direction, and a plurality of positive elements each inclined in the positive direction relative 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 the negative direction relative to the circumferential direction, and a plurality of positive elements each inclined in the positive direction relative to the circumferential direction. These negative elements and positive elements are arranged alternately along the circumferential direction.

[0018] Preferably, in the first main groove, the absolute value of the angle of the negative element relative to the circumferential direction is 10° to 20°, and the absolute value of the angle of the positive element relative to the circumferential direction is 10° to 20°. Preferably, in the second main groove, the absolute value of the angle of the negative element relative to the circumferential direction is 10° to 20°, and the absolute value of the angle of the positive element relative to the circumferential direction is 10° to 20°.

[0019] Preferably, the second transverse groove is located on the back side of the negative element of the first main groove, and the first transverse groove is located on the back side of the positive element of the first main groove. Preferably, the second transverse groove is located on the front side of the negative element of the second main groove, and the first transverse groove is located on the front side of the positive element of the second main groove.

[0020] Preferably, the absolute value of the angle of the first lateral groove with respect to the axial direction is 10° or more and 40° or less. Preferably, the absolute value of the angle of the second lateral groove with respect to the axial direction is 10° or more and 40° or less.

[0021] Preferably, there are the following on the surface side of the equatorial plane:

[0022] A plurality of second lateral grooves arranged in a row along the circumferential direction, and

[0023] The plurality of first lateral grooves are arranged in rows along the circumferential direction.

[0024] Preferably, the width of the first main groove is greater than the width of the first lateral groove and the width of the second lateral groove. Preferably, the width of the second main groove is greater than the width of the first lateral groove and the width of the second lateral groove.

[0025] The tire may further include a plurality of sipes. Preferably, each sipe is sandwiched between the first main groove and the second main groove.

[0026] The tire of the present invention is comprehensively excellent in wet grip performance, dry grip performance, controllability, and wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a front view showing a tire according to one embodiment of the present invention together with a vehicle.

[0028] Figure 2 Yes Figure 1 An enlarged cross-sectional view of a portion of a tire.

[0029] Figure 3 Yes Figure 1 An expanded view of a portion of the tread pattern of a tire.

[0030] Figure 4 It is along Figure 3 Enlarged cross-sectional view taken along line IV-IV.

[0031] Figure 5 It is along Figure 3 An enlarged cross-sectional view taken along the V-V line.

[0032] Figure 6 It is along Figure 3 An enlarged cross-sectional view taken along line VI-VI.

[0033] Figure 7 Yes Figure 3 An enlarged view of a portion of the first main groove of the tread pattern.

[0034] Figure 8 Yes Figure 3 An enlarged view of the first transverse groove of the tread pattern.

[0035] Figure 9 Yes Figure 3 An enlarged view of the second transverse groove of the tread pattern.

[0036] Description of Reference Signs

[0037] 2…tire; 4…vehicle; 6…body; 8…axle; 10…tread; 24…tread surface; 34…dorsal half; 36…front half; 38…first main groove; 40…second main groove; 42…first rib; 44…second rib; 46…third rib; 48…first transverse groove; 50…second transverse groove; 52…sipe; 54…unit; 56…inclined portion; 58…inclined portion; 60…negative element; 62…positive element. DETAILED DESCRIPTION

[0038] Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

[0039] exist Figure 1 , the tire 2 is shown together with the vehicle 4. The vehicle 4 includes a vehicle body 6 and an axle 8. The tire 2 is connected to the axle 8 via a wheel and a hub (both not shown). Figure 1 The right side in FIG is the front side (Face side) of the tire 2. This front side is also the outer side in the width direction of the vehicle 4. Figure 1 The left side in FIG is the back side of the tire 2. The back side is also the inner side in the width direction of the vehicle 4.

[0040] Figure 2 Shown along Figure 1 A portion of a cross section of the tire 2 cut along a plane including the rotation axis. Figure 2 In the figure, 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 is the circumferential direction of the tire 2. Figure 2 In FIG, the dot-dash line CL represents the equatorial plane of the tire 2. Except for the tread pattern described later, the shape of the tire 2 is mirror-symmetrical with respect to the equatorial plane CL. The dot-dash line CL is also the center line of the tire 2 in the axial direction.

[0041] The tire 2 includes 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 include various other components. The tire 2 is a tubeless type. The tire 2 is typically mounted on a four-wheeled vehicle.

[0042] The tread 10 is convex radially outward. It has a tread surface 24 that contacts the road surface. The tread 10 is made of a cross-linked rubber composition. The tread 10 may have a base portion and a top portion covering the base portion. The tread 10 may have three or more layers. The tread 10 has a tread pattern, which will be described in detail below.

[0043] Each sidewall 12 extends radially inward from the tread 10. A portion of the sidewall 12 is bonded to the tread 10. The sidewall 12 is made of a cross-linked rubber having excellent cut resistance and weather resistance. The sidewall 12 protects the tire carcass 16 from damage.

[0044] Each bead 14 is located axially inward of the sidewall 12. The bead 14 includes a core 26 and an apex 28 extending radially outward from the core 26. The core 26 is annular and comprises a wound, inelastic wire. The wire is typically made of steel. The apex 28 tapers radially outward. It is made of a high-hardness cross-linked rubber.

[0045] The carcass 16 is strung between the tire beads 14 on either side, extending along the tread 10 and sidewalls 12. The carcass 16 comprises a plurality of cords and a topping rubber arranged side by side. The absolute value of the angle formed by each cord relative to the equatorial plane CL is 75° to 90°. In other words, the carcass 16 has a radial structure. The cords are composed of organic fibers. Preferred organic fibers include polyester, nylon, rayon, polyethylene naphthalate, and aramid.

[0046] The belt 18 is located radially inward of the tread 10. The belt 18 is stacked on the carcass 16. The belt 18 reinforces the carcass 16. The belt 18 has an inner layer 30 and an outer layer 32. The inner layer 30 and the outer layer 32 each have a plurality of cords and a rubber topping arranged side by side. Each cord is inclined relative to the equatorial plane CL. The normal absolute value of the inclination angle is greater than 10° and less than 35°. The inclination direction of the cords of the inner layer 30 relative to the equatorial plane CL is opposite to the inclination direction of the cords of the outer layer 32 relative to the equatorial plane CL. The preferred material of the cord is steel. Organic fibers can also be used for the cords. Examples of organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

[0047] The belt 20 is located radially outward from the belt 18. The belt 20 comprises a cord and a topping rubber. The cord is wound helically. The belt 20 has a so-called seamless construction. The cord extends substantially in the circumferential direction. The angle of the cord relative to the circumferential direction is 5° or less, and further 2° or less. The cord is composed of organic fibers. Preferred organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

[0048] Figure 3 Yes Figure 1 A development diagram of a portion of the tread pattern of tire 2. Figure 3 In the figure, the up-down direction is the circumferential direction, and the left-right direction is the axial direction. The up-down direction is also the direction of travel of the tire 2 (in other words, the front side). Figure 3 In the figure, the right side is the surface side and the left side is the back side. Figure 3 In FIG, the clockwise direction is the positive direction of rotation. The tread surface 24 is divided by the equatorial plane CL into a dorsal half 34 and a front half 36. The dorsal half 34 is located further back than the equatorial plane CL. The front half 36 is located further forward than the equatorial plane CL.

[0049] This tread pattern includes first main grooves 38 and second main grooves 40. The first main grooves 38 are located further back than the equatorial plane CL. The second main grooves 40 are located further back than the equatorial plane CL. The second main grooves 40 are located further forward than the first main grooves 38. The tread pattern of this embodiment does not include main grooves further forward than the equatorial plane CL. This tread pattern is asymmetric with respect to the equatorial plane CL.

[0050] The tread surface 24 is divided into three ribs by the first main groove 38 and the second main groove 40. 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. Figure 3 , reference symbol TW represents the width of the tread 10 .

[0051] This tread pattern includes a plurality of first lateral grooves 48 and a plurality of second lateral grooves 50. These lateral grooves 48 and 50 are dispersed throughout the first rib 42 and the third rib 46. 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, there are no lateral grooves in the second rib 44.

[0052] This tread pattern includes a plurality of sipes 52. Each sipe 52 is located on 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 axially. The area of ​​the tread 10 surface other than the grooves 38, 40, 48, 50 and the sipes 52 is land.

[0053] In this tread pattern, Figure 3 The pattern of the units 54 shown is repeated circumferentially. Thus, the spacing of the grooves is constant. The tread pattern may also have variations in the spacing of the grooves.

[0054] Figure 4 It is along Figure 3 Enlarged cross-sectional view taken along line IV-IV. Figure 4 The vicinity of the first main groove 38 is shown. The first main groove 38 is recessed from the tread surface 24. The first main groove 38 has a pair of inclined portions 56. Each inclined portion 56 is formed by a chamfer. These inclined portions 56 can contribute to the wear resistance of the tread 10. The angle of the inclined portion 56 relative to the radial direction is preferably not less than 45° and not more than 70°. 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 an inclined portion 56 formed by a chamfer.

[0055] Figure 5 It is along Figure 3 An enlarged cross-sectional view taken along the V-V line. Figure 5 The vicinity of the first transverse groove 48 is shown. The first transverse groove 48 is recessed from the tread surface 24. The first transverse groove 48 has an inclined portion 58 formed by a chamfer. Figure 3 As clearly shown, the inclined portion 58 is annular. This inclined portion 58 can contribute to the wear resistance of the tread 10. The angle of the inclined portion 58 relative to the radial direction is preferably greater than 45° and less than 70°. 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 an inclined portion 58 formed by chamfering.

[0056] Figure 6 It is along Figure 3 An enlarged cross-sectional view taken along line VI-VI. Figure 6 The vicinity of the sipe 52 is shown. The sipe 52 is recessed from the tread surface 24.

[0057] Figure 7 : is an enlarged view showing a portion of the first main groove 38. Figure 7 , the up-down direction is the circumferential direction, and the left-right direction is the axial direction. The first main groove 38 extends roughly 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 negative element 60 is inclined in the negative direction (counterclockwise) relative to the circumferential direction. Each positive element 62 is inclined in the positive direction (clockwise) relative to the circumferential direction. These negative elements 60 and positive elements 62 are arranged alternately along the circumferential direction. The negative element 60 is continuous with the positive element 62 at one end and continuous with other positive elements 62 at the other end. The positive element 62 is continuous with the negative element 60 at one end and continuous with other negative elements 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 greater than 10 and less than 20, and the number of positive elements 62 is preferably greater than 10 and less than 20.

[0058] In this embodiment, all the negative elements 60 have the same shape and size. However, these negative elements 60 may have different shapes or sizes.

[0059] In this embodiment, all the positive elements 62 have the same shape and size. However, these positive elements 62 may have different shapes. These positive elements 62 may also have different sizes.

[0060] As according to Figure 3 As is clear, 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 Figure 7 As shown, there are multiple negative elements 60 and multiple positive elements 62. Figure 3 As is clear, in this embodiment, the phases of the negative element 60 and the positive element 62 in the second main groove 40 coincide with the phases of the elements in the first main groove 38 .

[0061] Figure 8 : is an enlarged view showing the first transverse groove 48. Figure 8 In the embodiment, the up-down direction is the circumferential direction, and the left-right direction is the axial direction. The outline of the first transverse groove 48 is roughly horizontally long. In this embodiment, the outline of the first transverse groove 48 is an elongated circle. The first transverse groove 48 can also have other outline shapes. The first transverse groove 48 is inclined in the negative direction relative to the axial direction. The outline of the first transverse groove 48 is closed. Therefore, the first transverse groove 48 and the first main groove 38 (refer to Figure 3 ) and also separated from the second main groove 40. The first lateral grooves 48 are not connected to the main grooves. In this embodiment, all first lateral grooves 48 have a uniform shape and size. These first lateral grooves 48 may also have varying shapes. These first lateral grooves 48 may also have varying sizes.

[0062] Figure 9 : is an enlarged view showing the second lateral groove 50. Figure 9 In the embodiment, the up-down direction is the circumferential direction, and the left-right direction is the axial direction. The outline of the second transverse groove 50 is generally horizontally long. In the present embodiment, the outline of the second transverse groove 50 is an oblong. The second transverse groove 50 may also have other outline shapes. The second transverse groove 50 is inclined in the positive direction relative to the axial direction. The outline 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 is not connected to the main groove. In the present embodiment, the shape and size of all the second transverse grooves 50 are unified. These second transverse grooves 50 may also have variations in shape. These second transverse grooves 50 may also have variations in size.

[0063] As described above, the first row R1 is located on the back side of the first main groove 38. Figure 3 As shown, 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 arranged alternately along the circumferential direction. The number of first lateral grooves 48 in the first row R1 is preferably 10 or more and 20 or less. The number of second lateral grooves 50 in the first row R1 is preferably 10 or more and 20 or less. The total number N1 of lateral grooves in the first row R1 is preferably 20 or more and 40 or less.

[0064] As described above, the second row R2 is located on the surface side of the second main groove 40. Figure 3As shown, 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 arranged alternately along the circumferential direction. Each first transverse groove 48 straddles the equatorial plane CL. The axial center point of each first transverse groove 48 is located on the outer side of the equatorial plane CL. Each second transverse groove 50 straddles the equatorial plane CL. The axial center point of the second transverse groove 50 is located on the outer side of the equatorial plane CL. The number of first transverse grooves 48 in the second row R2 is preferably 10 or more and 20 or less. The number of second transverse grooves 50 in the second row R2 is preferably 10 or more and 20 or less. The total number N2 of transverse grooves 48 and 50 in the second row R2 is preferably 20 or more and 40 or less.

[0065] As mentioned above, the third row R3 is located on the front side of the second row R2. Figure 3 As shown, 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 intervals. Each second transverse groove 50 is located on the surface side of the equatorial plane CL. The number of second transverse grooves 50 in the third row R3 is preferably 20 or more and 40 or less. In this embodiment, the third row R3 does not include first transverse grooves 48. The third row R3 may also include first transverse grooves 48. The total number N3 of transverse grooves in the third row R3 is preferably 20 or more and 40 or less.

[0066] As mentioned above, the fourth row R4 is located on the front side of the third row R3. Figure 3 As shown, the fourth row R4 includes a plurality of first transverse grooves 48. These first transverse grooves 48 are arranged along the circumferential direction. In this embodiment, these first transverse grooves 48 are arranged at equal intervals. Each first transverse groove 48 is located on the surface side of the equatorial plane CL. The number of first transverse grooves 48 in the fourth row R4 is preferably 20 or more and 40 or less. In this embodiment, the fourth row R4 does not include second transverse grooves 50. The fourth row R4 may also include second transverse grooves 50. The total number N4 of transverse grooves in the fourth row R4 is preferably 20 or more and 40 or less.

[0067] like Figure 3 As shown, the sipe 52 is located in an area sandwiched between the corner portion of the first main groove 38 protruding toward the rear and the corner portion of the second main groove 40 protruding toward the rear. The sipe 52 can suppress the rigidity of the tread 10 in this area. The sipe 52 is separated from both the first main groove 38 and the second main groove 40. The sipe 52 does not promote uneven wear.

[0068] During straight-ahead travel on a vehicle 4 with a tire 2 mounted at a negative camber angle, the rear half 34 of the tread surface 24 primarily contacts the ground. In this tire 2, the first main grooves 38 and the second main grooves 40 contribute to drainage during straight-ahead travel on wet roads. This tire 2 exhibits excellent wet grip performance.

[0069] When the vehicle 4 turns, the top half 36 of the tread surface 24 also contacts the road with strong pressure. No main grooves exist in this area. Therefore, with this tire 2, a wide area of ​​the tread surface 24 contacts the road surface during cornering on dry roads. Furthermore, the tread 10 in this area is highly rigid. This tire 2 exhibits excellent dry road grip.

[0070] As mentioned above, the first main grooves 38 and the second main grooves 40 each have a zigzag shape. In other words, the tread surface 24 has multiple edges. These edges prevent the tire 2 from slipping on the road surface. The first main grooves 38 and the second main grooves 40 can contribute to both dry and wet grip performance.

[0071] The first main grooves 38 and the second main grooves 40 each have a zigzag shape, thereby suppressing the distribution of rigidity on the tread surface 24. Even if a region of the tread surface 24 subject to a heavy load shifts due to, for example, slight slip during driving, grip performance does not significantly fluctuate. This tire 2 exhibits excellent controllability.

[0072] As described above, the first lateral grooves 48 and the second lateral grooves 50 are each separated from the first main grooves 38 and the second main grooves 40. The tread 10 has appropriate rigidity. This rigidity contributes to dry road grip and control performance. Furthermore, the tread 10 can suppress uneven wear. The tire 2 has excellent wear resistance.

[0073] From the perspective 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, particularly preferably 2 or more. From the perspective of suppressing uneven wear, the number of main grooves located in the back half 34 is preferably 3 or less, particularly preferably 2 or less. The ideal number of main grooves located in the back half 34 is 2. From the perspective 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 on the entire tread surface 24 is preferably 1 or more and 3 or less, particularly preferably 2. A main groove that crosses the equatorial plane CL and has an area larger than that belonging to the front half 36 and belongs to the back half 34 is a "main groove located in the back half 34." A main groove that crosses the equatorial plane CL and has an area larger than that belonging to the front half 36 and belongs to the back half 34 is a "main groove located in the front half 36."

[0074] exist Figure 3In the diagram, arrow L1 indicates the distance from the rear end of the first main groove 38 to the equatorial plane CL, and arrow L2 indicates the distance from the rear end of the second main groove 40 to the equatorial plane CL. From the perspective of achieving both drainage performance during straight driving and drainage performance during cornering, the ratio of distance L1 to the width TW of the tread 10 is preferably 20% to 40%, and the ratio of distance L2 to the width TW of the tread 10 is preferably 10% to 20%.

[0075] From the perspective of wet grip performance, the land ratio Pb of the tread surface 24 on the back side relative to the equatorial plane CL is preferably smaller. From the perspective of dry grip performance during cornering, the land ratio Pf of the tread surface 24 on the front side relative to the equatorial plane CL is preferably larger. From the perspective 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. The ratio (Pb / Pf) is preferably 40 / 60 or more. The land ratio Pt of the tread 10 as a whole is preferably 70% or more and 85% or less. Each land ratio is the ratio of the area of ​​land present in that region to the area of ​​the surface of that region assuming that the grooves and sipes 52 do not exist.

[0076] exist Figure 7 , arrow α is the angle of the negative element 60 relative to the circumferential direction. The absolute value of the angle α is preferably greater than 10° and less than 20°. The negative element 60 with an absolute value of greater than 10° can contribute to the grip performance through the edge effect. The negative element 60 with an absolute value of greater than 10° can also contribute to the suppression of the rigidity distribution. From these viewpoints, the absolute value is more preferably greater than 12°, and particularly preferably greater than 13°. The negative element 60 with an absolute value of less than 20° can contribute to drainage. From this viewpoint, the absolute value is more preferably less than 18°, and particularly preferably less than 17°. Although not shown in the figure, the angle of the negative element 60 of the second main groove 40 relative to the circumferential direction is the same as the angle α.

[0077] exist Figure 7 , arrow β is the angle of the positive element 62 relative to the circumferential direction. The absolute value of the angle β is preferably greater than 10° and less than 20°. The positive element 62 with an absolute value of greater than 10° can contribute to the grip performance through the edge effect. The positive element 62 with an absolute value of greater than 10° can also contribute to the suppression of the rigidity distribution. From these viewpoints, the absolute value is more preferably greater than 12°, and particularly preferably greater than 13°. The positive element 62 with an absolute value of less than 20° can contribute to drainage. From this viewpoint, the absolute value is more preferably less than 18°, and particularly preferably less than 17°. Although not shown in the figure, the angle of the positive element 62 of the second main groove 40 relative to the circumferential direction is the same as the angle β.

[0078] exist Figure 8In the figure, arrow θ1 represents the angle of the first lateral groove 48 relative to the axial direction. The absolute value of angle θ1 is preferably greater than 10° and less than 40°. The first lateral groove 48 having an absolute value of greater than 10° can suppress the rigidity distribution and contribute to the control performance. From this viewpoint, the absolute value is more preferably greater than 13°, and particularly preferably greater than 15°. The tread 10 having an absolute value of less than 40° has excellent axial rigidity. The tread 10 has excellent steering stability and wear resistance during cornering. From these viewpoints, the absolute value is preferably less than 30°, and particularly preferably less than 25°.

[0079] exist Figure 9 In the figure, arrow θ2 represents the angle of the second lateral groove 50 relative to the axial direction. The absolute value of angle θ2 is preferably greater than 10° and less than 40°. Second lateral grooves 50 with an absolute value of greater than 10° can suppress rigidity distribution and contribute to control performance. From this perspective, the absolute value is more preferably greater than 13°, and particularly preferably greater than 15°. A tread 10 with an absolute value of less than 40° has superior axial rigidity. This tread 10 has excellent steering stability and wear resistance during cornering. From these perspectives, the absolute value is preferably less than 30°, and particularly preferably less than 25°.

[0080] like Figure 3 As shown, the first transverse grooves 48 of the first row R1 are located on the back side of the positive element 62 of the first main groove 38. The second transverse grooves 50 of the first row R1 are located on the back side of the negative element 60 of the first main groove 38. As described above, the first transverse grooves 48 are inclined in the negative direction relative to the axial direction. In other words, the first transverse grooves 48 are inclined in the positive direction relative to the circumferential direction. As described above, the second transverse grooves 50 are inclined in the positive direction relative to the axial direction. In other words, the second transverse grooves 50 are inclined in the negative direction relative to the circumferential direction.

[0081] Thus, the first lateral grooves 48 and the positive elements 62 of the first main grooves 38 in the first row R1 are tilted in the positive direction relative to the circumferential direction. The second lateral grooves 50 and the negative elements 60 of the first main grooves 38 in the first row R1 are tilted in the negative direction relative to the circumferential direction. The phase of the lateral grooves in the first row R1 is aligned with that of the first main grooves 38. These lateral grooves in the first row R1 suppress the stiffness distribution of the first rib 42 caused by the first main grooves 38. These lateral grooves contribute to control performance.

[0082] like Figure 3 As shown, the first transverse grooves 48 of the second row R2 are located on the front side of the positive element 62 of the second main groove 40. The second transverse grooves 50 of the second row R2 are located on the front side of the negative element 60 of the second main groove 40. As described above, the first transverse grooves 48 are inclined in the negative direction relative to the axial direction. In other words, the first transverse grooves 48 are inclined in the positive direction relative to the circumferential direction. As described above, the second transverse grooves 50 are inclined in the positive direction relative to the axial direction. In other words, the second transverse grooves 50 are inclined in the negative direction relative to the circumferential direction.

[0083] Thus, the first lateral grooves 48 and the positive elements 62 of the second main grooves 40 in the second row R2 are tilted in the positive direction relative to the circumferential direction. The second lateral grooves 50 and the negative elements 60 of the second main grooves 40 in the second row R2 are tilted in the negative direction relative to the circumferential direction. The phase of the lateral grooves in the second row R2 is aligned with that of the second main grooves 40. The lateral grooves in the second row R2 suppress the stiffness distribution of the third ribs 46 caused by the second main grooves 40. These lateral grooves can contribute to control performance.

[0084] As described above, the third row R3 includes second lateral grooves 50, and the fourth row R4 includes first lateral grooves 48. Therefore, the grooves in the fourth row R4 have an inclination direction opposite to that of the grooves in the third row R3. The number of first lateral grooves 48 in the fourth row R4 matches the number of second lateral grooves 50 in the third row R3. The circumferential positions of the first lateral grooves 48 in the fourth row R4 are offset from the circumferential positions of the second lateral grooves 50 in the third row R3. In other words, the plurality of second lateral grooves 50 and the plurality of first lateral grooves 48 are arranged in a zigzag pattern. The third and fourth rows R3 and R4 suppress the stiffness distribution of the third ribs 46.

[0085] exist Figure 4 In FIG, arrow Wm indicates the width of the first main groove 38 (or the second main groove 40). The width Wm is preferably not less than 2.0 mm and not more than 8.0 mm. The ratio of the width Wm to the width TW of the tread 10 is preferably not less than 3% and not more than 8%. Figure 4 In FIG. 4 , arrow Dm indicates 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.

[0086] exist Figure 5 In FIG, arrow Wt indicates the width of the first lateral groove 48 (or the second lateral groove 50). The width Wt is preferably not less than 1.5 mm and not more than 7.0 mm. The ratio of the width Wt to ​​the width TW of the tread 10 is preferably not less than 2% and not more than 7%. Figure 5 In FIG, arrow Dt indicates 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.

[0087] In this embodiment, width Wm is greater than width Wt. In this tire 2, first main grooves 38 and second main grooves 40 contribute to drainage. In this tire 2, first lateral grooves 48 and second lateral grooves 50 do not impair rigidity. The ratio of width Wm to width Wt (Wm / Wt) is preferably 1.1 or greater, more preferably 1.2 or greater, and particularly preferably 1.3 or greater. This ratio (Wm / Wt) is preferably 2.5 or less.

[0088] exist Figure 6In FIG, arrow Ws indicates the width of the sipe 52. The width Wt is preferably not less than 0.3 mm and not more than 2.0 mm. Figure 6 In FIG. 5 , arrow Ds indicates the depth of the sipe 52. The depth Ds is preferably 3.0 mm or more and 10.0 mm or less.

[0089] exist Figure 8 (or Figure 9 ), the arrow Lt indicates the axial length of the first lateral groove 48 (or the second lateral groove 50). The length Lt is preferably not less than 10% and not more than 20% of the width Wt of the tread 10.

[0090] From the viewpoints of grip performance, steering stability, and wear resistance, the hardness of the tread 10 is preferably 40 to 60. The hardness is measured using a type A durometer in accordance with JIS K6253 at a temperature of 23°C.

[0091] In the present invention, the dimensions and angles of the various components of the tire 2 are measured after the tire 2 is assembled on a regular rim and filled with air to a regular internal pressure. During the measurement, no load is applied to the tire 2. In this specification, a regular rim means a rim specified in the specifications to which the tire 2 is based. The "standard rim" in the JATMA specifications, the "design rim" in the TRA specifications, and the "measuring rim" in the ETRTO specifications are regular rims. In this specification, the regular internal pressure means the internal pressure specified in the specifications to which the tire 2 is based. The "maximum air pressure" in the JATMA specifications, the "maximum value" listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA specifications, and the "INFLATION PRESSURE" in the ETRTO specifications are regular internal pressures.

[0092] Example

[0093] Hereinafter, the effects of the present invention will be clarified by way of examples, but the present invention should not be limitedly interpreted based on the description of these examples.

[0094] [Example 1]

[0095] Made Figure 1 - Figure 9 The pneumatic tire shown is 225 / 45R17 in size. The tread pattern specifications of the tire are as follows.

[0096] Number of major grooves in the dorsal half: 2

[0097] Number of major grooves on the top half: 0

[0098] Transverse groove: separated from the main groove

[0099] Main groove angle α and angle β: 15°

[0100] Angle θ1 and Angle θ2 of transverse groove: 20°

[0101] Phase of the first row of transverse grooves / Phase of the first main groove: Coincident

[0102] Phase of the second row of transverse grooves / Phase of the second main groove: consistent

[0103] Inclination of the third row of transverse grooves / Inclination of the fourth row of transverse grooves: opposite directions

[0104] First horizontal groove and second horizontal groove of the first row: alternating

[0105] First and second transverse grooves of the second row: alternating

[0106] Transverse groove of the second rib: None

[0107] The width of the main groove Wm: larger than the width of the transverse groove Wt

[0108] Tread surface land ratio Pt: 75%

[0109] Land rate ratio (Pb / Pf): 45 / 55

[0110] Number of horizontal grooves in each row: 30

[0111] Main groove depth Dm: 5.0mm

[0112] Transverse groove depth Dt: 5.0mm

[0113] Position of the sipe: The main groove protrudes toward the dorsal side

[0114] The shape of the main groove and transverse groove: chamfered

[0115] [Example 2]

[0116] The tire of Example 2 was obtained in the same manner as Example 1 except that the width Wt of the lateral groove was larger than the width Wm of the main groove and the land ratio Pb of the rear half was larger than the land ratio Pf of the front half.

[0117] [Example 3]

[0118] A tire of Example 3 was obtained in the same manner as in Example 1 except that another main groove was provided between the first main groove and the second main groove.

[0119] [Example 4]

[0120] A tire of Example 4 was obtained in the same manner as in Example 1 except that the angle α and the angle β of the main groove were set to 30°.

[0121] [Example 5]

[0122] The tire of Example 5 was obtained in the same manner as in Example 1 except that the main grooves were also provided on the front half.

[0123] [Example 6]

[0124] The tire of Example 6 was obtained in the same manner as in Example 1 except that the angles θ1 and θ2 of the lateral grooves were set to 60°.

[0125] [Example 7]

[0126] The tire of Example 7 was obtained in the same manner as in Example 1 except that the phase of the first row was opposite to the phase of the first main groove, and the phase of the second row was opposite to the phase of the second main groove.

[0127] [Example 8]

[0128] The tire of Example 8 was obtained by performing the same operation as Example 1 except that 30 first lateral grooves were provided in the third row.

[0129] [Example 9]

[0130] The tire of Example 9 was obtained by performing the same operation as in Example 1 except that lateral grooves were provided in the second ribs.

[0131] [Example 10]

[0132] The tire of Example 10 was obtained in the same manner as in Example 1 except that the width Wt of the lateral grooves was larger than the width Wm of the main grooves.

[0133] [Example 11]

[0134] The tire of Example 11 was obtained by following the same procedures as in Example 1 except that the main groove width Wm and the lateral groove width Wt were reduced and the land ratio Pt was increased.

[0135] [Example 12]

[0136] The 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 set to 60.

[0137] [Example 13]

[0138] A tire of Example 13 was obtained in the same manner as in Example 1 except that the depth Dm of the main groove was set to 8.0 mm and the depth Dt of the lateral groove was set to 8.0 mm.

[0139] [Example 14]

[0140] The tire of Example 14 was obtained in the same manner as in Example 1 except that sipes were provided at positions where the main grooves protruded toward the front side.

[0141] [Example 15]

[0142] The tire of Example 15 was obtained in the same manner as in Example 1 except that main grooves and lateral grooves that were not chamfered were provided.

[0143] [Comparative Example 1]

[0144] A tire of Comparative Example 1 was obtained in the same manner as in Example 1 except that the pattern was provided in a mirror-symmetrical manner with respect to the equatorial plane.

[0145] [Comparative Example 2]

[0146] 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 grooves.

[0147] [Comparative Example 3]

[0148] A tire of Comparative Example 3 was obtained in the same manner as in Example 1 except that a straight main groove was provided.

[0149] [Comparative Example 4]

[0150] In addition to setting Figure 3 A tire of Comparative Example 4 was obtained by making the same arrangement as in Example 1 except that the pattern shown was reversed left to right.

[0151] [Comparative Example 5]

[0152] A tire of Comparative Example 5 was obtained in the same manner as in Example 1 except that the lateral grooves in the first row were connected to the first main grooves, and the lateral grooves in the second row were connected to the second main grooves.

[0153] [Comparative Example 6]

[0154] A tire of Comparative Example 6 was obtained in the same manner as in Example 1 except that the angles θ1 and θ2 of the lateral grooves were set to 0°.

[0155] [Comparative Example 7]

[0156] 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.

[0157] [Dry road grip performance]

[0158] The tire was assembled onto a 17×8.5J rim. Air was filled into the tire to an internal pressure of 180 kPa. The rim was then mounted on a 2000cc rear-wheel drive vehicle. The vehicle was driven on a circular course on a dry road, and the driver evaluated the grip performance. The results are shown in Tables 1-4 below, using an index with Example 1 set to 100. Tires with higher indexes have superior dry road grip performance.

[0159] [Wet road grip performance]

[0160] The above-mentioned vehicle was driven on a road surface with 5 mm deep puddles, and the driver evaluated the grip performance. The results are shown in Tables 1 to 4 below as indices, with Example 1 being 100. Tires with larger indices have superior wet grip performance.

[0161] [Control performance]

[0162] During the dry road grip performance test, the driver evaluated the control performance (grip performance stability). The results are shown in Tables 1 to 4 below as indices, with Example 1 being 100. Tires with larger indices have superior control performance.

[0163] [Abrasion resistance]

[0164] The above-mentioned vehicles were driven on a circular route on dry roads. After a distance of 20 km, the tread surface was visually observed to evaluate the degree of uneven wear. The results are shown in Tables 1-4 below as an index, with Example 1 set to 100. Tires with higher indexes have superior wear resistance.

[0165] Table 1

[0166] Table 1 Evaluation results

[0167]

[0168] Table 2

[0169] Table 2 Evaluation results

[0170]

[0171] Table 3

[0172] Table 3 Evaluation results

[0173]

[0174] Table 4

[0175] Table 4 Evaluation results

[0176]

[0177] As shown in Tables 1 to 4, the tires of each Example had a high total score. The superiority of the present invention is clearly demonstrated from these evaluation results.

[0178] Industrial application possibilities

[0179] The tire of the present invention can be mounted on various vehicles.

Claims

1. A tire comprising a tread having a tread surface, wherein: The tread has: a first main groove located on the back side of the tire's equatorial plane, extending in the circumferential direction, and having a zigzag shape; a second main groove located on the dorsal side of the equatorial plane and on the front side of the first main groove, extending in the circumferential direction and having a zigzag shape; a plurality of first lateral grooves, each of which is inclined counterclockwise relative to the axial direction of the tire and is separated from the first main groove and the second main groove; and a plurality of second lateral grooves, each of which is inclined clockwise relative to the axial direction and is separated from the first main groove and the second main groove; The first lateral grooves and the second lateral grooves are alternately arranged along the circumferential direction at a position further back than the first main groove. The first lateral grooves and the second lateral grooves are alternately arranged along the circumferential direction at a position closer to the front side than the second main grooves.

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

3. The tire according to claim 1 or 2, characterized in that The number of main grooves in the tread is two.

4. The tire according to claim 1 or 2, characterized in that The first main groove has a plurality of negative elements each inclined counterclockwise relative to the circumferential direction, and a plurality of positive elements each inclined clockwise relative to the circumferential direction, wherein the negative elements and the positive elements are alternately arranged along the circumferential direction. The second main groove includes a plurality of negative elements each inclined counterclockwise with respect to the circumferential direction, and a plurality of positive elements each inclined clockwise with respect to the circumferential direction, and the negative elements and the positive elements are alternately arranged along the circumferential direction.

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

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

7. The tire according to claim 4, characterized in that The second transverse groove is located on the back side of the negative element of the first main groove. The first transverse groove is located on the back side of the positive element of the first main groove.

8. The tire according to claim 4, characterized in that The second transverse groove is located on the surface side of the negative element of the second main groove. The first transverse groove is located on the surface side of the positive element of the second main groove.

9. The tire according to any one of claims 1, 2, 5 to 8, characterized in that: 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. The tire according to any one of claims 1, 2, 5 to 8, characterized in that: A plurality of rows of second lateral grooves arranged in the circumferential direction and a plurality of rows of first lateral grooves arranged in the circumferential direction are present on the front side of the equatorial plane.

11. The tire according to any one of claims 1, 2, 5 to 8, characterized in that: 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, and 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.

12. The tire according to any one of claims 1, 2, 5 to 8, characterized in that: It also has multiple knife grooves. Each sipe is sandwiched between the first main groove and the second main groove.

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