pneumatic tires

Abstract

To provide a pneumatic tire having high design properties and capable of suppressing heat generation.SOLUTION: In a pneumatic tire 1 as one example of an embodiment, a tread 10 includes, in a tire axial end region including a ground contact edge E2, a plurality of first land portions 81 including a plurality of trapezoidal portions in plan view, which are formed at intervals in a tire circumferential direction and second land portions 82 including trapezoidal portions in plan view, which are formed alternately and side by side with the first land portions 81 in the tire circumferential direction. Sub grooves 85 are formed around the second land portion 82 from the three sides in the tread 10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, pneumatic tires with treads having a plurality of grooves extending in the tire circumferential direction or axial direction and a plurality of blocks defined by each groove have been widely known. For example, Patent Document 1 discloses a pneumatic tire including a center main groove extending continuously in a zigzag pattern in the tire circumferential direction, narrow grooves having a groove width smaller than that of the main groove, lateral grooves extending in the tire axial direction, and a plurality of blocks defined by each groove. In the tread pattern of the pneumatic tire disclosed in Patent Document 1, blocks that are pentagonal in plan view and blocks that are hexagonal in plan view are alternately arranged in the tire circumferential direction. Furthermore, each block is divided into small block pieces and large block pieces by a plurality of sipes, and the large and small block pieces are alternately arranged in the tire circumferential direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-37174 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 describes the effect of having the above-mentioned tread pattern, which allows for both good ice performance and good wear resistance. However, the pneumatic tire in Patent Document 1 does not take into consideration the suppression of heat generation during vehicle travel. Tire temperature rises due to tire deformation, friction, road surface temperature, and other factors during vehicle travel, and excessive temperature rise can impair tire performance. For this reason, it is an important issue to suppress heat generation by improving heat dissipation so that the tire temperature does not rise too much. Furthermore, there is a demand for tires that not only have such good performance but also have a high level of design.

[0005] An object of the present invention is to provide a pneumatic tire with an excellent design that can suppress heat generation. [Means for solving the problem]

[0006] The pneumatic tire of the present invention is a pneumatic tire having a tread, wherein the tread has, in an axial end region of the tire including the ground contact end of the tread, first lands including a plurality of trapezoidal portions in a plan view formed at intervals around the tire circumferential direction, and second lands including a trapezoidal portion in a plan view formed alternately with the first lands around the tire circumferential direction, the first and second lands being arranged so that their respective short sides face in opposite directions in the tire axial direction, and a first groove is formed surrounding the second land on three sides. [Effects of the Invention]

[0007] The pneumatic tire according to the present invention has a highly designable tread pattern and is excellent in heat generation suppression function. The tread pattern of the pneumatic tire according to the present invention is an innovative pattern characterized by an aggressive design, yet exhibits excellent heat dissipation properties. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a pneumatic tire according to an embodiment, showing the internal structure of the tire. [Figure 2] 1 is a plan view of a pneumatic tire as an example of an embodiment. [Figure 3] FIG. 3 is a diagram showing a part of a cross section taken along the line AA in FIG. 2. [Figure 4] FIG. 4 is an enlarged view of a portion F1 in FIG. 3. [Figure 5] FIG. 4 is an enlarged view of a portion F2 in FIG. 3. [Figure 6] FIG. 3 is a diagram showing a part of a cross section taken along the line BB in FIG. 2. [Figure 7] FIG. 3 is a diagram showing a part of a cross section taken along the line CC in FIG. 2. [Figure 8]FIG. 2 is a plan view of the second shoulder region. [Figure 9] FIG. 9 is a diagram showing a part of a cross section taken along the line DD in FIG. 8. [Figure 10] FIG. 9 is a diagram showing a part of a cross section taken along the line EE in FIG. 8. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an example of an embodiment of a pneumatic tire according to the present invention will be described in detail with reference to the drawings. The embodiment described below is merely an example, and the present invention is not limited to the following embodiment. Furthermore, the present invention includes configurations obtained by selectively combining the respective components of the multiple embodiments and modified examples described below.

[0010] FIG. 1 is a perspective view of a pneumatic tire 1 as an example of an embodiment. FIG. 1 also illustrates the internal structure of the pneumatic tire 1. As shown in FIG. 1, the pneumatic tire 1 has a tread 10, which is the portion that comes into contact with the road surface. The tread 10 has main grooves 20, 30 that extend in the tire circumferential direction and are formed in an annular shape along the tire circumferential direction. The main groove 20 does not bend in the tire axial direction, but is formed approximately straight along the tire circumferential direction. The main groove 30 extends in the tire circumferential direction while repeatedly bending in the tire axial direction.

[0011] The tread 10 has a center land 40 including a trapezoidal portion in a plan view, and a first quarter land 50 formed to surround three sides of the center land 40. The tread 10 also has a first shoulder land 60 including a trapezoidal portion in a plan view, a second quarter land 70 formed between the center land 40 and the first shoulder land 60, and a second shoulder region 80. The first shoulder land 60 is formed on one end side of the tread 10 in the tire axial direction, and the second shoulder region 80 is formed on the other end side of the tread 10 in the tire axial direction.

[0012] The tread 10 further has a groove-like depression 55 and a sub-groove 75 that separates the first shoulder land 60 and the second quarter land 70. The depression 55 is formed between the center land 40 and the first quarter land 50, and surrounds the center land 40 on three sides like a moat. The depression 55 is connected to the main groove 20 that separates the center land 40 and the second shoulder region 80, and is formed in a roughly U-shape in plan view. The sub-groove 75 extends from the tire axial center side of the tread 10 toward the contact edge E1, and is formed in a roughly U-shape in plan view.

[0013] The pneumatic tire 1 is, for example, a tire with a specified mounting direction relative to a vehicle. The tread 10 has a tread pattern that is asymmetrical with respect to the tire equator CL (see FIG. 2 ), and the pneumatic tire 1 is mounted on the vehicle in opposite directions on the right and left sides. The equator CL refers to a line along the tire circumferential direction that passes through the exact center of the tread 10 in the tire axial direction. The pneumatic tire 1 is preferably mounted on a vehicle so that the first shoulder land 60 is located on the inside of the vehicle. For convenience of explanation, the terms "left and right" are used in this specification, and these left and right refer to the left and right when the tire is mounted on the vehicle and viewed in the direction of travel of the vehicle.

[0014] The pneumatic tire 1 includes a pair of sidewalls 11 that bulge outward in the tire axial direction, and a pair of beads 12. The beads 12 are fixed to the rim of a wheel and include a bead core 17 and a bead filler 18. The sidewalls 11 and the beads 12 are formed in an annular shape along the tire circumferential direction, and constitute the side surfaces of the pneumatic tire 1. The sidewalls 11 extend radially from both axial ends of the tread 10.

[0015] The pneumatic tire 1 may have side ribs 13 formed between the ground contact edges E1, E2 of the tread 10 and the portions of the sidewalls 11 that protrude most axially outward. The ground contact edge E1 is the ground contact edge on the first shoulder land 60 side, and the ground contact edge E2 is the ground contact edge on the second shoulder region 80 side. The side ribs 13 protrude axially outward and are formed in an annular shape along the circumferential direction of the tire. The portions of the pneumatic tire 1 from the ground contact edges E1, E2 or their vicinity to the left and right side ribs 13 are also called shoulder or buttress regions.

[0016] The tread 10 and the sidewall 11 are generally made of different types of rubber. The shoulder may be made of the same rubber as the tread 10, or a different rubber. In this specification, the contact edges E1 and E2 are defined as both axial ends of the area that comes into contact with a flat road surface when an unused pneumatic tire 1 is mounted on a standard rim and inflated to a standard internal pressure, and a predetermined load is applied. In the case of passenger car tires, the predetermined load is a load equivalent to 88% of the standard load.

[0017] Here, a "regular rim" is a rim specified by the tire standard, and is a "standard rim" for JATMA and a "measuring rim" for TRA and ETRTO. "Regular internal pressure" is the "maximum air pressure" for JATMA, the maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table for TRA, and "INFLATION PRESSURE" for ETRTO. The regular internal pressure is usually 180 kPa for passenger car tires, but 220 kPa for tires labeled "Extra Load" or "Reinforced." "Regular load" is the "maximum load capacity" for JATMA, the maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table for TRA, and "LOAD CAPACITY" for ETRTO. For racing kart tires, the regular load is 392 N.

[0018] The pneumatic tire 1 includes a carcass 14, a belt 15, and an inner liner 16. The carcass 14 is a cord layer coated with rubber, and forms the skeleton of the pneumatic tire 1 that can withstand loads, impacts, air pressure, etc. The belt 15 is a reinforcing band that is placed between the carcass 14 and the rubber that makes up the tread 10. The belt 15 tightly fastens the carcass 14, increasing the rigidity of the pneumatic tire 1. The inner liner 16 is a rubber layer provided on the inner surface of the carcass 14, and maintains the air pressure of the pneumatic tire 1.

[0019] When the pneumatic tire 1 is used as a directional tire with a specified mounting direction on a vehicle, the pneumatic tire 1 preferably has a marking for indicating the mounting direction on the vehicle. The marking for indicating the mounting direction may be an arrow indicating the main rotation direction of the tire, and its configuration is not particularly limited. Generally, symbols called serial numbers are provided on the side of the pneumatic tire 1, and serial numbers may also be used as a marking for indicating the mounting direction.

[0020] The serial number includes information such as a size code, manufacturing date (manufacturing year and week), and manufacturing location (manufacturing factory code). The mounting direction of the pneumatic tire 1 on the vehicle may be specified by providing a serial number only on the side (sidewall 11) of the pneumatic tire 1 facing outward from the vehicle, or by providing different serial numbers on the side facing outward and the side facing inward from the vehicle. A specific example is providing a manufacturing factory code and a size code on both sides of the pneumatic tire 1, and providing the manufacturing year and week only on the side facing outward from the vehicle.

[0021] The tread pattern of the pneumatic tire 1 will be described in detail below with reference to FIG. 2. FIG. 2 is a plan view of the pneumatic tire 1 (tread 10). In FIG. 2, the upper surface of each land is indicated by dot hatching. The upper surface of the land is a surface along the profile surface α (see FIG. 4, etc.), and the range from the ground contact edge E1 to E2 is the contact surface that comes into contact with the road surface. The profile surface α is a surface along the outer peripheral surface of the tread 10.

[0022] As shown in Figure 2, the tread 10 has two main grooves 20, 30 extending in the tire circumferential direction, a groove-like depression 55 surrounding three sides of the center land 40, a secondary groove 75 surrounding three sides of the first shoulder land 60, and multiple lands defined by the grooves. The lands are portions that protrude radially outward from the tire. Generally, circumferentially continuous lands are called "ribs," while circumferentially discontinuous lands separated by grooves are called "blocks." The tread 10 has multiple lands that constitute the center land 40, first quarter land 50, first shoulder land 60, second quarter land 70, and second shoulder region 80.

[0023] The main groove 20 is formed between the center land 40 and the second shoulder region 80 on the side of the tread edge E2, and extends approximately straight along the tire circumferential direction. In this embodiment, the center land 40 and the first quarter land 50 are alternately arranged in the tire circumferential direction on the equator CL via recesses 55. The main groove 20 is formed in the tread 10 so as to separate the center land 40, the first quarter land 50, and the second shoulder region 80.

[0024] The main groove 30 is formed between the center land 40 and the first shoulder land 60 on the side of the tread edge E1, and extends in the tire circumferential direction while repeatedly bending in the tire axial direction. In this embodiment, the first quarter land 50 and the second quarter land 70 are interposed between the center land 40 and the first shoulder land 60. The first quarter land 50 and the second quarter land 70 are ribs that are continuous in the tire circumferential direction, and extend in the tire circumferential direction while bending in the tire axial direction so as to avoid the center land 40 and the first shoulder land 60. The main groove 30 is formed in the tread 10 so as to separate the first quarter land 50 and the second quarter land 70.

[0025] In this embodiment, the center land 40 is formed as a block that is trapezoidal in plan view and is not continuous in the tire circumferential direction, and multiple blocks are formed at intervals in the tire circumferential direction. Similarly, the first shoulder land 60 is a block that is trapezoidal in plan view and multiple blocks are formed at intervals in the tire circumferential direction. Note that the center land 40 and the first shoulder land 60 may be ribs that include a portion that is trapezoidal in plan view, like the first land 81 described below that constitutes the second shoulder region 80.

[0026] The main groove 20 includes a first portion 23, which is a portion including a plurality of narrow grooves 21 formed at a predetermined interval on the groove bottom, and a second portion 24, which is a portion without the plurality of narrow grooves 21 and is arranged alternately with the first portion 23 in the tire circumferential direction. The plurality of narrow grooves 21 formed at a predetermined interval on the groove bottom has the function of reducing noise generated from the tire while the vehicle is traveling. By arranging the first portions 23 of the main groove 20 at intervals in the tire circumferential direction, the noise reduction effect becomes more pronounced. In addition, the plurality of narrow grooves 21 enhances shadows, improving design and contributing to reducing the amount of rubber used.

[0027] Similar to the main groove 20, the main groove 30 has a first portion 33, which is a portion including a plurality of narrow grooves 31 formed at a predetermined interval at the groove bottom, and a second portion 34 where the plurality of narrow grooves 31 are not present. The main groove 30 is configured such that the first portions 33 and the second portions 34 are alternately arranged in the tire circumferential direction. The first portions 33 contribute to reducing tire noise, improving design, reducing the amount of rubber used, and the like. In this embodiment, the first portions 23 of the main groove 20 and the first portions 33 of the main groove 30 are arranged side by side in the tire axial direction. In this case, for example, the noise reduction effect becomes more pronounced, and the design becomes more cohesive, giving a sophisticated impression.

[0028] The tread 10 is formed with a first shoulder land 60, a second quarter land 70, a first quarter land 50, a center land 40, and a second shoulder region 80, in that order from the ground contact edge E1. As described above, the center land 40 and the first shoulder land 60 are not continuous in the tire circumferential direction, but are formed as a plurality of land sections spaced apart in the tire circumferential direction. The first quarter land 50 and the second quarter land 70 are ribs that are continuous in the tire circumferential direction and are formed in an annular shape along the tire circumferential direction.

[0029] The center land 40 and the first shoulder land 60 are trapezoidal in plan view and are arranged in a line in the tire circumferential direction. The first shoulder lands 60 are formed alternately with the center lands 40 in the tire circumferential direction on the contact edge E1 side of the tread 10. Part of the center land 40 and part of the first shoulder lands 60 overlap in the tire circumferential direction, and the first quarter lands 50, second quarter lands 70, and main grooves 30 are formed in a zigzag shape between the center land 40 and the first shoulder lands 60.

[0030] The center land 40 and the first shoulder land 60 are arranged so that the short and long sides, which are the bases of the trapezoids, are aligned in the tire circumferential direction. That is, the oblique sides of each trapezoid are inclined in the tire circumferential and axial directions. By aligning the trapezoidal lands in this way, stable traction performance is achieved. The short and long sides of the trapezoid are also called the upper base and lower base, respectively. Furthermore, the center land 40 and the first shoulder land 60 are arranged so that the short sides of each trapezoid are on the main groove 30 side. In this case, it is easy to regularly arrange the center land 40 and the first shoulder land 60 along the tire circumferential direction.

[0031] The center land 40 may be the same size as the first shoulder land 60 or may be larger than the first shoulder land 60, but in this embodiment, it is formed slightly smaller than the first shoulder land 60. As will be described in detail later, a first inclined surface 41, a second inclined surface 42, and third inclined surfaces 43 and 44 are formed along the short side, long side, and oblique side of the trapezoid of the center land 40, respectively. Similarly, a inclined surface 61 is formed along the short side of the trapezoid of the first shoulder land 60.

[0032] The center land 40 is surrounded by a groove-shaped depression 55 and the main groove 20. The depression 55 is formed in a roughly U-shape in plan view along the slopes 41, 43, and 44, and surrounds the center land 40 together with the main groove 20 extending along the slope 42. Each slope of the center land 40 constitutes part of the groove wall and groove bottom of the depression 55 and the main groove 20. A first quarter land 50 is formed outside the depression 55 so as to sandwich the depression 55 together with the center land 40.

[0033] The first quarter land 50 includes a first zone 51 formed along a recess 55 so as to be convex toward the ground contact edge E1, and a second zone 52 extending straight in the tire circumferential direction, and has a shape in which the first zones 51 and the second zones 52 are repeated alternately. The main groove 30 is formed along the first quarter land 50, and the second quarter land 70 is formed so as to face the first quarter land 50 across the main groove 30.

[0034] The second quarter land 70, like the first quarter land 50, includes a first zone 71 formed to be convex toward the ground contact edge E1 and a second zone 72 extending straight in the tire circumferential direction. The first zone 71 is formed between the first shoulder lands 60 adjacent in the tire circumferential direction and extends beyond the ground contact edge E1.

[0035] In the tread 10, a secondary groove 75 is formed along the short sides and oblique sides of the trapezoid of the first shoulder land 60, surrounding three sides of the trapezoid. The secondary groove 75 is formed in a roughly U-shape in plan view, and separates the first shoulder land 60 from the second quarter land 70. The secondary groove 75 extends axially outward from the equator CL side of the tread 10, and is formed to a position beyond the ground contact edge E1. In other words, the trapezoid of the first shoulder land 60 is formed by the ground contact edge E1 and the secondary groove 75 connected to the ground contact edge E1.

[0036] The second shoulder region 80, in the tire axial end region R2 including the ground contact edge E2 of the tread 10, has first lands 81 including a plurality of trapezoidal portions in a plan view formed at intervals in the tire circumferential direction, and second lands 82 including trapezoidal portions in a plan view formed alternately with the first lands 81 in the tire circumferential direction. The trapezoidal portions of the first lands 81 and the second lands 82 are arranged so that their short sides face in opposite directions in the tire axial direction. In addition, a sub-groove 85, which is a first groove, is formed in the tire axial end region R2 of the tread 10 so as to surround the second land 82 on three sides. By adopting this configuration, heat dissipation is effectively improved, and the temperature rise of the tire during vehicle travel is suppressed.

[0037] In the tire axial end region R2 of the tread 10, a secondary groove 86 extending in the tire circumferential direction is formed axially outward of the first land 81 and the second land 82. By providing the secondary groove 86, the heat generation suppression effect becomes more pronounced. A third land 83 is formed adjacent to the first land 81 in the tire axial direction, separated by the secondary groove 86. The third land 83 is a long, narrow block extending in the tire circumferential direction, and the upper surface of the third land 83 becomes the ground contact edge E2.

[0038] In this embodiment, first portions 81a of first lands 81 adjacent in the tire circumferential direction are connected via second portions 81b formed between sub-grooves 85 and 86. The first portions 81a have a trapezoidal shape in a plan view. The second portions 81b have an elongated shape extending in the tire circumferential direction, and by connecting the two first portions 81a, the rigidity of the second shoulder region 80 is increased. As will be described in detail later, the sub-groove 85 is a groove that is approximately U-shaped in a plan view and is not connected to the main groove 20 or the sub-groove 86, and multiple sub-grooves 85 are formed independently in the tire circumferential direction.

[0039] Hereinafter, each component of the tread pattern will be described in further detail with reference to Figures 3 to 10 as appropriate in addition to Figure 2. Figures 3, 6, and 7 are partial cross-sections taken along lines AA, BB, and CC in Figure 2, respectively. Figure 4 is an enlarged view of a portion F1 in Figure 3, and Figure 5 is an enlarged view of a portion F2 in Figure 3. Figure 8 is a plan view of the second shoulder region 80. Figure 9 is a cross-section taken along line DD in Figure 8, and Figure 10 is a cross-section taken along line EE in Figure 8.

[0040] [Main groove 20,30] As shown in FIG. 2 , the main grooves 20 and 30 are formed on both sides of the equator CL and extend in the tire circumferential direction without intersecting the equator CL. The main grooves 20 and 30 are formed to sandwich the center land 40 and the first quarter land 50, which are located at the axial center of the tread 10, from the left and right sides. As described above, the main groove 20 is formed substantially straight along the tire circumferential direction, while the main groove 30 extends in a zigzag pattern along the tire circumferential direction. The depths of the main grooves 20 and 30 are not constant along the tire circumferential direction; for example, shallow and deep portions are regularly repeated. The deepest points of the main grooves 20 and 30 are deeper than the deepest points of the recesses 55 and the sub-grooves 75.

[0041] The main groove 20 has a plurality of narrow grooves 21 formed at its bottom, and the first portion 23, which has the function of reducing tire noise, is formed slightly wider than the second portion 24. The first portion 23 includes a first region 25a in which the plurality of narrow grooves 21 are formed, and a second region 25b that slopes so as to become gradually deeper toward the first region 25a. The first region 25a is formed adjacent to the second shoulder region 80, and the second region 25b is formed adjacent to the first region 25a on the equator CL side. The first region 25a is formed in a trapezoidal shape in a plan view that is elongated along the main groove 20, with the base of the trapezoid parallel to the tire circumferential direction and the short side facing the equator CL. The inclination angle of the second region 25b with respect to the profile surface α of the tread 10 is, for example, 30° to 70°.

[0042] Each first portion 23 of the main groove 20 is adjacent to the second zone 52 of the first quarter land 50, and each second portion 24 is adjacent to the center land 40. That is, the first portion 23 and the second portion 24 of the main groove 20 are formed along the tire circumferential direction at the same repeating unit length (pitch) as the land at the tire axial center of the tread 10. Similarly, the first portion 33 and the second portion 34 of the main groove 30 are formed at the same pitch as the land at the tire axial center of the tread 10.

[0043] The main groove 30 is formed wider in a first portion 33, where a plurality of narrow grooves 31 are formed at the groove bottom, than in a second portion 34. The plurality of narrow grooves 31 are formed across the entire width of the main groove 30, and the first portion 33 is formed as a trapezoid in a plan view as a whole. The trapezoid of the first portion 33 has a base parallel to the tire circumferential direction and a short side facing the equator CL. The second portion 34 is a narrow groove portion extending along the first zone 51 of the first quarter land 50, and is formed in a roughly U-shape in a plan view so as to be convex toward the tread edge E1.

[0044] The multiple fine grooves 21, 31 may be formed in a random pattern, for example, with different groove widths and in different directions. However, to achieve a stable noise reduction effect and enhance design, it is preferable that they be formed with a certain degree of regularity. The fine grooves 21, 31 may extend in a direction intersecting the tire axial direction and circumferential direction, but in this embodiment, they are formed along the tire axial direction or circumferential direction. Noise generated by a pneumatic tire 1 is broadly divided into road noise and pattern noise. The fine grooves 21, 31 reduce noise generated by the tire by shifting the frequency band of pattern noise.

[0045] The multiple narrow grooves 21 are formed, for example, parallel to one another, and the first portion 23 has an uneven groove bottom structure formed by alternating narrow grooves 21 and ribs 22 sandwiched between the multiple narrow grooves 21 (the same applies to the narrow grooves 31). The narrow grooves 21, 31 extend in the tire axial direction at the tire circumferential center of the first portion 23, 33, and extend in the tire circumferential direction at both ends of the first portion 23, 33. In this case, the frequency band of pattern noise can be shifted more effectively, resulting in a more pronounced noise reduction effect. The design also gives an impression of novelty and sophistication. The narrow grooves 21, 31 may be bent midway and have a portion extending in the tire circumferential direction and a portion extending in the tire axial direction.

[0046] As shown in FIGS. 3 to 5 , the second portion 24 of the main groove 20 and the second portion 34 of the main groove 30 are arranged side by side in the tire axial direction, separated by the center land 40, the recess 55, and the first quarter land 50. The second portion 24 of the main groove 20 has a slope 26 that gradually deepens toward the tread edge E2 and a side groove 27 that extends along the second shoulder region 80. The side groove 27 extends straight in the tire circumferential direction and, like the second portion 34 of the main groove 30, is formed with a narrow width and deep depth. In this embodiment, the bottom of the side groove 27 and the bottom of the narrow groove 21 are formed to the same depth, forming the deepest portion of the main groove 20. Furthermore, the bottom of the narrow groove 31 of the main groove 30 and the bottom of the second portion 34 are formed to the same depth, forming the deepest portion of the main groove 30.

[0047] The groove depth of the second portion 24 gradually deepens from the center land 40 side toward the second shoulder region 80 side. The slope 42 of the center land 40 that forms the groove wall of the second portion 24 is inclined at an angle θ2 with respect to the profile plane α. The slope 26 is formed from the lower end of the slope 42 to the side gutter 27 with a width exceeding 50% of the width of the second portion 24. The slope 26 is inclined at an angle θ5 with respect to a plane β that is parallel to the profile plane α. The angle θ5 is smaller than the angle θ2, and the slope 26 has a gentler slope than the slope 42.

[0048] As shown in Figure 7, the first portion 23 of the main groove 20 and the first portion 33 of the main groove 30 are arranged side by side in the tire axial direction, separated by the second zone 52 of the first quarter land 50. In the first portions 23, 33, the narrow grooves 21, 31 are formed to the same depth, and the ribs 22, 32 are formed to the same height. Below, the configuration of the groove bottom uneven shape will be further explained using the first portion 23 as an example.

[0049] An example of the depth of the narrow groove 21 is 0.5 mm to 2 mm. In other words, the depth of the narrow groove 21 is the height of the rib 22 from the bottom of the narrow groove 21. The upper surface of the rib 22 is formed to a depth approximately equal to that of the slope 26 of the second portion 24 of the main groove 20, and can be considered as the first groove bottom of the main groove 20. The upper surface of the rib 22 may be inclined like the second region 25b, but in this embodiment, it is formed parallel to the profile surface α. The bottom of the narrow groove 21 is approximately equal to the depth of the bottom of the side groove 27 of the second portion 24, and can be considered as the second groove bottom. In other words, the main groove 20 is formed to a depth of at least two stages.

[0050] The widths of the multiple narrow grooves 21 may be different from one another, but in this embodiment, each narrow groove 21 is formed with the same width W. An example of the width of the narrow groove 21 is 0.1 mm to 0.5 mm. The width of the rib 22 may be equal to or less than the width W of the narrow groove 21, but in this embodiment, it is larger than the width W of the narrow groove 21. From the standpoint of design and land durability, a suitable example of a groove bottom uneven structure is a structure in which the intervals between the narrow grooves 21 are uniform (the width of the ribs 22 is constant) and the width of the ribs 22 is larger than the width of the narrow groove 21. The multiple narrow grooves 21 may be formed at intervals equivalent to at least 10% of the groove width from the side wall of the main groove 20. In this case, the load transmitted from the land to the rib 22 is reduced, and the stability of the groove bottom uneven shape is improved.

[0051] The tread 10 is provided with a wear indicator (not shown). The wear indicator is a protrusion disposed on the bottom of at least one of the main grooves 20, 30, and serves as an indicator for checking the wear level of the tread rubber. The height of the ribs 22, 32 is preferably equal to or less than the height of the wear indicator, and is particularly preferably equal to the height of the wear indicator. In this case, even if the tread rubber wears down to the height of the wear indicator, the noise reduction function, i.e., the uneven structure of the groove bottom, can be maintained.

[0052] [Center Land 40] As shown in FIG. 2, the center land 40 is a trapezoidal block in a plan view formed at the center of the tread 10 in the tire axial direction, with slopes along each side of the trapezoid. The center land 40 may have any shape as long as its upper surface (contact surface) is trapezoidal. The trapezoid may be substantially trapezoidal, for example, it may be approximately trapezoidal with chamfered and rounded corners. The center land 40 is arranged with the short side of the trapezoid facing the contact edge E1 and the long side facing the contact edge E2, with the short side and long side parallel to the tire circumferential direction. The long side of the trapezoid of the center land 40 is located closer to the equator CL than the short side.

[0053] The trapezoidal hypotenuse of the center land 40 is inclined with respect to the tire circumferential direction and the axial direction. The two hypotenuses of the trapezoid are inclined away from each other in the tire axial direction from the ground contact edge E1 side to the ground contact edge E2 side, but for example, the inclination angle of each hypotenuse with respect to the tire axial direction is the same, and the length of each hypotenuse is also the same. Third inclined surfaces 43, 44 are formed along the trapezoidal hypotenuse at both ends of the center land 40 in the tire circumferential direction. The inclined surfaces 43, 44 are formed to be the same size as each other.

[0054] As described above, the center lands 40 are arranged in a row in the tire circumferential direction at equal intervals. Here, "equal intervals" includes not only completely equal intervals but also cases where they are considered to be substantially equal intervals. By arranging the center lands 40 at equal intervals, stable traction performance can be ensured. The interval between adjacent center lands 40 in the tire circumferential direction (the shortest distance between the slope 43 of the first center land 40 and the slope 44 of the second center land 40) is, for example, longer than the length of the short side of the trapezoid of the center land 40 and shorter than the length of the long side of the trapezoid. An example of the number of center lands 40 along the tire circumferential direction is 20 to 30.

[0055] As shown in FIGS. 4 to 6, the inclination angles of the slopes relative to the profile surface α along the outer peripheral surface of the tread 10 gradually increase in the order of the third slopes 43 and 44, the first slope 41, and the second slope 42 (θ3, θ4 < θ1 < θ2). The inclination angles θ3 and θ4 of the slopes 43 and 44 relative to the profile surface α may be different from each other, but are the same in this embodiment. That is, the slopes 43 and 44 facing the tire circumferential direction have a gentle inclination, while the slopes 41 and 42 facing the tire axial direction have a steep inclination. In this case, traction performance can be improved while maintaining good ride comfort. In particular, increasing the inclination angle θ2 of the slope 42 facing outward from the vehicle improves cornering power (CP), for example.

[0056] The inclination angle θ1 of the slope 41 with respect to the profile surface α is preferably 30° to 70°, and more preferably 40° to 60°. The inclination angle θ2 of the slope 42 with respect to the profile surface α is preferably 60° to 80°, and more preferably 65° to 75°. The inclination angle θ3 of the slope 43 with respect to the profile surface α is preferably 20° to 50°, and more preferably 25° to 45°. If the inclination angles of the slopes of the center land 40 are within the above ranges, good ride comfort and traction performance can be more effectively achieved.

[0057] [First Quarter Riku 50] As shown in FIG. 2, the first quarter land 50 is formed to surround the center land 40 on three sides, with a recess 55 between them, and is continuous in the tire circumferential direction along the main groove 30. The first zone 51 of the first quarter land 50 is formed in a narrow strip shape with a constant width, and extends along the short side and two oblique sides of the trapezoid of the center land 40, with the recess 55 between them. The first zone 51 is formed in a roughly U-shape in plan view, convex toward the ground contact edge E1. The second zone 52 of the first quarter land 50 extends in the tire circumferential direction between each center land 40, connecting the two first zones 51.

[0058] The height of the first quarter land 50 is preferably equal to or less than the height of the center land 40 and higher than the height of the wear indicator. In this specification, the height of the land means the shortest distance from the reference surface of the tread 10 along the deepest part of the main grooves 20, 30 to the ground surface (the same applies to the wear indicator). In this embodiment, the first quarter land 50 is formed at the same height as the center land 40, and the upper surface of the first quarter land 50 forms the contact surface that comes into contact with the road surface.

[0059] As shown in Figures 3 and 4, the first zone 51 of the first quarter land 50 is sandwiched between the main groove 30 and the depression 55. By providing the first quarter land 50 between the main groove 30 and the depression 55, the overall land rigidity of the tread 10 can be increased while ensuring good drainage. In addition, the contact area is increased, improving, for example, traction performance and braking performance. The width of the first zone 51 is not particularly limited, but in this embodiment, it is narrower than the width of the depression 55 and wider than the width of the second portion 34 of the main groove 30.

[0060] As shown in Figure 6, on the equator CL of the tread 10, second zones 52 of center lands 40 and first quarter lands 50 are alternately arranged along the tire circumferential direction, separated by recesses 55. The length of the center land 40 along the tire circumferential direction is longer on the main groove 20 side and shorter on the main groove 30 side, while the length of the second zone 52 along the tire circumferential direction is shorter on the main groove 20 side and longer on the main groove 30 side. On the equator CL, the length of the center land 40 along the tire circumferential direction is longer than the length of the second zone 52 along the tire circumferential direction.

[0061] As shown in FIG. 7, the second zone 52 of the first quarter land 50 is sandwiched on both sides of the tire in the axial direction by the first portions 23, 33, where the main grooves 20, 30 are wider. The distance between the main grooves 20, 30 is smallest in the first portions 23, 33. The second zone 52 is formed wider than the first portions 23, 33. In this case, the rigidity of the land of the tread 10 is increased in the area where the two main grooves are closer to each other, effectively improving the durability of the land. Furthermore, the second zone 52 is reinforced by the ribs 22, 32 formed in the first portions 23, 33.

[0062] [Recess 55] As shown in FIG. 2, the recess 55 extends in a groove shape along the short sides and oblique sides of the trapezoid of the center land 40, and is formed in a roughly U-shape in plan view. Both ends of the recess 55 on the ground contact edge E2 side are connected to the main groove 20, allowing rainwater and the like around the center land 40 to flow into the main groove 20. The recess 55 is formed wider along the slope than along the short sides of the trapezoid of the center land 40, and the width gradually increases as it approaches the main groove 20. In this case, the drainage performance at the axial center of the tread 10 is improved.

[0063] The recesses 55 extend from the main groove 20 toward the ground contact edge E1 and are formed in the tire circumferential direction to positions that overlap with the secondary grooves 75. The secondary grooves 75 are formed at one axial end of the tread 10 at intervals in the tire circumferential direction, and the recesses 55 are formed so as to enter between the secondary grooves 75 that are adjacent in the tire circumferential direction. By arranging the recesses 55 and the secondary grooves 75 so that they overlap in the tire circumferential direction, drainage can be more effectively improved.

[0064] As shown in Figures 3, 4, and 6, the depth of the recess 55 is shallower than the main grooves 20 and 30, and gradually deepens as it approaches the main groove 20. In this case, drainage can be improved while ensuring the durability of the center land 40 and the first-quarter land 50. The widthwise depth of the recess 55 gradually deepens along the trapezoidal slope of the center land 40, and is deepest at the bottom end of the slope. It is preferable that the shallowest part of the recess 55 is deeper than the top surface of the wear indicator.

[0065] [First Shoulder Land 60] As shown in FIG. 2, the first shoulder land 60 is a trapezoidal land formed at one axial end of the tread 10 in a plan view, and has a slope 61 along at least its short side. The pneumatic tire 1 is preferably mounted on a vehicle so that the first shoulder land 60 is located on the inside of the vehicle. The first shoulder land 60 only needs to have a shape whose contact patch is substantially trapezoidal. The short sides and oblique sides of the trapezoid of the first shoulder land 60 are formed by the secondary grooves 75, and the contact edge E1 is the long side of the trapezoid.

[0066] The first shoulder land 60 is disposed with the short side of the trapezoid facing the equator CL and the short side and long side parallel to the tire circumferential direction. The trapezoidal hypotenuse of the first shoulder land 60 is inclined with respect to the tire circumferential direction and the axial direction, similar to the center land 40. The two hypotenuses of the trapezoid are inclined away from each other in the tire axial direction from the equator CL toward the ground contact edge E1. However, for example, the inclination angle of each hypotenuse with respect to the tire axial direction is the same, and the length of each hypotenuse is also the same. A slope may be formed along the hypotenuse of the trapezoid of the first shoulder land 60.

[0067] The first shoulder lands 60 are formed between adjacent center lands 40 in the tire circumferential direction and over a position overlapping the center lands 40 in the tire circumferential direction. In this case, the land rigidity of the tread 10 as a whole can be increased, and stable land durability and traction performance can be achieved. The contact area of ​​the first shoulder lands 60 may be larger than the contact area of ​​the center lands 40, for example, 1.1 to 1.5 times. The first shoulder lands 60 are formed in the tire circumferential direction at the same pitch and in the same number as the center lands 40.

[0068] As shown in Figure 7, the slope 61 along the short side of the trapezoid of the first shoulder land 60 may be formed to a depth equal to or greater than that of the ribs 22, 32 of the main grooves 20, 30. The slope 61 forms the groove wall and groove bottom of the secondary groove 75, and the depth of the secondary groove 75 is deepest at the bottom end of the slope 61. The inclination angle of the slope 61 with respect to the profile plane α may be greater than the inclination angle of the second region 25b of the main groove 20 and less than the inclination angle θ2 of the slope 42 of the center land 40. Increasing the inclination angle of the slope 61 facing outward from the vehicle can improve, for example, the CP characteristics.

[0069] [2nd Quarter Riku 70] As shown in FIG. 2, the second quarter land 70 is formed to surround the first shoulder land 60 on three sides, with the sub-groove 75 separating them. Like the first quarter land 50, the second quarter land 70 is formed along the main groove 30 and continues in the tire circumferential direction. The first zone 71 of the second quarter land 70 extends from the equator CL side toward the ground contact edge E1, between the first shoulder lands 60 adjacent in the tire circumferential direction, and beyond the ground contact edge E1. The second zone 72 of the second quarter land 70 extends along the tire circumferential direction between the center lands 40 and connects the two first zones 71.

[0070] The second quarter land 70 is formed at the same height as the center land 40 and the first shoulder land 60, and the upper surface of the second quarter land 70 forms a contact surface that comes into contact with the road surface. The first zone 71 of the second quarter land 70 includes a first portion that gradually expands in the tire circumferential direction from the contact edge E1 side toward the equator CL side, and a second portion that branches into two from the first portion along the main groove 30.

[0071] As shown in FIG. 7 , the second zone 72 of the second quarter land 70 is sandwiched between the first portion 33 of the main groove 30 and the secondary groove 75, and is formed parallel to the second zone 52 of the first quarter land 50. The width of the second zone 72 is, for example, equal to the width of the secondary groove 75 and narrower than the width of the first portion 33. In this embodiment, the second zones 52 and 72 are connected by the rib 32 of the first portion 33. In addition, the sidewalls of the second zone 72, which form the groove wall and groove bottom of the secondary groove 75, are gently inclined toward the first shoulder land 60. This ensures high durability of the land even in the wider groove portions.

[0072] [minor groove 75] As shown in FIG. 2, the secondary grooves 75 extend along the short sides and oblique sides of the trapezoid of the first shoulder land 60, forming a roughly U-shaped shape in a plan view. The secondary grooves 75 are wider between the short sides of the trapezoid and the second quarter land 70 than in other portions. The secondary grooves 75 are formed at equal intervals around the tire circumference and are not connected around the tire circumference or to the main grooves 30. The secondary grooves 75 extend from the tire axial center of the tread 10 to a position beyond the contact edge E1, allowing rainwater and the like to be easily drained from the center. In this case, good drainage performance can be achieved while maintaining high land rigidity.

[0073] In this embodiment, as described above, portions of the recesses 55 and portions of the sub-grooves 75 overlap in the tire circumferential direction, and the recesses 55 and the sub-grooves 75 are formed so as to be alternately arranged in the tire circumferential direction. That is, the recesses 55 and the sub-grooves 75 are arranged in a staggered pattern along the tire circumferential direction, similar to the arrangement of the center land 40 and the first shoulder land 60. Furthermore, the main groove 30 is formed between the recesses 55 and the sub-grooves 75, with the first quarter land 50 and the first shoulder land 60 interposed therebetween. This makes it easy to achieve both high land rigidity and good drainage.

[0074] As shown in Figure 7, in the wider portion of the secondary groove 75, i.e., the portion located between the short side of the trapezoid of the first shoulder land 60 and the second quarter land 70, slopes are formed from both sides of the width of the secondary groove 75 toward the groove bottom. The slopes are the slope 61 formed along the short side of the first shoulder land 60 and the inclined sidewall of the second zone 72 of the second quarter land 70. The slope 61 has a larger inclination angle with respect to the profile plane α than the sidewall of the second zone 72.

[0075] [Second shoulder region 80] As shown in FIG. 2, the second shoulder region 80 is composed of multiple lands of different shapes and is formed in the axial end region R2 of the tread 10. The axial end region R2 is a region that includes the ground contact edge E2, and refers to, for example, one-third of the region that includes the ground contact edge E2 when the range from ground contact edges E1 to E2 is divided into three equal parts in the axial direction of the tire. In other words, the second shoulder region 80 is formed in a region that is one-third of the ground contact width from the ground contact edge E2. The second shoulder region 80 may be formed from a position adjacent to the main groove 20 to a position beyond the ground contact edge E2.

[0076] As described above, the tread 10 has a plurality of trapezoidal center lands 40 in a plan view formed on the equator CL at intervals in the tire circumferential direction, and main grooves 20 extending in the tire circumferential direction and separating the center lands 40 from the first lands 81 and second lands 82 that constitute the second shoulder region 80. In this embodiment, the center lands 40 and the second lands 82 are arranged opposite each other via the main groove 20. The midpoints of the bases of the center lands 40 and the second lands 82 may be aligned in the tire axial direction. For example, a plurality of second lands 82 are arranged in the tire circumferential direction at the same pitch as the center lands 40.

[0077] In this embodiment, the second land 82 is formed as a block that is trapezoidal in plan view and is not continuous in the tire circumferential direction, and multiple second land 82 are formed at intervals in the tire circumferential direction. On the other hand, the first land 81 includes a first portion 81a that is trapezoidal in plan view and a second portion 81b that is formed between the sub-grooves 85, 86 and connects the first portions 81a that are adjacent in the tire circumferential direction, and has a rib shape that is continuous in the tire circumferential direction as a whole. Note that the first land 81 is not limited to the form of a rib and may be formed as a block.

[0078] 8 to 10, the second shoulder region 80 includes a plurality of lands: a first land 81, a second land 82, and a third land 83, which are defined by secondary grooves 85 and 86. The first portion 81a of the first land 81 and the second land 82 are trapezoidal in plan view, and are alternately arranged in the tire circumferential direction, with the short side of the first portion 81a facing the main groove 20 and the short side of the second land 82 facing the tread edge E2. The third land 83 is aligned axially with the first portion 81a of the first land 81 across the secondary groove 86, and the second portion 81b of the first land 81 is aligned axially with the second land 82 across the secondary groove 85.

[0079] The first portion 81a and the second land 82 of the first land 81 may have any shape as long as their contact surfaces are trapezoidal or approximately trapezoidal. In the example shown in Fig. 8, the first portion 81a is approximately trapezoidal in plan view, but the long sides of the first portion 81a are slightly bent toward the short sides near both ends, and the center portion of the long sides slightly protrudes toward the contact edge E2. The base of the trapezoid of each land is formed along the tire circumferential direction, and the short sides of the first portion 81a and the long sides of the second land 82 are formed on the same straight line along the edge of the main groove 20. The oblique sides of the trapezoid of each land are inclined with respect to the tire circumferential direction and the axial direction.

[0080] In this embodiment, a thin and long second portion 81b extending in the tire circumferential direction is connected to the oblique side of the first portion 81a, connecting the first portions 81a arranged between the second lands 82. The second portion 81b is sandwiched between the sub-grooves 85, 86 and extends along the short side of the second land 82. In the example shown in FIG. 8 , the second portion 81b is connected to a portion of the first portion 81a close to the ground contact edge E2, but the second portion 81b may be connected closer to the main groove 20. Alternatively, a configuration without the second portion 81b is possible, but it is preferable to provide the second portion 81b in consideration of the durability, heat dissipation, etc. of the block.

[0081] The first portion 81a of the first land 81 gradually becomes smaller toward the main groove 20, while the second land 82 gradually becomes larger toward the main groove 20. In other words, the first portion 81a gradually becomes larger toward the ground contact edge E2, and the second land 82 gradually becomes smaller toward the ground contact edge E2. The first portion 81a is formed, for example, with a larger area than the second land 82. That is, in the tire axial end region R2 of the tread 10, large and small trapezoidal lands are arranged alternately in the tire circumferential direction along the main groove 20.

[0082] The first portion 81a and the second land 82 of the first land 81 have a slope 88 in the portion adjacent to the main groove 20. The slope 88 is inclined at a certain angle, for example, from the contact surface of the first portion 81a and the second land 82 toward the bottom of the main groove 20 so as to gradually approach the equator CL. By forming the slope 88, the width of the main groove 20 is increased, improving drainage, and the amount of rubber used can be reduced, resulting in a lighter tire. The slope 88 also increases the surface area of ​​the land, improving heat dissipation. The inclination angle of the slope 88 with respect to the profile surface α is not particularly limited, but is, for example, 60° to 80°.

[0083] The secondary groove 85 is formed along the short sides and oblique sides of the second land 82, and has a first portion extending in the tire circumferential direction and a second portion intersecting the tire circumferential direction and the axial direction. The secondary groove 85 is a groove that terminates at a slope 88 and does not communicate with the main groove 20. In this case, the first land 81 and the second land 82 can be formed to increase the number of edges while ensuring high durability of the land, and the surface area of ​​the tread 10 can be expanded to improve heat dissipation. The secondary groove 85 is, for example, narrower than the secondary groove 86 and formed with a constant width over its entire length. The secondary groove 85 may be a sipe with a width of less than 1 mm.

[0084] The sub-groove 86 is formed along the axially outer edge of the first land 81 and continues in the circumferential direction of the tire. Forming the sub-groove 86 near the tread edge E2 more significantly suppresses heat generation and also improves drainage. The sub-groove 86 may be formed with a constant width, but in the example shown in FIG. 8 , the portion along the long side of the first portion 81a of the first land 81 is formed slightly wider than the other portions. The depths of the sub-grooves 85, 86 may be the same as or different from each other. In this embodiment, the sub-grooves 85, 86 are formed with the same depth as the main grooves 20, 30.

[0085] In the tire axial end region R2 of the tread 10, a slope 87 is further formed at a position aligned with the second land 82 in the tire axial direction across the auxiliary groove 86, and the third land 83 and the slope 87 are arranged alternately in the tire circumferential direction. The third land 83 has the same height as the first land 81, and its upper surface comes into contact with the road surface, but the slope 87 is formed lower than the third land 83 and does not come into contact with the road surface.

[0086] That is, the outer edge of the axial end region R2 of the tread 10 has an uneven structure formed by the third land 83 and the slope 87 along the tire circumferential direction. In other words, the ground contact edge E2 is discontinuous in the tire circumferential direction. In this case, the tire weight can be reduced and the heat generation suppression effect can be further improved. In addition, the ground contact pressure in the axial center portion of the tread 10 can be increased, making it easier to achieve good wear patterns.

[0087] As described above, the third land 83 is a long, narrow block formed axially outward of the first land 81, and forms an angular convex shape on the shoulder of the pneumatic tire 1. The slope 87 forms a flat slope on the shoulder of the pneumatic tire 1. In the pneumatic tire 1, the shapes of the outer peripheral surfaces near the left and right contact edges are significantly different, with the side facing the contact edge E1 being a gently curved surface and the side facing the contact edge E2 being an uneven, angular shape.

[0088] As described above, the pneumatic tire 1 has a novel tread pattern characterized by an aggressive design, and exhibits excellent heat dissipation to suppress significant temperature increases during vehicle operation. The second shoulder region 80 increases the surface area of ​​the tread 10 and forms a discontinuous ground contact edge E2. This effectively improves heat dissipation while reducing the tire's weight. The tread pattern of the pneumatic tire 1, while featuring a novel and sophisticated design, exhibits excellent heat suppression capabilities and contributes to reducing the tire's weight and improving its durability and traction performance on land.

[0089] The above-described embodiment can be modified as needed without impairing the object of the present invention. The tread pattern including the first shoulder region 60 and the second shoulder region 80 provides high durability, good traction, and excellent heat dissipation, making it suitable for all-season tires. However, if necessary, the above-described configuration of the second shoulder region 80 may be applied to both axial sides of the tread.

[0090] In the tread pattern of this embodiment, the land structures of the center land 40, first quarter land 50, first shoulder land 60, and second quarter land 70 are useful for improving land durability, traction performance, etc., as described above. Also, the configuration of the main grooves 20 and 30 is useful for reducing noise, improving drainage, etc. However, it is possible to achieve the object of the present invention by changing the configurations other than the second shoulder region 80 to other configurations. [Explanation of symbols]

[0091] 1 pneumatic tire, 10 tread, 11 sidewall, 12 bead, 13 side rib, 14 carcass, 15 belt, 16 inner liner, 17 bead core, 18 bead filler, 20, 30 main groove, 21, 31 narrow groove, 22, 32 rib, 22a first rib, 22b second rib, 23, 33 first portion, 24, 34 second portion, 25a first region, 25b second region, 26, 41, 42, 43, 44, 61, 87, 88 slope, 27 side groove, 40 center land, 50 first quarter land, 51, 71 first zone, 52, 72 second zone, 55 recess, 60 first shoulder land, 70 second quarter land, 75, 85, 86 secondary groove, 80 second shoulder region, 81 1st land, 81a 1st part, 81b 2nd part, 82 2nd land, 83 3rd land, CL equator, E1,E2 grounding edge

Claims

1. A pneumatic tire having a tread, The tread is a first land including a plurality of trapezoidal portions in a plan view formed at intervals in the tire circumferential direction in an axial end region of the tire including a ground contact edge of the tread; second lands each including a trapezoidal portion in a plan view, which are formed so as to alternate with the first lands in the tire circumferential direction; and the first and second lands are arranged such that their respective short sides face in opposite directions to each other in the tire axial direction, a first groove is formed so as to surround three sides of the second land; A pneumatic tire, wherein a second groove extending in the tire circumferential direction is formed in the axial end region of the tread, axially outward of the first and second lands, and a third land is formed adjacent to the first land in the tire axial direction, separated by the second groove.

2. a slope is formed in the axial end region of the tread at a position aligned with the second land in the tire axial direction across the second groove, The pneumatic tire according to claim 1 , wherein the third lands and the slopes are arranged alternately in the tire circumferential direction.

3. A pneumatic tire having a tread, The tread is a first land including a plurality of trapezoidal portions in a plan view formed at intervals in the tire circumferential direction in an axial end region of the tire including a ground contact edge of the tread; second lands each including a trapezoidal portion in a plan view, which are formed so as to alternate with the first lands in the tire circumferential direction; and the first and second lands are arranged such that their respective short sides face in opposite directions to each other in the tire axial direction, a first groove is formed so as to surround three sides of the second land; a second groove extending in the tire circumferential direction is formed in the tire axial end region of the tread, axially outward of the first and second lands; a first land including a first portion that is trapezoidal in a plan view, and a second portion that is formed between the first groove and the second groove and connects the first portions that are adjacent in the tire circumferential direction.

4. A pneumatic tire having a tread, The tread is a first land including a plurality of trapezoidal portions in a plan view formed at intervals in the tire circumferential direction in an axial end region of the tire including a ground contact edge of the tread; second lands each including a trapezoidal portion in a plan view, which are formed so as to alternate with the first lands in the tire circumferential direction; a plurality of center blocks each having a trapezoidal shape in a plan view, the center blocks being formed on the tire equator at intervals in the tire circumferential direction; a main groove extending in the tire circumferential direction and separating the center block from the first and second lands; and the first and second lands are arranged such that their respective short sides face in opposite directions in the tire axial direction, and have slopes in portions adjacent to the main grooves, A pneumatic tire, wherein a first groove is formed so as to surround three sides of the second land.

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