tire

Abstract

To provide a tire capable of improving mud-and-snow performance.SOLUTION: A tire 1 is provided with a plurality of shoulder lug grooves 311 which extend to a buttress portion beyond a tire ground-contact end T. In addition, the shoulder lug grooves 311 each have a protrusion 5 which protrudes from the groove bottom of the shoulder lug groove 311 and is disposed further outward in a tire width direction than the tire ground-contact end T. In addition, a distance D1 from the tire ground-contact end T to the protrusion 5 in the tire width direction is in the range of 0.02≤D1 / SH≤0.15 with respect to a tire cross-sectional height SH.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a tire, and more particularly to a tire that can improve mud and snow performance. [Background technology]

[0002] In recent years, all-terrain tires have been required to have improved mud and snow performance during off-road driving in addition to dry and wet performance. A conventional tire that addresses this issue is known to have a technology described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-142370 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a tire that can improve mud and snow performance. [Means for solving the problem]

[0005] In order to achieve the above object, the tire of the present invention is a tire having a plurality of shoulder lug grooves extending beyond the tire ground contact edge to the buttress portion, and is characterized in that the plurality of shoulder lug grooves have convex portions that protrude from the groove bottoms of the shoulder lug grooves and are positioned outward in the tire width direction from the tire ground contact edge. [Effects of the Invention]

[0006] In the tire according to the present invention, (1) the shoulder lug grooves have convex portions, which improve mud and snow removal from the shoulder lug grooves during off-road driving. Also, (2) the convex portions are positioned outward in the tire width direction from the tire contact edge, ensuring groove volume for the shoulder lug grooves in the tire contact area and improving tire traction. These advantages result in improved mud-and-snow performance. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view in the tire meridian direction showing a tire according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing the tread surface of the tire shown in FIG. [Figure 3] FIG. 3 is a side view showing a buttress portion of the tire shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view showing a buttress portion of the tire shown in FIG. [Figure 5] FIG. 5 is an enlarged plan view showing a buttress portion of the tire shown in FIG. [Figure 6] FIG. 6 is an explanatory view showing the convex portion of the shoulder lug groove shown in FIG. [Figure 7] FIG. 7 is an explanatory view showing the convex portion of the shoulder lug groove shown in FIG. [Figure 8] FIG. 8 is a table showing the results of performance tests on the tire according to the embodiment of the present invention. [Figure 9] FIG. 9 is a table showing the results of performance tests on the tire according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to these embodiments. Furthermore, the components of these embodiments include those that can be substituted and are obvious substitutes while maintaining the identity of the invention. Furthermore, the multiple modifications described in these embodiments can be arbitrarily combined within the scope obvious to those skilled in the art.

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

[0010] In the figure, the tire meridian cross section is defined as a cross section of the tire cut by a plane including the tire rotation axis (not shown). The tire equatorial plane CL is defined as a plane that passes through the midpoint of the tire section width defined by JATMA and is perpendicular to the tire rotation axis. The tire width direction is defined as the direction parallel to the tire rotation axis, and the tire radial direction is defined as the 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 Figure 1).

[0012] The pair of bead cores 11, 11 are formed by winding one or more steel bead wires in an annular and multiple pattern 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 disposed on the outer periphery of the pair of bead cores 11, 11 in the tire radial direction, respectively, to reinforce the bead portions.

[0013] The carcass layer 13 has a single-layer structure consisting of one carcass ply or a multi-layer structure consisting of multiple carcass plies stacked together, and is toroidally laid between the left and right bead cores 11, 11 to form the tire framework. Both ends of the carcass layer 13 are wrapped around and secured to the outside in the tire width direction so as to enclose the bead cores 11 and the bead fillers 12. The carcass ply of the carcass layer 13 is formed by covering multiple carcass cords made of steel or organic fiber material (e.g., aramid, nylon, polyester, rayon, etc.) with coating rubber and rolling them, and has a cord angle (defined as the inclination angle of the carcass cords in the longitudinal direction relative to the tire circumferential direction) of 80 degrees or more and 100 degrees or less.

[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 each 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 organic fiber material with coating rubber and rolling them, and have a cord angle (defined as the inclination angle of the belt cords in the longitudinal direction with respect to the tire circumferential direction) of 15 degrees or more and 55 degrees or less in absolute value. The pair of cross belts 141, 142 have cord angles of opposite signs to each other, and are layered with the longitudinal directions of the belt cords crossing each other (so-called cross-ply structure). The pair of cross belts 141, 142 are layered and arranged on the outer side of the carcass layer 13 in the tire radial direction.

[0016] The belt cover 143 is configured by covering a belt cover cord made of steel or organic fiber material with coating rubber, and has a cord angle of 0 degrees or more and 10 degrees or less in absolute value. The belt cover 143 is, for example, a strip material configured by covering one or more belt cover cords with coating rubber, and is configured by winding this strip material spirally multiple times around the outer circumferential surfaces of the cross belts 141, 142 in the tire circumferential direction. The multiple 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 of the carcass layer 13 and the belt layer 14 in the tire radial direction to form the tread portion of the tire 1. Made of a rubber material with excellent ground contact characteristics and weather resistance, it is exposed over the entire outer periphery of the tire to form the tread surface. A pair of sidewall rubbers 16, 16 are disposed on the outer sides of the carcass layer 13 in the tire width direction to form left and right sidewall portions. A pair of rim cushion rubbers 17, 17 extend from the inner side in the tire radial direction of the left and right bead cores 11, 11 and the turned-up portions of the carcass layer 13 to the outer side in the tire width direction 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 shown in FIG. 1. The figure shows the tread surface of an all-season tire with the mud and snow mark "M+S." In the figure, the tire circumferential direction refers to the direction around the tire rotation axis. Also, the symbol T indicates the tire contact edge, and the dimension symbol TW indicates the tire contact width. In the figure, because the tire 1 has a tread surface that is approximately point-symmetric with the centerline point on the tire equatorial plane CL, some of the symbols for the components in the area on the right side of the figure have been omitted.

[0019] 2, the tire 1 has, on its tread surface, a plurality of circumferential main grooves 21, 22 extending in the tire circumferential direction, 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 extends continuously around the entire circumference of the tire in the circumferential direction.

[0020] For example, in the configuration shown in FIG. 2, the tire 1 has a pair of shoulder main grooves 21, 21, a pair of center main grooves 22, 22, a pair of shoulder land portions 31, 31, and three rows of center land portions 32, 33, 32. However, the tire 1 is not limited to this configuration, and may have three circumferential main grooves and four rows of land portions, or 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 outermost main grooves in the tire width direction and are defined as left and right regions bounded by the tire equatorial plane CL. Furthermore, the center main groove (not shown) is defined as the main groove located closer to the tire equatorial plane CL than the shoulder main grooves 21, 21.

[0021] The main groove is defined as a groove that is required to display a wear indicator as specified by JATMA. The main groove has a groove width of 3.0 mm to 13 mm and a groove depth of 8.0 mm to 16 mm.

[0022] The groove width is measured as the 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 in an unloaded state. In a configuration in which the groove opening has a notch or chamfer, the groove width is measured using the intersection of an extension of the tread surface and an extension of the groove wall in a cross-sectional view parallel to the groove width direction and the groove depth direction as the endpoint.

[0023] The groove depth is measured as the distance from the tread surface to the groove bottom when the tire is mounted on a specified rim, inflated to a specified internal pressure, and under no load. If the tire has partial unevenness or sipes at the groove bottom, the groove depth is measured excluding these.

[0024] A specified rim is a "standard rim" as specified by JATMA, a "design rim" as specified by TRA, or a "measuring rim" as specified by ETRTO. Also, specified internal pressure is the "maximum air pressure" as specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" as specified by TRA, or the "inflation pressure" as specified by ETRTO. Also, specified load is the "maximum load capacity" as specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" as specified by TRA, or the "load capacity" as specified by ETRTO. However, in JATMA, for passenger car tires, the specified internal pressure is 180 kPa, and the specified load is 88% of the maximum load capacity at the specified internal pressure.

[0025] The land portions 31-33 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 land portions on the outer side in the tire width direction defined by the shoulder main grooves 21, 21. The pair of shoulder land portions 31, 31 are arranged in left and right regions bounded by the tire equatorial plane CL. The center land portions 32, 33 are defined as land portions arranged between the pair of shoulder land portions 31, 31.

[0026] 2, the tire 1 has a point-symmetric tread pattern with a center point on the tire equatorial plane CL. However, the tire 1 is not limited to this, and may have a tread pattern that is line-symmetric about the tire equatorial plane CL, a tread pattern that has directionality in the tire rotation direction, or an asymmetric tread pattern (not shown).

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

[0028] In addition, 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 relative to the tire ground contact width TW, and preferably in the range of 0.17≦Wb1 / TW≦0.25.

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

[0030] The tire contact width TW is measured as the linear distance in the axial direction of the tire at 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, and placed perpendicular to a flat plate in a stationary state and subjected to a load corresponding to a specified load.

[0031] The tire contact edge T is defined as the widest position in the axial direction of the tire at 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, and placed perpendicular to a flat plate in a stationary state and subjected to a load corresponding to a specified load.

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

[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 shoulder main groove 21 at one end, extends beyond the tire ground contact edge T in the tire width direction, and reaches the buttress portion. The shoulder lug grooves 311 are arranged at predetermined intervals in the tire circumferential direction. The shoulder lug grooves 311 have a groove width of 3.0 mm to 17.0 mm, preferably 5.0 mm to 15.0 mm, and a groove depth of 8.0 mm to 17.0 mm, preferably 10.0 mm to 16.0 mm, in the tire ground contact patch (dimension symbols omitted in the figure). The maximum groove width W11_max of the shoulder lug groove 311 (see FIG. 4) is in the range of 1.35≦W11_max / Wm≦1.85, preferably 1.45≦W11_max / Wm≦1.75, relative to the maximum groove width Wm of the shoulder main groove 21 (see FIG. 2). 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, preferably 0.80≦H11_max / Hm≦0.98, relative to the maximum groove depth Hm (not shown) of the shoulder main groove 21.

[0035] 2, as shown in FIGS. 4 and 5, the shoulder lug grooves 311 have a shape in which the groove width increases outward in the tire width direction, and have a maximum groove width W11_max and a maximum groove depth H11_max at the tire ground contact edge T. Furthermore, the shoulder lug grooves 311 extend beyond the tire ground contact edge T to the mold split position M.

[0036] The mold split position M is defined as a position corresponding to the connection of the split molds of the tire mold, and is placed in the buttress portion of the tire. At this mold split position M, a rib-like protrusion extending in the tire circumferential direction is formed from residual rubber that was bitten in during tire vulcanization and molding. Specifically, the split mold (not shown) is composed of a first molding die that moves forward and backward in the tire radial direction to form the tread portion, and left and right second molding dies that move forward and backward in the tire axial direction to form the side portions, so that a rib-like protrusion having a width of approximately 2 mm to 3 mm is formed at the mold split position M.

[0037] 4, the extension length L11 of the shoulder lug grooves 311 outside the tire contact patch is in the range of 0.15≦L11 / SH≦0.25, and preferably 0.17≦L11 / SH≦0.22, relative to the tire cross-sectional height SH (see FIG. 1). This improves tire traction during off-road driving. For example, in the configuration of FIG. 4, the shoulder lug grooves 311 extend beyond the tire contact edge T to the mold split position M, which is within the above-mentioned range of the L11 / SH ratio.

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

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

[0040] 4, the groove width W11' of the shoulder lug grooves 311 outside the tire contact patch, relative to the maximum groove width W11_max of the shoulder lug grooves 311 within the tire contact patch, is in the range of 0.80≦W11' / W11_max≦1.20, 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 grooves 311 is set to be approximately constant in the buttress portion.

[0041] 5, the groove depth H11 of the shoulder lug grooves 311 outside the tire contact patch is in the range of 0.10≦H11' / H11_max≦1.00, and preferably 0.15≦H11' / H11_max≦1.00, relative to the maximum groove depth H11_max of the shoulder lug grooves 311 within the tire contact patch. For example, in the configuration of FIG. 5, the groove depth H11' of the shoulder lug grooves 311 gradually decreases from the tire contact edge T toward the mold parting position M.

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

[0043] In the configuration of Fig. 1, the tire 1 includes side blocks 4 as shown in Fig. 3. The side blocks 4 are blocks that protrude from the tire side surfaces and have the function of protecting the tire side portions from external damage, particularly during off-road driving.

[0044] [Shoulder lug groove bottom convex part] Figures 6 and 7 are explanatory diagrams showing the convex portion 5 of the shoulder lug groove 311 shown in Figure 3. In these figures, Figure 6 shows a plan view of a single convex portion 5, and Figure 7 shows a cross-sectional view of the convex portion 5 in the groove length direction of the shoulder lug groove 311.

[0045] 2 and 3, the shoulder lug groove 311 includes a protrusion 5. As shown in Fig. 4, the protrusion 5 is disposed in a region further outward in the tire width direction than the tire ground contact edge T, and is disposed in an island-like manner spaced apart from the groove wall of the shoulder lug groove 311. Furthermore, as shown in Fig. 5, the protrusion 5 protrudes from the groove bottom of the shoulder lug groove 311.

[0046] In this configuration, (1) the shoulder lug grooves 311 have the protrusions 5, which improve mud and snow removal from the shoulder lug grooves 311 during off-road driving. Also, (2) because the protrusions 5 are positioned further outward in the tire width direction than the tire ground contact edge T, the groove volume of the shoulder lug grooves 311 in the tire ground contact area is secured, improving the tire's traction performance. These factors improve the tire's mud-and-snow performance.

[0047] For example, in the configuration shown in FIG. 2, each of the left and right shoulder lug grooves 311, 311 of the tire has a single protrusion 5 outside the tire contact patch. However, this is not a limitation, and only one of the shoulder lug grooves 311 may have a protrusion 5 (not shown). Also, in the configuration shown in FIG. 2, all of the multiple shoulder lug grooves 311 have a protrusion 5. However, this is not a limitation, and only some of the multiple shoulder lug grooves 311 may have a protrusion 5 (not shown).

[0048] 4, the extension length L5 of the protrusions 5 in the tire width direction relative to the tire cross-sectional height SH is in the range of 0.05≦L5 / SH≦0.15, and preferably 0.06≦L5 / SH≦0.12. The above lower limit ensures the extension length L5 of the protrusions 5, thereby ensuring the mud and snow removal function of the protrusions 5. The above upper limit reduces tire vulcanization failures caused by excessively large protrusions, ensuring tire productivity.

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

[0050] 4, the distance D1 in the tire width direction from the tire ground contact edge T to the convex portion 5 is in the range of 0.02≦D1 / SH≦0.15, and preferably 0.07≦D1 / SH≦0.11, relative to the tire cross-sectional height SH (see FIG. 1). The above lower limit ensures the distance D1 from the tire ground contact edge T to the convex portion 5, ensuring traction performance within the tire ground contact patch. The above upper limit ensures the mud and snow removal function of the convex portion 5.

[0051] The distance D1 of the protrusions 5 is measured as the distance between the shoulder lug grooves 311 in the tire width direction in a plan view.

[0052] 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, and preferably 0.30≦D2 / W11′≦0.37, relative to the groove width W11′ of the shoulder lug groove 311 outside the tire contact patch. This optimizes the distance D2 from the groove wall of the shoulder lug groove 311 to the convex portion 5, ensuring that the convex portion 5 improves mud-and-snow performance.

[0053] The distance D2 of the protrusions 5 is measured as the distance between the shoulder lug grooves 311 in the tire width direction in a plan view.

[0054] 4, the distance Dm from the mold split position M to the protrusions 5 is in the range of 0.10≦Dm / SH≦0.50, and preferably 0.20≦Dm / SH≦0.40, relative to the tire cross-sectional height SH (see FIG. 1). This ensures that the protrusions 5 improve mud-and-snow performance.

[0055] The distance Dm to the protrusion 5 is measured as the distance between the shoulder lug grooves 311 in the tire width direction in a plan view.

[0056] 4, the maximum width W5_max of the protrusions 5 is in the range of 0.25≦W5_max / W11′≦0.45, and preferably 0.32≦W5_max / W11′≦0.40, relative to the groove width W11′ of the shoulder lug groove outside the tire contact patch. This ensures that the protrusions 5 have the effect of improving mud-and-snow performance.

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

[0058] As shown in Fig. 4, the protrusions 5 are formed by connecting a wide portion 51 and a narrow portion 52, with the narrow portion 52 facing outward in the tire width direction. Therefore, the protrusions 5 have a shape that narrows toward the outside in the tire width direction. This improves the mud and snow removal function of the protrusions 5. As shown in Fig. 5, the height H51 (see Fig. 7) of the protrusions 5 monotonically decreases toward the outside in the tire width direction.

[0059] 6, the extension length L51 of the wide portions 51 in the tire width direction is in the range of 0.35≦L51 / L5≦0.55, and preferably 0.40≦L51 / L5≦0.45, relative to the extension length L5 of the projections 5. The width W51 of the wide portions 51 is in the range of 0.90≦W51 / W5_max≦1.00, and preferably 0.97≦W51 / W5_max≦1.00, relative to the maximum width W5_max of the projections 5. This ensures the volume of the projections 5, and ensures the mud and snow removal functions of the projections 5.

[0060] 6, the extension length L52 of the narrow width portions 52 in the tire width direction is in the range of 0.30≦L52 / L5≦0.50, and preferably in the range of 0.37≦L52 / L5≦0.45, relative to the extension length L5 of the protrusions 5. The width W52 of the narrow width portions 52 is in the range of 0.30≦W52 / W5_max≦0.50, and preferably in the range of 0.40≦W52 / W5_max≦0.48, relative to the maximum width W5_max of the protrusions 5. This ensures the volume of the protrusions 5, and ensures the mud and snow removal functions of the protrusions 5.

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

[0062] The widths W51, W52 of the wide portion 51 and the narrow portion 52 are measured as the width of the top surface of the protrusion 5 in 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, the protrusions 5 have a tapered shape that narrows toward the outside in the tire width direction, as shown in Fig. 6. The connecting portions between the wide portions 51 and the narrow portions 52, i.e., the tapered narrowing portions, have an inclination angle (dimension symbols omitted in the figure) in the range of 30 degrees to 50 degrees relative to the longitudinal direction of the protrusions 5. This improves the mud and snow removal function of the protrusions 5.

[0064] 5, the thickness of the protrusions 5 gradually decreases toward the outer side in the tire width direction, as shown in FIG. 7. The maximum thickness position of the protrusions 5 is preferably located at a vent position of the tire mold. This reduces vulcanization defects of the protrusions 5.

[0065] 7, the maximum thickness H5_max of the protrusions 5 is in the range of 0.8 mm≦H5_max≦1.5 mm. The lower limit ensures the mud and snow removal performance of the protrusions 5, and the upper limit reduces vulcanization failure of the protrusions 5.

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

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

[0068] [Shallow grooves in the buttress section] In the configuration shown in Fig. 2, the tire 1 includes shallow grooves 6 as shown in Fig. 3. The shallow grooves 6 are formed in the region on the outer side of the tire contact edge in the tire width direction, i.e., in the buttress portion, extend in the tire circumferential direction, and connect to shoulder lug grooves 311 at least at one end. In this configuration, the edge action of the shallow grooves 6 during off-road driving improves the snow and mud performance of the tire.

[0069] For example, in the configuration shown in Fig. 3, the shallow groove 6 has a bent shape and extends circumferentially to connect adjacent shoulder lug grooves 311. The connection portion of the shallow groove 6 to the shoulder lug groove 311 overlaps the protrusion 5 when viewed in circumferential projection. This improves the tire's snow and mud performance.

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

[0071] [effect] As described above, [1] the tire 1 has a plurality of shoulder lug grooves 311 that extend beyond the tire ground contact edge T to the buttress portion (see FIGS. 2 and 3). The plurality of shoulder lug grooves 311 also have protrusions 5 that protrude from the groove bottoms of the shoulder lug grooves 311 and are positioned outward in the tire width direction from the tire ground contact edge T.

[0072] In this configuration, (1) the shoulder lug grooves 311 have the protrusions 5, which improve mud and snow removal from the shoulder lug grooves 311 during off-road driving. Also, (2) because the protrusions 5 are positioned further outward in the tire width direction than the tire ground contact edge T, the groove volume of the shoulder lug grooves 311 in the tire ground contact area is secured, improving the tire's traction performance. These advantages result in improved mud-and-snow performance of the tire.

[0073] [2] In the tire 1 described in [1] above, the distance D1 (see FIG. 4) in the tire width direction from the tire ground contact edge T to the convex portion 5 is in the range of 0.02≦D1 / SH≦0.15 relative to the tire cross-sectional height SH (see FIG. 1). The lower limit ensures the distance D1 from the tire ground contact edge T to the convex portion 5, ensuring traction performance within the tire ground contact patch, while the upper limit has the advantage of ensuring the mud and snow removal function of the convex portion 5.

[0074] [3] In the tire 1 described in [1] or [2] above, the extension length L5 of the protrusions 5 in the tire width direction (see FIG. 4) is in the range of 0.05≦L5 / SH≦0.15 relative to the tire cross-sectional height SH (see FIG. 1). The lower limit ensures the extension length L5 of the protrusions 5, ensuring the mud and snow removal function of the protrusions 5, while the upper limit reduces tire vulcanization failures caused by the protrusions being excessively large, thereby ensuring tire productivity.

[0075] [4] In the tire 1 according to any one of the above [1] to [3], the extension length L11 (see FIG. 4) of the shoulder lug grooves 311 outside the tire contact patch is in the range of 0.15≦L11 / SH≦0.25 relative to the tire cross-sectional height SH (see FIG. 1). This has the advantage of improving the traction of the tire during off-road driving.

[0076] [5] In the tire 1 according to any one of the above [1] to [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, where W11′ is the groove width of the shoulder lug groove 311 outside the tire contact patch (see FIG. 4). This optimizes the distance D2 from the groove wall of the shoulder lug groove 311 to the convex portion 5, which has the advantage of ensuring the effect of the convex portion 5 in improving mud-and-snow performance.

[0077] [6] In the tire 1 according to any one of the above [1] to [5], the maximum width W5_max of the protrusions 5 is in the range of 0.25≦W5_max / W11′≦0.45 relative to the groove width W11′ of the shoulder lug grooves 311 outside the tire contact patch (see FIG. 4). This has the advantage of ensuring the effect of improving mud-and-snow performance by the protrusions 5.

[0078] [7] In the tire 1 according to any one of the above [1] to [6], the protrusions 5 are formed by connecting the wide portions 51 and the narrow portions 52, and the narrow portions 52 are arranged facing outward in the tire width direction (see FIG. 4). This has the advantage of improving the mud and snow removal function of the protrusions 5.

[0079] [8] In the tire 1, in the tire 1 described in any one of [1] to [7] above, the protruding portions 5 are formed by connecting the wide portions 51 and the narrow portions 52, and the extension length L51 of the wide portions 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 protruding portions 5 (see FIG. 6). This has the advantage of ensuring the volume of the protruding portions 5 and ensuring the mud and snow removal function of the protruding portions 5.

[0080] [9] In the tire 1, in the tire 1 described in any one of the above [1] to [8], the protruding portions 5 are formed by connecting the wide portions 51 and the narrow portions 52, and the width W52 of the narrow portions 52 is in the range of 0.30≦W52 / W5_max≦0.50 relative to the maximum width W5_max of the protruding portions 5 (see FIG. 6). This ensures the volume of the protruding portions 5, which has the advantage of ensuring the mud and snow removal function of the protruding portions 5.

[0081]

[10] In the tire 1 according to any one of the above items [1] to [9], the thickness H5 of the protruding portions 5 is in the range of 0.4 mm≦H5≦3.0 mm (see FIG. 7). The lower limit ensures mud and snow removal performance of the protruding portions 5, and the upper limit has the advantage of reducing vulcanization failure of the protruding portions 5.

[0082]

[11] In the tire 1 according to any one of the above [1] to

[10] , the thickness of the protruding portions 5 gradually decreases toward the outer side in the tire width direction. This has the advantage of reducing vulcanization failures of the protruding portions 5.

[0083]

[12] The tire 1 is the tire 1 according to any one of the above [1] to

[11] , further comprising shallow grooves 6 formed in a region on the outer side in the tire width direction than the tire ground contact edge T, extending in the tire circumferential direction and connecting at least one end thereof to shoulder lug grooves 311 (see FIG. 3). Furthermore, the connection portion of the shallow groove 6 with the shoulder lug groove 311 overlaps the protrusion 5 in a projected view in the tire circumferential direction. This has the advantage of improving the snow and mud performance of the tire.

[0084] Applies to In this embodiment, as described above, a pneumatic tire has been described as an example of a tire. However, the present invention is not limited to this, and the configuration described in this embodiment can be applied to other tires as desired within the scope of what is obvious to those skilled in the art. Examples of other tires include airless tires and solid tires. [Example]

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

[0086] In this performance test, the mud and snow performance of several types of test tires was evaluated. The test tires, measuring LT265 / 70R17 121 / 118S, were mounted on rims measuring 17x8J, and the test tires were pressurized to 450 kPa (front) and 550 kPa (rear), and the specified JATMA load was applied. The test tires were also mounted on all four wheels of the test vehicle, a 4WD SUV (Sport Utility Vehicle).

[0087] In the evaluation of mud and snow performance, the test vehicle is driven on a designated muddy road, and the test driver performs a sensory evaluation of traction. This evaluation is performed using an index rating with the comparative example set as the standard (100), and the higher the number, the better.

[0088] The test tire of the example has the configuration shown in Figures 1 to 5, and the shoulder lug grooves 311 have island-shaped convex portions 5 at the groove bottom outside the tire contact patch. The tire cross-sectional height SH is 186 mm. The shoulder lug grooves 311 have a groove length L11 of 32 mm outside the tire contact patch, and three groove widths W11' of 10.5 mm, 12.5 mm, and 14.5 mm. The shoulder lug grooves 311 have a groove depth H11' of 2.2 mm at the position where the convex portions 5 are located.

[0089] In the test tire of the comparative example, in the test tire of Example 1, the protrusion 5 extends over the entire area of the shoulder lug groove 311 in the groove length direction and intersects with the tire ground contact edge T.

[0090] As the test results show, the test tires of the examples show improved mud and snow performance. [Explanation of symbols]

[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 portion; 311 shoulder lug groove; 312 shoulder block; 32 center land portion; 4 side block; 5 convex portion; 51 wide portion; 52 narrow portion; 6 shallow groove

Claims

1. A tire having a plurality of shoulder lug grooves extending beyond the tire ground contact edge to the buttress portion, a tire characterized in that the plurality of shoulder lug grooves have protrusions that protrude from the groove bottoms of the shoulder lug grooves and are positioned outward in the tire width direction from the tire ground contact edge.

2. The tire according to claim 1, wherein a distance D1 from a tire ground contact edge to the convex portion in the tire width direction is in a range of 0.02≦D1 / SH≦0.15 relative to a tire cross section height SH.

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

4. 2. The tire according to claim 1, wherein an extension length L11 of the shoulder lug groove outside the tire contact patch is in a range of 0.15≦L11 / SH≦0.25 relative to a tire cross-sectional height SH.

5. 2. The tire according to claim 1, wherein a distance D2 from a groove wall of the shoulder lug groove to the convex portion is in a range of 0.20≦D2 / W11′≦0.40 relative to a groove width W11′ of the shoulder lug groove outside the tire contact patch.

6. The tire according to claim 1, wherein a maximum width W5_max of the convex portion is in a range of 0.25≦W5_max / W11′≦0.45 relative to a groove width W11′ of the shoulder lug groove outside the tire contact patch.

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 outward in the tire width direction.

8. 2. The tire according to claim 1, wherein the convex portion is formed by connecting a wide portion and a narrow portion, and an extension length L51 of the wide portion in the tire width direction relative to an extension length L5 of the convex portion is in a range of 0.35≦L51 / L5≦0.

55.

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

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

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

12. A shallow groove is formed in a region on the outer side of the tire ground contact edge in the tire width direction, extends in the tire circumferential direction, and connects to the shoulder lug groove at least at one end thereof; and The tire according to claim 1 , wherein a connection portion of the shallow groove with the shoulder lug groove overlaps the convex portion when viewed in a circumferential projection of the tire.

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