Tire

Abstract

To provide a tire capable of improving mud and snow performance. 【Solution means】This tire 1 includes a plurality of shoulder lug grooves 311 extending to the buttress portion beyond the tire ground contact end T. Further, the plurality of shoulder lug grooves 311 have a convex portion 5 that protrudes from the groove bottom of the shoulder lug groove 311 and is disposed outside the tire width direction from the tire ground contact end T. Further, the distance D1 from the tire ground contact end T to the convex portion 5 in the tire width direction is in the range of 0.02 ≦ D1 / SH ≦ 0.15 with respect to the tire section height SH.

Description

Technical Field

[0001] The present invention relates to a tire, and more particularly to a tire capable of improving mud and snow performance.

Background Art

[0002] In recent all-terrain tires, in addition to dry performance and wet performance, there is a demand to improve mud and snow performance during off-road driving. As a conventional tire related to such problems, the technique described in Patent Document 1 is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a tire capable of improving mud and snow performance.

Means for Solving the Problems

[0005] To achieve the above object, a tire according to the present invention is a tire including a plurality of shoulder lug grooves extending to a buttress portion beyond a tire ground contact end, wherein the plurality of shoulder lug grooves have a convex portion that protrudes from a groove bottom of the shoulder lug groove and is disposed outside the tire width direction with respect to the tire ground contact end, and the convex portion is disposed separately from a groove wall of the shoulder lug groove in an island shape , The thickness H5 of the convex portion is outside the tire contact surface and in a range of 0.02 ≦ H5 / H11' ≦ 0.50 with respect to a depth H11' of the shoulder lug groove at a position where the convex portion is disposed and the whole of the convex portion is within the shoulder lug groove characterized by this. Furthermore, the tire according to the present invention is a tire provided with a plurality of shoulder lug grooves extending to the buttress portion beyond the tire ground contact end, wherein the plurality of shoulder lug grooves have a convex portion protruding from the groove bottom of the shoulder lug groove and arranged on the outer side in the tire width direction relative to the tire ground contact end, and are formed in a region on the outer side in the tire width direction relative to the tire ground contact end, and are provided with a shallow groove extending in the tire circumferential direction and connected to the shoulder lug groove at at least one end, and the connection portion of the shallow groove to the shoulder lug groove overlaps the convex portion in a projection view in the tire circumferential direction. .

Advantages of the Invention

[0006] In the tire according to the present invention, (1) since the shoulder lug groove has a convex portion, the mud and snow discharging action from the shoulder lug groove during off-road driving is improved. Also, (2) since the convex portion is arranged on the outer side in the tire width direction relative to the tire ground contact end, the groove volume of the shoulder lug groove in the tire ground contact area is ensured, and the traction performance of the tire is improved. As a result, there is an advantage that the mud-and-snow performance of the tire is improved.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

[0008] Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by this embodiment. In addition, the components of this embodiment include those that can be replaced and are self-evidently replaceable while maintaining the identity of the invention. Further, a plurality of modifications described in this embodiment can be arbitrarily combined within the scope self-evident to those skilled in the art.

[0009] [Tire] FIG. 1 is a cross-sectional view of a tire 1 according to an embodiment of the present invention in the tire meridian direction. The figure shows a cross-sectional view of one side region in the tire radial direction. In this embodiment, as an example of the tire, a pneumatic radial tire for a light truck will be described.

[0010] In the figure, the cross-section in the tire meridian direction is defined as the cross-section when the tire is cut by a plane including the tire rotation axis (not shown). Further, the tire equatorial plane CL is defined as a plane passing through the midpoint of the tire cross-sectional width defined by JATMA and perpendicular to the tire rotation axis. Further, the tire width direction is defined as a direction parallel to the tire rotation axis, and the tire radial direction is defined as a direction perpendicular to the tire rotation axis.

[0011] The tire 1 has an annular structure centered on the tire rotation axis, and includes a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, a tread rubber 15, a pair of sidewall rubbers 16, 16, and a pair of rim cushion rubbers 17, 17 (see FIG. 1).

[0012] The pair of bead cores 11, 11 are formed by winding one or more bead wires made of steel in a circular and multiple manner, and are embedded in the bead portions to form the cores of the left and right bead portions. The pair of bead fillers 12, 12 are respectively arranged on the outer periphery in the tire diameter direction of the pair of bead cores 11, 11 to reinforce the bead portions.

[0013] The carcass layer 13 has a single-layer structure composed of one carcass ply or a multi-layer structure formed by laminating a plurality of carcass plies, and is bridged in a toroidal shape between the left and right bead cores 11, 11 to form the skeleton of the tire. Further, both ends of the carcass layer 13 are wound back and locked to the outside in the tire width direction so as to wrap the bead core 11 and the bead filler 12. Further, the carcass ply of the carcass layer 13 is formed by coating a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coating rubber and rolling them, and has a cord angle of 80° or more and 100° or less (defined as the inclination angle of the longitudinal direction of the carcass cord with respect to the tire circumferential direction).

[0014] The belt layer 14 is formed by laminating a plurality of belt plies 141 to 144, and is disposed by being wound around the outer periphery of the carcass layer 13. The belt plies 141 to 144 include a pair of cross belts 141, 142 and a plurality of belt covers 143, 144.

[0015] The pair of cross belts 141, 142 are formed by coating a plurality of belt cords made of steel or an organic fiber material with a coating rubber and rolling them, and have a cord angle of 15° or more and 55° or less in absolute value (defined as the inclination angle of the longitudinal direction of the belt cord with respect to the tire circumferential direction). Further, the pair of cross belts 141, 142 have cord angles with opposite signs to each other, and are laminated with the longitudinal directions of the belt cords crossing each other (so-called cross-ply structure). Further, the pair of cross belts 141, 142 are laminated and disposed on the outer side in the tire diameter direction of the carcass layer 13.

[0016] The belt cover 143 is formed by coating a belt cover cord made of steel or organic fiber material with a coating rubber, and has a cord angle of 0° or more and 10° or less in absolute value. Further, the belt cover 143 is, for example, a strip material formed by coating one or a plurality of belt cover cords with a coating rubber, and this strip material is wound around the outer peripheral surfaces of the cross belts 141 and 142 a plurality of times in a spiral shape in the tire circumferential direction. Further, a plurality of belt covers 143, 143 are arranged to cover the entire area of the cross belts 141, 142.

[0017] The tread rubber 15 is disposed on the outer periphery in the tire radial direction of the carcass layer 13 and the belt layer 14 to form the tread portion of the tire 1. It is made of a rubber material excellent in ground contact characteristics and weather resistance, and is exposed over the entire outer peripheral surface of the tire to form a tread surface. The pair of sidewall rubbers 16, 16 are respectively disposed on the outer sides in the tire width direction of the carcass layer 13 to form the left and right sidewall portions. The pair of rim cushion rubbers 17, 17 extend from the inner side in the tire radial direction to the outer side in the tire width direction of the left and right bead cores 11, 11 and the folded-back portion of the carcass layer 13 to form the rim fitting surface of the bead portion.

[0018] [Tread surface] FIG. 2 is a plan view showing the tread surface of the tire 1 described in FIG. 1. This figure shows the tread surface of an all-season tire having a mud and snow mark "M + S". The tread surface is shown. In this figure, the tire circumferential direction means the direction around the tire rotation axis. Further, the symbol T is the tire ground contact end, and the dimension symbol TW is the tire ground contact width. Also, in this figure, since the tire 1 has a substantially point-symmetric tread surface with a center line point on the tire equatorial plane CL, some of the reference numerals of the components in the region on the right side of the figure are omitted.

[0019] As shown in FIG. 2, the tire 1 has, on its tread surface, a plurality of circumferential main grooves 21, 22 extending in the circumferential direction of the tire, and a plurality of land portions 31 to 33 defined by these circumferential main grooves 21, 22. The circumferential main grooves 21, 22 have an annular structure that continuously extends over the entire circumference in the circumferential direction of the tire.

[0020] For example, in the configuration of FIG. 2, the tire 1 includes a pair of shoulder main grooves 21, 21 and a pair of center main grooves 22, 22, and a pair of shoulder land portions 31, 31 and three rows of center land portions 32, 33, 32. However, the present invention is not limited to this, and the tire 1 may include three circumferential main grooves and four rows of land portions, or may include five or more circumferential main grooves and six or more rows of land portions (not shown). In these cases, the pair of shoulder main grooves 21, 21 are the main grooves located on the outermost side in the tire width direction, and are defined in each of the left and right regions with the tire equatorial plane CL as a boundary. Further, the center main groove (not shown) is defined as a main groove located closer to the tire equatorial plane CL side than the shoulder main grooves 21, 21.

[0021] The main groove is defined as a groove having an obligation to display a wear indicator as defined by JATMA. Further, the main groove has a groove width of 3.0 [mm] or more and 13 [mm] or less, and a groove depth of 8.0 [mm] or more and 16 [mm] or less.

[0022] The groove width is measured as the distance between the opposing groove walls at the groove opening on the tread surface in a non-loaded state where the tire is mounted on a specified rim and filled with a specified internal pressure. In a configuration having a notch or a chamfer at the groove opening, the groove width is measured with the intersection of the extension line of the tread surface and the extension line of the groove wall in a cross-sectional view parallel to the groove width direction and the groove depth direction as an end point.

[0023] The groove depth is measured as the distance from the tread surface to the groove bottom in a non-loaded state where the tire is mounted on a specified rim and filled with a specified internal pressure. Further, in a configuration having partial uneven portions or sipes at the groove bottom, the groove depth is measured excluding these.

[0024] The specified rim refers to the "Standard Rim" defined by JATMA, the "Design Rim" defined by TRA, or the "MEASURING RIM" defined by ETRTO. Also, the specified internal pressure refers to the "Maximum Air Pressure" defined by JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" defined by TRA, or the "INFLATION PRESSURES" defined by ETRTO. Further, the specified load refers to the "Maximum Load Capacity" defined by JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" defined by TRA, or the "LOAD CAPACITY" defined by ETRTO. However, in the case of passenger car tires in JATMA, the specified internal pressure is 180 [kPa] of air pressure, and the specified load is 88 [%] of the maximum load capacity at the specified internal pressure.

[0025] The land portions 31 to 33 are composed of a pair of shoulder land portions 31, 31 and three rows of center land portions 32, 33, 32. The shoulder land portions 31, 31 are defined as the land portions on the outer side in the tire width direction partitioned by the shoulder main grooves 21, 21. Also, the pair of shoulder land portions 31, 31 are arranged in the left and right regions with the tire equatorial plane CL as the boundary. The center land portions 32, 33 are defined as the land portions arranged between the pair of shoulder land portions 31, 31.

[0026] Also, in the configuration of FIG. 2, the tire 1 has a point-symmetrical tread pattern having a center point on the tire equatorial plane CL. However, it is not limited to this, and the tire 1 may have a line-symmetrical tread pattern centered on the tire equatorial plane CL, a tread pattern having directivity in the tire rotation direction, or a left-right asymmetrical tread pattern (not shown).

[0027] In addition, in the configuration of FIG. 2, the circumferential main grooves 21 and 22 have a zigzag shape or a bent shape with an amplitude in the tire width direction. However, it is not limited to this, and the circumferential main grooves 21 and 22 may have a straight shape, or may have a wavy shape or a step shape with an amplitude in the tire width direction (not shown).

[0028] Also, in FIG. 2, the maximum ground contact width Wb1 of the shoulder land portion 31 is in the range of 0.15 ≦ Wb1 / TW ≦ 0.30 with respect to the tire ground contact width TW, and preferably in the range of 0.17 ≦ Wb1 / TW ≦ 0.25.

[0029] The ground contact width of the land portion is measured as the linear distance in the tire axial direction at the contact surface between the land portion and the flat plate when the tire is mounted on a specified rim, the specified internal pressure is applied, and a load corresponding to the specified load is applied while the tire is placed perpendicular to the flat plate in a stationary state.

[0030] The tire ground contact width TW is measured as the linear distance in the tire axial direction at the contact surface between the tire and the flat plate when the tire is mounted on a specified rim, the specified internal pressure is applied, and a load corresponding to the specified load is applied while the tire is placed perpendicular to the flat plate in a stationary state.

[0031] The tire ground contact end T is defined as the maximum width position in the tire axial direction at the contact surface between the tire and the flat plate when the tire is mounted on a specified rim, the specified internal pressure is applied, and a load corresponding to the specified load is applied while the tire is placed perpendicular to the flat plate in a stationary state.

[0032] [Shoulder land portion] FIGS. 3 to 5 are a side view (FIG. 3), a cross-sectional view (FIG. 4), and an enlarged plan view (FIG. 5) showing the buttress portion of the tire 1 described in FIG. 2. In these figures, FIG. 3 shows a plan view of one shoulder land portion 31 seen from the tire side surface, FIG. 4 shows a developed view of the shoulder lug groove 311 outside the tire contact surface, and FIG. 5 shows a cross-sectional view along the groove length direction of the shoulder lug groove 311.

[0033] As shown in FIG. 2, the shoulder land portion 31 includes a plurality of shoulder lug grooves 311 and a plurality of shoulder blocks 312.

[0034] As shown in FIG. 2, the shoulder lug groove 311 opens into the main shoulder groove 21 at one end, extends in the tire width direction beyond the tire contact end T, and reaches the buttress portion. Further, the plurality of shoulder lug grooves 311 are arranged at predetermined intervals in the tire circumferential direction. Also, the shoulder lug groove 311 has a groove width of 3.0 [mm] or more and 17.0 [mm] or less, preferably 5.0 [mm] or more and 15.0 [mm] or less, and a groove depth of 8.0 [mm] or more and 17.0 [mm] or less, preferably 10.0 [mm] or more and 16.0 [mm] or less, within the tire contact surface (dimension symbols in the figure are omitted). Further, the maximum groove width W11_max (see FIG. 4) of the shoulder lug groove 311 is in the range of 1.35 ≦ W11_max / Wm ≦ 1.85 with respect to the maximum groove width Wm (see FIG. 2) of the main shoulder groove 21, preferably in the range of 1.45 ≦ W11_max / Wm ≦ 1.75. Also, the maximum groove depth H11_max (see FIG. 5) of the shoulder lug groove 311 is in the range of 0.75 ≦ H11_max / Hm ≦ 1.00 with respect to the maximum groove depth Hm (not shown) of the main shoulder groove 21, preferably in the range of 0.80 ≦ H11_max / Hm ≦ 0.98.

[0035] For example, in the configuration of FIG. 2, as shown in FIGS. 4 and 5, the shoulder lug groove 311 has a shape with the groove width expanding toward the outer side in the tire width direction, and has the maximum groove width W11_max and the maximum groove depth H11_max at the tire contact end T. Also, the shoulder lug groove 311 extends beyond the tire contact end T to the mold parting position M.

[0036] The split position M of the mold is defined as the position corresponding to the connection part of the split molds of the tire molding die, and is arranged at the buttless part of the tire. At this split position M of the mold, rib-shaped protrusions made of residual rubber bitten in during tire vulcanization molding and extending in the tire circumferential direction are formed. Specifically, since the split mold (not shown) consists of a first molding die that moves forward and backward in the tire diameter direction to form the tread part and left and right second molding dies that move forward and backward in the tire axial direction to form the side parts, rib-shaped protrusions having a width of about 2 [mm] to 3 [mm] are formed at the split position M of the mold.

[0037] Also, in FIG. 4, the extension length L11 of the shoulder lug groove 311 outside the tire contact surface is in the range of 0.15 ≦ L11 / SH ≦ 0.25 with respect to the tire section height SH (see FIG. 1), and preferably in the range of 0.17 ≦ L11 / SH ≦ 0.22. Thereby, the traction of the tire during off-road driving is improved. For example, in the configuration of FIG. 4, the shoulder lug groove 311 extends beyond the tire contact end T to the split position M of the mold, and the split position M of the mold is within the range of the ratio L11 / SH.

[0038] The extension length L11 of the shoulder lug groove 311 is measured as the extension length in the tire width direction in a plan view of the shoulder lug groove 311.

[0039] The tire section height SH is the distance that is half of the difference between the tire outer diameter and the rim diameter, and is measured with the tire mounted on a specified rim and a specified internal pressure applied and in a no-load state.

[0040] Also, in FIG. 4, the groove width W11' of the shoulder lug groove 311 outside the tire contact surface is in the range of 0.80 ≦ W11' / W11_max ≦ 1.20 with respect to the maximum groove width W11_max of the shoulder lug groove 311 inside the tire contact surface, and preferably in the range of 0.95 ≦ W11' / W11_max ≦ 1.05. For example, in the configuration of FIG. 4, the groove width W11' of the shoulder lug groove 311 is set to be substantially constant at the buttless part.

[0041] Further, in FIG. 5, the groove depth H11 of the shoulder lug groove 311 outside the tire contact surface is in the range of 0.10 ≦ H11’ / H11_max ≦ 1.00 with respect to the maximum groove depth H11_max of the shoulder lug groove 311 inside the tire contact surface, and preferably in the range of 0.15 ≦ H11’ / H11_max ≦ 1.00. For example, in the configuration of FIG. 5, the groove depth H11’ of the shoulder lug groove 311 gradually decreases from the tire ground contact end T toward the mold cut position M.

[0042] As shown in FIG. 2, the shoulder block 312 is defined by a plurality of shoulder lug grooves 311. Further, a plurality of shoulder blocks 312 are arranged at predetermined intervals in the tire circumferential direction to form a single block row.

[0043] In addition, in the configuration of FIG. 1, as shown in FIG. 3, the tire 1 includes a side block 4. The side block 4 is a block that protrudes from the tire side surface and has a function of protecting the tire side portion from damage particularly during off-road driving.

[0044] [Convex Portion at the Bottom of the Shoulder Lug Groove] FIGS. 6 and 7 are explanatory views showing the convex portion 5 of the shoulder lug groove 311 described in FIG. 3. In these figures, FIG. 6 shows a plan view of the single convex portion 5, and FIG. 7 shows a cross-sectional view of the convex portion 5 in the groove length direction of the shoulder lug groove 311.

[0045] As shown in FIGS. 2 and 3, the shoulder lug groove 311 includes a convex portion 5. The convex portion 5 is arranged in a region outside the tire width direction with respect to the tire ground contact end T, and is arranged in an island shape separated from the groove wall of the shoulder lug groove 311. Further, as shown in FIG. 5, it protrudes from the groove bottom of the shoulder lug groove 311.

[0046] In such a configuration, (1) since the shoulder lug groove 311 has the convex portion 5, the mud and snow discharging effects from the shoulder lug groove 311 during off-road driving are improved. Also, (2) since the convex portion 5 is arranged outside the tire ground contact end T in the tire width direction, the groove volume of the shoulder lug groove 311 in the tire ground contact area is ensured, and the traction performance of the tire is improved. As a result, the mud and snow performance of the tire is improved.

[0047] For example, in the configuration of FIG. 2, each of the shoulder lug grooves 311, 311 on the left and right of the tire has a single convex portion 5 outside the tire ground contact surface. However, it is not limited to this, and only one of the shoulder lug grooves 311 may have the convex portion 5 (not shown). Also, in the configuration of FIG. 2, all of the plurality of shoulder lug grooves 311 have the convex portion 5. However, it is not limited to this, and only a part of the plurality of shoulder lug grooves 311 may have the convex portion 5 (not shown).

[0048] Also, in FIG. 4, the extension length L5 of the convex portion 5 in the tire width direction is in the range of 0.05 ≦ L5 / SH ≦ 0.15 with respect to the tire cross-sectional height SH, preferably in the range of 0.06 ≦ L5 / SH ≦ 0.12. By the above lower limit, the extension length L5 of the convex portion 5 is ensured, and the mud and snow discharging effects by the convex portion 5 are ensured. By the above upper limit, the vulcanization failure of the tire caused by the convex portion becoming excessive is reduced, and the productivity of the tire is ensured.

[0049] The extension length L5 of the convex portion 5 is measured as the extension length in the tire width direction in a plan view of the shoulder lug groove 311.

[0050] Also, in FIG. 4, the distance D1 from the tire ground contact end T to the convex portion 5 in the tire width direction is in the range of 0.02 ≦ D1 / SH ≦ 0.15 with respect to the tire cross-sectional height SH (see FIG. 1), preferably in the range of 0.07 ≦ D1 / SH ≦ 0.11. By the above lower limit, the distance D1 of the convex portion 5 from the tire ground contact end T is ensured, and the traction performance in the tire ground contact surface is ensured. By the above upper limit, the mud and snow discharging effects by the convex portion 5 are ensured.

[0051] The distance D1 of the convex portion 5 is measured as the separation distance in the tire width direction in a plan view of the shoulder lug groove 311.

[0052] Also, in FIG. 4, the distance D2 from the groove wall of the shoulder lug groove 311 to the convex portion 5 is in the range of 0.20 ≦ D2 / W11' ≦ 0.40 with respect to the groove width W11' of the shoulder lug groove 311 outside the tire contact surface, preferably in the range of 0.30 ≦ D2 / W11' ≦ 0.37. Thereby, the distance D2 of the convex portion 5 from the groove wall of the shoulder lug groove 311 is optimized, and the effect of improving the mud and snow performance by the convex portion 5 is ensured.

[0053] The distance D2 of the convex portion 5 is measured as the separation distance in the tire width direction in a plan view of the shoulder lug groove 311.

[0054] Also, in FIG. 4, the distance Dm from the split position M of the mold to the convex portion 5 is in the range of 0.10 ≦ Dm / SH ≦ 0.50 with respect to the tire section height SH (see FIG. 1), preferably in the range of 0.20 ≦ Dm / SH ≦ 0.40. Thereby, the effect of improving the mud and snow performance by the convex portion 5 is ensured.

[0055] The distance Dm to the convex portion 5 is measured as the separation distance in the tire width direction in a plan view of the shoulder lug groove 311.

[0056] Also, in FIG. 4, the maximum width W5_max of the convex portion 5 is in the range of 0.25 ≦ W5_max / W11' ≦ 0.45 with respect to the groove width W11' of the shoulder lug groove outside the tire contact surface, preferably in the range of 0.32 ≦ W5_max / W11' ≦ 0.40. Thereby, the effect of improving the mud and snow performance by the convex portion 5 is ensured.

[0057] The maximum width W5_max of the convex portion 5 is measured as the width of the top surface of the convex portion 5 with respect to the direction perpendicular to the tire width direction in a plan view of the shoulder lug groove 311.

[0058] Further, as shown in FIG. 4, the convex portion 5 is formed by connecting a wide portion 51 and a narrow portion 52, and the narrow portion 52 is arranged facing outward in the tire width direction. Therefore, the convex portion 5 has a shape in which the width is narrowed toward the outside in the tire width direction. Thereby, the mud and snow discharging action by the convex portion 5 is improved. Also, as shown in FIG. 5, the height H51 (see FIG. 7) of the convex portion 5 monotonically decreases toward the outside in the tire width direction.

[0059] Further, in FIG. 6, the extension length L51 of the wide portion 51 in the tire width direction is in the range of 0.35 ≦ L51 / L5 ≦ 0.55 with respect to the extension length L5 of the convex portion 5, preferably in the range of 0.40 ≦ L51 / L5 ≦ 0.45. Also, the width W51 of the wide portion 51 is in the range of 0.90 ≦ W51 / W5_max ≦ 1.00 with respect to the maximum width W5_max of the convex portion 5, preferably in the range of 0.97 ≦ W51 / W5_max ≦ 1.00. Thereby, the volume of the convex portion 5 is ensured, and the mud and snow discharging action by the convex portion 5 is ensured.

[0060] Further, in FIG. 6, the extension length L52 of the narrow portion 52 in the tire width direction is in the range of 0.30 ≦ L52 / L5 ≦ 0.50 with respect to the extension length L5 of the convex portion 5, preferably in the range of 0.37 ≦ L52 / L5 ≦ 0.45. Also, the width W52 of the narrow portion 52 is in the range of 0.30 ≦ W52 / W5_max ≦ 0.50 with respect to the maximum width W5_max of the convex portion 5, preferably in the range of 0.40 ≦ W52 / W5_max ≦ 0.48. Thereby, the volume of the convex portion 5 is ensured, and the mud and snow discharging action by the convex portion 5 is ensured.

[0061] The extension lengths L51 and L52 of the wide portion 51 and the narrow portion 52 are measured as the extension length in the tire width direction in a plan view of the shoulder lug groove 311.

[0062] The widths W51 and W52 of the wide portion 51 and the narrow portion 52 are measured as the width of the top surface of the convex portion 5 with respect to the direction perpendicular to the tire width direction in a plan view of the shoulder lug groove 311.

[0063] For example, in the configuration of FIG. 4, as shown in FIG. 6, the convex portion 5 has a shape in which the width is tapered toward the outer side in the tire width direction. Further, the connection portion between the wide portion 51 and the narrow portion 52, that is, the inclination angle of the tapered width-reducing portion (dimension symbols in the figure are omitted) is in the range of 30° or more and 50° or less with respect to the longitudinal direction of the convex portion 5. Thereby, the mud and snow discharge effects by the convex portion 5 are enhanced.

[0064] Further, in the configuration of FIG. 5, as shown in FIG. 7, the thickness of the convex portion 5 gradually decreases toward the outer side in the tire width direction. Further, it is preferable that the position of the maximum thickness of the convex portion 5 is arranged at the vent position of the tire molding die. Thereby, the vulcanization failure of the convex portion 5 is reduced.

[0065] Further, in FIG. 7, the maximum thickness H5_max of the convex portion 5 is in the range of 0.8 [mm] ≤ H5_max ≤ 1.5 [mm]. By the above lower limit, the mud and snow discharge performance of the convex portion 5 is ensured, and by the above upper limit, the vulcanization failure of the convex portion 5 is reduced.

[0066] Further, in FIG. 7, the thickness H5 of the convex portion 5 is in the range of 0.02 ≤ H5 / H11’ ≤ 0.50 with respect to the depth H11’ of the shoulder lug groove 311 at the arrangement position of the convex portion 5, preferably in the range of 0.25 ≤ H5 / H11’ ≤ 0.45. The thickness H5 of the convex portion 5 is in the range of 0.4 [mm] ≤ H5 ≤ 3.0 [mm], preferably in the range of 0.5 [mm] ≤ H5 ≤ 1.5 [mm]. Further, the minimum thickness H5_min of the convex portion 5 is in the range of 0.40 ≤ H5_min / H5_max ≤ 0.60 with respect to the maximum thickness H5_max of the convex portion 5. In the configuration of FIG. 7, since the thickness of the convex portion 5 gradually decreases toward the outer side in the tire width direction, the convex portion 5 has the maximum thickness H5_max at one edge portion and the minimum thickness H5_min at the other edge portion.

[0067] The thickness H5 of the convex portion 5 is measured as the distance from the groove bottom of the shoulder lug groove 311 to the top surface or the edge portion of the convex portion 5.

[0068] [Shallow groove of the buttress portion] In the configuration of FIG. 2, as shown in FIG. 3, the tire 1 is provided with shallow grooves 6. The shallow grooves 6 are formed in a region outside the tire ground contact end in the tire width direction, that is, in the buttress portion, extend in the tire circumferential direction, and are connected to the shoulder lug grooves 311 at at least one end. With such a configuration, when driving off-road, the snow-and-mud performance of the tire is improved by the edge action of the shallow grooves 6.

[0069] For example, in the configuration of FIG. 3, the shallow grooves 6 have a bent shape, extend in the tire circumferential direction, and connect the adjacent shoulder lug grooves 311, 311. Also, the connection portion of the shallow grooves 6 to the shoulder lug grooves 311 overlaps the convex portion 5 in the projection view in the tire circumferential direction. Thereby, the snow-and-mud performance of the tire is improved.

[0070] Also, in FIG. 4, the groove width W6 of the shallow grooves 6 is in the range of 0.50 ≦ W6 / W11' ≦ 1.20 with respect to the groove width W11' of the shoulder lug grooves 311 outside the tire ground contact surface, preferably in the range of 0.60 ≦ W6 / W11' ≦ 1.10. Also, the groove width W6 of the shallow grooves 6 is in the range of 7.0 [mm] ≦ W6 ≦ 12.0 [mm], preferably in the range of 8.5 [mm] ≦ W6 ≦ 10.5 [mm]. Also, in FIG. 7, the groove depth H6 of the shallow grooves 6 is in the range of 0.35 ≦ H6 / H11' ≦ 0.55 with respect to the groove depth H11' of the shoulder lug grooves 311 outside the tire ground contact surface, preferably in the range of 0.40 ≦ H6 / H11' ≦ 0.50.

[0071] [Effect] As described above, [1] this tire 1 is provided with a plurality of shoulder lug grooves 311 that extend from the tire ground contact end T to the buttress portion (see FIGS. 2 and 3). Also, the plurality of shoulder lug grooves 311 have a convex portion 5 that protrudes from the groove bottom of the shoulder lug grooves 311 and is arranged outside the tire ground contact end T in the tire width direction.

[0072] In such a configuration, (1) since the shoulder lug groove 311 has the convex portion 5, the mud and snow discharge effect from the shoulder lug groove 311 during off-road driving is improved. Also, (2) since the convex portion 5 is disposed outside the tire width direction from the tire ground contact end T, the groove volume of the shoulder lug groove 311 in the tire ground contact area is ensured, and the traction performance of the tire is improved. As a result, there is an advantage that the mud and snow performance of the tire is improved.

[0073] Also, [2] in this tire 1, in the tire 1 described in [1] above, the distance D1 (see FIG. 4) from the tire ground contact end T to the convex portion 5 in the tire width direction is in the range of 0.02 ≦ D1 / SH ≦ 0.15 with respect to the tire cross-sectional height SH (see FIG. 1). Due to the above lower limit, the distance D1 of the convex portion 5 from the tire ground contact end T is ensured, and the traction performance in the tire ground contact surface is ensured. Due to the above upper limit, there is an advantage that the mud and snow discharge effect by the convex portion 5 is ensured.

[0074] Also, [3] in this tire 1, in the tire 1 described in [1] or [2] above, the extension length L5 (see FIG. 4) of the convex portion 5 in the tire width direction is in the range of 0.05 ≦ L5 / SH ≦ 0.15 with respect to the tire cross-sectional height SH (see FIG. 1). Due to the above lower limit, the extension length L5 of the convex portion 5 is ensured, and the mud and snow discharge effect by the convex portion 5 is ensured. Due to the above upper limit, there is an advantage that the vulcanization failure of the tire caused by the convex portion becoming excessive is reduced, and the productivity of the tire is ensured.

[0075] Also, [4] in this tire 1, in the tire 1 described in any one of [1] to [3] above, the extension length L11 (see FIG. 4) of the shoulder lug groove 311 outside the tire ground contact surface is in the range of 0.15 ≦ L11 / SH ≦ 0.25 with respect to the tire cross-sectional height SH (see FIG. 1). As a result, there is an advantage that the traction performance of the tire during off-road driving is improved.

[0076] Also, in this tire 1, in the tire 1 described in any one of [1] to [4] above, the distance D2 from the groove wall of the shoulder lug groove 311 to the convex portion 5 is in the range of 0.20 ≦ D2 / W11’ ≦ 0.40 with respect to the groove width W11’ of the shoulder lug groove 311 outside the tire contact surface (see Fig. 4). Thereby, the distance D2 of the convex portion 5 from the groove wall of the shoulder lug groove 311 is optimized, and there is an advantage that the effect of improving the mud and snow performance by the convex portion 5 is ensured.

[0077] Also, in this tire 1, in the tire 1 described in any one of [1] to [5] above, the maximum width W5_max of the convex portion 5 is in the range of 0.25 ≦ W5_max / W11’ ≦ 0.45 with respect to the groove width W11’ of the shoulder lug groove 311 outside the tire contact surface (see Fig. 4). Thereby, there is an advantage that the effect of improving the mud and snow performance by the convex portion 5 is ensured.

[0078] Also, in this tire 1, in the tire 1 described in any one of [1] to [6] above, the convex portion 5 is formed by connecting a wide portion 51 and a narrow portion 52, and the narrow portion 52 is arranged facing the outside in the tire width direction (see Fig. 4). Thereby, there is an advantage that the mud and snow discharging effect by the convex portion 5 is improved.

[0079] Also, in this tire 1, in the tire 1 described in any one of [1] to [7] above, the convex portion 5 is formed by connecting a wide portion 51 and a narrow portion 52, and the extending length L51 of the wide portion 51 in the tire width direction is in the range of 0.35 ≦ L51 / L5 ≦ 0.55 with respect to the extending length L5 of the convex portion 5 (see Fig. 6). Thereby, the volume of the convex portion 5 is ensured, and there is an advantage that the mud and snow discharging effect by the convex portion 5 is ensured.

[0080] Also, in this tire 1, in the tire 1 described in any one of the above [1] to [8], the convex portion 5 is formed by connecting a wide portion 51 and a narrow portion 52, and the width W52 of the narrow portion 52 is in the range of 0.30 ≦ W52 / W5_max ≦ 0.50 with respect to the maximum width W5_max of the convex portion 5 (see Fig. 6). Thereby, the volume of the convex portion 5 is ensured, and there is an advantage that the mud and snow discharge effects by the convex portion 5 are ensured.

[0081] Also, in this tire 1, in the tire 1 described in any one of the above [1] to [9], the thickness H5 of the convex portion 5 is in the range of 0.4 [mm] ≦ H5 ≦ 3.0 [mm] (see Fig. 7). By the above lower limit, the mud and snow discharge performance of the convex portion 5 is ensured, and by the above upper limit, there is an advantage that the vulcanization failure of the convex portion 5 is reduced.

[0082] Also, in this tire 1, in the tire 1 described in any one of the above [1] to

[10] , the thickness of the convex portion 5 gradually decreases toward the outer side in the tire width direction. Thereby, there is an advantage that the vulcanization failure of the convex portion 5 is reduced.

[0083] Also, in this tire 1, in the tire 1 described in any one of the above [1] to

[11] , it is formed in a region on the outer side in the tire width direction than the tire ground contact end T, extends in the tire circumferential direction, and includes a shallow groove 6 that connects to the shoulder lug groove 311 at at least one end (see Fig. 3). Further, the connection portion of the shallow groove 6 to the shoulder lug groove 311 overlaps the convex portion 5 in a projection view in the tire circumferential direction. Thereby, there is an advantage that the snow and mud performance of the tire is improved.

[0084] [Applicable target] Note that, in this embodiment, as described above, a pneumatic tire has been described as an example of the tire. However, the present invention is not limited to this, and the configuration described in this embodiment can be arbitrarily applied to other tires within the scope obvious to those skilled in the art. Examples of other tires include, for example, airless tires, solid tires, and the like.

Example

[0085] Figures 8 and 9 are charts showing the results of the performance tests of the tire according to the embodiment of the present invention.

[0086] In this performance test, evaluations regarding mud and snow performance were conducted on multiple types of test tires. Also, a test tire with a tire size of LT265 / 70R17 121 / 118S was assembled on a rim with a rim size of 17×8J, and an internal pressure of 450 [kPa] for the front wheels / 550 [kPa] for the rear wheels and the specified load of JATMA were applied to this test tire. Further, the test tire was mounted on all four wheels of an SUV (Sport Utility Vehicl), which is a test vehicle.

[0087] In the evaluation regarding mud and snow performance, the test vehicle travels on a predetermined muddy road, and the test driver conducts a sensory evaluation regarding traction performance. This evaluation is performed by an index evaluation based on a comparative example as a reference (100), and the larger the numerical value, the more preferable.

[0088] The test tire of the example has the configurations of FIGS. 1 to 5, and the shoulder lug groove 311 has an island-shaped convex portion 5 at the groove bottom outside the tire contact surface. Also, the tire section height SH is 186 [mm]. Further, the groove length L11 of the shoulder lug groove 311 outside the tire contact surface is 32 [mm], and the groove widths W11' are three types: 10.5 [mm], 12.5 [mm], and 14.5 [mm]. Also, the groove depth H11' of the shoulder lug groove 311 at the arrangement position of the convex portion 5 is 2.2 [mm].

[0089] The test tire of the comparative example is such that, in the test tire of Example 1, the convex portion 5 extends over the entire region in the groove length direction of the shoulder lug groove 311 and intersects the tire ground contact end T.

[0090] As shown by the test results, it can be seen that the mud and snow performance of the tire is improved in the test tire of the example.

Explanation of Reference Numerals

[0091] 1 Tire; 11 Bead core; 12 Bead filler; 13 Carcass layer; 14 Belt layer; 141, 142 Cross belt; 143 Belt cover; 15 Tread rubber; 16 Sidewall rubber; 17 Rim cushion rubber; 21 Shoulder main groove; 22 Center main groove; 31 Shoulder land; 311 Shoulder lug groove; 312 Shoulder block; 32 Center land; 4 Side block; 5 Protrusion; 51 Wide part; 52 Narrow part; 6 Shallow groove

Claims

1. A tire comprising a plurality of shoulder lug grooves extending from a tire ground contact end to a buttress portion beyond the tire ground contact end, wherein the plurality of shoulder lug grooves have a convex portion that protrudes from the groove bottom of the shoulder lug groove and is disposed outside the tire width direction relative to the tire ground contact end, the convex portion is disposed in an island-like manner spaced apart from the groove wall of the shoulder lug groove, the thickness H5 of the convex portion is in the range of 0.02 ≦ H5 / H11' ≦ 0.50 with respect to the depth H11' of the shoulder lug groove at the position where the convex portion is disposed outside the tire ground contact surface, and the entire convex portion is within the shoulder lug groove, characterized in that the tire.

2. The tire according to claim 1, wherein the distance D1 from the tire ground contact end to the convex portion in the tire width direction is in the range of 0.02 ≦ D1 / SH ≦ 0.15 with respect to the tire cross-sectional height SH.

3. The tire according to claim 1, wherein the extending length L5 of the convex portion in the tire width direction is in the range of 0.05 ≦ L5 / SH ≦ 0.15 with respect to the tire cross-sectional height SH.

4. The tire according to claim 1, wherein the extending length L11 of the shoulder lug groove outside the tire ground contact surface is in the range of 0.15 ≦ L11 / SH ≦ 0.25 with respect to the tire cross-sectional height SH.

5. The tire according to claim 1, wherein the distance D2 from the groove wall of the shoulder lug groove to the convex portion is in the range of 0.20 ≦ D2 / W11' ≦ 0.40 with respect to the groove width W11' of the shoulder lug groove outside the tire ground contact surface.

6. The tire according to claim 1, wherein the maximum width W5_max of the convex portion is in the range of 0.25 ≦ W5_max / W11' ≦ 0.45 with respect to the groove width W11' of the shoulder lug groove outside the tire ground contact surface.

7. The tire according to claim 1, wherein the convex portion is formed by connecting a wide portion and a narrow portion, and the narrow portion is disposed facing the outside in the tire width direction.

8. The tire according to claim 1, wherein the convex portion is formed by connecting a wide portion and a narrow portion, and the extending length L51 of the wide portion in the tire width direction is in the range of 0.35 ≦ L51 / L5 ≦ 0.55 with respect to the extending length L5 of the convex portion.

9. The tire according to claim 1, wherein the convex portion is formed by connecting a wide portion and a narrow portion, and the width W52 of the narrow portion is in the range of 0.30 ≦ W52 / W5_max ≦ 0.50 with respect to the maximum width W5_max of the convex portion.

10. The tire according to claim 1, wherein the thickness H5 of the convex portion is in the range of 0.4 [mm] ≦ H5 ≦ 3.0 [mm].

11. The tire according to claim 1, wherein the thickness of the convex portion gradually decreases toward the outer side in the tire width direction.

12. A shallow groove is formed in a region outside the tire ground contact end in the tire width direction, extends in the tire circumferential direction, and is connected to a shoulder lug groove at at least one end, and The tire according to claim 1, wherein a connection portion of the shallow groove to the shoulder lug groove overlaps the convex portion in a projection view in the tire circumferential direction.

13. The tire according to claim 1, wherein the groove depth H11' of the shoulder lug groove gradually decreases from the tire ground contact end toward the mold parting position M.

14. A tire having a plurality of shoulder lug grooves extending beyond the tire ground contact end to the buttress portion, wherein the plurality of shoulder lug grooves have a convex portion protruding from the groove bottom of the shoulder lug groove and arranged outside the tire ground contact end in the tire width direction, A tire characterized in that a shallow groove is formed in a region outside the tire ground contact end in the tire width direction, extends in the tire circumferential direction, and is connected to a shoulder lug groove at at least one end, and a connection portion of the shallow groove to the shoulder lug groove overlaps the convex portion in a projection view in the tire circumferential direction.

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