Pneumatic tire

Abstract

In this pneumatic tire, first width-direction grooves and second width-direction grooves are alternatingly lined up in the tire circumferential direction while set apart from each other. One first width-direction groove constituting a pair has a first portion extending to one side in the tire circumferential direction from an outer (inner) side toward an inner (outer) side in a tire width direction. One second width-direction groove constituting a pair extends toward the other side in the tire circumferential direction from the outer (inner) side toward the inner (outer) side in the tire width direction. The tire-widthwise inner (outer) end of the one second width-direction groove constituting the pair is positioned farther outward in the tire width direction than the tire-widthwise inner (outer) end of the one first width-direction groove constituting the pair.

Description

pneumatic tires

[0001] The present invention relates to a pneumatic tire.

[0002] Conventionally, for pneumatic tires used at high speeds exceeding 150 km / h, it has been proposed to provide widthwise grooves extending in the tire width direction in the outer shoulder land portion when mounted on a vehicle, thereby appropriately reducing the rigidity of the land portion and improving grip performance.

[0003] International Publication No. 2021 / 054261 Brochure

[0004] However, in the technology of Patent Document 1, multiple widthwise grooves (71) that extend mainly in the same direction are arranged, and while the rigidity is high against inputs from the extension direction of the widthwise grooves, the rigidity is low against inputs, for example, from a direction perpendicular to the extension direction of the widthwise grooves, and there is a problem that the land portion is easily deformed, and there is room for improvement in grip performance.

[0005] An object of the present invention is to provide a pneumatic tire with improved grip performance.

[0006] The gist of the present invention is as follows: (1) A pneumatic tire having one or more circumferential main grooves extending in the tire circumferential direction on a tread surface, the pneumatic tire having a plurality of land portions defined between the circumferential main groove and a tread edge or between the circumferential main grooves, the pneumatic tire having a plurality of first widthwise grooves extending in the tire width direction in an outermost land portion as mounted on a vehicle, the first widthwise grooves and the second widthwise grooves extending in the tire width direction, the first widthwise grooves and the second widthwise grooves being spaced apart from each other in the tire circumferential direction and arranged alternately in the tire circumferential direction, one first widthwise groove and one second widthwise groove adjacent to one first widthwise groove on one side in the tire circumferential direction, the one first widthwise groove constituting the pair having a first portion extending from the outer side in the tire width direction toward the inner side, a second widthwise groove of the pair extending from the outer side in the tire width direction toward the inner side toward the other side in the tire circumferential direction, and an inner end in the tire width direction of the second widthwise groove of the pair being located outer in the tire width direction than an inner end in the tire width direction of the first widthwise groove of the pair.

[0007] Here, the term "tread surface" refers to the entire circumferential surface of the tread outer surface that comes into contact with the road when the pneumatic tire is mounted on an applicable rim, inflated to a specified internal pressure, and subjected to a maximum load. The term "tread edge" refers to both outermost points of the tread surface in the tire width direction. The term "circumferential main groove" refers to a groove extending in the tire circumferential direction, having a groove width (opening width) of 2 mm or more in a reference state when the pneumatic tire is mounted on an applicable rim, inflated to a specified internal pressure, and under no load. The term "first widthwise groove" refers to a groove extending in the tire width direction, having a groove width (opening width) of 2 mm or more over 80% or more of its extension length in the reference state. The term "second widthwise groove" refers to a groove extending in the tire width direction, having a groove width (opening width) of 2 mm or more over 80% or more of its extension length in the reference state. Here, the "inclination angle" of the shallow grooves described below refers to the inclination angle of the line segment connecting both ends of the shallow grooves when the shallow grooves do not extend linearly.

[0008] In this specification, the term "applicable rim" refers to the standard rim (referred to as "Measuring Rim" in the ETRTO STANDARDS MANUAL and "Design Rim" in the TRA YEAR BOOK) for the applicable size, which is an industrial standard valid in the region where the tire is produced and used, and which is described in the JATMA YEAR BOOK of the Japan Automobile Tire Manufacturers Association (JATMA) in Japan, the STANDARDS MANUAL of the European Tire and Rim Technical Organization (ETRTO) in Europe, and the YEAR BOOK of the Tire and Rim Association, Inc. (TRA) in the United States, or which will be described in the future. "rim" refers to the rim (i.e., the above "rim" includes not only current sizes but also sizes that may be included in the above industry standards in the future. An example of a "size to be described in the future" is a size listed under "FUTURE DEVELOPMENTS" in the 2013 edition of ETRTO). However, for sizes not listed in the above industry standards, it refers to a rim with a width corresponding to the bead width of the tire. Furthermore, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel for the applicable size / ply rating listed in the above JATMA etc., and for sizes not listed in the above industry standards, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted. Furthermore, "maximum applied load" refers to the load corresponding to the above maximum load capacity.

[0009] (2) A pneumatic tire having one or more circumferential main grooves extending in the tire circumferential direction on a tread surface, the pneumatic tire having a plurality of land portions partitioned between the circumferential main groove and a tread edge or between the circumferential main grooves, the pneumatic tire having a plurality of first widthwise grooves extending in the tire width direction in an outermost land portion as mounted on a vehicle, the first widthwise grooves having at least one end terminating within the outermost land portion as mounted on a vehicle, the first widthwise grooves and the second widthwise grooves being arranged alternately in the tire circumferential direction while being spaced apart from each other in the tire circumferential direction, one first widthwise groove and one second widthwise groove adjacent to one first widthwise groove on one side in the tire circumferential direction, the one first widthwise groove constituting the pair having a first portion extending from the inner side in the tire width direction to the outer side, a second widthwise groove of the pair extending from the inner side in the tire width direction toward the outer side toward the other side in the tire circumferential direction, and an outer end in the tire width direction of the second widthwise groove of the pair being located more outer in the tire width direction than an outer end in the tire width direction of the first widthwise groove of the pair.

[0010] According to the present invention, a pneumatic tire with improved grip performance can be provided.

[0011] The present invention relates to a pneumatic tire having a tread pattern, a pneumatic tire having a tread width, a tire width of a tire ...

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0013] (First embodiment) The internal structure of a pneumatic tire according to a first embodiment of the present invention (hereinafter also simply referred to as a "tire") can be the same as that of a conventional tire, and therefore detailed description thereof will be omitted. Meanwhile, as one example, the tire can include a pair of bead portions, a carcass that toroidally spans between the pair of bead portions, and a belt that is disposed radially outward of a crown portion of the carcass.

[0014] 1 is a diagram showing the tread pattern of a pneumatic tire according to a first embodiment of the present invention. In the following description, dimensions and the like refer to dimensions in the standard state unless otherwise specified.

[0015] As shown in FIG. 1 , this tire has one or more (two in the illustrated example) circumferentially extending circumferential main grooves 2 (2 a, 2 b) on a tread surface 1. The tire also has a plurality of land portions 3 (3 a, 3 b (3 b 1, 3 b 2)) defined between the circumferential main groove 2 and a tread edge TE or between the circumferential main grooves 2 (2 a, 2 b). Specifically, on the outer side of the tire as mounted on a vehicle, defined by the circumferential main groove 2 a and the tread edge TE, is an outermost land portion 3 a defined by the circumferential main groove 2 a and the tread edge TE. On the inner side of the tire as mounted on a vehicle, defined by the tire equatorial plane CL, is an inner land portion 3 b defined by the space between the circumferential main grooves 2 a, 2 b or by the circumferential main groove 2 b and the tread edge TE. An inner land portion 3b2 of the inner land portion when mounted on a vehicle is defined between the circumferential main grooves 2a, 2b, and an outer land portion 3b1 of the inner land portion when mounted on a vehicle is defined by the circumferential main groove 2a and the tread edge TE.

[0016] This tire has a plurality of first widthwise grooves 4 extending in the tire width direction and having at least one end (both ends in the illustrated example) terminating within the outermost land portion 3a when mounted on a vehicle, which is the land portion on the outer side in the tire width direction when mounted on a vehicle, and a plurality of second widthwise grooves 5 extending in the tire width direction.

[0017] As shown in the figure, the first widthwise grooves 4 and the second widthwise grooves 5 are alternately arranged in the tire circumferential direction while being spaced apart from each other in the tire circumferential direction. In other words, one first widthwise groove 4 is paired with one second widthwise groove 5 adjacent to the one first widthwise groove 4 on one side in the tire circumferential direction, and a plurality of such pairs are provided at intervals in the tire circumferential direction. The tire circumferential pitch interval of the first widthwise grooves 4 is not particularly limited, but may be, for example, 40 to 140 mm. The tire circumferential pitch interval of the second widthwise grooves 5 is also not particularly limited, but may be, for example, 40 to 140 mm. The shortest distance between a pair of first widthwise grooves 4 and second widthwise grooves 5 is not particularly limited, but may be, for example, 15 to 60 mm.

[0018] Each of the pair of first widthwise grooves 4 has a first portion 41 extending from the outer side in the tire width direction toward the inside toward one side in the tire circumferential direction. The first widthwise groove 4 further has a second portion 42 extending from the inner end in the tire width direction of the first portion 41 toward one side in the tire circumferential direction. This second portion 42 can further ensure drainage performance.

[0019] The groove width (opening width) of the first widthwise grooves 4 is not particularly limited, but may be, for example, 5 to 20 mm, considering the balance between drainage (compliance with regulations when used in racing tires; the same applies below) and land portion rigidity. The groove depth (maximum depth) of the first widthwise grooves 4 is not particularly limited, but may be, for example, 5 to 8 mm, considering the balance between drainage and land portion rigidity. The inclination angle of the first portions 41 relative to the tire width direction is also not particularly limited, but may be, for example, 10 to 20°. By setting the inclination angle to 20° or less, rigidity against widthwise input (rigidity against shear deformation due to input from the outside to the inside in the width direction during vehicle cornering) can be increased, and by setting the inclination angle to 10° or more, the difference in inclination direction with the second widthwise grooves 5 can be made clearer, as described below, both of which can improve grip performance. The inclination angle of the second portions 42 relative to the tire circumferential direction is also not particularly limited, but may be, for example, 10 to 15°.

[0020] As shown in the figure, one of the pair of second widthwise grooves 5 extends from the outer side toward the inner side in the tire width direction to the other side in the tire circumferential direction. That is, the first widthwise groove 4 and the second widthwise groove 5 are inclined in opposite directions in the tire circumferential direction with respect to the tire width direction.

[0021] The groove width (opening width) of the second widthwise grooves 5 is not particularly limited, but may be, for example, 5 to 20 mm, in consideration of the balance between drainage (compliance with regulations when used in racing tires; the same applies below) and land portion rigidity. The groove depth (maximum depth) of the second widthwise grooves 5 is not particularly limited, but may be, for example, 5 to 8 mm, in consideration of the balance between drainage and land portion rigidity. The inclination angle of the second widthwise grooves 5 relative to the tire width direction is also not particularly limited, but may be, for example, 5 to 15°. By setting the inclination angle to 15° or less, rigidity against widthwise input (rigidity against shear deformation due to input from the outside to the inside in the width direction during vehicle cornering) can be increased, and by setting the inclination angle to 5° or more, the difference in the direction of inclination with the first widthwise grooves 4 can be made clearer, as described below, and both can improve grip performance.

[0022] Here, the inner end in the tire width direction of one second widthwise groove 5 constituting the pair is located outward in the tire width direction from the inner end in the tire width direction of one first widthwise groove 4 constituting the pair (in this example, the inner end in the tire width direction of the second portion 42). Although not particularly limited, it is preferable that the inner end in the tire width direction of one second widthwise groove 5 constituting the pair is located outward in the tire width direction from the inner end in the tire width direction of one first widthwise groove 4 constituting the pair (in this example, the inner end in the tire width direction of the second portion 42) by a distance of 50 to 80% of the tire width direction width of the first widthwise groove 4 (the tire width direction width when projected in the tire circumferential direction). In the illustrated example, the second widthwise groove 5 (its outer end in the tire width direction) communicates with the outer tread edge TE when mounted on a vehicle. In the illustrated example, one first widthwise groove 4 constituting the pair and one second widthwise groove 5 constituting the pair have overlapping portions when projected in the tire circumferential direction. This overlap width is not particularly limited, but can be, for example, 20 to 50% of the width of the first widthwise groove 4 in the tire width direction (the width in the tire width direction when projected in the tire circumferential direction).

[0023] At least a portion of the first portion 41 or at least a portion of the second portion 42 has a chamfered portion at its opening to the tread surface 1. This ensures high drainage when new (making it easier to comply with regulations when used in racing tires), while also ensuring grip performance by suppressing a decrease in rigidity compared to when the opening width is the same up to the groove bottom. A chamfered portion may be formed only on the first portion 41 (all around or part of the circumference) (no chamfered portion may be formed on the second portion 42). Alternatively, a chamfered portion may be formed only on the second portion 42 (all around or part of the circumference) (no chamfered portion may be formed on the first portion 41). Alternatively, a chamfered portion may be formed on both the first portion 41 (all around or part of the circumference) and the second portion 42 (all around or part of the circumference). In this example, a chamfered portion is formed on the entire circumference of the first portion 41 and the entire circumference of the second portion 42. Similarly, at least a portion of the second widthwise grooves 5 (all around or part of the circumference, in this example, all around) has a chamfered portion at its opening to the tread surface 1. With respect to the first widthwise groove 4, in the reference state, the inclination angle of the tapered surface of the chamfered portion of the second portion 42 relative to the tire radial direction is preferably larger than the inclination angle of the tapered surface of the chamfered portion of the first portion 41 relative to the tire radial direction. This is because the second portion 42 can further suppress a decrease in rigidity when ensuring drainage performance in a new tire.

[0024] Furthermore, this tire has only two circumferential main grooves 2 a, 2 b in the vehicle-mounted inner land portion 3 b, which is on the inner side when mounted on a vehicle, thereby ensuring a good balance between drainage performance and rigidity of the land portion.

[0025] When mounted on a vehicle, the outer land portion 3b1 of the inner land portion 3b has a plurality of third widthwise grooves 6 arranged therein, extending in the tire width direction. The third widthwise grooves 6 (their outer ends in the tire width direction) communicate with the tread edge TE. This improves drainage. On the other hand, the third widthwise grooves 6 (their inner ends in the tire width direction) do not communicate with the circumferential main groove 2a. This ensures the rigidity of the land portion.

[0026] The groove width (opening width) of the third widthwise grooves 6 is not particularly limited, but may be, for example, 10 to 25 mm, considering the balance between drainage (compliance with regulations when used in racing tires; the same applies below) and land portion rigidity. The groove depth (maximum depth) of the third widthwise grooves 6 is not particularly limited, but may be, for example, 5 to 8 mm, considering the balance between drainage and land portion rigidity. The inclination angle of the third widthwise grooves 6 relative to the tire width direction is also not particularly limited, but may be, for example, 5 to 15°. By setting the inclination angle to 15° or less, rigidity against widthwise input (rigidity against shear deformation due to input from the outside to the inside in the width direction during vehicle cornering) can be increased, and by setting the inclination angle to 5° or more, localized reduction in rigidity in the tire circumferential direction can be prevented. It is preferable that at least a portion (all or part of the circumference) of the opening of the third widthwise groove 6 is also chamfered.

[0027] Furthermore, a plurality of cutouts 7 that communicate with the circumferential main grooves 2a are provided on the inner side of the circumferential main grooves 2a in the tire width direction. This allows the rigidity of the land portions where the cutouts 7 are provided to be appropriately reduced, thereby improving grip performance. Furthermore, because the cutouts 7 are provided within the inner land portions 3b when mounted on a vehicle, they are less susceptible to the effects of lateral forces during cornering.

[0028] It is preferable that the first widthwise groove 4 and the second widthwise groove 5 provided in the outermost land portion 3a when mounted on a vehicle and the third widthwise groove 6 provided in the inner land portion 3b when mounted on a vehicle do not overlap each other when projected in the tire width direction, or that only the chamfered portions overlap. This is because this allows for balancing the rigidity of the land portions in the tire circumferential direction. The effects of the pneumatic tire of the first embodiment will be described below.

[0029] The pneumatic tire of the first embodiment has a plurality of first widthwise grooves 4 extending in the tire width direction in an outermost land portion 3a as mounted on a vehicle, the first widthwise grooves 4 having at least one end (both ends in the illustrated example) terminating within the outermost land portion 3a as mounted on a vehicle, and a plurality of second widthwise grooves 5 extending in the tire width direction. This increases rigidity against input in the width direction (rigidity against shear deformation due to input from the outer side to the inside in the width direction during cornering of the vehicle) and improves grip performance. In addition, in the pneumatic tire of the first embodiment, one first widthwise groove 4 constituting a pair has a first portion 41 extending from the outer side in the tire width direction toward the inside, toward one side in the tire circumferential direction, and one second widthwise groove 5 constituting the pair extends from the outer side in the tire width direction toward the inside, toward the other side in the tire circumferential direction. As a result, two widthwise grooves (with opposite inclination directions in the tire circumferential direction relative to the tire width direction) are always present in response to inputs from various directions, which solves the problem of land portions being easily deformed in response to inputs from a specific direction, thereby improving grip performance. Furthermore, with this configuration, the first portions 41 and the second widthwise grooves 5 are spaced apart from each other in the tire circumferential direction as they move toward the outer sides in the tire width direction, thereby ensuring a large area for the land portions on the outer sides in the tire width direction and improving grip performance. On the other hand, when only the direction of inclination is considered, the circumferential distance between the first portion 41 and the second widthwise groove 5 decreases toward the inner side in the tire width direction, but in the pneumatic tire of the first embodiment, the inner end of one second widthwise groove 5 that constitutes a pair is located further outward in the tire width direction than the inner end of one first widthwise groove 4 that constitutes the pair, thereby minimizing the occurrence of an area where the first widthwise groove 4 and the second widthwise groove 5 are close to each other in the tire circumferential direction, thereby ensuring a large land area even on the inner side in the tire width direction and improving grip performance. As described above, the pneumatic tire of the first embodiment can improve grip performance.

[0030] Here, it is preferable that the second widthwise grooves 5 communicate with the outer tread edge when mounted on a vehicle, because this can further improve drainage performance.

[0031] Furthermore, it is preferable that one of the paired first widthwise grooves 4 and one of the paired second widthwise grooves 5 have an overlapping portion when projected in the tire circumferential direction, because this makes it easier to ensure a sufficient extension length of the widthwise grooves even when taking into consideration the positional relationship with other grooves (in the example of FIG. 1, the circumferential main groove 2a).

[0032] Each first widthwise groove 4 preferably further has a second portion 42 extending from the inner end of the first portion 41 in the tire width direction to one side in the tire circumferential direction, and at least a part of the first portion 41 or at least a part of the second portion 42 preferably has a chamfered portion at the opening to the tread surface, because this can further improve drainage performance when new while minimizing reduction in rigidity.

[0033] In the reference state, the inclination angle of the tapered surface of the chamfered portion of the second portion 42 relative to the tire radial direction is preferably larger than the inclination angle of the tapered surface of the chamfered portion of the first portion 41 relative to the tire radial direction. This is because it is possible to further improve drainage performance when new while minimizing deterioration in rigidity.

[0034] It is preferable that only two circumferential main grooves 2a, 2b are provided in the inner land portion 3b, which is on the inner side when mounted on a vehicle. This ensures a good balance between drainage performance and rigidity of the land portion.

[0035] (Second embodiment) Here, in a second embodiment, both the direction of inclination of the first portion of the first widthwise groove toward the tire circumferential direction relative to the tire width direction and the direction of inclination of the second widthwise groove toward the tire circumferential direction relative to the tire width direction may be opposite to those in the first embodiment described above. That is, the tire of the second embodiment has a basic configuration similar to that of the first embodiment described above, and has one or more circumferential main grooves extending in the tire circumferential direction on the tread surface, and has a plurality of land portions partitioned between the circumferential main groove and the tread edge or between the circumferential main grooves, and has a plurality of first widthwise grooves extending in the tire width direction at the outermost land portion as mounted on the vehicle, which is the land portion on the outermost side in the tire width direction when mounted on the vehicle, and at least one end (preferably both ends) terminating within the outermost land portion as mounted on the vehicle, and a plurality of second widthwise grooves extending in the tire width direction, the first widthwise grooves and the second widthwise grooves being arranged alternately in the tire circumferential direction while being spaced apart from each other in the tire circumferential direction, and one first widthwise groove is paired with one second widthwise groove adjacent to the one first widthwise groove on one side in the tire circumferential direction. On the other hand, unlike the first embodiment described above, in the tire of the second embodiment, one of the first widthwise grooves constituting a pair has a first portion extending from the inner side in the tire width direction toward the outer side toward one side in the tire circumferential direction, one of the second widthwise grooves constituting a pair extends from the inner side in the tire width direction toward the outer side toward the other side in the tire circumferential direction, and the tire widthwise outer end of one of the second widthwise grooves constituting a pair is located outward in the tire width direction than the tire widthwise outer end of one of the first widthwise grooves constituting a pair.

[0036] The tire of the second embodiment also includes a plurality of first widthwise grooves extending in the tire width direction in the outermost land portion, which is the outermost land portion in the tire width direction when mounted on the vehicle, and at least one end (preferably both ends) terminating within the outermost land portion when mounted on the vehicle, and a plurality of second widthwise grooves extending in the tire width direction. This increases rigidity against widthwise input (rigidity against shear deformation due to input from the outer side to the inner side in the width direction during cornering of the vehicle) and improves grip performance. Furthermore, in the pneumatic tire of the second embodiment, one first widthwise groove of the pair has a first portion extending from the inner side to the outer side in the tire width direction toward one side in the tire circumferential direction, and one second widthwise groove of the pair extends from the inner side to the outer side in the tire width direction toward the other side in the tire circumferential direction. This results in the presence of widthwise grooves with two different extending directions (with inclination directions toward the tire circumferential direction relative to the tire width direction) in response to inputs from various directions, thereby eliminating the problem of land portions being easily deformed in response to inputs from a specific direction and improving grip performance. Furthermore, with this configuration, the circumferential distance between the first portion and the second widthwise groove increases toward the inner side in the tire width direction, thereby ensuring a large land area on the inner side in the tire width direction and improving grip performance. On the other hand, considering only the direction of inclination, the circumferential distance between the first portion and the second widthwise groove decreases toward the outer side in the tire width direction. However, in the pneumatic tire of the second embodiment, the outer end of one second widthwise groove that constitutes a pair is located further outward in the tire width direction than the outer end of one first widthwise groove that constitutes the pair. This minimizes the occurrence of an area where the first widthwise groove and the second widthwise groove are close to each other in the tire circumferential direction, ensuring a large land area even on the outer side in the tire width direction and improving grip performance. As described above, the pneumatic tire of the second embodiment also enables improved grip performance.

[0037] In the second embodiment, the second widthwise groove preferably communicates with the outer tread edge when mounted on a vehicle, because this can further improve drainage.

[0038] In the second embodiment, it is preferable that one of the first widthwise grooves constituting the pair and one of the second widthwise grooves constituting the pair have an overlapping portion when projected in the tire circumferential direction, because this makes it easier to ensure a sufficient extension length of the widthwise groove even when taking into consideration the arrangement relationship with other grooves.

[0039] In the second embodiment, it is preferable that one first widthwise groove further has a second portion extending from an inner end of the first portion in the tire width direction to one side in the tire circumferential direction, and that at least a part of the first portion or at least a part of the second portion has a chamfered portion at an opening to the tread surface, because this can further improve drainage performance in a new tire while minimizing a decrease in rigidity.

[0040] In the second embodiment, in the reference state, the inclination angle of the tapered surface of the chamfered portion of the second portion relative to the tire radial direction is preferably larger than the inclination angle of the tapered surface of the chamfered portion of the first portion relative to the tire radial direction, because this can further improve drainage performance when new while minimizing deterioration in rigidity.

[0041] In the second embodiment, it is preferable that the inner land portion, which is on the inner side when mounted on a vehicle, has only two circumferential main grooves, thereby ensuring a good balance between drainage performance and rigidity of the land portion.

[0042] In the second embodiment, the dimensions and inclination angles of the first widthwise groove (first portion, second portion) and the second widthwise groove may be the same as those of the first embodiment, except for the direction of inclination in the tire circumferential direction relative to the tire width direction. Similarly, the overlap width in the tire width direction of the first widthwise groove and the second widthwise groove and the separation distance in the tire width direction between the outer ends thereof may also be the same as those of the first embodiment.

[0043] (Third embodiment) As shown in Fig. 3 , this tire has one or more (two in the illustrated example) circumferentially extending circumferential main grooves 2 (2a, 2b) on a tread surface 1. The tire also has a plurality of land portions 3 (3a, 3b (3b1, 3b2)) defined between the circumferential main groove 2 and the tread edge TE or between the circumferential main grooves 2 (2a, 2b). Specifically, on the outer side of the tire as mounted on a vehicle, defined by the circumferential main groove 2a and the tread edge TE, is an outermost land portion 3a. On the inner side of the tire as mounted on a vehicle, defined by the tire equatorial plane CL, is an inner land portion 3b defined between the circumferential main grooves 2a, 2b or between the circumferential main groove 2b and the tread edge TE. An inner land portion 3b2 of the inner land portion when mounted on a vehicle is defined between the circumferential main grooves 2a, 2b, and an outer land portion 3b1 of the inner land portion when mounted on a vehicle is defined by the circumferential main groove 2a and the tread edge TE.

[0044] This tire has a plurality of first widthwise grooves 4 extending in the tire width direction in the outermost land portion 3a when mounted on a vehicle, which is the land portion that is outermost in the tire width direction on the outside when mounted on a vehicle, and at least one end (both ends in the illustrated example) terminating within the outermost land portion 3a when mounted on a vehicle, and a plurality of second widthwise grooves 5 extending in the tire width direction and at least one end (one end in the illustrated example) terminating within the outermost land portion 3a when mounted on a vehicle.

[0045] As shown in the figure, the first widthwise grooves 4 and the second widthwise grooves 5 are alternately arranged in the tire circumferential direction while being spaced apart from each other in the tire circumferential direction. In other words, one first widthwise groove 4 is paired with one second widthwise groove 5 adjacent to the one first widthwise groove 4 on one side in the tire circumferential direction, and a plurality of such pairs are provided at intervals in the tire circumferential direction. The tire circumferential pitch interval of the first widthwise grooves 4 is not particularly limited, but may be, for example, 40 to 140 mm. The tire circumferential pitch interval of the second widthwise grooves 5 is also not particularly limited, but may be, for example, 40 to 140 mm. The shortest distance between a pair of first widthwise grooves 4 and second widthwise grooves 5 is not particularly limited, but may be, for example, 15 to 60 mm.

[0046] Each of the pair of first widthwise grooves 4 has a first portion 41 extending from the outer side in the tire width direction toward the inside toward one side in the tire circumferential direction. The first widthwise groove 4 further has a second portion 42 extending from the inner end in the tire width direction of the first portion 41 toward one side in the tire circumferential direction. This second portion 42 can further ensure drainage performance.

[0047] The groove width (opening width) of the first widthwise grooves 4 is not particularly limited, but may be, for example, 5 to 20 mm, considering the balance between drainage (compliance with regulations when used in racing tires; the same applies below) and land portion rigidity. The groove depth (maximum depth) of the first widthwise grooves 4 is not particularly limited, but may be, for example, 5 to 8 mm, considering the balance between drainage and land portion rigidity. The inclination angle of the first portions 41 relative to the tire width direction is also not particularly limited, but may be, for example, 10 to 20°. By setting the inclination angle to 20° or less, rigidity against widthwise input (rigidity against shear deformation due to input from the outside to the inside in the width direction during vehicle cornering) can be increased, and by setting the inclination angle to 10° or more, the difference in inclination direction with the second widthwise grooves 5 can be made clearer, as described below, both of which can improve grip performance. The inclination angle of the second portions 42 relative to the tire circumferential direction is also not particularly limited, but may be, for example, 10 to 15°.

[0048] As shown in the figure, one of the pair of second widthwise grooves 5 extends from the outer side toward the inner side in the tire width direction to the other side in the tire circumferential direction. That is, the first widthwise groove 4 and the second widthwise groove 5 are inclined in opposite directions in the tire circumferential direction with respect to the tire width direction.

[0049] The groove width (opening width) of the second widthwise grooves 5 is not particularly limited, but may be, for example, 5 to 20 mm, in consideration of the balance between drainage (compliance with regulations when used in racing tires; the same applies below) and land portion rigidity. The groove depth (maximum depth) of the second widthwise grooves 5 is not particularly limited, but may be, for example, 5 to 8 mm, in consideration of the balance between drainage and land portion rigidity. The inclination angle of the second widthwise grooves 5 relative to the tire width direction is also not particularly limited, but may be, for example, 5 to 15°. By setting the inclination angle to 15° or less, rigidity against widthwise input (rigidity against shear deformation due to input from the outside to the inside in the width direction during vehicle cornering) can be increased, and by setting the inclination angle to 5° or more, the difference in the direction of inclination with the first widthwise grooves 4 can be made clearer, as described below, and both can improve grip performance.

[0050] Here, the inner end in the tire width direction of one second widthwise groove 5 constituting the pair is located outward in the tire width direction from the inner end in the tire width direction of one first widthwise groove 4 constituting the pair (in this example, the inner end in the tire width direction of the second portion 42). Although not particularly limited, it is preferable that the inner end in the tire width direction of one second widthwise groove 5 constituting the pair is located outward in the tire width direction from the inner end in the tire width direction of one first widthwise groove 4 constituting the pair (in this example, the inner end in the tire width direction of the second portion 42) by a distance of 50 to 80% of the tire width direction width of the first widthwise groove 4 (the tire width direction width when projected in the tire circumferential direction). In the illustrated example, the second widthwise groove 5 (its outer end in the tire width direction) communicates with the outer tread edge TE when mounted on a vehicle. In the illustrated example, one first widthwise groove 4 constituting the pair and one second widthwise groove 5 constituting the pair have overlapping portions when projected in the tire circumferential direction. This overlap width is not particularly limited, but can be, for example, 20 to 50% of the width of the first widthwise groove 4 in the tire width direction (the width in the tire width direction when projected in the tire circumferential direction).

[0051] At least a portion of the first portion 41 or at least a portion of the second portion 42 has a chamfered portion at its opening to the tread surface 1. This ensures high drainage when new (making it easier to comply with regulations when used in racing tires), while also ensuring grip performance by suppressing a decrease in rigidity compared to when the opening width is the same up to the groove bottom. A chamfered portion may be formed only on the first portion 41 (all around or part of the circumference) (no chamfered portion may be formed on the second portion 42). Alternatively, a chamfered portion may be formed only on the second portion 42 (all around or part of the circumference) (no chamfered portion may be formed on the first portion 41). Alternatively, a chamfered portion may be formed on both the first portion 41 (all around or part of the circumference) and the second portion 42 (all around or part of the circumference). In this example, a chamfered portion is formed on the entire circumference of the first portion 41 and the entire circumference of the second portion 42. Similarly, at least a portion of the second widthwise grooves 5 (all around or part of the circumference, in this example, all around) has a chamfered portion at its opening to the tread surface 1. With respect to the first widthwise groove 4, in the reference state, the inclination angle of the tapered surface of the chamfered portion of the second portion 42 relative to the tire radial direction is preferably larger than the inclination angle of the tapered surface of the chamfered portion of the first portion 41 relative to the tire radial direction. This is because the second portion 42 can further suppress a decrease in rigidity when ensuring drainage performance in a new tire.

[0052] Furthermore, this tire has only two circumferential main grooves 2 a, 2 b in the vehicle-mounted inner land portion 3 b, which is on the inner side when mounted on a vehicle, thereby ensuring a good balance between drainage performance and rigidity of the land portion.

[0053] When mounted on a vehicle, the outer land portion 3b1 of the inner land portion 3b has a plurality of third widthwise grooves 6 arranged therein, extending in the tire width direction. The third widthwise grooves 6 (at their outer ends in the tire width direction) communicate with the tread edge TE. This improves drainage. On the other hand, the third widthwise grooves 6 (at their inner ends in the tire width direction) do not communicate with the circumferential main grooves 2a. This ensures the rigidity of the land portion. Fourth widthwise grooves 9 are further arranged between the third widthwise grooves 6 in the tire circumferential direction. This further improves drainage. Both ends of the fourth widthwise groove 9 terminate within the outer land portion 3b1. This ensures the rigidity of the land portion. In this example, the groove width of the fourth widthwise groove 9 is smaller than the groove width of the third widthwise groove 6.

[0054] The groove width (opening width) of the third widthwise groove 6 is not particularly limited, but may be, for example, 10 to 25 mm, in consideration of the balance between drainage (compliance with regulations when used in racing tires; the same applies below) and land portion rigidity. The groove depth (maximum depth) of the third widthwise groove 6 is not particularly limited, but may be, for example, 5 to 8 mm, in consideration of the balance between drainage and land portion rigidity. The inclination angle of the third widthwise groove 6 with respect to the tire width direction is also not particularly limited, but may be, for example, 5 to 15°. By setting the inclination angle to 15° or less, rigidity against widthwise input (rigidity against shear deformation due to input from the outside to the inside in the width direction during vehicle cornering) can be increased, and by setting the inclination angle to 5° or more, localized reduction in rigidity in the tire circumferential direction can be prevented. The groove width (opening width) of the fourth widthwise groove 9 is not particularly limited, but may be, for example, 2 to 6 mm, in consideration of the balance between drainage (compliance with regulations when used in racing tires; the same applies below) and land portion rigidity. The groove depth (maximum depth) of the fourth widthwise groove 9 is not particularly limited, but may be, for example, 5 to 8 mm, taking into consideration the balance between drainage and rigidity of the land portion. The inclination angle of the fourth widthwise groove 9 with respect to the tire width direction is also not particularly limited, but may be, for example, 5 to 15°. By setting the inclination angle to 15° or less, rigidity against widthwise input (rigidity against shear deformation due to input from the outside to the inside in the width direction during cornering) can be increased, and by setting the inclination angle to 5° or more, localized reduction in rigidity in the tire circumferential direction can be prevented. It is preferable that at least a portion (all or part) of the openings of the third widthwise groove 6 and the fourth widthwise groove 9 be chamfered.

[0055] Furthermore, a plurality of cutouts 7 that communicate with the circumferential main grooves 2a are provided on the inner side of the circumferential main grooves 2a in the tire width direction. This allows the rigidity of the land portions where the cutouts 7 are provided to be appropriately reduced, thereby improving grip performance. Furthermore, because the cutouts 7 are provided within the inner land portions 3b when mounted on a vehicle, they are less susceptible to the effects of lateral forces during cornering.

[0056] When projected in the tire width direction, it is preferable that the first widthwise groove 4 and the second widthwise groove 5 provided in the outermost land portion 3 a as mounted on the vehicle and the third widthwise groove 6 provided in the inner land portion 3 b as mounted on the vehicle do not overlap each other, or that only the chamfered portions overlap. This is because this allows for balancing the rigidity of the land portions in the tire circumferential direction. Similarly, when projected in the tire width direction, it is preferable that the first widthwise groove 4 and the second widthwise groove 5 provided in the outermost land portion 3 a as mounted on the vehicle and the fourth widthwise groove 9 provided in the inner land portion 3 b as mounted on the vehicle do not overlap each other, or that only the chamfered portions overlap.

[0057] This tire further includes, in the outermost land portion 3 a when mounted on a vehicle, shallow grooves 8, one ends of which communicate with the other ends of the first widthwise grooves 4. The other ends of the shallow grooves 8 communicate with the circumferential main grooves 2 b. The groove depth (maximum depth) of the shallow grooves 8 is shallower than the groove depth (maximum depth) of the first widthwise grooves 4.

[0058] The groove depth (maximum depth) of the shallow grooves 8 is preferably 1.0 mm or more and 2.5 mm or less. A depth of 1.0 mm or more can further improve drainage, while a depth of 2.5 mm or less can suppress a decrease in rigidity of the outermost land portion 3a when mounted on a vehicle. The groove width (opening width) of the shallow grooves 8 is preferably 3.0 to 10.0 mm. A depth of 3.0 mm or more can further improve drainage, while a depth of 10.0 mm or less can suppress a decrease in rigidity of the outermost land portion 3a when mounted on a vehicle.

[0059] The shallow grooves 8 extend from the outer side in the tire width direction toward the inner side to one side in the tire circumferential direction. The shallow grooves 8 preferably extend at an inclination angle of 40 to 60 degrees with respect to the tire circumferential direction. This is because an angle of 40 degrees or more can suppress a decrease in rigidity of local land portions due to the formation of acute angles, while an angle of 60 degrees or less can further improve drainage.

[0060] It is preferable that the shallow groove 8 communicates with an end portion on one circumferential side (the kick-off side in this example) of the first widthwise groove 4 (the second portion 42 in the illustrated example), because this can encourage water that has entered the first widthwise groove 4 to be drained via the shallow groove 8 to the circumferential main groove 2a, thereby further improving drainage.

[0061] In this example, the first widthwise grooves 4, the second widthwise grooves 5, and the shallow grooves 8 as configured above are provided only in the outermost land portions 3a when mounted on a vehicle. The effects of the pneumatic tire of the third embodiment will now be described.

[0062] The pneumatic tire of the third embodiment has a plurality of first widthwise grooves 4 extending in the tire width direction in the outermost land portion 3a, which is the outermost land portion in the tire width direction when mounted on a vehicle, and at least one end (both ends in the illustrated example) terminating within the outermost land portion 3a when mounted on a vehicle, and a plurality of second widthwise grooves 5 extending in the tire width direction and at least one end (one end in the illustrated example) terminating within the outermost land portion 3a when mounted on a vehicle. This increases rigidity against widthwise input (rigidity against shear deformation due to input from the outer side to the inside in the width direction during cornering of the vehicle) and improves grip performance. In addition, in the pneumatic tire of the third embodiment, one first widthwise groove 4 constituting a pair has a first portion 41 extending from the outer side in the tire width direction toward the inside, toward one side in the tire circumferential direction, and one second widthwise groove 5 constituting the pair extends from the outer side in the tire width direction toward the inside, toward the other side in the tire circumferential direction. As a result, two widthwise grooves (with opposite inclination directions in the tire circumferential direction relative to the tire width direction) are always present in response to inputs from various directions, which solves the problem of land portions being easily deformed in response to inputs from a specific direction, thereby improving grip performance. Furthermore, with this configuration, the first portions 41 and the second widthwise grooves 5 are spaced apart from each other in the tire circumferential direction as they move toward the outer sides in the tire width direction, thereby ensuring a large area for the land portions on the outer sides in the tire width direction and improving grip performance. On the other hand, when considering only the direction of inclination, the circumferential distance between the first portion 41 and the second widthwise groove 5 decreases toward the inner side in the tire width direction, but in the pneumatic tire of the third embodiment, the inner end of one second widthwise groove 5 that constitutes a pair is located outward in the tire width direction from the inner end of one first widthwise groove 4 that constitutes the pair, thereby minimizing the occurrence of an area where the first widthwise groove 4 and the second widthwise groove 5 are close to each other in the tire circumferential direction, thereby ensuring a large land area even on the inner side in the tire width direction and improving grip performance. As described above, the pneumatic tire of the third embodiment can improve grip performance.

[0063] In a tire such as the third embodiment, the first widthwise grooves 4 are closed within the ground contact patch, and when the air in the closed space is compressed by the load and released, a pumping sound is generated, which can cause pattern noise. In contrast, the tire of the third embodiment further includes shallow grooves 8, one end of which communicates with the other end of the first widthwise grooves 4, and the other end of the shallow grooves 8 communicates with the circumferential main grooves 2b. This allows the shallow grooves 8 to function as an escape route for air when the first widthwise grooves 4 are positioned within the ground contact patch, thereby suppressing the generation of the above-mentioned pattern noise. Furthermore, drainage performance can be further improved by the drainage provided by the shallow grooves 8 themselves and by the shallow grooves 8 effectively connecting the circumferential main grooves 2b and the first widthwise grooves 4. Furthermore, because the groove depth of the shallow grooves 8 is shallower than the groove depth of the first widthwise grooves 4, a decrease in the rigidity of the land portions can also be suppressed. As wear progresses, the shallow grooves 8 may disappear, but as wear progresses, the depth of the first widthwise grooves 4 also becomes shallower, thereby reducing the pumping noise that may be generated.

[0064] Here, it is preferable that the second widthwise grooves 5 communicate with the outer tread edge when mounted on a vehicle, because this can further improve drainage performance.

[0065] Furthermore, it is preferable that one of the paired first widthwise grooves 4 and one of the paired second widthwise grooves 5 have an overlapping portion when projected in the tire circumferential direction, because this makes it easier to ensure a sufficient extension length of the widthwise grooves even when taking into consideration the positional relationship with other grooves (in the example of FIG. 2, the circumferential main groove 2a).

[0066] Each first widthwise groove 4 preferably further has a second portion 42 extending from the inner end of the first portion 41 in the tire width direction to one side in the tire circumferential direction, and at least a part of the first portion 41 or at least a part of the second portion 42 preferably has a chamfered portion at the opening to the tread surface, because this can further improve drainage performance when new while minimizing reduction in rigidity.

[0067] In the reference state, the inclination angle of the tapered surface of the chamfered portion of the second portion 42 relative to the tire radial direction is preferably larger than the inclination angle of the tapered surface of the chamfered portion of the first portion 41 relative to the tire radial direction. This is because it is possible to further improve drainage performance when new while minimizing deterioration in rigidity.

[0068] It is preferable that only two circumferential main grooves 2a, 2b are provided in the inner land portion 3b, which is on the inner side when mounted on a vehicle. This ensures a good balance between drainage performance and rigidity of the land portion.

[0069] (Fourth embodiment) Here, in a fourth embodiment, both the direction of inclination of the first portion of the first widthwise groove toward the tire circumferential direction relative to the tire width direction and the direction of inclination of the second widthwise groove toward the tire circumferential direction relative to the tire width direction may be opposite to those in the third embodiment described above. That is, the tire of the fourth embodiment has a basic configuration similar to that of the third embodiment, and has, on its tread surface, one or more circumferential main grooves extending in the tire circumferential direction, and a plurality of land portions partitioned between the circumferential main groove and the tread edge or between the circumferential main grooves, and has, in the outermost land portion as mounted on a vehicle, a plurality of first widthwise grooves extending in the tire width direction and at least one end (e.g., both ends) terminating within the outermost land portion as mounted on a vehicle, which is the land portion outermost in the tire width direction when mounted on a vehicle, and a plurality of second widthwise grooves extending in the tire width direction and at least one end (e.g., one end) terminating within the outermost land portion as mounted on a vehicle, the first widthwise grooves and the second widthwise grooves being arranged alternately in the tire circumferential direction while being spaced apart from each other in the tire circumferential direction, and one first widthwise groove is paired with one second widthwise groove adjacent to the one first widthwise groove on one side in the tire circumferential direction. The tire of the fourth embodiment further includes a shallow groove 8, one end of which communicates with the other end of the first widthwise groove 4. The shallow groove 8 has a groove depth shallower than that of the first widthwise groove 4, and the other end of the shallow groove 8 communicates with the circumferential main groove 2a. The shallow groove 8 extends from the outer side toward the inner side in the tire width direction to the other side in the tire circumferential direction. However, unlike the third embodiment, in the tire of the fourth embodiment, one first widthwise groove of the pair has a first portion extending from the inner side toward the outer side in the tire width direction to one side in the tire circumferential direction, one second widthwise groove of the pair extends from the inner side toward the outer side in the tire width direction to the other side in the tire circumferential direction, and the outer end of the one second widthwise groove of the pair is located outward in the tire width direction than the outer end of the one first widthwise groove of the pair.

[0070] The tire of the fourth embodiment also has a plurality of first widthwise grooves extending in the tire width direction in the outermost land portion, which is the land portion on the outer side in the tire width direction when mounted on a vehicle, and at least one end (e.g., both ends) terminating within the outermost land portion when mounted on a vehicle, and a plurality of second widthwise grooves extending in the tire width direction and at least one end (e.g., one end) terminating within the outermost land portion when mounted on a vehicle. This increases rigidity against widthwise input (rigidity against shear deformation due to input from the outside to the inside in the width direction during cornering of the vehicle) and improves grip performance. In addition, in the pneumatic tire of the fourth embodiment, one first widthwise groove of the pair has a first portion extending from the inside to the outside in the tire width direction to one side in the tire circumferential direction, and one second widthwise groove of the pair extends from the inside to the outside in the tire width direction to the other side in the tire circumferential direction. As a result, two widthwise grooves with different extending directions (with inclination directions in the tire circumferential direction opposite to each other with respect to the tire width direction) are always present in response to inputs from various directions, thereby solving the problem of land portions being easily deformed in response to inputs from a specific direction and improving grip performance. Furthermore, with this configuration, the first portion and the second widthwise groove are spaced apart from each other in the tire circumferential direction more inward in the tire width direction, thereby ensuring a large land area on the inner side in the tire width direction and improving grip performance. On the other hand, considering only the direction of inclination, the first portion and the second widthwise groove are spaced apart from each other in the tire circumferential direction more inward in the tire width direction. However, in the pneumatic tire of the fourth embodiment, the outer end of one second widthwise groove of the pair is located more outward in the tire width direction than the outer end of one first widthwise groove of the pair. This minimizes the occurrence of an area where the first widthwise groove and the second widthwise groove are close to each other in the tire circumferential direction, ensuring a large land area even on the outer side in the tire width direction and improving grip performance. As described above, the pneumatic tire of the fourth embodiment can also improve grip performance.

[0071] The tire of the fourth embodiment also includes a shallow groove 8, one end of which communicates with the other end of the first widthwise groove 4, and the other end of the shallow groove 8 communicates with the circumferential main groove 2a. This allows the shallow groove 8 to function as an air escape route when the first widthwise groove 4 is positioned in the ground contact patch, thereby suppressing the generation of the above-mentioned pattern noise. Furthermore, drainage performance can be further improved by the drainage of the shallow groove 8 itself and the effective drainage provided by the shallow groove 8 communicating the circumferential main groove 2b with the first widthwise groove 4. Furthermore, since the groove depth of the shallow groove 8 is shallower than the groove depth of the first widthwise groove 4, a decrease in the rigidity of the land portion can also be suppressed. Although the shallow groove 8 may disappear as wear progresses, the groove depth of the first widthwise groove 4 also becomes shallow as wear progresses, thereby reducing the pumping noise that may be generated.

[0072] In the fourth embodiment, the groove depth (maximum depth) of the shallow grooves 8 is preferably 1.0 mm or more and 2.5 mm or less. Setting it to 1.0 mm or more further improves drainage, while setting it to 2.5 mm or less can prevent a decrease in rigidity of the outermost land portion 3 a when mounted on a vehicle. The groove width (opening width) of the shallow grooves 8 is preferably 3.0 to 10.0 mm. Setting it to 3.0 mm or more further improves drainage, while setting it to 10.0 mm or less can prevent a decrease in rigidity of the outermost land portion 3 a when mounted on a vehicle.

[0073] In the fourth embodiment, too, it is preferable that the shallow grooves 8 extend at an inclination angle of 40 to 60 degrees with respect to the tire circumferential direction. This is because an angle of 40 degrees or more can suppress a decrease in rigidity of local land portions due to the formation of acute-angled portions, while an angle of 60 degrees or less can further improve drainage performance.

[0074] In the fourth embodiment, too, it is preferable that the shallow groove 8 communicate with the end of the first widthwise groove 4 (the second portion 42 in the illustrated example) on one circumferential side of the tire (the kick-off side in this example), because this can encourage water that has entered the first widthwise groove 4 to be drained to the circumferential main groove 2b via the shallow groove 8, thereby further improving drainage.

[0075] In the fourth embodiment, it is also preferable that the first widthwise groove 4, the second widthwise groove 5, and the shallow groove 8 as configured above are provided only in the outermost land portion 3a when mounted on a vehicle.

[0076] In the fourth embodiment, the second widthwise grooves preferably communicate with the outer tread edge when mounted on a vehicle, because this can further improve drainage.

[0077] In the fourth embodiment, it is preferable that one of the first widthwise grooves constituting the pair and one of the second widthwise grooves constituting the pair have an overlapping portion when projected in the tire circumferential direction, because this makes it easier to ensure a sufficient extension length of the widthwise groove even when taking into consideration the arrangement relationship with other grooves.

[0078] In the fourth embodiment, it is preferable that one first widthwise groove further has a second portion extending from an inner end of the first portion in the tire width direction to one side in the tire circumferential direction, and that at least a part of the first portion or at least a part of the second portion has a chamfered portion at an opening to the tread surface, because this can further improve drainage performance in a new tire while minimizing a decrease in rigidity.

[0079] In the fourth embodiment, in the reference state, the inclination angle of the tapered surface of the chamfered portion of the second portion relative to the tire radial direction is preferably larger than the inclination angle of the tapered surface of the chamfered portion of the first portion relative to the tire radial direction, because this can further improve drainage performance when new while minimizing deterioration in rigidity.

[0080] In the fourth embodiment, it is preferable that the inner land portion, which is on the inner side when mounted on a vehicle, has only two circumferential main grooves, thereby ensuring a good balance between drainage performance and rigidity of the land portion.

[0081] In the fourth embodiment, the dimensions and inclination angles of the first widthwise groove (first portion, second portion) and the second widthwise groove may be the same as those of the third embodiment, except for the direction of inclination in the tire circumferential direction relative to the tire width direction. Similarly, the overlap width in the tire width direction of the first widthwise groove and the second widthwise groove and the separation distance in the tire width direction between the outer ends thereof may also be the same as those of the third embodiment.

[0082] The following describes a case where a communication device is provided in a tire. FIG. 3 is a diagram illustrating an example of the arrangement of the communication device. As shown in FIG. 3, the tire may be equipped with an RF tag as the communication device 91. The RF tag includes an IC chip and an antenna. The RF tag may be disposed, for example, by being sandwiched between multiple components of the same or different types that constitute the tire. This makes it easy to attach the RF tag during tire production, thereby improving the productivity of tires equipped with RF tags. In this example, the RF tag may be disposed, for example, by being sandwiched between a bead filler and another component adjacent to the bead filler. The RF tag may also be embedded in any of the components that constitute the tire. This reduces the load applied to the RF tag compared to when the RF tag is disposed by being sandwiched between multiple components that constitute the tire. This improves the durability of the RF tag. In this example, the RF tag may be embedded in a rubber component such as a tread rubber or a side rubber. It is preferable that the RF tag is not placed at a position that is a boundary between members with different rigidities in the periphery length direction, which is a direction along the tire outer surface in a cross-sectional view in the tire width direction. In this way, the RF tag is not placed in a position where strain is likely to concentrate due to a rigidity difference. Therefore, the load applied to the RF tag can be reduced. This can improve the durability of the RF tag. In this example, it is preferable that the RF tag is not placed at a position that is, for example, a boundary between an end of the carcass and a member adjacent to the end of the carcass (e.g., a side rubber, etc.) in a cross-sectional view in the tire width direction. The number of RF tags is not particularly limited. A tire may be equipped with only one RF tag, or may be equipped with two or more RF tags. Here, an RF tag is described as an example of a communication device, but a communication device other than an RF tag may also be used.

[0083] The RF tag may be disposed, for example, in the tread portion of the tire. In this manner, the RF tag will not be damaged by a side cut of the tire. The RF tag may be disposed, for example, in the tread center portion in the tire width direction. The tread center portion is a position in the tread portion where flexure is less likely to concentrate. In this manner, the load applied to the RF tag can be reduced. This improves the durability of the RF tag. Also, it is possible to prevent differences in communication with the RF tag from both outer sides of the tire in the tire width direction. In this example, the RF tag may be disposed, for example, within a range of 1 / 2 of the tread width centered on the tire equatorial plane in the tire width direction. The RF tag may be disposed, for example, at the tread edge in the tire width direction. If the position of a reader that communicates with the RF tag is predetermined, the RF tag may be disposed, for example, at the tread edge on one side closer to the reader. In this example, the RF tag may be disposed, for example, within a range of 1 / 4 of the tread width in the tire width direction, with the tread edge as the outer end.

[0084] The RF tag may be positioned, for example, closer to the tire cavity than a carcass including one or more carcass plies spanning between bead portions. This configuration makes the RF tag less susceptible to damage from impacts applied from outside the tire or damage such as side cuts or nail penetration. As an example, the RF tag may be positioned in close contact with the surface of the carcass facing the tire cavity. As another example, if there is another component closer to the tire cavity than the carcass, the RF tag may be positioned, for example, between the carcass and another component located closer to the tire cavity than the carcass. An example of another component located closer to the tire cavity than the carcass is an inner liner that forms the tire inner surface. As another example, the RF tag may be attached to the tire inner surface facing the tire cavity. Configuring the RF tag to be attached to the tire inner surface makes it easier to attach the RF tag to the tire and to inspect and replace the RF tag. In other words, the ease of attaching and maintaining the RF tag can be improved. Furthermore, by attaching the RF tag to the inner surface of the tire, it is possible to prevent the RF tag from becoming a nucleus of tire failure, compared to a configuration in which the RF tag is embedded in the tire. Furthermore, when the carcass has multiple carcass plies and there is a position where multiple carcass plies are overlapped, the RF tag may be disposed between the overlapped carcass plies.

[0085] The RF tag may be arranged, for example, in the tread portion of the tire, radially outward of a belt including one or more belt plies. As one example, the RF tag may be arranged radially outward of the belt in the tire radial direction and in close contact with the belt. As another example, if a reinforcing belt layer is provided, the RF tag may be arranged radially outward of the reinforcing belt layer in close contact with the reinforcing belt layer. As another example, the RF tag may be embedded in the tread rubber radially outward of the belt. By arranging the RF tag radially outward of the belt in the tread portion of the tire, communication with the RF tag from the outside of the tire in the tire radial direction is less likely to be obstructed by the belt. Therefore, communication with the RF tag from the outside of the tire in the tire radial direction can be improved. As another example, the RF tag may be arranged radially inward of the belt in the tread portion of the tire. In this way, the outer side of the RF tag in the tire radial direction is covered by the belt, making the RF tag less susceptible to damage from impacts from the tread surface or nail penetration. As one example, the RF tag may be disposed in the tread portion of the tire between the belt and the carcass located radially inward of the belt. Furthermore, if the belt has multiple belt plies, the RF tag may be disposed in the tread portion of the tire between any two belt plies. In this manner, the outer side of the RF tag in the tire radial direction is covered by one or more belt plies, making the RF tag less susceptible to damage from impacts from the tread surface, nail penetration, and the like.

[0086] The RF tag may be disposed, for example, in a sidewall portion or a bead portion of the tire. The RF tag may be disposed, for example, in one sidewall portion or one bead portion that is closer to a reader capable of communicating with the RF tag. This improves communication between the RF tag and the reader. As an example, the RF tag may be disposed between the carcass and the side rubber or between the tread rubber and the side rubber. The RF tag may be disposed, for example, between the tire's maximum width position and the tread surface position in the tire radial direction. This improves communication with the RF tag from the tire's outer side in the tire radial direction compared to a configuration in which the RF tag is disposed radially inward of the tire's maximum width position. The RF tag may be disposed, for example, radially inward of the tire's maximum width position. This allows the RF tag to be disposed near the bead portion, which has high rigidity. This reduces the load applied to the RF tag. This improves durability of the RF tag. As an example, the RF tag may be disposed adjacent to the bead core in the tire radial direction or the tire width direction. Distortion is less likely to concentrate near the bead core. This reduces the load on the RF tag, improving the durability of the RF tag. In particular, it is preferable that the RF tag be positioned radially inward of the tire's maximum width position and radially outward of the bead core of the bead portion. This improves the durability of the RF tag, and communication between the RF tag and a reader is less likely to be obstructed by the bead core, improving the communication performance of the RF tag. Furthermore, when the side rubber is composed of multiple rubber members of the same or different types adjacent in the tire radial direction, the RF tag may be sandwiched between the multiple rubber members that make up the side rubber.

[0087] The RF tag may be disposed sandwiched between a bead filler and a member adjacent to the bead filler. This allows the RF tag to be disposed in a position where strain is less likely to concentrate due to the bead filler. Therefore, the load on the RF tag can be reduced. This improves the durability of the RF tag. The RF tag may be disposed sandwiched between, for example, a bead filler and a carcass. The portion of the carcass that sandwiches the RF tag together with the bead filler may be located on the outer side of the bead filler in the tire width direction, or on the inner side of the bead filler in the tire width direction. When the portion of the carcass that sandwiches the RF tag together with the bead filler is located on the outer side of the bead filler in the tire width direction, the load on the RF tag due to impact or damage from the outside of the tire in the tire width direction can be further reduced. This improves the durability of the RF tag. The bead filler may also have a portion disposed adjacent to a side rubber. In this case, the RF tag may be disposed by being sandwiched between the bead filler and the side rubber. Furthermore, the bead filler may have a portion disposed adjacent to the rubber chafer. In this case, the RF tag may be disposed by being sandwiched between the bead filler and the rubber chafer.

[0088] The RF tag may be arranged, for example, sandwiched between the rubber chafer and the side rubber. In this way, the RF tag can be arranged in a position where the placement of the rubber chafer makes it less likely for distortion to concentrate. This reduces the load on the RF tag. This improves the durability of the RF tag. The RF tag may be arranged, for example, sandwiched between the rubber chafer and the carcass. In this way, it reduces the load on the RF tag due to impacts or damage from the rim. This improves the durability of the RF tag.

[0089] The RF tag may be sandwiched between the wire chafer and another adjacent member on the inner or outer side of the wire chafer in the tire width direction. This makes it difficult for the position of the RF tag to fluctuate when the tire deforms. Therefore, the load applied to the RF tag when the tire deforms can be reduced. This improves the durability of the RF tag. The other adjacent member on the inner or outer side of the wire chafer in the tire width direction may be, for example, a rubber member such as a rubber chafer. Furthermore, the other adjacent member on the inner or outer side of the wire chafer in the tire width direction may be, for example, a carcass.

[0090] A belt reinforcing layer may be further provided on the radially outer side of the belt. For example, the belt reinforcing layer may be formed by winding a cord made of polyethylene terephthalate continuously in a spiral shape in the tire circumferential direction. Here, the cord may be 6.9 x 10 －２ The belt reinforcement layer may be formed by applying an adhesive treatment under a tension of 1000 N / tex or more, and have an elastic modulus of 2.5 mN / dtex% or more when measured at 160°C under a load of 29.4 N. Furthermore, the belt reinforcement layer may be disposed so as to cover the entire belt or only both ends of the belt. Furthermore, the winding density per unit width of the belt reinforcement layer may vary depending on the position in the width direction. By doing so, road noise and flat spots can be reduced without reducing high-speed durability.

[0091] 1: tread surface, 2, 2a, 2b: circumferential main groove, 3: land portion, 3a: outermost land portion when mounted on vehicle, 3b: inner land portion when mounted on vehicle, 3b1: outer land portion of inner land portion when mounted on vehicle, 3b2: inner land portion of inner land portion when mounted on vehicle, 4: first widthwise groove, 41: first portion, 42: second portion, 5: second widthwise groove, 6: third widthwise groove, 7: cutout portion, 8: shallow groove, 9: fourth widthwise groove, 91: communication device, CL: tire equatorial plane, TE: tread edge

Claims

1. A pneumatic tire having one or more circumferential main grooves extending in the tire circumferential direction on a tread surface, the pneumatic tire having a plurality of land portions partitioned between the circumferential main groove and a tread edge or between the circumferential main grooves, the pneumatic tire having a plurality of first widthwise grooves extending in the tire width direction in an outermost land portion as mounted on a vehicle, the outermost land portion being the land portion in the tire width direction on the outer side when mounted on a vehicle, and at least one end of the first widthwise grooves terminating within the outermost land portion as mounted on a vehicle, the first widthwise grooves and the second widthwise grooves terminating in the tire width direction, the first widthwise grooves and the second widthwise grooves circumferentially arranged alternately in the tire circumferential direction while being spaced apart from each other in the tire circumferential direction, one first widthwise groove and one second widthwise groove adjacent to one side in the tire circumferential direction of the one first widthwise groove form a pair, the one first widthwise groove forming the pair has a first portion extending from the outer side in the tire width direction toward the inside to one side in the tire circumferential direction, a second widthwise groove of the pair extending from an outer side in the tire width direction toward an inner side in the tire circumferential direction to the other side in the tire circumferential direction, and an inner end in the tire width direction of the second widthwise groove of the pair being located outer in the tire width direction than an inner end in the tire width direction of the first widthwise groove of the pair.

2. The pneumatic tire according to claim 1, wherein both ends of the first widthwise groove terminate within the outermost land portion when mounted on a vehicle.

3. A pneumatic tire as set forth in claim 1 or 2, wherein the second widthwise groove communicates with an outer tread edge when mounted on a vehicle.

4. A pneumatic tire as described in any one of claims 1 to 3, wherein the one first widthwise groove that constitutes the pair and the one second widthwise groove that constitutes the pair have an overlapping portion when projected in the tire circumferential direction.

5. A pneumatic tire according to any one of claims 1 to 4, wherein the one first widthwise groove further has a second portion extending from an inner end of the first portion in the tire width direction to one side in the tire circumferential direction, and at least a part of the first portion or at least a part of the second portion has a chamfered portion at an opening to the tread surface.

6. A pneumatic tire as set forth in claim 5, wherein, in a reference state in which the pneumatic tire is mounted on an applicable rim, inflated to a specified internal pressure, and no load is applied, the inclination angle of the tapered surface of the chamfered portion of the second portion relative to the tire radial direction is greater than the inclination angle of the tapered surface of the chamfered portion of the first portion relative to the tire radial direction.

7. A pneumatic tire according to any one of claims 1 to 6, wherein the first widthwise groove has one end terminating within the outermost land portion when mounted on the vehicle, and the second widthwise groove has at least one end terminating within the outermost land portion when mounted on the vehicle, and further comprises a shallow groove having one end communicating with the other end of the first widthwise groove, a groove depth of the shallow groove being shallower than the groove depth of the first widthwise groove, and the other end of the shallow groove communicating with the circumferential main groove.

8. The pneumatic tire according to claim 7, wherein the shallow grooves have a depth of 2.5 mm or less.

9. The pneumatic tire according to claim 7 or 8, wherein the shallow grooves extend at an inclination angle of 40 to 60 degrees with respect to the circumferential direction of the tire.

10. The pneumatic tire according to any one of claims 7 to 9, wherein the shallow groove is connected to an end portion of the first widthwise groove on one side in the tire circumferential direction.

11. A pneumatic tire having one or more circumferential main grooves extending in the tire circumferential direction on a tread surface, the pneumatic tire having a plurality of land portions partitioned between the circumferential main groove and a tread edge or between the circumferential main grooves, the pneumatic tire having a plurality of first widthwise grooves extending in the tire width direction in an outermost land portion as mounted on a vehicle, the outermost land portion being the land portion in the tire width direction on the outer side when mounted on a vehicle, and at least one end of the first widthwise grooves terminating within the outermost land portion as mounted on a vehicle, the first widthwise grooves and the second widthwise grooves being arranged alternately in the tire circumferential direction while being spaced apart from each other in the tire circumferential direction, one of the first widthwise grooves being paired with one of the second widthwise grooves adjacent to the one of the first widthwise grooves on one side in the tire circumferential direction, the one of the first widthwise grooves constituting the pair having a first portion extending from the inner side in the tire width direction toward the outer side to one side in the tire circumferential direction, a second widthwise groove of the pair extending from the inner side in the tire width direction toward the outer side to the other side in the tire circumferential direction, and an outer end in the tire width direction of the second widthwise groove of the pair being positioned outer in the tire width direction than an outer end in the tire width direction of the first widthwise groove of the pair.

12. The pneumatic tire according to claim 11, wherein both ends of the first widthwise groove terminate within the outermost land portion when mounted on a vehicle.

13. A pneumatic tire as set forth in claim 11 or 12, wherein the second widthwise groove communicates with an outer tread edge when mounted on a vehicle.

14. A pneumatic tire according to any one of claims 11 to 13, wherein the one first widthwise groove that constitutes the pair and the one second widthwise groove that constitutes the pair have an overlapping portion when projected in the tire circumferential direction.

15. A pneumatic tire according to any one of claims 11 to 14, wherein the one first widthwise groove further has a second portion extending from an inner end of the first portion in the tire width direction to one side in the tire circumferential direction, and at least a part of the first portion or at least a part of the second portion has a chamfered portion at an opening to the tread surface.

16. A pneumatic tire as described in claim 15, wherein, in a reference state in which the pneumatic tire is mounted on an applicable rim, inflated to a specified internal pressure, and no load is applied, the inclination angle of the tapered surface of the chamfered portion of the second portion relative to the tire radial direction is greater than the inclination angle of the tapered surface of the chamfered portion of the first portion relative to the tire radial direction.

17. A pneumatic tire according to any one of claims 11 to 16, wherein the first widthwise groove has one end terminating within the outermost land portion when mounted on the vehicle, and the second widthwise groove has at least one end terminating within the outermost land portion when mounted on the vehicle, and further comprises a shallow groove having one end communicating with the other end of the first widthwise groove, a groove depth of the shallow groove being shallower than the groove depth of the first widthwise groove, and the other end of the shallow groove communicating with the circumferential main groove.

18. The pneumatic tire according to claim 17, wherein the shallow grooves have a groove depth of 2.5 mm or less.

19. The pneumatic tire according to claim 17 or 18, wherein the shallow grooves extend at an inclination angle of 40 to 60 degrees with respect to the circumferential direction of the tire.

20. A pneumatic tire according to any one of claims 17 to 19, wherein the shallow groove is connected to an end portion of the first widthwise groove on one side in the tire circumferential direction.

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