Tire

Abstract

To suppress generation of a crack from a recess, as a starting point, specifying a maximum depth of a regeneration groove.SOLUTION: A tire includes: a circumferential main groove 21 extending in a tire circumferential direction at a tread surface; a tread wear indicator 2 provided while projecting in a groove bottom 21A of the circumferential main groove 21; and a recess 3 formed in the apex 2A of the tread wear indicator 2 and specifying a maximum depth after re-grooving the circumferential main groove 21. The recess 3 has: a depth Hr from the apex 2A of the tread wear indicator 2 which is formed within a range of 2.5 mm or more and 10.0 mm or less; a round-chamfering radius Rr1 of an opening 3A which is formed within a range of 0.5 mm or more and 8.0 mm or less; and a round-chamfering radius Rr2 of a bottom 3C which is formed within a range of 0.5 mm or more and 4.0 mm or less.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to tires. [Background technology]

[0002] For example, Patent Document 1 describes an invention of a tire in which, in order to reclaim the grooves of the tread, a recessed portion that defines the maximum depth of the groove after reclamation is disposed at the groove bottom. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2013 / 087473 Summary of the Invention [Problem to be solved by the invention]

[0004] If a recess is provided at the groove bottom, there is a risk that cracks will occur starting from the recess due to stress applied to the groove bottom during running.

[0005] An object of the present invention is to provide a tire that can suppress the occurrence of cracks originating from recesses that define the maximum depth of retreaded grooves. [Means for solving the problem]

[0006] In order to achieve the above object, a tire according to one embodiment of the present invention includes a circumferential main groove extending circumferentially on a tread surface of the tire, a treadwear indicator protruding from the bottom of the circumferential main groove, and a recess formed at the top of the treadwear indicator to determine the maximum depth of the circumferential main groove after regrooving, wherein the recess is formed so that its depth from the top of the treadwear indicator is in the range of 2.5 mm to 10.0 mm, the radius of the R chamfer at the opening is in the range of 0.5 mm to 8.0 mm, and the radius of the R chamfer at the bottom is in the range of 0.5 mm to 4.0 mm. [Effects of the Invention]

[0007] According to this invention, it is possible to suppress the occurrence of cracks originating from the recess that defines the maximum depth of the reproduction groove. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a meridian cross-sectional view of a pneumatic tire according to an embodiment. [Figure 2] FIG. 2 is an enlarged plan view of a circumferential main groove of the pneumatic tire according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along the line BB in FIG. [Figure 5] FIG. 5 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. [Figure 6] FIG. 6 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail 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.

[0010] In the following description, the tire radial direction refers to the direction perpendicular to the tire rotational axis (not shown), which is the rotational axis of the pneumatic tire 1 of this embodiment. The tire radial inner side refers to the side toward the tire rotational axis in the tire radial direction, and the tire radial outer side refers to the side away from the tire rotational axis in the tire radial direction. The tire circumferential direction refers to the direction around the tire rotational axis as the central axis. The tire width direction refers to the direction parallel to the tire rotational axis. The tire width inner side refers to the side toward the tire equatorial plane (tire equator 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 that is perpendicular to the tire rotational axis and passes through the center of the tire width of the pneumatic tire 1. The tire equatorial plane CL coincides in position in the tire width direction with the tire width centerline, which is the center position of the pneumatic tire 1 in the tire width direction. The tire equator line refers to a line that is on the tire equatorial plane CL and runs along the tire circumferential direction of the pneumatic tire 1. Also, a cross section in the tire meridian direction (meridian cross section) refers to a cross section of the tire cut by a plane including the tire rotation axis.

[0011] 1 is a meridian cross section of a pneumatic tire 1 according to an embodiment, showing a cross section of one side of the tire rotation axis in the tire radial direction. In this embodiment, a heavy-duty pneumatic radial tire mounted on heavy-duty vehicles such as trucks and buses will be described as an example. The pneumatic tire 1 according to this embodiment is particularly suitable as a tire mounted on the drive axle of a heavy-duty vehicle.

[0012] The pneumatic tire 1 of the embodiment has an annular structure centered on the tire rotation axis, and as shown in Figure 1, includes a pair of bead cores 11, a pair of bead fillers 12, 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 17.

[0013] The pair of bead cores 11 are formed by winding one or more bead wires made of steel in an annular and multiply fashion, and are embedded in the bead portions to form the cores of the bead portions on both sides in the tire width direction.

[0014] The pair of bead fillers 12 are made up of a lower filler 121 and an upper filler 122, and are respectively arranged on the outer periphery of the pair of bead cores 11 in the tire radial direction to reinforce the bead portion.

[0015] 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 laid between the bead cores 11 to form the tire framework. Both ends of the carcass layer 13 are wound back 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 with coating rubber and rolling them, and has a cord angle (defined as the inclination angle of the carcass cords in the longitudinal direction of the tire) of 80 degrees or more and 90 degrees or less in absolute value for a radial tire, or 30 degrees or more and 45 degrees or less in absolute value for a bias tire.

[0016] The belt layer 14 is formed by laminating multiple belt plies 141 to 144 and is disposed around the outer periphery of the carcass layer 13. These belt plies 141 to 144 include a high-angle belt 141, a pair of cross belts 142 and 143, and a belt cover 144. The high-angle belt 141 is formed by covering multiple steel belt cords with coating rubber and rolling them, and has a cord angle (defined as the inclination angle of the belt cords in the longitudinal direction with respect to the tire circumferential direction) of 45 degrees or more and 70 degrees or less in absolute value. The pair of cross belts 142 and 143 are formed by covering multiple steel belt cords 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 10 degrees or more and 55 degrees or less in absolute value. The pair of cross belts 142 and 143 have cord angles of opposite signs to each other and are laminated with the belt cords' longitudinal directions crossing each other (having a so-called cross-ply structure). The belt cover 144 is made by covering a plurality of belt cover cords made of steel or organic fiber material with coating rubber and rolling them, and has a cord angle of 10 degrees or more and 55 degrees or less in absolute value.

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

[0018] The pair of sidewall rubbers 16 are disposed on the outer sides of the carcass layer 13 in the tire width direction, and form sidewall portions on both sides in the tire width direction.

[0019] The pair of rim cushion rubbers 17 extend from the inner side in the tire radial direction to the outer side in the tire width direction of each bead core 11 and the turned-up portion of the carcass layer 13, and form the rim fitting surface of the bead portion.

[0020] 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.

[0021] Specified rim refers to the "standard rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. 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. 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.

[0022] The groove width is measured as the maximum distance between the opposing groove walls at the groove opening on the tread surface when the tire is mounted on a specified rim, inflated to a specified internal pressure, and 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 as the endpoint in a cross section parallel to the tire width direction and the tire radial direction.

[0023] The groove depth is measured as the maximum 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] The pneumatic tire 1 has at least two circumferential main grooves 21 on the tread surface 15A. The pneumatic tire 1 of the embodiment also has circumferential narrow grooves 22 on the tread surface 15A.

[0025] The circumferential main grooves 21 extend in the tire circumferential direction and have an annular structure that is continuously provided around the entire tire circumference. Two circumferential main grooves 21 are provided side by side in the tire width direction, sandwiching the tire equatorial plane CL therebetween. The circumferential main grooves 21 are defined as grooves that are required to display a treadwear indicator 2 (see FIGS. 2 to 4) defined by JATMA at their groove bottoms 21A. In this embodiment, the circumferential main grooves 21 have a groove width W of 10.0 mm or more and 20.0 mm or less, as shown in FIG. 2, and a groove depth H of 10.0 mm or more and 25.0 mm or less, as shown in FIG. 4.

[0026] The pneumatic tire 1 has two circumferential main grooves 21 that form three rows of land portions 31, 32 arranged in the tire width direction along the tire circumferential direction on the tread surface 15A. 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 positioned to include the tire equatorial plane CL. The shoulder land portions 32 are positioned on both outermost sides of the tread surface 15A in the tire width direction.

[0027] The circumferential narrow groove 22 extends in the tire circumferential direction in the center land portion 31 and has an annular structure provided continuously around the entire tire circumference. In the embodiment, two circumferential main grooves 21 are provided adjacent to each other in the tire width direction with the tire equatorial plane CL sandwiched therebetween. At least one circumferential narrow groove 22 may be provided in the center land portion 31. In the embodiment, the circumferential narrow groove 22 has a groove width of 1.0 mm or more and 5.0 mm or less and a groove depth of 5.0 mm or more and 25.0 mm or less. The circumferential narrow groove 22 has a groove width smaller than that of the circumferential main groove 21.

[0028] When the pneumatic tire 1 has one circumferential narrow groove 22, the central land portion 31 has two rows of first central land portions 31A defined between the circumferential main groove 21 and the circumferential narrow groove 22 that are adjacent in the tire width direction. When the pneumatic tire 1 has two circumferential narrow grooves 22, the central land portion 31 has two rows of first central land portions 31A defined between the circumferential main groove 21 and the circumferential narrow groove 22 that are adjacent in the tire width direction, and one row of second central land portions 31B defined between the two circumferential narrow grooves 22. The second central land portion 31B is arranged to include the tire equatorial plane CL.

[0029] In the pneumatic tire 1 of the embodiment, when the groove depth of the circumferential main groove 21 becomes shallower and the remaining groove area becomes smaller due to wear of the tread surface 15A, it is possible to perform regroofing to deepen the groove bottom 21A in order to ensure the remaining groove depth of the circumferential main groove 21. A pneumatic tire 1 that can be regroofed is configured so that the volume of the tread rubber 15 from the groove bottom 21A of the circumferential main groove 21 to the belt layer 14 (belt ply 143 in FIG. 1 ) closest in the tire radial direction before regroofing can be maintained even after regroofing. A pneumatic tire 1 that can be regroofed is marked "REGROOVABLE" on the sidewall portion.

[0030] When rim grooving is performed, it is necessary to ensure that the volume of tread rubber 15 from the groove bottom 21A of the newly cut circumferential main groove 21 to the nearest belt layer 14 in the tire radial direction (belt ply 143 in FIG. 1 ) is maintained after the rim grooving. For this reason, as shown in FIGS. 2 to 4, a recess 3 is formed in the pneumatic tire 1 before the rim grooving is performed to determine the maximum depth to be cut. This recess 3 is called a regroove depth indicator. The recess 3 is formed in the apex 2A of the treadwear indicator 2, which is the radially outer surface of the tire.

[0031] The treadwear indicator 2, in which the recess 3 is provided, is provided so as to protrude from the groove bottom 21A of the circumferential main groove 21 toward the tread surface side (the tire radial outer side) where the circumferential main groove 21 opens. The height T of the treadwear indicator 2 is set to 1.6 mm. As shown in FIGS. 2 and 3, the treadwear indicator 2 has an arc-shaped rising portion 2B rising from the groove bottom 21A of the circumferential main groove 21, with a radius Rt1 in the range of 5 mm to 25 mm. The treadwear indicator 2 has an arc-shaped shoulder portion 2C connecting the rising portion 2B to the peak 2A, with a radius Rt2 in the range of 1 mm to 15 mm. The peak 2A, where the portion not having the recess 3, is formed as a surface shaped along the tire circumferential direction. As shown in FIGS. 2 and 4, the treadwear indicator 2 has an arc-shaped connecting portion that connects to the groove wall 21B of the circumferential main groove 21, and the radius Rt3 of the connecting portion is in the range of 1 mm to 6 mm. The treadwear indicator 2 has a tire circumferential length (dimension) Lt1 between the portions where the rising portion 2B connects to the groove bottom 21A of the circumferential main groove 21, and this length Lt1 is in the range of 30 mm to 120 mm. The treadwear indicator 2 has a tire circumferential length (dimension) Lt2 between the intersection of the surface of the crest 2A and the extension of the rising portion 2B, and this length Lt2 is in the range of 15 mm to 30 mm. The treadwear indicator 2 has a tire widthwise length (dimension) Wt between the connecting portions that connect to the groove walls 21B of the circumferential main groove 21, and this length Wt is in the range of 5 mm to 20 mm.

[0032] As described above, the recess 3 is provided at the top 2A of the treadwear indicator 2 and recessed radially inward from the top 2A. The recess 3 is formed so that its depth Hr from the top 2A of the treadwear indicator 2 is in the range of 2.5 mm to 10.0 mm.

[0033] The recess 3 is formed such that the radius Rr1 of the R-chamfer that forms the edge of the opening 3A that opens at the top 2A of the treadwear indicator 2 is in the range of 0.5 mm to 8.0 mm. At the opening 3A, the recess 3 smoothly connects the top 2A of the treadwear indicator 2 and the inner wall surface 3B with the R-chamfer.

[0034] The recess 3 is formed in a range of 2 mm to 18 mm in length (dimension) Lr in the tire circumferential direction at the edge where the R chamfer of the opening 3A connects to the top 2A of the treadwear indicator 2. The recess 3 is formed in a range of 2 mm to 10 mm in length (dimension) Wr in the tire width direction at the edge where the R chamfer of the opening 3A connects to the top 2A of the treadwear indicator 2.

[0035] The recess 3 is formed such that the inner diameter Dr of the inner wall surface 3B is in the range of 1.2 mm to 8.0 mm. The inner wall surface 3B of the recess 3 is formed to have a circular shape in a plan view seen from the tread surface 15A. Alternatively, the inner wall surface 3B of the recess 3 is formed to have an elliptical shape in a plan view seen from the tread surface 15A.

[0036] The recess 3 has an inner wall surface 3B that narrows from the R-chamfered opening 3A to the R-chamfered bottom 3C, and is formed at an angle of 0 to 45 degrees relative to the tire radial direction. That is, the recess 3 may be a cylindrical or elliptical cylindrical hole, or may be a conical hole that narrows from the opening 3A to the bottom 3C.

[0037] The recess 3 is formed such that the radius Rr2 of the R-chamfer around the bottom 3C is in the range of 0.5 mm to 4.0 mm. The recess 3 includes the bottom 3C, and the bottom 3C and the inner wall surface 3B are smoothly connected by the R-chamfer.

[0038] The pneumatic tire 1 of the present embodiment described above is characterized in that the recess 3 is formed so that the depth Hr from the top 2A of the treadwear indicator 2 is in the range of 2.5 mm or more and 10.0 mm or less, the radius Rr1 of the R chamfer of the opening 3A is in the range of 0.5 mm or more and 8.0 mm or less, and the radius Rr2 of the R chamfer of the bottom 3C is in the range of 0.5 mm or more and 4.0 mm or less.

[0039] With this pneumatic tire 1, even in the final stage of wear (for example, just before the top 2A of the treadwear indicator 2 appears on the tread surface 15A), it is possible to suppress the occurrence of cracks originating from the opening 3A of the recess 3. To achieve this effect, the pneumatic tire 1 preferably has the recess 3 formed with a depth Hr in the range of 3.0 mm to 5.0 mm, the R-chamfer radius Rr1 of the opening 3A in the range of 2.0 mm to 5.0 mm, and the R-chamfer radius Rr2 of the bottom 3C in the range of 1.0 mm to 3.0 mm.

[0040] In addition, in the pneumatic tire 1 of the embodiment, the recess 3 is formed so that the inner diameter Dr is in the range of 1.2 mm or more and 8.0 mm or less, and the angle of the inner wall surface 3B, which may narrow from the R chamfer of the opening 3A to the R chamfer of the bottom 3C, with respect to the tire radial direction is formed so that it is 0 degrees or more and 45 degrees or less.

[0041] The pneumatic tire 1 has a remarkable effect of suppressing the occurrence of cracks originating from the opening 3A of the recessed portion 3. To achieve this effect, the pneumatic tire 1 preferably has the recessed portion 3 with an inner diameter Dr of 2.0 mm or more and 6.0 mm or less, and the inner wall surface 3B is formed at an angle of 0 degrees or more and 15 degrees or less with respect to the tire radial direction.

[0042] In the pneumatic tire 1 of the embodiment, the recess 3 is formed so that the ratio of the length (dimension) Lr of the opening 3A in the tire circumferential direction to the length (dimension) Lt2 of the top 2A of the treadwear indicator 2 in the tire circumferential direction is in the range of 20% to 70%. Furthermore, in the pneumatic tire 1 of the embodiment, the recess 3 is formed so that the ratio of the length (dimension) Lr of the opening in the tire width direction to the length (dimension) Wt of the treadwear indicator 2 in the tire width direction is in the range of 20% to 95%.

[0043] This pneumatic tire 1 significantly reduces the occurrence of cracks originating from the openings 3A of the recessed portions 3. To achieve this effect, the pneumatic tire 1 preferably has an Lr / Lt2 ratio of 40% and an Lr / Wt ratio of 90% for a tire size of 315 / 70R22.5, for example.

[0044] In the pneumatic tire 1 of the embodiment, the recess 3 is formed such that the edge where the R-chamfer of the opening 3A connects to the peak 2A of the treadwear indicator 2 is circular in plan view from the tread surface 15A. Alternatively, the recess 3 is formed such that the edge where the R-chamfer of the opening 3A connects to the peak 2A of the treadwear indicator 2 is elliptical in plan view from the tread surface 15A. That is, the recess 3 is formed such that the opening 3A is circular or elliptical when viewed from the tread surface 15A.

[0045] According to this pneumatic tire 1, it is possible to obtain a remarkable effect of suppressing the occurrence of cracks originating from the openings 3A of the recessed portions 3.

[0046] In addition, in the pneumatic tire 1 of the embodiment, the opening 3A is formed in a circular or elliptical shape when viewed from the tread surface 15A, and when viewed in a plan view from the tread surface 15A, the R chamfer of the opening 3A is formed so that the aspect ratio of the edge connecting to the top 2A of the treadwear indicator 2 is in the range of 1.0 or more and 5.0 or less.

[0047] According to this pneumatic tire 1, it is possible to obtain a remarkable effect of suppressing the occurrence of cracks originating from the openings 3A of the recessed portions 3.

[0048] In addition, in the pneumatic tire 1 of the embodiment, the recess 3 is formed such that the connection portion between the R chamfer of the opening 3A and the groove wall 21B of the circumferential main groove 21 is connected by an R chamfer, and the radius Rr3 of the R chamfer of the connection portion is in the range of 1.0 mm or more and 5.0 mm or less.

[0049] According to this pneumatic tire 1, the occurrence of cracks can be suppressed by smoothly connecting the groove wall 21B of the circumferential main groove 21 and the opening 3A of the recess 3 with R-chamfering. To achieve this effect, the pneumatic tire 1 is preferably formed such that the radius Rr3 of the R-chamfering at the connecting portion is 2.0 mm.

[0050] Furthermore, the pneumatic tire 1 of the embodiment is provided with two or more circumferential main grooves 21. The recessed portion 3 is disposed in the circumferential main groove 21 that is outermost in the tire width direction.

[0051] According to this pneumatic tire 1, the strain at the groove bottom 21A of the circumferential main groove 21 on the outermost side in the tire width direction is higher during running than that of the other circumferential main grooves 21, and therefore the effect of suppressing the occurrence of cracks due to the recess 3 configured as described above is significantly achieved.

[0052] In the present embodiment, as described above, a pneumatic tire 1 has been described as an example of a tire. The pneumatic tire 1 can be filled with air, an inert gas such as nitrogen, or other gases. However, the tread pattern configuration of the pneumatic tire 1 described in the present 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]

[0053] 5 and 6 are tables showing the results of performance tests of pneumatic tires according to the embodiment. Performance evaluation tests conducted on a conventional pneumatic tire, a comparative pneumatic tire, and an example pneumatic tire according to the embodiment will be described below. The performance evaluation tests were conducted to measure crack resistance.

[0054] The crack resistance evaluation test involves mounting a 315 / 70R22.5 size pneumatic tire (test tire) on a specified rim, inflating it to 78% of the specified internal pressure, and running the tire on a drum tester at a specified load and speed of 50 km / h in an atmosphere with an ambient temperature of 30°C and an ozone concentration of 150 pphm. The running distance is measured when a crack occurs at the bottom of the circumferential main groove (or, if a recess is provided, a crack originating from the recess). Based on the measurement results, an index rating is calculated, with the conventional tire being used as the reference (100). The higher the rating, the better.

[0055] The conventional pneumatic tire has a recessed portion, but the shape is not within the specified range. The comparative pneumatic tire does not have a recessed portion.

[0056] The pneumatic tire of the example has a recessed portion, and the shape is within the specified range.

[0057] As shown in the test results, it is understood that the pneumatic tire of this example has improved crack resistance performance compared to the conventional example.

[0058] The present disclosure includes the following inventions. [Invention 1] A circumferential main groove extending in the tire circumferential direction on the tread surface; a treadwear indicator provided so as to protrude from a groove bottom of the circumferential main groove; a recess formed at a top of the treadwear indicator to define a maximum depth of the circumferential main groove after regrooving; Including, The recessed portion is The depth of the treadwear indicator from the top is formed in the range of 2.5 mm to 10.0 mm, The radius of the R chamfer at the opening is formed in the range of 0.5 mm to 8.0 mm, The radius of the bottom chamfer is formed in the range of 0.5 mm to 4.0 mm. tire. [Invention 2] The recessed portion is The inner diameter is formed in the range of 1.2 [mm] to 8.0 [mm], The angle of the inner wall surface that may narrow from the R chamfer of the opening to the R chamfer of the bottom with respect to the tire radial direction is formed to be equal to or greater than 0 [deg] and equal to or less than 45 [deg]. A tire according to invention 1. [Invention 3] The recessed portion is The ratio of the circumferential dimension of the opening to the circumferential dimension of the top of the treadwear indicator is formed in a range of 20% to 70%. The ratio of the tire width direction dimension of the opening to the tire width direction dimension of the treadwear indicator is formed in a range of 20% to 95%. The tire according to claim 1 or 2. [Invention 4] The recessed portion is When viewed from the tread surface, the opening is formed in a circular or elliptical shape. A tire according to any one of inventions 1 to 3. [Invention 5] The recessed portion is When viewed from the tread surface, the openings are formed in a circular or elliptical shape, and the aspect ratio is formed in a range of 1.0 to 5.0. A tire according to any one of inventions 1 to 3. [Invention 6] The recessed portion is a connection portion between the R chamfer of the opening and the groove wall of the circumferential main groove is connected by an R chamfer, The radius of the R chamfer of the connection portion is formed in the range of 1.0 [mm] to 5.0 [mm]. A tire according to any one of inventions 1 to 5. [Invention 7] Two or more of the circumferential main grooves are provided, The recessed portion is disposed in the outermost circumferential main groove in the tire width direction, A tire according to any one of inventions 1 to 6. [Explanation of symbols]

[0059] 1. Pneumatic tires (tires) 2 Treadwear indicator 2A Top 3 recess 3A opening 3B Inner wall surface 3C bottom 21 Circumferential main groove 21A groove bottom 21B Groove wall

Claims

1. A circumferential main groove extending in the tire circumferential direction on the tread surface; a treadwear indicator provided so as to protrude from a groove bottom of the circumferential main groove; a recess formed at a top of the treadwear indicator to define a maximum depth of the circumferential main groove after regrooving; Including, The recessed portion is The depth of the treadwear indicator from the top is formed in the range of 2.5 mm to 10.0 mm, The radius of the R chamfer of the opening is formed in the range of 0.5 mm to 8.0 mm, The radius of the R chamfer at the bottom is formed in the range of 0.5 mm to 4.0 mm. tire.

2. The recessed portion is The inner diameter is formed in the range of 1.2 mm to 8.0 mm, an angle of an inner wall surface that may narrow from the R-chamfer of the opening to the R-chamfer of the bottom with respect to the tire radial direction is formed to be equal to or greater than 0 degrees and equal to or less than 45 degrees; 2. The tire of claim 1.

3. The recessed portion is The ratio of the circumferential dimension of the opening to the circumferential dimension of the top of the treadwear indicator is in the range of 20% to 70%. The ratio of the dimension of the opening in the tire width direction to the dimension of the treadwear indicator in the tire width direction is formed in a range of 20% to 95%.

2. The tire of claim 1.

4. The recessed portion is When viewed from the tread surface, the opening is formed in a circular or elliptical shape.

2. The tire of claim 1.

5. The recessed portion is When viewed from the tread surface, the opening is formed in a circular or elliptical shape, and the aspect ratio is formed in a range of 1.0 to 5.

0.

2. The tire of claim 1.

6. The recessed portion is a connection portion between the R-chamfer of the opening and a groove wall of the circumferential main groove is connected by an R-chamfer, The radius of the R chamfer of the connection portion is formed in the range of 1.0 mm to 5.0 mm.

2. The tire of claim 1.

7. Two or more of the circumferential main grooves are provided, The recessed portion is disposed in the outermost circumferential main groove in the tire width direction, 2. The tire of claim 1.

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