tire

Abstract

To achieve both low fuel consumption performance and wet braking performance.SOLUTION: A pneumatic tire 1 is provided on a tread part with a plurality of circumferential direction grooves 22 which extend along tire circumferential direction continuously and are adjoined in a tire width direction and more than three rows of rib-like land parts 311, 312 which extend along the tire circumferential direction continuously by being sectioned at the tire width direction by the plurality of circumferential direction groove 22. The circumferential direction grooves 22 include a convex land part 220 with which the rib-like land parts 311, 312 and a tread 15A continue by protruding from either of groove walls 22a, 22b to groove inside and which protrudes from each of groove walls 22a, 22b alternatively in the tire circumferential direction, a circumferential direction narrow groove 221 which extends along the tire circumferential direction by being formed between protrusion end 220a of the convex land part 220 and the groove walls 22a, 22b and a trad narrow groove which consists of a width direction narrow groove 222 which extends along the tire width direction by being formed between each convex land parts 220. Opening groove width WL of the circumferential direction narrow groove 221 is in the range of 0.5 mm or more and 3.0 mm or less.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] For example, Patent Document 1 describes an invention for a tire that achieves both low rolling resistance and wet performance by providing a tie bar at the bottom of a circumferential groove that connects adjacent land portions on either side of the circumferential groove, and by providing a slit that penetrates this tie bar in the circumferential direction of the tire.

[0003] Patent Document 2 also describes an invention for a tire that can improve drainage performance and suppress an increase in rolling resistance by having a cavity extending along the tire circumferential direction inside the rib-like land portion, a first slit portion that connects to the cavity portion on the surface of the rib-like land portion from one side in the tire width direction of the tire, a second slit portion that connects to the cavity portion on the surface of the rib-like land portion from the other side in the tire width direction of the tire, and a third slit that connects the first slit portion and the second slit portion on the surface of the rib-like land portion and connects to the cavity portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-126525 [Patent Document 2] Patent Publication No. 2021-091374 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, some tires used for heavy-duty vehicles such as trucks and buses have a tread pattern based on a rib pattern that mainly consists of rib-shaped land portions extending in the tire circumferential direction in the tread portion. Tires based on this rib pattern have a trade-off between low fuel consumption performance and wet braking performance. Therefore, there is a demand for tires based on a rib pattern that achieve both low fuel consumption performance and wet braking performance.

[0006] An object of the present invention is to provide a tire that can achieve both low fuel consumption performance and wet braking performance. [Means for solving the problem]

[0007] In order to achieve the above object, a tire according to one embodiment of the present invention has, in a tread portion, a plurality of circumferential grooves extending continuously along the tire circumferential direction and adjacent to each other in the tire width direction, and three or more rows of rib-like land portions partitioned in the tire width direction by the plurality of circumferential grooves and extending continuously along the tire circumferential direction, wherein the circumferential grooves have convex land portions protruding from the groove walls toward the inside of the groove and having tread surfaces continuous with the rib-like land portions, and have tread narrow grooves consisting of convex land portions protruding alternately from each groove wall in the tire circumferential direction, circumferential narrow grooves formed between the protruding ends of the convex land portions and the groove walls and extending along the tire circumferential direction, and widthwise narrow grooves formed between each of the convex land portions and extending along the tire width direction, and an opening groove width WL of the circumferential narrow grooves is in the range of 0.5 mm or more and 3.0 mm or less. Effect of the Invention

[0008] According to the present invention, it is possible to achieve both low fuel consumption and wet braking performance. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a meridian cross-sectional view of a pneumatic tire according to an embodiment. [Diagram 2] FIG. 2 is a plan view of a tread of a pneumatic tire according to the embodiment. [Diagram 3]FIG. 3 is a partially enlarged meridian cross section of the pneumatic tire according to the embodiment. [Figure 4] FIG. 4 is a plan view of a tread of a pneumatic tire according to the embodiment when the tire is in contact with the ground. [Diagram 5] FIG. 5 is a partially enlarged meridian cross-sectional view of the pneumatic tire according to the embodiment when the tire is in contact with the ground. [Figure 6] FIG. 6 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. [Figure 7] FIG. 7 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. [Figure 8] FIG. 8 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment. In addition, the components of this embodiment include those that can be substituted and are obvious to be substituted while maintaining the identity of the invention. In addition, the multiple modified examples described in this embodiment can be arbitrarily combined within the scope obvious to those skilled in the art.

[0011] In the following description, the tire radial direction refers to a direction perpendicular to the tire rotation axis (not shown) which is the rotation axis of the pneumatic tire 1 of the embodiment, the tire radial inner side refers to the side facing 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 a direction around the tire rotation axis as the central axis. The tire width direction refers to a direction parallel to the tire rotation axis, the tire width inner side refers to the side facing the tire equatorial plane (tire equatorial line) CL in the tire width direction, and the tire width outer side refers to the side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL is a plane perpendicular to the tire rotation axis and passing through the center of the tire width of the pneumatic tire 1, and the tire equatorial plane CL coincides in position in the tire width direction with the tire width centerline which is the center position in the tire width direction of the pneumatic tire 1. The tire equatorial line refers to a line on the tire equatorial plane CL along the tire circumferential direction of the pneumatic tire 1. Additionally, a cross section in the tire meridian direction (meridian section) refers to a cross section obtained by cutting the tire along a plane including the tire rotation axis.

[0012] 1 is a meridian cross section of a pneumatic tire 1 according to an embodiment. In this embodiment, as an example, a heavy-duty pneumatic radial tire mounted on heavy-duty vehicles such as trucks and buses will be described. The pneumatic tire 1 according to this embodiment is particularly suitable for use as a tire mounted on the steering axle and drive axle of a heavy-duty vehicle.

[0013] The pneumatic tire 1 is formed symmetrically in the tire width direction with the tire equatorial plane CL as the boundary. Therefore, Fig. 1 shows a portion of one side in the tire width direction with the tire equatorial plane CL as the boundary. The pneumatic tire 1 is also formed symmetrically in the tire radial direction with the tire rotation axis as the boundary. Therefore, Fig. 1 shows a portion of one side region in the tire radial direction with the tire rotation axis as the boundary.

[0014] The pneumatic tire 1 of the embodiment has an annular structure centered on the tire rotation axis, and as shown in FIG. 1, includes a pair of bead cores (not shown), a pair of bead fillers (not shown), a carcass layer 13, a belt layer 14, a tread rubber 15, a pair of sidewall rubbers 16, and a pair of rim cushion rubbers (not shown).

[0015] Although not shown in the figure, the pair of bead cores are made by winding one or more bead wires made of steel in a circular shape in multiple layers, and are embedded in the bead portions to form the cores of the bead portions on both sides in the tire width direction.

[0016] Although not shown in the drawings, the pair of bead fillers are made up of a lower filler and an upper filler, and are disposed on the outer periphery of the pair of bead cores in the tire radial direction, respectively, to reinforce the bead portion.

[0017] 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. The carcass layer 13 is toroidally stretched between both bead cores to form the tire framework. The carcass layer 13 has both ends wound back and secured to the outside in the tire width direction so as to envelop the bead cores and the bead fillers. The carcass ply of the carcass layer 13 is formed by coating multiple carcass cords made of steel 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° to 90° in absolute value for radial tires and 30° to 45° in absolute value for bias tires.

[0018] The belt layer 14 is also called a belt member, and is formed by laminating a plurality of belt plies (also called belts) 141 to 143, and is disposed by being wound around the outer periphery of the carcass layer 13. These belt plies 141 to 143 include a 0-degree belt 142 and a pair of cross belts 141, 143 sandwiching the 0-degree belt 142. The 0-degree belt 142 is formed by covering a plurality of belt cords (also called wire rods) made of steel with a coating rubber and rolling it, and has a cord angle (defined as the inclination angle of the longitudinal direction of the belt cord with respect to the tire circumferential direction) of 0° or more and 2° or less in absolute value. The pair of cross belts 141, 143 is formed by covering a plurality of belt cords made of steel with a coating rubber and rolling it, and has a cord angle of 10° or more and 55° or less in absolute value. In addition, the pair of cross belts 141, 143 have cord angles of opposite signs to each other, and are laminated with the longitudinal directions of the belt cords crossing each other (having a so-called cross-ply structure).

[0019] 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 a tread portion of the pneumatic tire 1. In the tread portion, the tread rubber 15 forms a contact surface (also called a tread surface) 15A on the outer periphery surface that comes into contact with the road surface during running.

[0020] The pair of sidewall rubbers 16 are disposed on the outer sides of the carcass layer 13 in the tire width direction, respectively, to form sidewall portions on both sides in the tire width direction.

[0021] Although not shown in the drawings, the pair of rim cushion rubbers extend from the inner side in the tire radial direction of each bead core and the turned-up portion of the carcass layer 13 to the outer side in the tire width direction, and form the rim fitting surface of the bead portion.

[0022] The pneumatic tire 1 of the embodiment has a tread pattern on a tread surface 15A as shown in Fig. 2. Here, each dimension of the tread pattern is measured in an unloaded state with the tire mounted on a specified rim and inflated to a specified internal pressure.

[0023] The specified rim refers to the "standard rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. The specified internal pressure refers to the "maximum air pressure" specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" specified by TRA, or the "inflation pressures" specified by ETRTO. The specified load refers to the "maximum load capacity" specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" specified by TRA, or the "load capacity" specified by ETRTO.

[0024] The groove width (also called the open 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 in an unloaded state. In a configuration in which the groove opening has a notch or chamfer, the groove width is measured with the intersection of an extension of the tread surface and an extension of the groove wall as the endpoint in a cross section parallel to the tire width direction and tire radial direction.

[0025] The 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 a specified internal pressure, and under no load. In the case of a structure having partial unevenness or sipes at the bottom of the groove, the groove depth is measured excluding these.

[0026] As shown in FIG. 2, the pneumatic tire 1 of the embodiment has a circumferential main groove 21, a circumferential groove 22, and widthwise grooves 23 and 24 on the tread surface 15A.

[0027] The circumferential main groove 21 has an annular structure that extends along the tire circumferential direction and is continuously provided around the entire tire circumference. The circumferential main grooves 21 are provided in parallel in the tire width direction with the tire equatorial plane CL sandwiched therebetween. The circumferential main grooves 21 are defined as grooves that are required to display a wear indicator as stipulated by JATMA. In the embodiment, as shown in FIG. 1, the circumferential main groove 21 has a groove width W1 of 10.0 mm or more and 20.0 mm or less, and a groove depth D1 of 10.0 mm or more and 25.0 mm or less. In addition, the distance from the groove bottom of the circumferential main groove 21 to the tire radially outermost belt (belt ply 143) (groove bottom thickness of the tread rubber 15) is defined as d.

[0028] When new, the opening of the circumferential main groove 21 is formed in a straight line along the circumferential direction of the tire, but the groove wall to the groove bottom is formed in a wavy (serpentine) shape along the circumferential direction of the tire, and as the tire wears, the shape changes from straight to wavy.

[0029] In the pneumatic tire 1, three rows of land portions 31, 32 are formed in the tread portion along the tire circumferential direction and in the tire width direction by the two circumferential main grooves 21. Specifically, the pneumatic tire 1 has a center land portion 31 defined between the two circumferential main grooves 21, and two shoulder land portions 32 defined on the tire width direction outer sides of each circumferential main groove 21. The center land portion 31 is disposed so as to include the tire equatorial plane CL. The shoulder land portions 32 are disposed on both outermost sides of the tread portion in the tire width direction.

[0030] The pneumatic tire 1 has ground contact ends T at both outermost ends in the tire width direction of the tread surface 15A, which are outer ends in the tire width direction of each shoulder land portion 32. The linear distance in the tire width direction between each ground contact end T of the pneumatic tire 1 is defined as the tread developed width TW of the tread surface 15A. In the pneumatic tire 1 of the embodiment, the ratio of the tire width direction dimension CW of the center land portion 31 to the tread developed width TW is in the range of 0.4 to 0.7.

[0031] The circumferential groove 22 has an annular structure that extends along the tire circumferential direction in the center land portion 31 and is continuously provided around the entire tire circumference. The circumferential groove 22 is a groove that does not have the obligation to display a wear indicator as stipulated by JATMA, and can be distinguished from the circumferential main groove 21. A plurality of circumferential grooves 22 (two in the embodiment) are provided adjacent to each other in the tire width direction with the tire equatorial plane CL sandwiched therebetween. Adjacent (or adjacent to) means that there is no other groove that is continuous along the tire circumferential direction between grooves that are continuous along the tire circumferential direction in the tire width direction. In the embodiment, as shown in FIG. 1, the circumferential groove 22 has a groove width W2 of 5.0 mm or more and 15.0 mm or less, and a groove depth D2 of 10.0 mm or more and 25.0 mm or less. In addition, the distance from the groove bottom 22c of the circumferential groove 22 to the belt (belt ply 143) on the outermost side in the tire radial direction (groove bottom thickness of the tread rubber 15) is defined as D.

[0032] In the pneumatic tire 1, rib-like land portions 311, 312 are formed in the center land portion 31 by a plurality (two) of circumferential grooves 22, which extend along the tire circumferential direction and are continuously provided around the entire circumference of the tire. The rib-like land portions 311, 312 are arranged in three or more rows in the tire width direction. Specifically, the pneumatic tire 1 of the embodiment has a center rib-like land portion 311 defined between the two circumferential grooves 22, and two side rib-like land portions 312 defined between the circumferential main grooves 21 on the outer side of each circumferential groove 22 in the tire width direction. The center rib-like land portion 311 is located in a center region defined by the two circumferential grooves 22, and is arranged including the tire equatorial plane CL.

[0033] As shown in Fig. 3, the circumferential groove 22 has groove walls 22a, 22b on both sides formed from the tread surface 15A to the groove bottom 22c in the tread portion. That is, the circumferential groove 22 opens on the tread surface 15A side between the groove walls 22a, 22b and closes toward the groove bottom 22c. The groove walls 22a, 22b are formed so that the groove bottom 22c is narrow and gradually widens toward the tread surface 15A. The circumferential groove 22 has groove walls 22a, 22b formed in a substantially symmetrical shape in the tire width direction. As shown in Figs. 2 and 3, the circumferential groove 22 has a convex land portion 220 and tread surface narrow grooves 221, 222.

[0034] The convex land portion 220 protrudes from one of the groove walls 22a, 22b toward the inside of the groove in the tire width direction, continues from the rib-like land portion 311 (or the rib-like land portion 312) to the tread surface 15A, and the protruding end 220a is provided away from the other groove wall 22b. The convex land portion 220 protrudes from the other groove wall 22b toward the inside of the groove in the tire width direction, continues from the rib-like land portion 311 (or the rib-like land portion 312) to the tread surface 15A, and the protruding end 220a is provided away from one groove wall 22b. The convex land portion 220 protruding from one groove wall 22a is formed so that the protruding end 220a gradually approaches the groove wall 22b as it moves from the vicinity of the groove bottom 22c of the circumferential groove 22 toward the opening in the tire radial direction, as shown in FIG. 3, the convex land portion 220 protruding from the other groove wall 22b is formed such that the protruding end 220a gradually approaches the groove wall 22a from the vicinity of the groove bottom 22c of the circumferential groove 22 toward the opening in the tire radial direction. The convex land portion 220 protruding from one groove wall 22a and the convex land portion 220 protruding from the other groove wall 22b are formed in a substantially symmetrical shape in the tire width direction. The convex land portion 220 protruding from one groove wall 22a and the convex land portion 220 protruding from the other groove wall 22b protrude from the groove walls 22a, 22b alternately in the tire circumferential direction in which the circumferential groove 22 extends.

[0035] As shown in Fig. 3, in a meridian section viewed in the tire circumferential direction, the convex land portion 220 protruding from one groove wall 22a overlaps with the convex land portion 220 protruding from the other groove wall 22b. In Fig. 3, the convex land portion 220 is shown in a form in which the convex land portion 220 protruding from the other groove wall 22b appears to be on the near side, and a part of the convex land portion 220 protruding from one groove wall 22a appears to overlap on the far side. Therefore, in the meridian section, the other groove wall 22b does not appear as a line, and is shown in Fig. 3 as a virtual broken line.

[0036] The circumferential groove 22 is formed in a see-through shape having a void portion 22d penetrating the circumferential groove 22 when viewed in the tire circumferential direction, where a convex land portion 220 protruding from one groove wall 22a and a convex land portion 220 protruding from the other groove wall 22b do not overlap with each other. In the pneumatic tire 1 of the embodiment, the void portion 22d is formed in a range of 30% to 70% of the groove depth D2 from the groove bottom 22c.

[0037] 3, the circumferential groove 22 defines a tire width direction distance Wa from the tread surface 15A to the protruding end 220a of the convex land portion 220 protruding from the imaginary line of the groove wall 22b. The circumferential groove 22 defines a tire width direction distance Wb from the imaginary line of the groove wall 22b to the protruding end 220a of the convex land portion 220 protruding from the imaginary line of the groove wall 22b at a position of 50% of the groove depth D2. The circumferential groove 22 defines a maximum tire width direction distance Wc at the void portion 22d. The circumferential groove 22 defines an angle θ between the imaginary line of the groove wall 22b and the tread surface 15A of the convex land portion 220 protruding from the groove wall 22b as an acute angle. The above tire width direction distances Wa and Wb are shown as distances parallel to the tread surface 15A of the convex land portion 220.

[0038] 3, the circumferential groove 22 has a chamfered portion 22e at an intersection between the tread surface 15A and the groove walls 22a, 22b. The chamfered portion 22e is, for example, configured as a C-chamfer, and preferably has a width in the tire width direction of 0.5 mm to 4.5 mm and a depth in the tire radial direction of 1.5 mm to 5.0 mm.

[0039] 1, the tread narrow grooves 221, 222 are grooves that are formed between the convex land portion 220 and the groove walls 22a, 22b by forming the convex land portion 220 in the circumferential groove 22 and open to the tread 15A. As described above, the tread narrow grooves 221, 222 are formed in a zigzag shape by the convex land portion 220 protruding from one groove wall 22a and the convex land portion 220 protruding from the other groove wall 22b alternately protruding from the groove walls 22a, 22b in the tire circumferential direction in which the circumferential groove 22 extends. Specifically, the tread narrow grooves 221, 222 include a circumferential narrow groove 221 formed between the protruding end 220a of the convex land portion 220 and each groove wall 22a, 22b and extending along the tire circumferential direction, and a widthwise narrow groove 222 formed between the side ends 220b facing the tire circumferential direction of each convex land portion 220 adjacent in the tire circumferential direction and extending along the tire width direction. The circumferential narrow groove 221 is relatively long, and the widthwise narrow groove 222 is relatively short. Each circumferential narrow groove 221 has the same length in the tire circumferential direction, and the widthwise narrow grooves 222 therebetween are arranged at approximately equal intervals in the tire circumferential direction.

[0040] In addition, the circumferential groove 22 has an opening groove width of the circumferential narrow groove 221 that opens onto the tread surface 15A as WL. The circumferential groove 22 has an opening groove width of the widthwise narrow groove 222 that opens onto the tread surface 15A as WS.

[0041] 2, the circumferential groove 22 is provided at a position offset from the tire equatorial plane CL. The circumferential groove 22 has a protruding end 220a of a convex land portion 220 forming a circumferential narrow groove 221 and each groove wall 22a, 22b formed in an arc shape that is convex toward the tire equatorial plane CL. Therefore, the circumferential narrow groove 221 has an arc shape that is convex toward the tire equatorial plane CL.

[0042] The widthwise grooves 23, 24 are grooves that connect the circumferential grooves 22 and the circumferential main grooves 21 that are adjacent in the tire width direction, or grooves that connect the circumferential grooves 22 that are adjacent in the tire width direction. The groove that connects the circumferential groove 22 and the circumferential main groove 21 is referred to as a first widthwise groove 23, and the groove that connects the circumferential grooves 22 is referred to as a second widthwise groove 24. In the embodiment, the widthwise grooves 23, 24 have a groove width of 0.5 mm or more and 1.4 mm or less, and a groove depth of 6.0 mm or more and 15.0 mm or less.

[0043] The second width direction groove 24 is formed extending along the tire width direction so as to connect the short width direction narrow grooves 222 of the circumferential grooves 22. Here, the circumferential grooves 22 adjacent to each other in the tire width direction are symmetrical with respect to a straight line (for example, the tire equatorial plane CL) extending in the tire circumferential direction, and the tire width direction positions of the width direction narrow grooves 222 are arranged shifted in the tire circumferential direction. Therefore, the second width direction groove 24 connecting the width direction narrow grooves 222 is arranged so as to be inclined with respect to the tire width direction. Moreover, the second width direction groove 24 is formed in a wavy shape along its extension direction. Moreover, the second width direction groove 24 is connected to every other width direction narrow groove 222 in the tire circumferential direction. In addition, when, for example, three circumferential grooves 22 are adjacent in the tire width direction, the second widthwise groove 24 connecting the circumferential groove 22 in the center in the tire width direction to one of the circumferential grooves 22 in the tire width direction and the second widthwise groove 24 connecting the circumferential groove 22 in the center in the tire width direction to the other circumferential groove 22 in the tire width direction are configured to be inclined in opposite directions relative to the tire width direction.

[0044] The first width direction groove 23 is formed to extend along the tire width direction so as to connect the short width direction narrow groove 222 of the circumferential groove 22 and the circumferential main groove 21. The first width direction groove 23 is arranged so as to be inclined with respect to the tire width direction. The first width direction groove 23 is formed in a wavy shape along its extending direction. The first width direction groove 23 is configured to be arranged so as to be inclined with respect to the tire width direction in the opposite direction to the second width direction groove 24 that communicates with the circumferential groove 22 to which it communicates.

[0045] Further, the widthwise narrow groove 222, through which the first widthwise groove 23 and the second widthwise groove 24 communicate, has a protruding end 222a at an end where the first widthwise groove 23 and the second widthwise groove 24 communicate with each other, which protrudes further than the circumferential narrow groove 221. That is, the first widthwise groove 23 and the second widthwise groove 24 communicate with the protruding end 222a of the widthwise narrow groove 222.

[0046] The pneumatic tire 1 of the above-described embodiment is characterized in that the tread portion includes a plurality of circumferential grooves 22 that extend continuously along the tire circumferential direction and are adjacent to each other in the tire width direction, and three or more rows of rib-like land portions 311, 312 that are partitioned in the tire width direction by the plurality of circumferential grooves 22 and extend continuously along the tire circumferential direction. The circumferential grooves 22 protrude from any of the groove walls 22a, 22b toward the inside of the groove so that the rib-like land portions 311, 312 and the tread surface 15A are The tire has a tread narrow groove consisting of convex land portions 220 that are continuous and protrude alternately from each groove wall 22a, 22b in the tire circumferential direction, circumferential narrow grooves 221 that are formed between the protruding ends 220a of the convex land portions 220 and the groove walls 22a, 22b and extend along the tire circumferential direction, and widthwise narrow grooves 222 that are formed between each convex land portion 220 and extend along the tire width direction, and the opening groove width WL of the circumferential narrow groove 221 is in the range of 0.5 mm or more and 3.0 mm or less.

[0047] According to this pneumatic tire 1, the plurality of circumferential grooves 22 adjacent in the tire width direction are provided with convex land portions 220 that protrude alternately in the tire circumferential direction from the groove walls 22a, 22b and are continuous with the rib-like land portions 311, 312 and the tread surface 15A, so that the groove walls 22a, 22b and the convex land portions 220 support each other when the tire comes into contact with the ground, improving the rigidity of the rib-like land portions 311, 312 and suppressing rolling resistance, and thus improving fuel efficiency performance can be expected. In this pneumatic tire 1, the opening groove width WL of the circumferential narrow groove 221 between the protruding end 220a of the convex land portion 220 forming the tread surface narrow groove and the groove walls 22a, 22b is set in the range of 0.5 mm to 3.0 mm, and the rigidity of the rib-like land portions 311, 312 can be improved. On the other hand, the pneumatic tire 1 can ensure drainage performance by having the circumferential narrow grooves 221 and the widthwise narrow grooves 222 that form the tread narrow grooves. As a result, the pneumatic tire 1 of the embodiment can achieve both low fuel consumption performance and wet braking performance.

[0048] In the pneumatic tire 1 of the embodiment, the open groove width WS of the widthwise narrow groove 222 is in the range of 0.5 mm or more and 7.0 mm or less.

[0049] According to this pneumatic tire 1, by making the opening groove width WS of the widthwise narrow grooves 222 between the convex land portions 220 protruding alternately from each groove wall 22a, 22b in the tire circumferential direction greater than or equal to the opening groove width WL of the circumferential narrow grooves 221, it is possible to improve drainage performance and more significantly achieve both low fuel consumption performance and wet braking performance.

[0050] In the pneumatic tire 1 of the embodiment, the rib-like land portion 311 formed between the circumferential grooves 22 is located on the tire equatorial plane CL.

[0051] According to this pneumatic tire 1, the rib-like land portion 311 is located on the tire equatorial plane CL, in other words, the circumferential grooves 22 having the convex land portion 220 and the tread narrow grooves 221, 222 are arranged away from the tire equatorial plane CL and on both sides of it in the tire width direction, thereby achieving a symmetrical arrangement with respect to the tire equatorial plane CL and suppressing uneven wear.

[0052] In the pneumatic tire 1 of the embodiment, as shown in Figs. 4 and 5, at least the circumferential narrow groove 221 is closed when the tire is in contact with the ground, and the rib-like land portions 311, 312 adjacent to each other across the circumferential groove 22 are continuous on the tread surface 15A.

[0053] According to this pneumatic tire 1, by reducing the groove area when the tire is in contact with the ground and making the portion having the circumferential grooves 22 the ground contact surface of the aggregate of land portions, it is possible to reduce rolling resistance and improve fuel efficiency.

[0054] In addition, in the pneumatic tire 1 of the embodiment, the tread grooves have a zigzag shape in which long circumferential grooves 221 and short widthwise grooves 222 are alternately connected. The opening groove width WL of the circumferential grooves 221 and the opening groove width WS of the widthwise grooves 222 satisfy the relationship of 0.1 ≦ WL / WS < 1.0. As shown in FIGS. 4 and 5, only the circumferential grooves 221 are closed when the tire contacts the ground.

[0055] According to this pneumatic tire 1, by making the circumferential grooves 221 long and the widthwise grooves 222 short, the groove area in the widthwise component can be reduced, and the low fuel consumption performance can be improved. Moreover, according to this pneumatic tire 1, since the opening groove width WS of the widthwise grooves 222 is made larger than the opening groove width WL of the circumferential grooves 221 and the short widthwise grooves 222 do not close when the tire contacts the ground, the drainage performance during grounding can be ensured while maintaining the low fuel consumption performance.

[0056] In addition, in the pneumatic tire 1 of the embodiment, the circumferential groove 22 has a void portion 22d formed to penetrate in the circumferential direction of the tire in the range of 30% or more and 70% or less of the groove depth D2 from the groove bottom 22c.

[0057] According to this pneumatic tire 1, by setting the void portion 22d where the overlap of the convex land portions 220 overlapping in the circumferential direction of the tire is interrupted in the middle stage of wear, the wet braking performance after the middle stage of wear can be ensured.

[0058] In addition, in the pneumatic tire 1 of the embodiment, the angle θ formed by the virtual lines of the groove walls 22a and 22b of the circumferential groove 22 and the tread surface 15A of the convex land portion 220 protruding from the groove walls 22a and 22b is an acute angle, and the tire widthwise distance Wa on the tread surface 15A from the virtual line of the groove walls 22a and 22b to the protruding end 220a of the convex land portion 220 and the tire widthwise distance Wb at the position of 50% of the groove depth D2 of the circumferential groove 22 satisfy the relationship of 0.1 < Wb / Wa < 0.6.

[0059] According to this pneumatic tire 1, by making the angle θ formed between the tread surface 15A and the convex land portion 220 protruding from the groove walls 22a and 22b an acute angle and defining the ratio of the tire width direction distances Wa and Wb, the rigidity of the convex land portion 220 can be effectively maintained until the mid-wear stage.

[0060] Further, in the pneumatic tire 1 of the embodiment, the circumferential groove 22 has a void portion 22d formed to penetrate in a view in the tire circumferential direction within a range of a predetermined groove depth from the groove bottom 22c, and the tire width direction distance Wa on the tread surface 15A from the virtual lines of the groove walls 22a and 22b of the circumferential groove 22 to the protruding end 220a of the convex land portion 220 protruding therefrom, and the maximum tire width direction distance Wc in the void portion 22d satisfy the relationship of 0.6 < Wc / Wa < 0.9.

[0061] According to this pneumatic tire 1, by setting the tire width direction distance Wc width of the void portion 22d on the groove bottom 22c side to the above relationship with respect to the tire width direction distance Wa of the convex land portion 220 on the tread surface 15A, wet braking performance after wear can be ensured.

[0062] Further, in the pneumatic tire 1 of the embodiment, the circumferential groove 22 has a chamfered portion 22e at the intersection of the groove walls 22a and 22b facing the protruding end 220a of the convex land portion 220 and the tread surface 15A.

[0063] According to this pneumatic tire 1, by providing the chamfered portion 22e, an improvement in wet braking performance can be expected while ensuring the land rigidity.

[0064] Further, in the pneumatic tire 1 of the embodiment, there is a circumferential main groove 21 that extends along the tire circumferential direction on both outer sides in the tire width direction of the plurality of circumferential grooves 22 and changes from a linear shape to a wavy shape as wear progresses, and the opening groove width WL of the circumferential fine groove 221 and the opening groove width W1 of the circumferential main groove 21 satisfy the relationship of 0.1 < WL / W1 < 0.4.

[0065] According to this pneumatic tire 1, wet braking performance can be ensured by providing the circumferential main groove 21 that satisfies the above-mentioned relationship with the opening groove width WL of the circumferential narrow groove 221. Moreover, according to this pneumatic tire 1, by changing the groove shape of the circumferential main groove 21 in plan view to become wavy as the wear progresses, the rigidity of the land portion can be increased, and improvement in fuel efficiency can be expected.

[0066] In addition, in the pneumatic tire 1 of the embodiment, the tread portion has a circumferential main groove 21 extending along the tire circumferential direction on both outer sides in the tire width direction of the multiple circumferential grooves 22, and a first widthwise groove 23 connecting the widthwise narrow groove 222 and the circumferential main groove 21.

[0067] According to this pneumatic tire 1, by providing the first widthwise groove 23 that connects the circumferential groove 22 with the circumferential main groove 21 on the outer side in the tire width direction, further improvement in wet braking performance can be expected.

[0068] Furthermore, in the pneumatic tire 1 of the embodiment, the tread portion has second widthwise grooves 24 that connect the widthwise narrow grooves 222 of the circumferential grooves 22 adjacent to each other in the tire width direction.

[0069] According to this pneumatic tire 1, by providing the second widthwise grooves 24 connecting the circumferential grooves 22 with each other, further improvement in wet braking performance can be expected.

[0070] In the pneumatic tire 1 of the embodiment, the circumferential grooves 22 are provided at positions offset from the tire equatorial plane CL, and the circumferential narrow grooves 221 have an arc shape that protrudes toward the tire equatorial plane CL.

[0071] According to this pneumatic tire 1, the circumferential narrow grooves 221 of the circumferential grooves 22 between which the tire equatorial plane CL is the boundary are formed into an arc shape so that the convex portions are aligned with each other, thereby increasing the rigidity of the rib-like land portion 311 between the circumferential grooves 22, and improving fuel efficiency can be expected.

[0072] Further, in the pneumatic tire 1 of the embodiment, in the tread portion, there is a circumferential main groove 21 extending along the tire circumferential direction on both outer sides in the tire width direction of a plurality of circumferential grooves 22, and it has a belt member 14 with a structure of three or less sheets. The tire radial distance D from the groove bottom 22c of the circumferential groove 22 to the outermost belt 143 in the tire radial direction and the tire radial distance d from the groove bottom of the circumferential main groove 21 to the outermost belt 143 in the tire radial direction satisfy the relationship of 0.8 < D / d < 1.3.

[0073] According to this pneumatic tire 1, the convex land portion 220 can prevent stones from entering the groove of the circumferential groove 22 and stone drilling. Therefore, in the belt member 14, a belt material for the protective layer is not required, and weight reduction of the tire can be expected. Moreover, according to this pneumatic tire 1, by making the distances D and d from the groove bottom to the belt member equal, the strain difference in the tire width direction of the tread portion can be reduced, and an improvement in uneven wear resistance performance can be expected.

[0074] Further, in the pneumatic tire 1 of the embodiment, in the tread portion, it has a belt 142 having a wire material at an angle of 0° or more and 2° or less with respect to the tire circumferential direction.

[0075] According to this pneumatic tire 1, the belt 142 having a wire material at an angle of 0° or more and 2° or less with respect to the tire circumferential direction effectively increases the rigidity in the tire circumferential direction, and the tire strength can be ensured even if the number of belt sheets is reduced (for example, three or less).

[0076] By the way, in the present embodiment, as described above, the pneumatic tire 1 has been described as an example of the tire. This pneumatic tire 1 can be filled with air, an inert gas such as nitrogen, and other gases. However, the configuration of the tread pattern of the pneumatic tire 1 described in the present 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.

Examples

[0077] 6 to 8 are tables showing the results of performance tests of the pneumatic tires according to the embodiment. Below, performance evaluation tests conducted on a conventional pneumatic tire and an example pneumatic tire according to the embodiment will be described. The performance evaluation tests were conducted on fuel efficiency, stone trapping resistance, wet braking performance, and uneven wear resistance.

[0078] The fuel economy performance evaluation test involves mounting a pneumatic tire (test tire) with a tire size of 11R22.5 on a heavy-duty vehicle (2-DD (tractor head)) and measuring the rolling resistance coefficient (ratio of rolling resistance to the load on the test tire) when new under test conditions that comply with ECE R117-02 (ECE Regulation No. 117 Revision 2). Then, based on the measurement results, an index evaluation is performed with the conventional example as the standard (100). The higher the value, the better the evaluation.

[0079] The stone-trapping resistance evaluation test involves mounting a test tire of the above tire size on the above heavy-duty vehicle, driving 40 km on a dirt road at a speed of 20 km / h, and then measuring the number of stones trapped in the grooves. Based on the measurement results, an index evaluation is performed with the conventional example set as the standard (100). The higher the evaluation value, the better.

[0080] In the wet braking performance evaluation test, the test tire of the above tire size is mounted on the above heavy-duty vehicle, and the vehicle is driven at a speed of 40 km / h on a wet road surface with 1 mm of water depth, and the braking distance after braking is measured. Then, based on the measurement results, an index evaluation is performed with the conventional example as the standard (100). The more the value of this evaluation is 95 or higher, the better.

[0081] In the evaluation test of uneven wear resistance, the test tire of the above tire size is mounted on the above heavy-duty vehicle, and the degree of uneven wear is measured after driving 80,000 km on a dry asphalt pavement. Then, based on the measurement results, an index evaluation is performed with the conventional example as the standard (100). The higher the value of this evaluation, the better.

[0082] The conventional pneumatic tire has two circumferential grooves in the tread portion that extend in the tire circumferential direction and are aligned in the tire width direction, and the circumferential grooves have a configuration corresponding to the convex land portion of the embodiment, but does not satisfy the regulations corresponding to the grooves corresponding to the circumferential narrow grooves or the widthwise narrow grooves.

[0083] The pneumatic tire of the embodiment has two circumferential grooves in the tread portion extending in the tire circumferential direction and aligned in the tire width direction, and the circumferential grooves have a configuration corresponding to the convex land portion of the embodiment, and meets the provisions for the circumferential narrow grooves and widthwise narrow grooves.

[0084] The dimensions of the mold that satisfy the specific regulations of the pneumatic tire of the embodiment are as follows. The circumferential groove has a groove depth D2 of 16.7 mm and a groove width W2 of 9.1 mm. The groove width WL of the circumferential narrow groove is 1.5 mm. The width WS of the narrow groove in the width direction is 2.8 mm. -WL / WS is 0.53. ·Wb / Wa is 0.28. ·Wc / Wa is 0.68. The circumferential main groove has a groove depth D1 of 16.7 mm and a groove width W1 of 13.0 mm. -WL / W1 is 0.12. ·D / d is 1.00.

[0085] As shown by the test results, the pneumatic tire of this embodiment has improved fuel economy performance, stone trapping resistance, wet braking performance, and uneven wear resistance compared to the conventional tire.

[0086] The present disclosure includes the following inventions. [Invention 1] In the tread area, A plurality of circumferential grooves extending continuously along the tire circumferential direction and adjacent to each other in the tire width direction; Three or more rows of rib-like land portions that are partitioned in the tire width direction by a plurality of the circumferential grooves and extend continuously along the tire circumferential direction; Equipped with The circumferential groove is convex land portions that protrude from the groove walls toward the inside of the groove, have a tread surface that is continuous with the rib-like land portions, and protrude alternately from each of the groove walls in the tire circumferential direction; a tread narrow groove including a circumferential narrow groove formed between a protruding end of the convex land portion and the groove wall and extending along the circumferential direction of the tire, and a widthwise narrow groove formed between each of the convex land portions and extending along the width direction of the tire; having The opening groove width WL of the circumferential narrow groove is in the range of 0.5 mm to 3.0 mm. tire. [Invention 2] The width WS of the widthwise narrow groove is in the range of 0.5 mm to 7.0 mm. A tire according to claim 1. [Invention 3] the rib-like land portion formed between the circumferential grooves is located on the tire equatorial plane, 3. The tire according to claim 1 or 2. [Invention 4] When the tire contacts the ground, at least the circumferential narrow groove is closed, and each of the rib-like land portions adjacent to each other across the circumferential groove is connected on the tread surface. A tire according to any one of claims 1 to 3. [Invention 5] The tread narrow groove has a zigzag shape in which the long circumferential narrow grooves and the short widthwise narrow grooves are alternately connected, an open groove width WL of the circumferential narrow groove and an open groove width WS of the widthwise narrow groove satisfy a relationship of 0.1≦WL / WS<1.0, and only the circumferential narrow groove is closed when the tire is in contact with the ground; A tire according to any one of claims 1 to 4. [Invention 6] The circumferential groove has a void portion formed penetrating the circumferential groove in a range of 30% to 70% of the groove depth from the groove bottom as viewed in the tire circumferential direction. A tire according to any one of claims 1 to 5. [Invention 7] an angle formed by a virtual line of a groove wall of the circumferential groove and the tread surface of the convex land portion protruding from the groove wall is an acute angle, The tire width direction distance Wa on the tread surface from the virtual line of the groove wall to the protruding end of the convex land portion, and the tire width direction distance Wb of the convex land portion at the position of 50% of the groove depth of the circumferential groove satisfy the relationship of 0.1 < Wb / Wa < 0.6. The tire according to any one of Inventions 1 to 6. [Invention 8] The circumferential groove has a void portion formed to penetrate in the tire circumferential direction view within a range of a predetermined groove depth from the groove bottom. The tire width direction distance Wa on the tread surface from the virtual line of the groove wall of the circumferential groove to the protruding end of the convex land portion protruding therefrom, and the maximum tire width direction distance Wc in the void portion satisfy the relationship of 0.6 < Wc / Wa < 0.9. The tire according to any one of Inventions 1 to 7. [Invention 9] The circumferential groove has a chamfered portion at the intersection of the groove wall facing the protruding end of the convex land portion and the tread surface. The tire according to any one of Inventions 1 to 8. [Invention 10] It has circumferential main grooves that extend along the tire circumferential direction on both outer sides in the tire width direction of a plurality of the circumferential grooves and change from linear to wavy as wear progresses. The opening groove width WL of the circumferential fine groove and the opening groove width W1 of the circumferential main groove satisfy the relationship of 0.1 < WL / W1 < 0.4. The tire according to any one of Inventions 1 to 9. [Invention 11] On the tread portion Circumferential main grooves that extend along the tire circumferential direction on both outer sides in the tire width direction of a plurality of the circumferential grooves, First width direction grooves that connect the width direction fine grooves and the circumferential main grooves, and has The tire according to any one of Inventions 1 to 10. [Invention 12] On the tread portion In each of the circumferential grooves adjacent to each other in the tire width direction, it has second width direction grooves that connect the width direction fine grooves of each other. The tire according to any one of Inventions 1 to 11. [Invention 13] The circumferential groove is provided at a position deviated from the tire equatorial plane. The circumferential narrow groove has an arc shape that is convex toward the tire equatorial plane. The tire according to any one of Inventions 1 to 12. [Invention 14] In the tread portion Circumferential main grooves extending along the tire circumferential direction on both outer sides in the tire width direction of a plurality of the circumferential grooves; Having a belt member with a structure of three sheets or less, The tire radial distance D from the groove bottom of the circumferential groove to the outermost belt in the tire radial direction and the tire radial distance d from the groove bottom of the circumferential main groove to the outermost belt in the tire radial direction satisfy the relationship of 0.8 < D / d < 1.3. The tire according to any one of Inventions 1 to 13. [Invention 15] In the tread portion Having a belt having a wire at an angle of 0° or more and 2° or less with respect to the tire circumferential direction. The tire according to any one of Inventions 1 to 14.

Explanation of Signs

[0087] 1 Pneumatic tire (tire) 14 Belt member 15 Tread rubber (tread portion) 15A Tread surface 21 Circumferential main groove 22 Circumferential groove 22a, 22b Groove wall 22c Groove bottom 22d Gap portion 22e Chamfered portion 23 First width direction groove 24 Second width direction groove 142 0-degree belt (belt) 220 Convex land portion 220a Protruding end 221 Circumferential narrow groove 222 Width direction narrow groove 311,312 Ribbed land section CL Tire Equatorial Plane

Claims

1. In the tread area, A plurality of circumferential grooves extending continuously along the tire circumferential direction and adjacent to each other in the tire width direction; Three or more rows of rib-like land portions that are partitioned in the tire width direction by the plurality of circumferential grooves and extend continuously along the tire circumferential direction; Equipped with The circumferential groove is convex land portions that protrude from the groove walls toward the inside of the groove, have a tread surface that is continuous with the rib-like land portions, and protrude alternately from each of the groove walls in the tire circumferential direction; a tread narrow groove including a circumferential narrow groove formed between a protruding end of the convex land portion and the groove wall and extending along the circumferential direction of the tire, and a widthwise narrow groove formed between each of the convex land portions and extending along the width direction of the tire; having The opening groove width WL of the circumferential narrow groove is in the range of 0.5 mm to 3.0 mm. tire.

2. The width WS of the widthwise narrow groove is in the range of 0.5 mm to 7.0 mm.

2. The tire of claim 1.

3. the rib-like land portion formed between the circumferential grooves is located on the tire equatorial plane, 2. The tire of claim 1.

4. When the tire contacts the ground, at least the circumferential narrow groove is closed, and each of the rib-like land portions adjacent to each other across the circumferential groove is connected on the tread surface.

2. The tire of claim 1.

5. The tread narrow groove has a zigzag shape in which the long circumferential narrow grooves and the short widthwise narrow grooves are alternately connected, an open groove width WL of the circumferential narrow groove and an open groove width WS of the widthwise narrow groove satisfy a relationship of 0.1≦WL / WS<1.0, and only the circumferential narrow groove is closed when the tire is in contact with the ground; 2. The tire of claim 1.

6. The circumferential groove has a void portion formed penetrating the circumferential groove in a range of 30% to 70% of the groove depth from the groove bottom as viewed in the tire circumferential direction.

2. The tire of claim 1.

7. an angle formed by a virtual line of a groove wall of the circumferential groove and the tread surface of the convex land portion protruding from the groove wall is an acute angle, a tire width direction distance Wa on the tread surface from a virtual line of the groove wall to the protruding end of the convex land portion, and a tire width direction distance Wb of the convex land portion at a position of 50% of the groove depth of the circumferential groove satisfy a relationship of 0.1<Wb / Wa<0.6; 2. The tire of claim 1.

8. The circumferential groove has a gap portion formed penetrating the circumferential groove in a range of a predetermined groove depth from a groove bottom as viewed in the tire circumferential direction, a tire width direction distance Wa on the tread surface to the protruding end of the convex land portion protruding from a virtual line of a groove wall of the circumferential groove and a maximum tire width direction distance Wc in the gap portion satisfy a relationship of 0.6<Wc / Wa<0.9; 2. The tire of claim 1.

9. The circumferential groove has a chamfered portion at an intersection between a groove wall facing the protruding end of the convex land portion and a tread surface.

2. The tire of claim 1.

10. A circumferential main groove extends along the tire circumferential direction on both outer sides in the tire width direction of the plurality of circumferential grooves and changes from a straight line to a wavy shape as wear progresses, an opening groove width WL of the circumferential narrow groove and an opening groove width W1 of the circumferential main groove satisfy a relationship of 0.1<WL / W1<0.4; 2. The tire of claim 1.

11. The tread portion, A circumferential main groove extending along the tire circumferential direction on both outer sides in the tire width direction of the plurality of circumferential grooves; a first width direction groove connecting the width direction narrow groove and the circumferential direction main groove; having 2. The tire of claim 1.

12. The tread portion, Each of the circumferential grooves adjacent to each other in the tire width direction has a second width direction groove connecting the width direction narrow grooves to each other.

2. The tire of claim 1.

13. The circumferential groove is provided at a position offset from the tire equatorial plane, The circumferential narrow groove has an arc shape that is convex toward the tire equatorial plane.

2. The tire of claim 1.

14. The tread portion, A circumferential main groove extending along the tire circumferential direction on both outer sides in the tire width direction of the plurality of circumferential grooves; The belt member has a structure of three or less sheets, a tire radial direction distance D from a groove bottom of the circumferential groove to a tire radially outermost belt and a tire radial direction distance d from a groove bottom of the circumferential main groove to a tire radially outermost belt satisfy a relationship of 0.8<D / d<1.3; 2. The tire of claim 1.

15. The tread portion, The tire has a belt having wires at an angle of 0° or more and 2° or less with respect to the circumferential direction of the tire.

2. The tire of claim 1.

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