Tire

Abstract

To provide a tire excellent in snow performance, wet performance, and dry performance.SOLUTION: A tire 10 comprises: circumferential main grooves 16; an inner land part 18 formed by being demarcated by at least two of the circumferential main grooves 16; and outer land parts 20 each arranged at an outer side in a tire width direction relative to the inner land part 18. In the outer land part 20, an inclined groove 50, an inclined narrow groove 52, and a reverse inclined groove 54 are arranged. The inclined groove 50 extends outward in the tire width direction from the circumferential main groove 16, is inclined from a step-in side to a kick-out side, and has a tip 60 connected to a tread end T. The inclined narrow groove 52 extends outward in the tire width direction from the circumferential main groove 16, is inclined from the step-in side to the kick-out side, and has a tip 76 arranged in the outer land part 20. The reverse inclined groove 54 extends from the kick-out side toward the step-in side, and is inclined from an inner side to an outer side in the tire width direction. A groove width W2 of the inclined narrow groove 52 is 20% or more and 80% or less of a groove width W1 of the inclined groove 50.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Winter tires with improved braking performance on snowy roads are known. For example, Patent Document 1 discloses a tire in which a plurality of block rows are formed on the tread surface by at least two circumferential main grooves extending in the circumferential direction and a plurality of lateral grooves extending from both tread edges toward the tire centerline at an inclination in the radial direction, and each block has a plurality of sipes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-301508 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, winter tires have been required to have high levels of wet and dry performance in addition to performance on snowy roads.

[0005] An object of the present invention is to provide a tire that is excellent in snow performance, wet performance and dry performance. [Means for solving the problem]

[0006] A tire according to one aspect of the present invention includes: a circumferential main groove; an inner land portion defined by at least two of the circumferential main grooves; outer land portions disposed on the outer side in the tire width direction relative to the inner land portion, with the circumferential main groove interposed therebetween, The tire has an inclined groove, an inclined narrow groove, and an inverse inclined groove, which are arranged in the outer land portion, the inclined groove extends from the circumferential main groove toward an outer side in the tire width direction, inclines from a leading side to a trailing side in the tire circumferential direction, and has a tip connected to a tread edge, the inclined narrow groove extends from the circumferential main groove toward the outer side in the tire width direction, inclines from the leading side to the trailing side in the tire circumferential direction, and has a tip located within the outer land portion, The reverse inclined groove extends from the trailing side to the leading side in the tire circumferential direction and is inclined from the inner side to the outer side in the tire width direction, The groove width of the inclined narrow groove is 20% or more and 80% or less of the groove width of the inclined groove. [Effects of the Invention]

[0007] The tire of the present invention is excellent in snow performance, wet performance and dry performance. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a partial plan view of a tire according to a first embodiment. [Figure 2] 1 is a partially enlarged plan view of a tire according to a first embodiment, centered on the tire equatorial plane. [Figure 3] FIG. 3 is a partially enlarged cross-sectional view taken along line III-III in FIG. 2. [Figure 4] 1 is a partially enlarged plan view of one side in the tire width direction from the tire equatorial plane of a tire according to a first embodiment. [Figure 5] FIG. 5 is a partially enlarged cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a partially enlarged cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 6 is a partially enlarged cross-sectional view taken along line VI-VI in FIG. [Figure 8] FIG. 8 is a partially enlarged cross-sectional view taken along line VIII-VIII in FIG. [Figure 9] FIG. 6 is a partial plan view of a tire according to a second embodiment. [Figure 10]FIG. 6 is a partially enlarged plan view of a tire according to a second embodiment, centered on a tread edge. [Figure 11] FIG. 11 is a partially enlarged cross-sectional view taken along line XI-XI in FIG. [Figure 12] FIG. 5 is a partially enlarged cross-sectional view of a tire according to a modified example (1) taken along line VV in FIG. 4. [Figure 13] FIG. 10 is a partially enlarged plan view of a tire according to a modified example (2) centered on the tire equatorial plane. [Figure 14] FIG. 10 is a partially enlarged plan view of a tire according to a modified example (3) centered on the tire equatorial plane. [Figure 15] FIG. 10 is a partially enlarged plan view of a tire according to a fourth modification, the tire centered on the tire equatorial plane. [Figure 16] FIG. 10 is a partially enlarged cross-sectional view of a tire according to a modified example (5) taken along line XVI-XVI in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0009] The embodiments of the present invention relate to the following aspects.

[0010] [Aspect 1] a circumferential main groove; an inner land portion defined by at least two of the circumferential main grooves; outer land portions disposed on the outer side in the tire width direction relative to the inner land portion, with the circumferential main groove interposed therebetween, The tire has an inclined groove, an inclined narrow groove, and an inverse inclined groove, which are arranged in the outer land portion, the inclined groove extends from the circumferential main groove toward an outer side in the tire width direction, inclines from a leading side to a trailing side in the tire circumferential direction, and has a tip connected to a tread edge, the inclined narrow groove extends from the circumferential main groove toward the outer side in the tire width direction, inclines from the leading side to the trailing side in the tire circumferential direction, and has a tip located within the outer land portion, The reverse inclined groove extends from the trailing side to the leading side in the tire circumferential direction and is inclined from the inner side to the outer side in the tire width direction, The tire, wherein the groove width of the inclined narrow groove is 20% or more and 80% or less of the groove width of the inclined groove.

[0011] [Aspect 2] Aspect 2. The tire according to aspect 1, wherein an angle formed between an extension direction of the reverse inclined groove and the tire circumferential direction is equal to or greater than 5° and equal to or less than 50°.

[0012] [Aspect 3] The inclined groove is a main slope portion having a first groove depth; a bottom-up portion having a second groove depth shallower than the first groove depth between an end portion of the main inclined portion on an inner side in the tire width direction and the circumferential main groove; 3. The tire of claim 1 or 2, having

[0013] [Aspect 4] the inner land portion is disposed at a position including the tire equatorial plane, and has an inner inclined groove, the inner inclined groove includes a first inner inclined groove and a second inner inclined groove, the first inner inclined groove extending inward in the tire width direction from the circumferential main groove and inclined from the trailing side to the leading side in the tire circumferential direction, and having a tip located within the inner land portion, Aspect 4. The tire according to any one of aspects 1 to 3, wherein the first inner oblique groove intersects with the tire equatorial plane.

[0014] [Aspect 5] the first inner inclined groove has a first inclined portion, a second inclined portion, and a bent portion, the first inclined portion and the second inclined portion are connected via the bent portion, Aspect 5. The tire according to aspect 4, wherein the first inclined portion and the second inclined portion extend in different directions at the bent portion.

[0015] [Aspect 6] A tire according to aspect 5, wherein θa is an angle formed between the extension direction of the first inclined portion and the tire circumferential direction, and θb is an angle formed between the extension direction of the second inclined portion and the tire circumferential direction, θa is equal to or greater than 30° and equal to or less than 70°, and satisfies the following formula (1): θa+5°≦θb≦90°····Formula (1)

[0016] [Aspect 7] A tire according to any one of aspects 4 to 6, wherein the groove depth of the inner oblique groove is 30% to 80% of the groove depth of the circumferential main groove.

[0017] [Aspect 8] A tire according to aspect 4, wherein the inclined groove or the inclined narrow groove is disposed on an extension line of the inner inclined groove.

[0018] [Aspect 9] A tire according to any one of aspects 1 to 8, wherein the tire satisfies the following formula (2), where LDE is the distance between tread ends in the tire width direction, and Wce is the length of the inner land portion in the tire width direction. 0.08≦Wce / LDE≦0.20···Formula (2)

[0019] [Aspect 10] A tire according to any one of aspects 1 to 9, wherein, when the groove width of the opening end of the inclined groove connected to the circumferential main groove is Wa and the groove width of the opening end of the inclined groove at the tread edge is Wb, the following formula (3) is satisfied: 0.3≦Wa / Wb≦0.8...Equation (3)

[0020] [Aspect 11] A tire according to any one of aspects 1 to 10, wherein the groove depth of the inclined narrow groove is 20% to 60% of the groove depth of the circumferential main groove.

[0021] [Aspect 12] The inclined narrow groove has a groove bottom sipe, The groove bottom sipe is formed at the groove bottom of the inclined narrow groove, A tire according to any one of aspects 1 to 11, wherein the following formula (4) is satisfied, where Dg is the groove depth of the inclined narrow groove and Ds is the groove depth of the groove bottom sipe: 0.7≦Ds / Dg≦1.3...Equation (4)

[0022] [Aspect 13] A tire according to any one of aspects 1 to 12, wherein the groove depth of the reverse oblique groove is 40% or more and 80% or less of the groove depth of the circumferential main groove.

[0023] [Aspect 14] the outer land portion has a plurality of blocks defined by the inclined groove, the inclined narrow groove, and the reverse inclined groove, Aspects 14. The tire according to any one of aspects 1 to 13, wherein some of the plurality of blocks have external sipes.

[0024] [Aspect 15] 15. The tire of aspect 14, wherein the external sipes extend along the oblique grooves.

[0025] [Aspect 16] The inner land portion has an inner sipe, A tire according to any one of aspects 1 to 15, wherein the inner sipes extend along the tire width direction.

[0026] [Aspect 17] A tire according to aspect 14 or 15, wherein among the plurality of blocks, an outermost block arranged outermost in the tire width direction has a recessed portion, the recessed portion being arranged outward in the tire width direction from a tip of the inclined narrow groove, and the recessed portion has a plurality of edges intersecting in the tire circumferential direction.

[0027] [Aspect 18] 18. The tire of embodiment 17, wherein the recess has a depth of 0.5 mm or greater and 3.0 mm or less.

[0028] [Aspect 19] A tire according to any one of aspects 1 to 18, having circumferential narrow grooves extending from the ground contact edge to the inner side in the tire width direction, in a range of 5% to 15% of the tire width direction length from the tire equatorial plane to the ground contact edge.

[0029] [Aspect 20] A tire according to aspect 19, wherein two circumferential narrow grooves are provided on each side in the tire width direction, and when the groove width of the circumferential narrow groove on the outer side in the tire width direction of the two circumferential narrow grooves is Wout and the groove width of the circumferential narrow groove on the inner side in the tire width direction is Win, the following formula (5) is satisfied: 0.3≦Wout / Win≦0.7...Equation (5)

[0030] [Aspect 21] A tire according to aspect 19 or 20, wherein two circumferential narrow grooves are provided on each side in the tire width direction, and when the groove depth of the circumferential narrow groove on the outer side in the tire width direction of the two circumferential narrow grooves is Dout and the groove depth of the circumferential narrow groove on the inner side in the tire width direction of the two circumferential narrow grooves is Din, the following formula (6) is satisfied: 0.4≦Dout / Din≦0.8...Equation (6)

[0031] [Aspect 22] A tire according to any one of aspects 1 to 21, wherein the inclined grooves and the inclined narrow grooves are arranged alternately in the tire circumferential direction.

[0032] (definition) The tire radial direction refers to the direction perpendicular to the tire rotation axis, the tire radial inner side refers to the side toward the tire rotation axis in the tire radial direction, and the tire radial outer side refers to the side away from the tire rotation axis in the tire radial direction. The tire circumferential direction refers to the direction around the tire rotation axis as the center axis. The tire width direction refers to the direction parallel to the tire rotation axis, the inner side in the tire width direction refers to the side toward the tire equatorial plane (tire equatorial plane) in the tire width direction, and the outer side in the tire width direction refers to the side away from the tire equatorial plane in the tire width direction. The tire equatorial plane refers to a plane that is perpendicular to the tire rotation axis and passes through the center of the tire width. "Along" a given reference includes being along a direction within a range of less than ±20°, less than ±10°, or less than ±5° relative to the reference. "Center" includes the midpoint equidistant from two given points, and a range of ±10% of the distance from the midpoint between the two points. The circumferential main groove is a circumferential groove having a wear indicator that indicates the end of wear, and generally has a groove width of 5.0 mm or more and a groove depth of 5.0 mm or more. Note that the groove width and groove depth of the circumferential main groove are not limited to the above ranges. A sipe is a cut formed in a land portion, and generally has a groove width of less than 1.5 mm. The groove width is measured as the maximum distance between the opposing groove walls at the groove opening on the tread surface when the tire is mounted on a specified rim, inflated to a specified internal pressure, and under no load. In the case of a configuration in which the groove opening has a notch or chamfer, the groove width is the value measured with the intersection of an extension of the tread surface and an extension of the groove wall as the endpoint in a cross-sectional view parallel to the groove width direction and the groove depth direction. Groove depth is measured as the maximum distance from the tread surface to the bottom of the groove when the tire is mounted on a specified rim, inflated to the specified internal pressure, and under no load. If the groove in question has partial unevenness or sipes at the bottom of the groove, the groove depth shall be the value measured excluding the partial unevenness or sipes. The tread edges are the two ends of the tread pattern of the tire, and are also called design ends. The contact edge is the maximum position in the tire width direction on the contact surface between the tire and a flat plate when the tire is mounted on a specified rim, pressurized to a specified internal pressure, placed perpendicular to a flat plate in a stationary state, and subjected to a load corresponding to a specified load (80% of the maximum load capacity). The tire width along the tread surface between the two contact edges is called the contact width. The tire width along the tread surface from the tire equatorial plane to one of the contact edges is sometimes called half the contact width.

[0033] In the following explanation, a regular rim refers to an "applicable rim" as defined by JATMA, a "design rim" as defined by TRA, or a "measuring rim" as defined by ETRTO. Similarly, in the following explanation, "normal internal pressure" refers to the "maximum air pressure" specified by JATMA, the maximum value specified in "Tire Load Limits at Various Cold Inflation Pressures" specified by TRA, or the "Inflation Pressures" specified by ETRTO. Also, "normal load" refers to the "maximum load capacity" specified by JATMA, the maximum value specified in "Tire Load Limits at Various Cold Inflation Pressures" specified by TRA, or the "Load Capacity" specified by ETRTO.

[0034] 1. First embodiment (Tire composition) A first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a diagram showing both sides in the tire width direction with respect to the tire equatorial plane CP of a tire 10 according to the first embodiment in a plan view seen from the outer side in the tire radial direction. Note that the drawing shows the tire portion in a state where the tire is mounted on a rim and has a normal internal pressure applied, and is in an unloaded state.

[0035] Although not shown in its entirety, the tire 10 of this embodiment has a meridian cross-sectional shape similar to that of a conventional pneumatic tire. That is, the tire 10 of this embodiment has, from the inner side to the outer side in the tire radial direction, a bead portion, a sidewall portion, a shoulder portion, and a tread portion 12. The tire 10 has, for example, a carcass layer extending from the tread portion 12 to both bead portions and wound around a pair of bead cores in the tire meridian cross-sectional view, and a belt layer and, in some cases, a belt cover layer on the outer side in the tire radial direction of the carcass layer.

[0036] The rotation direction of the tire 10 is specified. The tire 10 is equipped with a rotation direction indicator (not shown) that indicates the tire rotation direction. The tire rotation direction refers to the rotation direction that is frequently used when the tire is in use, for example, the rotation direction when the vehicle is moving forward. Based on the display of this rotation direction indicator, the first side of the block to contact the ground (the so-called leading side or toe side) and the last side to contact the ground (the so-called trailing side or heel side) are defined (see Figure 1). The leading side is the side that contacts the ground first when the tire rolls in the specified rotation direction, and the trailing side is the side opposite to the leading side. The rotation direction indicator is configured, for example, by marks or irregularities provided on the sidewall of the tire 10. The lower side in Figure 1 is the leading side. The upper side in Figure 1 is the trailing side.

[0037] The tread portion 12 is formed of a rubber material (tread rubber). The tread portion 12 has a tread surface 14 that comes into contact with the road surface when the vehicle is traveling. The tread surface 14 is annular, centered on the rotational axis of the tire 10, has a predetermined length in the tire width direction, and is continuous in the tire circumferential direction. A predetermined tread pattern is engraved on the tread surface 14. The tread pattern is asymmetric with respect to the tire equatorial plane CP, between both sides of the tire equatorial plane CP in the tire width direction. In FIG. 1, the symbol EL indicates the contact edge line (a line connecting consecutive contact edges E in the tire circumferential direction). The distance between the tread edges T along the tire profile is designated as LDE.

[0038] As shown in FIG. 1 , a tire 10 according to the first embodiment includes two circumferential main grooves 16, an inner land portion 18, and an outer land portion 20 on a tread surface 14. The tire 10 includes a first circumferential main groove 22 on one side of the tire equatorial plane CP in the tire width direction and a second circumferential main groove 24 on the other side in the tire width direction. The first circumferential main groove 22 and the second circumferential main groove 24 extend in the tire circumferential direction. That is, the first circumferential main groove 22 and the second circumferential main groove 24 are preferably formed so that imaginary lines parallel to the tire circumferential direction can pass through the grooves. Therefore, at least a portion of water that has flowed into the first circumferential main groove 22 and the second circumferential main groove 24 can move linearly in the tire circumferential direction through the first circumferential main groove 22 and the second circumferential main groove 24. In the following description, unless otherwise specified, the first circumferential main groove 22 and the second circumferential main groove 24 will be referred to as the circumferential main groove 16.

[0039] The inner land portion 18 is defined by two circumferential main grooves 16. The inner land portion 18 has an outer edge in the tire width direction defined by the two circumferential main grooves 16 and a shape that is continuous in the tire circumferential direction. The inner land portion 18 according to this embodiment is disposed at a position where the center in the tire width direction overlaps with the tire equatorial plane CP. The length in the tire width direction of the inner land portion 18 along the tire profile is denoted as Wce.

[0040] The inner land portion 18 may have a circumferential narrow groove 26 extending in the tire circumferential direction. The circumferential narrow groove 26 extends in a direction along the tire circumferential direction. The circumferential narrow groove 26 has a groove width that is 20% to 60% of the groove width Wm of the circumferential main groove 16, and a groove depth that is 5% to 50% of the groove depth Dm of the circumferential main groove 16. The circumferential narrow groove 26 may be disposed at a position that overlaps with the tire equatorial plane CP.

[0041] The inner land portion 18 has an inner inclined groove 28 and an inner sipe 30. The inner inclined groove 28 extends inward in the tire width direction from the circumferential main groove 16 and is inclined from the trailing edge to the leading edge. One end 32 of the inner inclined groove 28 is connected to the circumferential main groove 16, and the other end 34 is located within the inner land portion 18. The inner inclined groove 28 shown in FIG. 1 has a tapered shape in which the groove width gradually decreases from the one end 32 to the other end 34. The inner inclined groove 28 preferably has a groove width of 5% to 125% of the groove width Wm of the circumferential main groove 16. The groove width of the inner inclined groove 28 is the average value of the groove width at the one end 32 and the groove width at the other end 34.

[0042] The inner inclined grooves 28 have a first inner inclined groove 36 and a second inner inclined groove 38. The first inner inclined groove 36 extends inward in the tire width direction from the circumferential main groove 16, is inclined from the trailing edge to the leading edge, and intersects with the tire equatorial plane CP. The other end 34f of the first inner inclined groove 36 is disposed between the circumferential main groove 16 opposite to the connected circumferential main groove 16 and the tire equatorial plane CP. The second inner inclined groove 38 extends inward in the tire width direction from the circumferential main groove 16, is inclined from the trailing edge to the leading edge, and does not intersect with the tire equatorial plane CP. The other end 34s of the second inner inclined groove 38 is disposed between the connected circumferential main groove 16 and the tire equatorial plane CP.

[0043] In the present embodiment, the first inner inclined grooves 36 and the second inner inclined grooves 38 are arranged alternately in the tire circumferential direction. The first inner inclined grooves 36 and the second inner inclined grooves 38 are arranged on both sides of the tire equatorial plane CP. That is, in the tire 10 shown in FIG. 1 , the first inner inclined groove 36 and the second inner inclined groove 38 are arranged in this order from the trailing edge to the leading edge on the first circumferential main groove 22 side, and the second inner inclined groove 38 and the first inner inclined groove 36 are arranged in this order from the trailing edge to the leading edge on the second circumferential main groove 24 side. The first inner inclined groove 36 and the second inner inclined groove 38 are arranged in positions facing each other with respect to the tire equatorial plane CP.

[0044] As shown in FIG. 2 , the first inner inclined groove 36 may have a first inclined portion 40, a second inclined portion 42, and a bent portion 44. The first inclined portion 40 and the second inclined portion 42 are connected via the bent portion 44. The extending directions of the first inclined portion 40 and the second inclined portion 42 change at the bent portion 44. One end 32 of the first inclined portion 40 is connected to the circumferential main groove 16. The other end of the first inclined portion 40 is connected to the bent portion 44. One end 34f of the second inclined portion 42 is disposed between the tire equatorial plane CP and the circumferential main groove 16 opposite to the connected circumferential main groove 16.

[0045] The angle formed by the extension direction of the first inclined portion 40 and the tire circumferential direction is defined as θa. The extension direction of the first inclined portion 40 is defined as the extension direction of an imaginary line connecting the midpoint of the groove width at one end 32 of the first inclined portion 40 to the midpoint of the groove width at the other end. The angle formed by the extension direction of the second inclined portion 42 and the tire circumferential direction is defined as θb. The extension direction of the second inclined portion 42 is defined as the extension direction of an imaginary line connecting the midpoint of the groove width at one end 34f of the second inclined portion 42 connected to the bent portion 44 to the midpoint of the groove width at the other end 34f.

[0046] As shown in FIG. 3, the first groove depth D1, which is the groove depth of the inner inclined groove 28, is preferably 30% or more and 80% or less of the groove depth Dm of the circumferential main groove 16.

[0047] Each of the inner sipes 30 has a tip 31 on the outer side in the tire width direction connected to each of the circumferential main grooves 16. The inner sipes 30 may have a zigzag shape that inclines alternately to each side in the tire circumferential direction. The angle between the extension direction of the inner sipes 30 and the tire width direction is ±20° or less, 15° or less, or 10° or less. The extension direction of the inner sipes 30 is the direction of an imaginary line connecting each of the tips 31 connected to the circumferential main grooves 16.

[0048] The outer land portion (FIG. 1) 20 is adjacent to the inner land portion 18 on the outer side in the tire width direction, with two circumferential main grooves 16 sandwiched between them. The outer land portion 20 has a plurality of inclined grooves 50, inclined narrow grooves 52, and reverse inclined grooves 54. The outer land portion 20 is defined into a plurality of blocks 56 by the plurality of inclined grooves 50, inclined narrow grooves 52, and reverse inclined grooves 54.

[0049] The inclined grooves 50 extend from the circumferential main groove 16 toward the outside in the tire width direction and are inclined from the leading side to the trailing side. A plurality of inclined grooves 50 are arranged at predetermined intervals in the tire circumferential direction. An inner tip 58 of the inclined groove 50 in the tire width direction is connected to the circumferential main groove 16, and an outer tip 60 of the inclined groove 50 in the tire width direction is connected to the tread edge T. The inclined groove 50 may extend in the direction along the tire width direction in a range from the ground contact edge E to the outside in the tire width direction. The inclined groove 50 is preferably arranged on an extension of the inner inclined groove 28.

[0050] As shown in FIG. 4, the opening width of a tip 58 of the inclined groove 50 connected to the circumferential main groove 16 is defined as Wa. The opening width Wa is the distance between the end points where the groove wall 16w of the circumferential main groove 16 intersects with the groove wall 50w of the inclined groove 50. The opening width of a tip 60 of the inclined groove 50 connected to the tread edge T is defined as Wb. The opening width Wb is the distance between the end points where the tread edge T intersects with the groove wall 50w of the inclined groove 50. When the tips 58, 60 of the inclined groove 50 have chamfered portions, the opening widths Wa, Wb are the distances between the end points where an extension line of the groove wall 50w of the inclined groove 50 intersects with an extension line of the groove wall 16w of the circumferential main groove 16 or the tread edge T. The groove width of the inclined groove 50 shown in FIG. 4 gradually increases from the inner side in the tire width direction to the outer side in the tire width direction. The groove width W1 of the inclined groove 50 is preferably 70% to 120% and more preferably 80% to 110% of the groove width Wm of the circumferential main groove 16. The groove width W1 of the inclined groove 50 is the average value of the opening width Wa and the opening width Wb.

[0051] As shown in FIG. 5 , the inclined groove 50 has a main inclined portion 62 and a bottom-up portion 64. The main inclined portion 62 has a second groove depth D2. The second groove depth D2 is 50% or more and 120% or less of the groove depth Dm of the circumferential main groove 16. The bottom-up portion 64 is disposed between an inner tip 66 of the main inclined portion 62 in the tire width direction and a groove wall 16w of the circumferential main groove 16. The bottom-up portion 64 has a third groove depth D3. The third groove depth D3 is shallower than the second groove depth D2. The third groove depth D3 is 15% or more and 70% or less of the second groove depth D2. The length of the bottom-up portion 64 in the tire width direction is preferably 3 mm or more and 15 mm or less, and more preferably 5 mm or more and 10 mm or less.

[0052] The raised bottom portion 64 shown in Figure 5 extends from a tip 66 on the inner side in the tire width direction of the main inclined portion 62 toward the circumferential main groove 16. The raised bottom portion 64 is connected to the circumferential main groove 16. The raised bottom portion 64 has an inclined surface 68 and a flat surface 70. The inclined surface 68 extends from the tip 66 on the inner side in the tire width direction of the main inclined portion 62 toward the circumferential main groove 16 and is inclined outward in the tire radial direction. The flat surface 70 extends from a tip 72 on the inner side in the tire width direction of the inclined surface 68 toward the circumferential main groove 16 in a direction along the tread surface 14.

[0053] The inclined narrow grooves 52 extend from the circumferential main groove 16 outward in the tire width direction and are inclined from the leading-in side to the trailing-out side in the tire circumferential direction (FIG. 4). A plurality of inclined narrow grooves 52 are arranged at predetermined intervals in the tire circumferential direction. A tip 74 of the inclined narrow groove 52 on the inner side in the tire width direction is connected to the circumferential main groove 16, and a tip 76 on the outer side in the tire width direction is arranged in the outer land portion 20. The inclined narrow grooves 52 are preferably arranged on an extension line of the inner inclined groove 28. The inclined narrow grooves 52 and the inclined grooves 50 according to this embodiment are arranged alternately in the tire circumferential direction.

[0054] The groove width W2 of the inclined narrow groove 52 is preferably 20% or more and 80% or less of the groove width W1 of the inclined groove 50, and more preferably 35% or more and 55% or less.

[0055] The groove width W2 of the inclined narrow groove 52 is preferably 5% to 25% of the block width W4, and more preferably 10% to 20%. The block width W4 refers to the widthwise length of the block 56c adjacent to the circumferential main groove 16. The widthwise length of the block 56c is measured as follows. First, the intersection of an extension of the groove wall 50w of the inclined groove 50 on the trailing edge of the target block 56c and an extension of the groove wall 16w of the circumferential main groove 16 is defined as a first endpoint P1. Next, the intersection of a straight line drawn from the first endpoint P1 and perpendicular to the trailing edge groove wall 50w of the block 56c with the leading edge groove wall 50w of the block 56c is defined as a second endpoint P2. The distance between the first endpoint P1 and the second endpoint P2 is defined as the block width W4.

[0056] The inclined narrow groove 52 has a groove bottom sipe 78. As shown in Fig. 6, the groove bottom sipe 78 is formed at the groove bottom 52u of the inclined narrow groove 52. That is, the groove bottom sipe 78 is a groove that has an opening 78t at the groove bottom 52u of the inclined narrow groove 52 and a bottom surface 78b on the inner side in the tire radial direction, and extends in a direction along the inclined narrow groove 52.

[0057] The groove depth of the inclined narrow groove 52 is Dg, and the groove depth of the groove bottom sipe 78 is Ds. The groove depth Dg of the inclined narrow groove 52 is preferably 20% to 60% of the groove depth Dm of the circumferential main groove 16, and more preferably 30% to 50%. The inclined narrow groove 52 is arranged along the inclined groove 50. The groove bottom sipe 78 is arranged at the center of the inclined narrow groove 52 in the groove width direction.

[0058] The groove bottom sipes 78 are preferably shorter than the groove length of the inclined narrow grooves 52 and do not communicate with the reverse inclined grooves 54 (FIG. 4). That is, the length of the groove bottom sipes 78 is defined as Ls, and the groove length of the inclined narrow grooves 52 is defined as Lg. The length Ls of the groove bottom sipes 78 is the length in a direction perpendicular to the groove width direction and groove depth direction of the groove bottom sipes 78. The groove length Lg of the inclined narrow grooves 52 is defined as the distance between the midpoints of the groove widths at the tips 74, 76 of the inclined narrow grooves 52 that connect to the reverse inclined grooves 54, when the inclined narrow grooves 52 provided in a certain block 56 defined by reverse inclined grooves 54 on both sides in the tire width direction are the target. In this case, the groove length Ls of the groove bottom sipes 78 is preferably 0.75 or more ≦(Ls / Lg)≦0.95.

[0059] The reverse inclined grooves 54 extend from the trailing edge to the leading edge in the tire circumferential direction and are inclined from the inner side to the outer side in the tire width direction ( FIG. 4 ). There are preferably two to four reverse inclined grooves 54 on each side of the tire equatorial plane CP. Although not shown, the inner and outer ends of the reverse inclined grooves 54 in the tire width direction are disposed within the outer land portion 20. The reverse inclined grooves 54 intersect with the inclined grooves 50 and the inclined narrow grooves 52. The groove width W3 of the reverse inclined groove 54 is preferably 30% to 90% of the groove width Wm of the circumferential main groove 16, and more preferably 40% to 60%.

[0060] The angle θc between the extension direction of the reverse inclined grooves 54 and the tire circumferential direction is preferably 5° or more and 50° or less, and more preferably 10° or more and 30° or less (FIG. 1). The angle θc between the extension direction of the reverse inclined grooves 54 and the tire circumferential direction may be specified for each block. That is, the angle θc between the extension direction of the reverse inclined grooves 54 and the tire circumferential direction is the angle between the tire circumferential direction and a first imaginary line L1 connecting the midpoint of the groove width at the trailing-side end and the midpoint of the groove width at the leading-side end of the reverse inclined groove 54 in each block 56.

[0061] As shown in FIG. 7, the fourth groove depth D4 of the reverse oblique groove 54 is preferably 40% to 80% of the groove depth Dm of the circumferential main groove 16, and more preferably 50% to 70%.

[0062] Each of the multiple blocks 56 has an outer sipe 84 (FIG. 4). Preferably, one or two outer sipes 84 are provided in each block 56. Preferably, one or two outer sipes 84 are provided in each block 56, on both sides of the inclined narrow groove 52 in the tire circumferential direction. The outer sipes 84 may be zigzag-shaped, inclining alternately to each side in the tire circumferential direction. The angle θd between the extension direction of the outer sipes 84 and the extension direction of the inclined narrow groove 52 is ±20° or less, ±15° or less, or ±10° or less. The extension direction of the outer sipes 84 is the direction of an imaginary line connecting the inner end and the outer end in the tire width direction. The extension direction of the inclined narrow groove 52 is the direction of an imaginary line connecting the midpoint of the groove width at the inner end in the tire width direction within the block 56 in which the outer sipe 84 is formed and the midpoint of the groove width at the outer end in the tire width direction.

[0063] The outer land portion 20 has an outermost block 56s arranged outermost in the tire width direction. The outermost block 56s has an outer edge in the tire circumferential direction defined by the inclined grooves 50, an outer edge on the inner side in the tire width direction defined by the reverse inclined grooves 54, and an inclined narrow groove 52 in the tire circumferential center.

[0064] The outermost block 56s is provided with a tip 76 of the inclined narrow groove 52 on the outside in the tire width direction. The outermost block 56s has a recess 86. The recess 86 is provided on the outside in the tire width direction of the outermost tip 76 of the inclined narrow groove 52 on the outside in the tire width direction. It is preferable that at least a portion of the recess 86 is provided in a region on the outside in the tire width direction of the ground contact edge E.

[0065] In this embodiment, the recessed portion 86 is rectangular. A total of six recessed portions 86 are arranged in each outermost block 56s, including multiple recessed portions 86 arranged in the tire circumferential direction (three in the case of FIG. 4) and multiple recessed portions 86 arranged in the tire width direction (two in the case of FIG. 4). The recessed portions 86 provided in each outermost block 56s have different lengths in the tire circumferential direction. In this embodiment, the tire circumferential length gradually increases from the trailing edge to the leading edge. The recessed portion 86 has an edge 86e extending in a direction intersecting the tire circumferential direction. The depth D5 of the recessed portion 86 shown in FIG. 8 is 0.5 mm or more and 3.0 mm or less. Multiple edges 86e are arranged in the tire circumferential direction.

[0066] The angle θa formed between the extension direction of the first inclined portion 40 and the tire circumferential direction is preferably smaller than the angle θb formed between the extension direction of the second inclined portion 42 and the tire circumferential direction. Specifically, the angle θa formed between the extension direction of the first inclined portion 40 and the tire circumferential direction is preferably 30° or more and 70° or less, and the angle θa and the angle θb formed between the extension direction of the second inclined portion 42 and the tire circumferential direction preferably satisfy the following formula (1):

[0067] θa+5°≦θb≦90° (1)

[0068] When the distance LDE between the tread ends T in the tire width direction and the length Wce of the inner land portion 18 in the tire width direction are taken as LDE and Wce, respectively, it is preferable that the following formula (2) be satisfied.

[0069] 0.08≦Wce / LDE≦0.20···Formula (2)

[0070] It is preferable that the groove width Wa of the tip 58 of the inclined groove 50 connecting to the circumferential main groove 16 and the groove width Wb of the tip 60 of the inclined groove 50 at the tread edge T satisfy the following formula (3).

[0071] 0.3≦Wa / Wb≦0.8...Equation (3) It is preferable that the groove depth Dg of the inclined narrow groove 52 and the groove depth Ds of the groove bottom sipe 78 satisfy the following formula (4).

[0072] 0.7≦Ds / Dg≦1.3...Equation (4)

[0073] The tire 10 of this embodiment described above is obtained through each of the usual manufacturing steps, i.e., a tire material mixing step, a tire material processing step, a green tire molding step, a vulcanization step, and a post-vulcanization inspection step, etc. When manufacturing the tire of this embodiment, convex portions and concave portions corresponding to a predetermined tread pattern are formed on the inner wall of a vulcanization mold, and vulcanization is carried out using this mold.

[0074] (Action and effect) The tire 10 according to this embodiment includes a circumferential main groove 16, an inner land portion 18 defined by the two circumferential main grooves 16, and outer land portions 20 disposed on the outer side of the inner land portion 18 in the tire width direction, with the circumferential main groove 16 sandwiched between them. The outer land portion 20 also includes an inclined groove 50, an inclined narrow groove 52, and a reverse inclined groove 54. The inclined groove 50 is inclined from the leading edge to the trailing edge in the tire circumferential direction, and its tip 60 connects to the tread edge T. The inclined narrow groove 52 extends from the circumferential main groove 16 toward the outer side in the tire width direction, and is inclined from the leading edge to the trailing edge in the tire circumferential direction. The reverse inclined groove 54 extends from the trailing edge to the leading edge in the tire circumferential direction, and is inclined from the inner side to the outer side in the tire width direction.

[0075] On snowy roads, the tire 10 compacts snow that has entered the grooves. When driving force, braking force, or lateral force during cornering acts on the tire in this state, so-called snow column shear force is generated in the snow in the grooves. The tire 10 has circumferential main grooves 16, inclined grooves 50, inclined narrow grooves 52, and reverse inclined grooves 54, which enable it to exert excellent snow column shear force and provide excellent drainage. This gives the tire 10 excellent snow and wet performance.

[0076] The outer tip 76 of the inclined narrow groove 52 in the tire width direction is disposed within the outermost block 56s. This prevents a decrease in the rigidity of the outermost block 56s. The groove width W2 of the inclined narrow groove 52 is 20% to 80% of the groove width W1 of the inclined groove 50, which prevents a decrease in the rigidity of the outer land portion 20. This provides the tire 10 with excellent dry performance.

[0077] As a result, the tire 10 has excellent snow performance, wet performance, and dry performance.

[0078] By providing two or more reverse inclined grooves 54 on each side in the tire width direction relative to the tire equatorial plane CP, the tire 10 has excellent snow performance and wet performance. By providing four or less reverse inclined grooves 54, a decrease in rigidity of each block 56 is suppressed. Therefore, the tire 10 has excellent dry performance.

[0079] By making the groove width W2 of the inclined narrow groove 52 5% or more of the block width W4, snow column shear force can be more reliably exerted. By making the groove width W2 of the inclined narrow groove 52 25% or less of the block width W4, a sufficient ground contact area can be secured. Therefore, the tire 10 can suppress a decrease in dry performance.

[0080] By making the angle θc between the extension direction of the reverse inclined grooves 54 and the tire circumferential direction 50° or more, the tire 10 can more reliably exert snow shear force during driving or braking. By making the angle θc 50° or less, the tire 10 can more reliably exert snow column shear force during cornering.

[0081] The inclined groove 50 has the bottom-raised portion 64, which can suppress a decrease in rigidity on the inner side in the tire width direction of the outer land portion 20. The tire 10 has excellent dry performance because a decrease in rigidity on the inner side in the tire width direction where the ground contact pressure is higher is suppressed.

[0082] The first inner oblique grooves 36 intersect with the tire equatorial plane CP, and are therefore formed in an area with higher ground contact pressure, thereby more reliably exerting snow column shear force. The inner ends of the second inner oblique grooves 38 in the tire width direction are positioned between the connected circumferential main grooves 16 and the tire equatorial plane CP, thereby maintaining the rigidity of the inner land portion 18. Therefore, by providing the first inner oblique grooves 36 and the second inner oblique grooves 38, the tire 10 has excellent snow performance and dry performance.

[0083] The first inner inclined groove 36 has a first inclined portion 40, a second inclined portion 42, and a bent portion 44. The extending directions of the first inclined portion 40 and the second inclined portion 42 change at the bent portion 44. The first inner inclined groove 36 has the bent portion 44, thereby ensuring the groove length and groove area. This allows the first inner inclined groove 36 to receive more snow, allowing the tire 10 to more reliably exert snow column shear force.

[0084] The angle θa between the extension direction of the first inclined portion 40 and the tire circumferential direction is smaller than the angle θb between the extension direction of the second inclined portion 42 and the tire circumferential direction, so that the bent portion 44 has a shape that is convex toward the leading side. By having the bent portion 44 that is convex toward the leading side, the tire 10 can more reliably exert snow column shear force during driving.

[0085] The angle θa between the extension direction of the first inclined portion 40 and the tire circumferential direction is 30° or more and 70° or less, and the angle θa and the angle θb between the extension direction of the second inclined portion 42 and the tire circumferential direction satisfy the above formula (1), thereby allowing the tire 10 to more reliably exert snow column shear force when driven.

[0086] The first groove depth D1 of the inner oblique grooves 28 is 30% or more of the groove depth Dm of the circumferential main grooves 16, thereby enabling the snow column shear force to be exerted more reliably. The first groove depth D1 of the inner oblique grooves 28 is 80% or less of the groove depth Dm of the circumferential main grooves 16, thereby enabling the tire 10 to suppress a decrease in rigidity of the inner land portion 18.

[0087] By arranging the inclined grooves 50 or the inclined narrow grooves 52 on the extension lines of the inner inclined grooves 28, water can easily flow from the inner inclined grooves 28 on the inner side in the tire width direction to the outer side in the tire width direction through the inclined grooves 50 or the inclined narrow grooves 52. Therefore, the tire 10 has improved drainage and excellent wet performance.

[0088] The distance LDE between the tread ends T in the tire width direction and the length Wce of the inner land portion 18 in the tire width direction satisfy the above formula (2). The tire 10 can obtain excellent dry performance when the relationship between the distance LDE and the length Wce is equal to or greater than the lower limit of the above formula (2). The tire can obtain excellent snow performance when the relationship between the distance LDE and the length Wce is equal to or less than the upper limit of the above formula (2).

[0089] The groove width Wa of the tip 58 of the inclined groove 50 connecting to the circumferential main groove 16 and the groove width Wb of the tip 60 of the inclined groove 50 at the tread end T satisfy the above formula (3). When the relationship between the groove width Wa and the groove width Wb is within the range of the above formula (3), the tire 10 can obtain the desired rigidity on the inner side in the tire width direction, and can obtain excellent snow column shear force by ensuring the groove area on the outer side in the tire width direction.

[0090] The tire 10 can more reliably exert snow column shear force by making the groove depth Dg of the inclined narrow groove 52 20% or more of the groove depth Dm of the circumferential main groove 16. The tire 10 can suppress a decrease in block rigidity by making the groove depth Dg of the inclined narrow groove 52 60% or less of the groove depth Dm of the circumferential main groove 16.

[0091] By having the groove bottom sipes 78, the inclined narrow grooves 52 have a larger cross-sectional area than inclined narrow grooves having the same groove width and groove depth but without the groove bottom sipes 78, so the tire 10 can improve its snow performance and wet performance while suppressing a decrease in block rigidity.

[0092] The groove depth Dg of the inclined narrow groove 52 and the groove depth Ds of the groove bottom sipe 78 satisfy the above formula (4). In the tire 10, the relationship between the groove depth Dg and the groove depth Ds is equal to or greater than the lower limit of the above formula (4), so that the proportion of the groove bottom sipe 78 is equal to or greater than a certain value, i.e., the cross-sectional area of ​​the inclined narrow groove 52 is equal to or less than a predetermined size, thereby suppressing a decrease in block rigidity and providing excellent dry performance. In the tire 10, the relationship between the groove depth Dg and the groove depth Ds is equal to or less than the upper limit of the above formula (4), so that the proportion of the groove bottom sipe 78 is equal to or less than a certain value, i.e., the cross-sectional area of ​​the inclined narrow groove 52 is equal to or greater than a predetermined size, thereby providing excellent wet and snow performance.

[0093] The groove depth D4 of the reverse oblique grooves 54 is 40% or more of the groove depth Dm of the circumferential main grooves 16, thereby more reliably exerting snow column shear force. The groove depth D4 of the reverse oblique grooves 54 is 80% or less of the groove depth Dm of the circumferential main grooves 16, thereby suppressing a decrease in block rigidity of the tire 10 and providing excellent dry performance.

[0094] Some of the multiple blocks 56 in the outer land portion 20 have outer sipes 84, which deform when the tire is stepped on so that the groove walls come into contact with each other, and one edge of the outer sipes 84 comes into contact with the road surface. This allows the tire 10 to achieve excellent snow performance. By providing each block 56 with two or fewer outer sipes 84, it is possible to prevent a decrease in the rigidity of the block 56. Because the outer sipes 84 extend along the inclined narrow grooves 52, the blocks 56 in which the outer sipes 84 are formed are more likely to deform in the direction that widens the groove width of the inclined narrow grooves 52 when the tire is stepped on, thereby more reliably exerting snow column shear force.

[0095] The inner sipes 30 extend along the tire width direction, and therefore, the inner land portion 18 deforms during driving and braking, forming edges on the inner sipes 30. Therefore, the tire 10 has excellent driving and braking performance on snow.

[0096] The recesses 86 are positioned outward in the tire width direction from the tips 76 of the inclined narrow grooves 52, and have multiple edges 86e that intersect in the tire circumferential direction, thereby achieving the effect of shoveling snow when driving on snow. By setting the depth D5 of the recesses 86 to 0.5 mm or more, the snow-shoveling effect is more reliably achieved. By setting the depth D5 of the recesses 86 to 3.0 mm or less, a decrease in rigidity of the outer land portion 20, particularly on the outer side in the tire width direction, is suppressed, and a decrease in cornering performance is suppressed.

[0097] 2. Second embodiment A second embodiment of the present invention will be described with reference to Fig. 9, in which the same reference numerals are used to designate the same components as in Fig. 1. Fig. 9 is a diagram showing portions of a tire 10A according to the second embodiment on both sides in the tire width direction with the tire equatorial plane CP as the reference, in a plan view seen from the outer side in the tire radial direction. Note that the figure shows the tire portion in a state where the tire is mounted on a rim and pressurized to the normal internal pressure, and in an unloaded state.

[0098] The tire 10A according to the second embodiment has two circumferential main grooves 16, an inner land portion 18, and an outer land portion 20 on a tread surface 14. The outer land portion 20 is adjacent to the inner land portion 18 on the outer side in the tire width direction, with the two circumferential main grooves 16 sandwiched between them. The outer land portion 20 has an inclined groove 50, an inclined narrow groove 52, and a reverse inclined groove 54. The outer land portion 20 has a plurality of blocks 56 defined by the inclined grooves 50, the inclined narrow grooves 52, and the reverse inclined grooves 54.

[0099] Furthermore, the tire 10A shown in Fig. 9 has a circumferential narrow groove 88 in the outer land portion 20. The circumferential narrow groove 88 is continuous in the tire circumferential direction and intersects with the inclined grooves 50 and the inclined narrow grooves 52. The groove width Wsub of the circumferential narrow groove 88 is preferably 15% to 70% of the groove width Wm of the circumferential main groove, and more preferably 20% to 50%. The groove depth Dsub of the circumferential narrow groove 88 is preferably 10% to 60% of the groove depth Dm of the circumferential main groove, and more preferably 15% to 50%.

[0100] The circumferential narrow grooves 88 are arranged in an outer region SH in the tire width direction of the outer land portion 20. The outer region SH is a region that is continuous in the tire circumferential direction, and refers to a range of 0.05 × Wh (mm) or more and 0.15 Wh (mm) or less from the tire tread edge E to the inner side in the tire width direction, where Wh is the distance in the tire width direction along the tire profile from the tire equatorial plane CP to the tire tread edge E.

[0101] In Figure 1, a line extending from the ground edge E to the inside in the tire width direction and parallel to the ground edge line EL at a position 5% of half the ground contact width Wh is defined as a second imaginary line L2. A line extending from the ground edge E to the inside in the tire width direction and parallel to the ground edge line EL at a position 15% of half the ground contact width Wh is defined as a third imaginary line L3. The outer region SH is the range between the second imaginary line L2 and the third imaginary line L3.

[0102] The tire 10A has excellent wet and snow performance because the circumferential narrow grooves 88 are arranged from a position 0.05×Wh (mm) inward in the tire width direction from the ground contact edge E to the inner side in the tire width direction, which improves drainage and provides snow column shear force during cornering. The tire 10A has excellent dry performance because the circumferential narrow grooves 88 are arranged from a position 0.15 Wh (mm) inward in the tire width direction from the ground contact edge E to the outer side in the tire width direction, which prevents a decrease in rigidity of the outer land portion 20.

[0103] Preferably, two circumferential narrow grooves 88 are formed in the outer regions SH on each side of the tire equatorial plane CP. That is, the tire 10A preferably has an outer narrow groove 90 and an inner narrow groove 92 in the outer regions SH on each side in the tire width direction with respect to the tire equatorial plane CP. The outer narrow groove 90 is disposed on the outer side in the tire width direction. The inner narrow groove 92 is disposed on the inner side of the outer narrow groove 90 in the tire width direction.

[0104] 10 and 11, the groove width of the outer narrow groove 90 is Wout, and the groove depth of the outer narrow groove 90 is Dout. The groove width of the inner narrow groove 92 is Win, and the groove depth of the inner narrow groove 92 is Din.

[0105] The groove width Wout of the outer narrow groove 90 is preferably smaller than the groove width Win of the inner narrow groove 92. A smaller groove width Wout of the outer narrow groove 90 can suppress a decrease in block rigidity near the tread edge E and suppress a decrease in dry performance. Specifically, the groove width Wout of the outer narrow groove 90 and the groove width Win of the inner narrow groove 92 preferably satisfy the following formula (5).

[0106] 0.3≦Wout / Win≦0.7...Equation (5)

[0107] The groove depth Dout of the outer narrow groove 90 is preferably shallower than the groove depth Din of the inner narrow groove 92. A smaller groove depth Dout of the outer narrow groove 90 suppresses a decrease in block rigidity near the contact edge E, resulting in excellent dry performance. Specifically, the groove depth Dout of the outer narrow groove 90 and the groove depth Din of the inner narrow groove 92 preferably satisfy the following formula (6):

[0108] 0.4≦Dout / Din≦0.8...Equation (6)

[0109] (Variation) The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the present invention.

[0110] For example, in the above embodiment, the tire 10 has been described as having the raised bottom portion 64 in the inclined groove 50, but the present invention is not limited to this and may not have the raised bottom portion 64. The tire 10 has been described as having the raised bottom portion 64 connected to the circumferential main groove 16, but the present invention is not limited to this. As shown in FIG. 12 , a deep groove portion 94 may be provided between the raised bottom portion 64 and the circumferential main groove 16. The groove depth of the deep groove portion 94 may be the same as the second groove depth D2 of the main inclined portion 62. Furthermore, the raised bottom portion 64 is not limited to having an inclined surface 68 and a flat surface 70, and may not have the flat surface 70. Furthermore, the raised bottom portion 64 may not have an inclined surface 68.

[0111] Although the case has been described in which the inner inclined groove 28 has the first inner inclined groove 36 and the second inner inclined groove 38, and the second inner inclined groove 38 does not intersect with the tire equatorial plane CP, the present invention is not limited to this. For example, as shown in Fig. 13, the inner inclined groove 28 may have the first inner inclined groove 36 and the second inner inclined groove 38 each extending inward in the tire width direction from the circumferential main groove 16, inclining from the trailing edge to the leading edge, and intersecting with the tire equatorial plane CP.

[0112] Although the first inner oblique grooves 36 and the second inner oblique grooves 38 are described as being alternately arranged in the tire circumferential direction, the present invention is not limited to this. A plurality of first inner oblique grooves 36 may be arranged consecutively in the tire circumferential direction. Also, a plurality of second inner oblique grooves 38 may be arranged consecutively in the tire circumferential direction. Furthermore, as shown in Figure 14, the first inner oblique grooves 36 and the second inner oblique grooves 38 may intersect each other on the tire equatorial plane.

[0113] Although the first inner inclined groove 36 has been described as having the first inclined portion 40, the second inclined portion 42, and the bent portion 44, the present invention is not limited to this. The first inner inclined groove 36 may not have the bent portion 44 and may intersect with the tire equatorial plane.

[0114] Although the angle θa between the extension direction of the first inclined portion 40 and the tire circumferential direction is smaller than the angle θb between the extension direction of the second inclined portion 42 and the tire circumferential direction in the above description, the present invention is not limited to this. For example, as shown in Fig. 15, the tire 10 may have a bent portion 44A in which the angle θa is larger than the angle θb, i.e., the bent portion 44A is convex toward the trailing edge. This allows the tire 10 to more reliably exert snow column shear force during braking.

[0115] It is preferable that the groove bottom sipes 78 do not communicate with the circumferential main grooves 16. As shown in Fig. 16, it is preferable that the groove depth Dg of the inclined narrow grooves 52 is shallower than the groove depth Dm of the circumferential main grooves 16. In this case, the inner tip 78ce of the groove bottom sipes 78 in the tire width direction is disposed within the inclined narrow groove 52. That is, the groove bottom 52u of the inclined narrow groove 52 is disposed between the inner tip 78ce of the groove bottom sipes 78 in the tire width direction and the groove wall 16w of the circumferential main groove 16. This enables the tire 10 to suppress a decrease in tread rigidity in the vicinity of the tire equatorial plane CP.

[0116] In the above embodiment, the tread pattern is asymmetric with respect to the tire equatorial plane CP, but the present invention is not limited to this, and the tread pattern may be symmetric with respect to the tire equatorial plane CP.

[0117] The inner land portion 18 is not limited to being disposed at a position where its center in the tire width direction overlaps with the tire equatorial plane CP, but may be disposed at a position where its center in the tire width direction is away from the tire equatorial plane CP to one side or the other side in the tire width direction. The inner land portion 18 may be disposed at a position where it does not overlap with the tire equatorial plane CP.

[0118] The number of circumferential main grooves 16 is not limited to two, but may be three or more. When three or more circumferential main grooves 16 are included, the land portion closest to the tire equatorial plane CP or including the tire equatorial plane CP is defined as the inner land portion 18.

[0119] The inclined groove 50 is not limited to a groove width that gradually increases from Wa to Wb from the inner side in the tire width direction to the outer side in the tire width direction. For example, the inclined groove 50 may have a portion where the groove width gradually increases and a portion where the groove width gradually decreases from the inner side in the tire width direction to the outer side in the tire width direction. The inclined groove 50 may include, at any position between the tip on the inner side in the tire width direction and the tip on the outer side in the tire width direction, a portion whose groove width is smaller than the groove width of the inclined groove 50 located on the inner side in the tire width direction.

[0120] The inner land portion 18 is not limited to a case in which it has a circumferential narrow groove 26 extending in the tire circumferential direction, and may not have the circumferential narrow groove 26 .

[0121] Although the above description has been given of a case in which two circumferential narrow grooves 88 are formed in each of the outer regions SH on each side in the tire width direction, the present invention is not limited to this. One circumferential narrow groove 88 may be formed in each of the outer regions SH on each side in the tire width direction, or three or more circumferential narrow grooves 88 may be formed. When there are three or more circumferential narrow grooves 88, the groove arranged on the outermost side in the tire width direction in the outer region SH is referred to as the outer narrow groove 90, and the groove arranged on the innermost side in the tire width direction in the outer region SH is referred to as the inner narrow groove 92.

[0122] The inner land portion 18 is not limited to having the inner inclined groove 28 and the inner sipe 30, and may include either one of them, or may not include both.

[0123] The inner sipes 30 are not limited to being zigzag slanted alternately to each side in the tire circumferential direction, but may also be linear. The outer sipes 84 are not limited to being zigzag slanted alternately to each side in the tire circumferential direction, but may also be linear.

[0124] The inclined grooves 50 and the inclined narrow grooves 52 are not limited to being arranged alternately in the tire circumferential direction, and for example, a plurality of inclined grooves 50 may be arranged continuously in the tire circumferential direction. Alternatively, a plurality of inclined narrow grooves 52 may be arranged continuously in the tire circumferential direction.

[0125] The inclined narrow groove 52 is not limited to having the groove bottom sipe 78. The inclined narrow groove 52 does not have to have the groove bottom sipe 78.

[0126] At least a portion of the recessed portion 86 is not limited to being disposed in a region on the outer side of the ground contact edge E in the tire width direction. The recessed portion 86 may be disposed in a region on the inner side of the ground contact edge E in the tire width direction.

[0127] The angle formed between the extending direction of the reverse inclined grooves 54 and the tire circumferential direction may be less than 5° or may be greater than 50°.

[0128] The angle θa formed between the extension direction of the first inclined portion 40 and the tire circumferential direction may be less than 30° or more than 70°.

[0129] The inclined groove 50 or the inclined narrow groove 52 is not limited to being arranged on the extension line of the inner inclined groove 28, but may also be arranged between the extension lines of multiple inner inclined grooves 28 arranged in the tire circumferential direction.

[0130] The groove depth D1 of the inner oblique groove 28 may be the same as the groove depth Dm of the circumferential main groove 16. The groove depth D1 of the oblique groove 50 may be the same as the groove depth Dm of the circumferential main groove 16. The groove depth Dg of the oblique narrow groove 52 may be the same as the groove depth Dm of the circumferential main groove 16. The groove depth D4 of the reverse oblique groove 54 may be the same as the groove depth Dm of the circumferential main groove 16. The groove depth D1 of the inner oblique groove 28 may be less than 30% or more than 80% of the groove depth Dm of the circumferential main groove 16. The groove depth Dg of the oblique narrow groove 52 may be less than 20% or more than 60% of the groove depth Dm of the circumferential main groove 16. The groove depth D4 of the reverse oblique groove 54 may be less than 40% or more than 80% of the groove depth Dm of the circumferential main groove 16.

[0131] The outer sipes 84 are not limited to extending along the inclined narrow grooves 52, but may extend in a direction that exceeds ±20° with respect to the extension direction of the inclined narrow grooves 52. The inner sipes 30 are not limited to extending along the tire width direction, but may extend in a direction that exceeds ±20° with respect to the tire width direction.

[0132] The outermost block 56s does not necessarily have to have the recess 86. The depth D5 of the recess 86 may be less than 0.5 mm or may exceed 2.0 mm.

[0133] (Example) Tires according to Examples 1 to 31 and pneumatic tires according to Reference Examples 1 to 3 were manufactured, each having a tire size of 245 / 45R19 102V (specified by JATMA) and having a raised portion with the shape shown in Fig. 1 when mounted on a rim. Detailed conditions of these tires are as shown in Tables 1 and 2 below.

[0134] In Tables 1 and 2, each item conforms to the definition described in this specification. For example, in the column "Positional relationship between inner inclined groove and inclined groove or inclined narrow groove," if the inclined groove or inclined narrow groove is arranged on an extension line of the inner inclined groove, it is written as "on extension line," if it is not on the extension line, it is written as "different," and if there is no inner inclined groove, it is written as "-." In the column "Extension direction of inclined narrow groove relative to outer sipe," if the outer sipe extends along the inclined narrow groove, it is written as "parallel." In the column "Circumferential narrow groove," if a circumferential narrow groove is provided in the outer region, it is written as "present," and if there is no circumferential narrow groove, it is written as "absent." In the column "Positional relationship between inclined groove and inclined narrow groove," if the inclined groove and the inclined narrow groove are arranged alternately in the tire circumferential direction, it is written as "alternate," if they are not arranged alternately, it is written as "different," and if there is no inner inclined groove, it is written as "-."

[0135] The tires of Examples 1 to 31 and Reference Examples 1 to 3 thus prepared were mounted on 19x9.0J aluminum rims at an air pressure (F / R) of 250 kPa / 250 kPa, and each test tire was mounted on a 4WD test vehicle (displacement: 3000 cc). Evaluations were then carried out on the handling stability on wet roads, snowy roads, and dry roads according to the following procedures.

[0136] (Steering stability on wet roads) A test driver conducted a sensory evaluation while driving on a wet road surface (1mm deep water). The evaluation results were expressed as an index, with the conventional example being set at 100. The higher the index value, the better the handling stability on wet road surfaces.

[0137] (Steering stability on snowy roads) A test driver conducted a sensory evaluation while driving on packed snow roads. The evaluation results were expressed as an index, with the conventional example being set at 100. The higher the index value, the better the handling stability on snowy roads.

[0138] (Steering stability on dry roads) A sensory evaluation was carried out by a test driver while driving on a dry road surface where high-speed driving is possible. The evaluation results are expressed as an index with Reference Example 1 being 100. A higher index value means better handling stability on dry road surfaces.

[0139] [Table 1]

[0140] [Table 2]

[0141] From Tables 1 and 2 above, it can be seen that the tires of the examples are superior to the tires of the reference examples in steering stability on wet roads, on snowy roads, and on dry roads. [Explanation of symbols]

[0142] 10 Tires 12 Tread section 14 Tread surface 16 Circumferential main groove 16w Groove wall (circumferential main groove) 18 Inner land area 20 Outer land area 22 1st circumferential main groove 24 2nd circumferential main groove 26 Circumferential thin groove 28 Inner inclined groove 30 inner sipe 31 Tip (internal sipe) 32 One end (inner inclined groove) 34 Other end (inner inclined groove) 34f The other end of the first inner inclined groove 34s The other end of the second inner inclined groove 36 1st inner inclined groove 38 2nd inner inclined groove 40 1st slope 41 Groove wall (first slope) 42 2nd slope part 43 Groove wall (second slope) 44 Bend 46 Tire width direction outer tip (first inclined portion) 50 Slant groove 50w groove wall (slanted groove) 52 Slanted narrow groove 52w Groove wall (slanted narrow groove) 52u groove bottom (slanted narrow groove) 54 Reverse slope groove 56 blocks 56c Block (adjacent to the circumferential main groove) 56s outermost block 58 Tip of inner side in tire width direction (inclined groove) 60 Outer edge of tire width direction (inclined groove) 62 Main slope 64 Bottom raised part 66 Tire width direction inner tip (main inclined part) 68 Slope 70 flat surface 72 Tire width direction inner tip (inclined surface) 74 Tip of inner side in tire width direction (inclined narrow groove) 76 Outer edge of tire width direction (inclined narrow groove) 78 Groove bottom sipe 78t Opening (groove bottom sipe) 78b Bottom (groove bottom sipe) 80 Tip of inner side in tire width direction (reverse inclined groove) 82 Outer edge of tire width direction (reverse inclined groove) 84 outer sipes 86 Recess 86e Edge (recess) 88 Circumferential narrow groove 90 Outer narrow groove 92 Medial narrow groove 94 Deep groove part CP tire equatorial plane E Ground end EL ground terminal wire LDE: The distance between the tread edges across the tire. Wce: Length of inner land portion in the tire width direction Wm Circumferential main groove width W1 Groove width (slope groove) W2 Groove width (slanted narrow groove) W3 Groove width (reverse slope groove) W4 block width Dm Circumferential main groove depth D1 First groove depth (inner inclined groove) D2 Second groove depth (main inclined part) D3 3rd groove depth (raised bottom) D4 groove depth (reverse slope groove) D5 Depth (recess) Dg Groove depth (inclined narrow groove) Ds Groove depth (groove bottom sipe) T Tread Edge P1 1st end point P2 2nd end point Lg Groove length (inclined narrow groove) Ls Groove length (groove bottom sipe) L1 First virtual line (extension direction of reverse inclined groove) L2 2nd virtual line (outer area) L3 Third virtual line (outer area) SH outer area θa angle (angle between the extension direction of the first inclined portion and the tire circumferential direction) θb angle (angle between the extension direction of the second inclined portion and the tire circumferential direction) θc angle (angle between the extension direction of the reverse inclined groove and the tire circumferential direction) θd angle (outside sipe)

Claims

1. a circumferential main groove; an inner land portion defined by at least two of the circumferential main grooves; outer land portions disposed on the outer side in the tire width direction relative to the inner land portion, with the circumferential main groove interposed therebetween, The tire has an inclined groove, an inclined narrow groove, and an inverse inclined groove, which are arranged in the outer land portion, the inclined groove extends from the circumferential main groove toward an outer side in the tire width direction, inclines from a leading side to a trailing side in the tire circumferential direction, and has a tip connected to a tread edge, the inclined narrow groove extends from the circumferential main groove toward the outer side in the tire width direction, inclines from the leading side to the trailing side in the tire circumferential direction, and has a tip located within the outer land portion, The reverse inclined groove extends from the trailing side to the leading side in the tire circumferential direction and is inclined from the inner side to the outer side in the tire width direction, The tire, wherein the groove width of the inclined narrow groove is 20% or more and 80% or less of the groove width of the inclined groove.

2. The tire according to claim 1 , wherein an angle formed between an extension direction of the reverse inclined groove and a tire circumferential direction is equal to or greater than 5° and equal to or less than 50°.

3. The inclined groove is a main slope portion having a first groove depth; a bottom-up portion having a second groove depth shallower than the first groove depth between an end portion of the main inclined portion on an inner side in the tire width direction and the circumferential main groove; 10. The tire of claim 1, wherein:

4. the inner land portion is disposed at a position including the tire equatorial plane, and has an inner inclined groove, the inner inclined groove includes a first inner inclined groove and a second inner inclined groove, the first inner inclined groove extending inward in the tire width direction from the circumferential main groove and inclined from the trailing edge side to the leading edge side in the tire circumferential direction, and having a tip located within the inner land portion, The tire of claim 1 , wherein the first inner oblique groove intersects the tire equatorial plane.

5. the first inner inclined groove has a first inclined portion, a second inclined portion, and a bent portion; the first inclined portion and the second inclined portion are connected via the bent portion, The tire according to claim 4 , wherein the first inclined portion and the second inclined portion extend in different directions at the bent portion.

6. 6. The tire according to claim 5, wherein, when an angle formed between an extension direction of the first inclined portion and a tire circumferential direction is θa and an angle formed between an extension direction of the second inclined portion and the tire circumferential direction is θb, θa is equal to or greater than 30° and equal to or less than 70°, and satisfies the following formula (1): θa+5°≦θb≦90°...Formula (1)

7. The tire according to claim 4, wherein the groove depth of the inner oblique groove is 30% or more and 80% or less of the groove depth of the circumferential main groove.

8. The tire according to claim 4 , wherein the inclined groove or the inclined narrow groove is disposed on an extension line of the inner inclined groove.

9. The tire according to claim 1, wherein the following formula (2) is satisfied, where LDE is a distance between tread ends in the tire width direction, and Wce is a length of the inner land portion in the tire width direction. 0.08≦Wce / LDE≦0.20...Formula (2)

10. 2. The tire according to claim 1, wherein, when a groove width of an opening end of the inclined groove connected to the circumferential main groove is Wa and a groove width of an opening end of the inclined groove at a tread end is Wb, the following formula (3) is satisfied: 0.3≦Wa / Wb≦0.8...Formula (3)

11. The tire according to claim 1, wherein the groove depth of the inclined narrow groove is 20% or more and 60% or less of the groove depth of the circumferential main groove.

12. The inclined narrow groove has a groove bottom sipe, The groove bottom sipe is formed at the groove bottom of the inclined narrow groove, The tire according to claim 1, wherein the following formula (4) is satisfied, where Dg is a groove depth of the inclined narrow groove and Ds is a groove depth of the groove bottom sipe. 0.7≦Ds / Dg≦1.3...Formula (4)

13. The tire according to claim 1, wherein the groove depth of the reverse oblique groove is 40% or more and 80% or less of the groove depth of the circumferential main groove.

14. the outer land portion has a plurality of blocks defined by the inclined groove, the inclined narrow groove, and the reverse inclined groove, The tire of claim 1 , wherein some of the blocks have external sipes.

15. 15. The tire of claim 14, wherein the external sipes extend along the oblique striations.

16. The inner land portion has an inner sipe, The tire according to claim 1 , wherein the inner sipe extends along the tire width direction.

17. 15. The tire according to claim 14, wherein among the plurality of blocks, an outermost block arranged outermost in the tire width direction has a recessed portion, the recessed portion being arranged outward in the tire width direction from a tip end of the inclined narrow groove, and the recessed portion has a plurality of edges intersecting in the tire circumferential direction.

18. 18. The tire of claim 17, wherein the depth of the recess is equal to or greater than 0.5 mm and equal to or less than 3.0 mm.

19. The tire according to claim 1, further comprising a circumferential narrow groove extending from the ground contact edge toward the inner side in the tire width direction, the narrow groove extending in a range of 5% to 15% of the tire width direction length from the tire equatorial plane to the ground contact edge.

20. 20. The tire according to claim 19, wherein two circumferential narrow grooves are provided on each side in the tire width direction, and when the groove width of the circumferential narrow groove on the outer side in the tire width direction of the two circumferential narrow grooves is Wout and the groove width of the circumferential narrow groove on the inner side in the tire width direction is Win, the tire satisfies the following formula (5): 0.3≦Wout / Win≦0.7...Formula (5)

21. 20. The tire according to claim 19, wherein two circumferential narrow grooves are provided on each side in the tire width direction, and when the groove depth of the circumferential narrow groove on the outer side in the tire width direction of the two circumferential narrow grooves is Dout and the groove depth of the circumferential narrow groove on the inner side in the tire width direction is Din, the following formula (6) is satisfied: 0.4≦Dout / Din≦0.8...Formula (6)

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