pneumatic tires

Abstract

To provide a pneumatic tire which can easily reduce air resistance of the tire during traveling of a vehicle and easily reduce fuel consumption of the vehicle.SOLUTION: A tire 1 includes: a tread 10 having a ground contact surface 10a; a first buttress 11a disposed at a vehicle outer side relative to the tread 10; and a second buttress 11b disposed at the vehicle inner side than the tread 10. A first thickness of the first buttress 11a disposed at a vehicle inner side of the tire 1 is set so as to be thinner than a second thickness of the second buttress disposed at the vehicle outer side of the tire 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] A conventional pneumatic tire is described in Patent Document 1. In this pneumatic tire, the radius of curvature of the contour of the buttress on the outer side of the vehicle is smaller than the radius of curvature of the contour of the buttress on the inner side of the vehicle, and the contact width of the buttress on the outer side of the vehicle is larger than the contact width of the buttress on the inner side of the vehicle. In this way, the contact area of ​​the buttress on the outer side of the vehicle is increased, improving the uneven wear resistance of the buttress on the outer side of the vehicle, which is subjected to large forces when the vehicle corners. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 11-321214 Summary of the Invention [Problem to be solved by the invention]

[0004] If the air resistance of a tire can be reduced when the vehicle is running, the vehicle's fuel consumption can be improved. However, even by referring to Patent Document 1, no knowledge can be obtained regarding a configuration for reducing the air resistance of a tire when the vehicle is running. Therefore, an object of the present invention is to provide a pneumatic tire that can reduce the air resistance of a tire when the vehicle is running, and that can easily improve the vehicle's fuel consumption. [Means for solving the problem]

[0005] A pneumatic tire according to the present invention comprises a tread having a contact surface, a first buttress positioned on the vehicle inner side of the tread, and a second buttress positioned on the vehicle outer side of the tread, wherein a first thickness of the first buttress is thinner than a second thickness of the second buttress.

[0006] The tire has a first annular rib on the inner side in the width direction and a second annular rib on the outer side in the width direction. The first thickness of the first buttress is defined as the thickness of the pneumatic tire at a location where the first rib is located on the inner side in the width direction, and the second thickness of the second buttress is defined as the thickness of the pneumatic tire at a location where the second rib is located on the outer side in the width direction. The vehicle inner side and vehicle outer side are defined as the thicknesses of the pneumatic tire when properly mounted on a vehicle.

[0007] When a pneumatic tire is mounted on a vehicle, the widthwise outer portion located on the outside of the vehicle is more susceptible to wind impingement from the front of the vehicle and is more susceptible to air resistance than the widthwise inner portion located on the inside of the vehicle. In light of this background, according to the present invention, the thickness of the second buttress (second shoulder) on the outside of the vehicle is greater than the thickness of the first buttress (first shoulder) on the inside of the vehicle. Therefore, the rigidity of the second buttress on the outside of the vehicle is high, which can prevent the second buttress on the outside of the vehicle from rising up while the vehicle is in motion, particularly when the vehicle is turning or traveling at high speeds, where large centrifugal forces are applied. This makes it easier for the second buttress to maintain its round shape while the vehicle is in motion, thereby reducing the air resistance the second buttress experiences while the vehicle is in motion. As a result, the air resistance of the second buttress, which significantly affects the air resistance of the entire pneumatic tire, can be reduced, thereby efficiently reducing the air resistance of the entire pneumatic tire and facilitating improved vehicle fuel economy. [Effects of the Invention]

[0008] According to the pneumatic tire according to the present disclosure, the air resistance of the tire when the vehicle is running can be reduced, which makes it easier to reduce the fuel consumption of the vehicle. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a half cross-sectional view including the width direction and the radial direction of a pneumatic tire according to one embodiment of the present invention. [Figure 2] 1 is a diagram illustrating the vulcanization molding of a tire. [Figure 3]2 is an enlarged cross-sectional view showing the periphery of a first buttress located on the anti-serial side in the width direction of the pneumatic tire in the cross section of FIG. 1. FIG. [Figure 4] 2 is an enlarged cross-sectional view showing the peripheral portion of a second buttress located on the serial side in the width direction of the pneumatic tire in the cross section of FIG. 1. FIG. [Figure 5] FIG. 2 is a schematic diagram illustrating the layer structure of a cap ply and an edge ply. [Figure 6] 1 is a diagram illustrating the direction of vehicle movement and the direction of wind flow. FIG. [Figure 7] 1 is a diagram illustrating forces that a normal pneumatic tire receives from wind and a vehicle body when the vehicle is turning. FIG. [Figure 8] 1A and 1B are diagrams illustrating forces that a pneumatic tire of the present disclosure receives from wind and a vehicle body when the vehicle is turning. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that, when multiple embodiments or variations are included below, it is assumed from the outset that new embodiments can be constructed by appropriately combining their characteristic features. In the following examples, the same components are denoted by the same reference numerals in the drawings, and redundant explanations will be omitted. The drawings include schematic diagrams, and the dimensional ratios of the length, width, height, etc. of each component between different drawings do not necessarily match.

[0011] Furthermore, among the components described below, components that are not recited in the independent claims that represent the highest concepts are optional components and are not essential components. Furthermore, the present disclosure is not limited to the following embodiments and their modifications, and various improvements and modifications are possible within the scope of the claims of this application and their equivalents.

[0012] In the following description, the width direction refers to the width direction of the pneumatic tire 1, the radial direction refers to the radial direction of the pneumatic tire, and the circumferential direction refers to the circumferential direction of the pneumatic tire. The width direction, radial direction, and circumferential direction are perpendicular to one another. In the following description, the terms "inside of a vehicle" and "outside of a vehicle" refer to a state in which the pneumatic tire 1 is properly mounted on a vehicle.

[0013] FIG. 1 is a half cross-sectional view, including the width direction and the radial direction, of a pneumatic tire 1 according to one embodiment of the present invention. As shown in FIG. 1, the pneumatic tire (hereinafter simply referred to as tire) 1 includes a tread 10, a pair of buttresses (a pair of shoulders) 11a, 11b, a pair of sidewalls 12a, 12b, and a pair of beads 13a, 13b. The tread 10 is disposed in the center in the width direction and includes a contact surface 10a that comes into contact with the road surface. The tread 10 is made of, for example, crosslinked rubber. A plurality of grooves 24 is provided on the outer peripheral surface of the tread 10. As is well known, the plurality of grooves 24 serve to drain rainwater that has entered between the road surface and the tire 1, thereby ensuring a contact area between the road surface and the tire 1.

[0014] The first buttress 11a, the first sidewall 12a, and the first bead 13a are portions that form the side surface of the tire 1 on the anti-serial side (the side facing the vehicle when the tire 1 is mounted on the vehicle). The second buttress 11b, the second sidewall 12b, and the second bead 13b are portions that form the side surface of the tire 1 on the serial side (the side facing the vehicle when the tire 1 is mounted on the vehicle).

[0015] The first buttress 11a, first sidewall 12a, and first bead 13a extend radially inward from the end of the tread 10 on the anti-serial side (tire inner side) in the width direction. The second buttress 11b, second sidewall 12b, and second bead 13b extend radially inward from the end of the tread 10 on the serial side (tire outer side) in the width direction. The outer peripheral surface of the tire 1 is formed by bonding together an annular tread rubber 61, an annular first sidewall rubber 62, an annular first buttress rubber 63, an annular second sidewall rubber 64, and an annular second buttress rubber 65. The tread rubber 61 includes a contact surface, and the first sidewall rubber 62 includes a first maximum width position 66 on the vehicle inner side. The first buttress rubber 63 is located between a widthwise center 67 and the first maximum width position 66. The second sidewall rubber 64 includes a second maximum width position 68 on the vehicle outer side, and the second buttress rubber 65 is located between the widthwise center 67 and the second maximum width position 68 in the width direction. In this embodiment, the first ground contact edge Ea on the inner side in the width direction of the tire 1 is defined as the boundary position between the tread 10 and the first buttress 11a on the outer peripheral surface of the tire 1, and the second ground contact edge Eb on the outer side in the width direction of the tire 1 is defined as the boundary position between the tread 10 and the second buttress 11b on the outer peripheral surface of the tire 1. The boundary position between the first sidewall rubber 62 and the first buttress rubber 63 on the outer peripheral surface of the tire 1 is defined as the boundary position between the first buttress 11a and the first sidewall 12a on the outer peripheral surface of the tire 1. The boundary position between the second sidewall rubber 64 and the second buttress rubber 65 on the outer peripheral surface of the tire 1 is defined as the boundary position between the second buttress 11b and the second sidewall 12b on the outer peripheral surface of the tire 1. The sidewalls 12a, 12b are rubber layers between the buttresses 11a, 11b and the beads 13a, 13b, and are the most flexible parts of the tire 1. The sidewalls 12a, 12b protect the carcass 15 and prevent it from stretching. The ground contact edges Ea, Eb refer to both widthwise ends of the part that comes into contact with the ground when the tire 1 is mounted on a standard rim, the internal pressure is adjusted to the standard internal pressure, and a standard load is applied (regarding standard rims, etc., the same as described in JP 2020-131965 A).

[0016] The buttresses 11a, 11b are shoulder portions of the tire 1, and protrude outward in the width direction from both widthwise ends of the tread 10 and extend radially inward. Similar to the tread 10, the buttresses 11a, 11b are provided in an annular shape along the circumferential direction. The sidewalls 12a, 12b extend radially inward from the buttresses 11a, 11b on both widthwise sides and are also provided in an annular shape along the circumferential direction. The sidewalls 12a, 12b include the portions that protrude most outward in the widthwise direction of the tire 1, and are gently curved so as to be convex outward.

[0017] The beads 13a, 13b extend radially inward from the sidewalls 12a, 12b on both sides in the width direction and are formed in an annular shape along the circumferential direction. The beads 13a, 13b are portions fixed to the rim of a wheel and constitute the inner circumferential portion of the tire 1. The beads 13a, 13b are gently curved so as to convex inward, and are located more inward in the width direction than the sidewalls 12a, 12b.

[0018] The tire 1 includes bead cores 26a, 26b and bead fillers 27a, 27b. The first bead core 26a and the first bead filler 27a are provided in the first bead 13a on the anti-serial side of the tire 1. The second bead core 26b and the second bead filler 27b are provided in the second bead 13b on the serial side of the tire 1. The bead cores 26a, 26b are ring-shaped members made of bundled steel wires covered with rubber. The bead fillers 27a, 27b are made of hard rubber and function to increase the rigidity of the beads 13a, 13b. The bead fillers 27a, 27b are arranged radially outward of the bead cores 26a, 26b.

[0019] FIG. 2 is a diagram illustrating the vulcanization molding of a tire 1. As shown in FIG. 2, the tire 1 is manufactured using a tire vulcanization mold (hereinafter simply referred to as a "mold") 30. The mold 30 has a circular ring shape. The mold 30 molds the outer surface of the tire 1. In FIG. 2, the mold 30 is illustrated together with the tire 1 that has been vulcanized.

[0020] The left side of the mold 30 in Fig. 2 is a portion for vulcanizing and molding the anti-serial side in the width direction of the tire 1. The right side of the mold 30 in Fig. 2 is a portion for vulcanizing and molding the serial side in the width direction of the tire 1.

[0021] The mold 30 includes a cylindrical sector mold 31 and a pair of annular side molds 32a, 32b located radially inward of the sector mold 31. The pair of side molds 32a, 32b are spaced apart in the width direction. The first side mold 32a is used to vulcanize and mold the anti-serial side of the tire 1 in the width direction, and includes an annular first side plate 36a and an annular first bead ring 38a. The second side mold 32b is used to vulcanize and mold the serial side of the tire 1 in the width direction, and includes an annular second side plate 36b and an annular second bead ring 38b.

[0022] The sector mold 31 and the side molds 32a, 32b have approximately the same axis A extending in the width direction. The internal space defined by the sector mold 31 and the pair of side molds 32a, 32b forms a cavity 33 in which a green tire before vulcanization that constitutes the tire 1 is set. After the green tire is set in the cavity 33, high-temperature gas, for example, high-temperature steam, is supplied to the cavity 33 through a supply pipe (not shown). In this manner, the green tire is subjected to a vulcanization process.

[0023] The sector mold 31 is movable in the radial direction indicated by the arrow α around the axis A. The inner peripheral surface of the sector mold 31 includes a tread molding surface 35 that molds the outer peripheral surface of the tread 10. A pair of side plates 36a, 36b are disposed radially inside the sector mold 31 so as to be able to come into contact with the sector mold 31. The first side plate 36a is fixed and immovable. The second side plate 36b is movable in the width direction indicated by the arrow β by a drive mechanism (not shown). The inner surface of the first side plate 36a includes a first sidewall molding surface 37a that molds the outer surface of the first sidewall 12a on the anti-serial side, and the inner surface of the second side plate 36b includes a second sidewall molding surface 37b that molds the outer surface of the second sidewall 12b on the serial side.

[0024] The first bead ring 38a is disposed radially and widthwise inward of the first side plate 36a so as to be able to come into contact with the first side plate 36a in the width direction. The second bead ring 38b is disposed radially and widthwise inward of the second side plate 36b so as to be able to come into contact with the second side plate 36b in the width direction. The first bead ring 38a is integrated with the first side plate 36a and immovably fixed thereto. The second bead ring 38b is integrated with the second side plate 36b and is movable in the width direction together with the second side plate 36b. The inner surface of the first bead ring 38a includes a first bead molding surface 39a that molds the outer surface of the first bead 13a. The inner surface of the second bead ring 38b includes a second bead molding surface 39b that molds the outer surface of the second bead 13b.

[0025] As shown in FIG. 2 , the shape of the inner peripheral surface of the sector mold 31 is asymmetric on both sides in the width direction. The shape of the inner molding surface located on the inner side in the width direction of the first side plate 36a is also different from the shape of the outer molding surface located on the inner side in the width direction of the second side plate 36b. Specifically, the tread molding surface 35 of the sector mold 31 curves radially inward on the anti-serial side in the width direction compared to the serial side in the width direction. In other words, the radial thickness of the sector mold 31 on the anti-serial side in the width direction is thicker than the radial thickness of the sector mold 31 on the serial side in the width direction. Similarly, the width thickness of the radially outer end of the first side plate 36a is thicker than the width thickness of the radially outer end of the second side plate 36b. That is, the inner surface of the mold 30 is curved such that the anti-serial side in the width direction protrudes toward the cavity 33 compared to the serial side in the width direction.

[0026] A first annular recess 41a having a beak-shaped (triangular cross section) cross section is present inside the fitting portion between the sector mold 31 and the first side plate 36a. Also, a second annular recess 41b having a beak-shaped (triangular cross section) cross section is present inside the fitting portion between the sector mold 31 and the second side plate 36b. Therefore, the tire 1 has annular ribs 51a, 51b (see FIGS. 3 and 4) on each buttress 11a, 11b corresponding to the annular recesses 41a, 41b.

[0027] Fig. 3 is an enlarged cross-sectional view showing the periphery of a first buttress 11a located on the anti-serial side in the width direction of the tire 1 in the cross section of Fig. 1. Also, Fig. 4 is an enlarged cross-sectional view showing the periphery of a second buttress 11b located on the serial side in the width direction of the tire 1 in the cross section of Fig. 1. As shown in Figs. 3 and 4, the tire 1 includes a carcass 15, a belt 16, a belt reinforcing material 17, and an inner liner 18.

[0028] The carcass 15 is a cord layer covered with rubber. The carcass 15 includes carcass plies and forms a tire framework that can withstand loads, impacts, air pressure, etc. The carcass 15 has a radial structure in which carcass cords are arranged extending in a direction perpendicular to the circumferential direction. The rubber layer that covers and protects the carcass 15 is generally made up of multiple rubber materials such as tread rubber and sidewall rubber.

[0029] The carcass plies 15a and 15b constituting the carcass 15 are laid across a pair of bead cores 26a and 26b from the inner side in the width direction and are folded back toward the sidewalls 12a and 12b so as to envelop the bead cores 26a and 26b and the bead fillers 27a and 27b. In the example shown in FIGS. 3 and 4, the carcass 15 includes two carcass plies 15a and 15b. As shown in FIG. 1, the ply end 24a of the first carcass ply 15a closer to the bead cores 26a and 26b is located at the beads 13a and 13b, and the ply end 24b of the second carcass ply 15b is located at the sidewalls 12a and 12b. Note that the carcass may have only one carcass ply, but in this case, the ply end of the carcass ply is generally located at the sidewall.

[0030] The inner liner 18 is a rubber layer for maintaining air pressure, and is attached to the inner surface of the carcass 15. The inner liner 18 is made of, for example, air-permeable rubber, and prevents air in the tire cavity from leaking to the outside.

[0031] The belt 16 is disposed between the tread 10 and the carcass 15. In the width direction, the belt 16 is installed over the entire area where the belt 16 radially overlaps the tread 10 and over some areas of the buttresses 11a and 11b. The belt 16 is a reinforcing band stretched in the circumferential direction, and it tightens the carcass 15 to increase the rigidity of the tread 10. The belt 16 has a two-layer structure, for example, made of a steel belt including a steel cord, and includes two steel belts 16a and 16b. However, the number of belts to be stacked is not limited to two. In addition, a belt including a tire cord using aramid fiber may be used instead of the steel belt. Alternatively, the belt may be configured with only one layer. By providing the belt 16, the rigidity of the tire 1 can be ensured, and the contact state between the tread 10 and the road surface can be improved.

[0032] The belt reinforcement 17 is disposed between the belt 16 and the tread 10. The belt reinforcement 17 is disposed in the entire area where it radially overlaps the tread 10 in the width direction and in some areas of the buttresses 11a and 11b. An outer end 22 of the belt reinforcement 17 in the width direction extends outward in the width direction beyond the belt 16. The belt reinforcement 17 has, for example, a three-layer structure and includes one cap ply 17a and edge plies 17b, 17c, 17d, and 17e disposed in two layers at each end in the width direction.

[0033] Specifically, the cap ply 17a extends in the width direction from the radially inner side of the first buttress 11a to the radially inner side of the second buttress 11b. The two first edge plies 17b, 17c are arranged in two layers on the radially inner side of the first buttress 11a, and the two second edge plies 17c, 17d are arranged in two layers on the radially inner side of the second buttress 11b. The cap ply 17a and the edge plies 17b, 17c, 17d, 17e are made of the same material, including an insulating organic fiber layer such as polyamide fiber, and are covered with a topping rubber. The belt reinforcement 17 is installed for purposes such as improving durability and reducing road noise during driving.

[0034] FIG. 5 is a schematic diagram illustrating the layer configuration of the cap ply 17a and the edge plies 17b, 17c, 17d, and 17e. Note that FIG. 5 illustrates the layer configuration from the center portion in the width direction to the serial side. As shown in FIG. 5, in addition to the cap ply 17a, edge plies 17d and 17e configured in two layers are arranged in the second buttress 11b. This increases the rigidity of the second buttress 11b, effectively suppressing deformation (rising) of the second buttress 11b when centrifugal force is applied to the tire 1. Note that while the edge plies 17d and 17e are arranged in two layers at the end on the serial side in the width direction, a configuration in which only one edge ply is arranged at each end in the width direction, or a configuration in which no edge ply is arranged at each end in the width direction, may also be used.

[0035] 3 and 4, the tire 1 has buttresses 11a, 11b with different rubber thicknesses on the serial side (outer side of the tire) and the anti-serial side (inner side of the tire). More specifically, as described above, the inner surface of the mold 30 is curved such that the anti-serial side in the width direction protrudes toward the cavity 33 compared to the serial side in the width direction (see FIG. 2). Corresponding to this, as shown in FIGS. 3 and 4, the thickness (rubber thickness) Ho of the second buttress 11b (see FIG. 4) is thicker than the thickness (rubber thickness) Hi of the first buttress 11a (see FIG. 3).

[0036] The first buttress 11a has an annular first rib 51a corresponding to the annular recess 41a (see FIG. 2), and the second buttress 11b has an annular second rib 51b corresponding to the annular recess 41a (see FIG. 2). In FIG. 3, Hi denotes the distance from the tip of the annular first rib 51a to the carcass 15, more specifically, the distance from a position on the outer circumferential surface of the carcass 15 to the tip of the first rib 51a when a normal direction to the outer circumferential surface of the carcass 15 passes through the tip of the first rib 51a. In FIG. 4, Ho denotes the distance from the tip of the annular second rib 51b to the carcass 15, more specifically, the distance from a position on the outer circumferential surface of the carcass 15 to the tip of the second rib 51b when a normal direction to the outer circumferential surface of the carcass 15 passes through the tip of the second rib 51b. However, with regard to the thickness of the first and second buttresses 11a, 11b, the second buttress 11b is thicker than the first buttress 11a even at positions where the ribs 51a, 51b are not present.

[0037] The first and second buttresses 11a, 11b may have any thickness as long as Ho>Hi is satisfied. However, in this embodiment, the first and second buttresses 11a, 11b have a thickness that satisfies the condition 1 mm<(Ho-Hi)≦2 mm. The reason why it is preferable to satisfy this condition will be explained below.

[0038] <Configuration of the tire disclosed herein and its effects> [Essential Configurations of the Tire of the Present Disclosure and Their Functions and Effects] The tire 1 includes a tread 10 having a contact surface 10a, a first buttress 11a disposed on the vehicle outer side of the tread 10, and a second buttress 11b disposed on the vehicle inner side of the tread 10. The first thickness Hi of the first buttress 11a is thinner than the second thickness Ho of the second buttress.

[0039] As shown in FIG. 6, assume that vehicles 90a, 90b are moving in the direction of arrow C, and tires 91, 1 are subjected to a wind flow flowing in the direction opposite to the direction of movement of the vehicles 90a, 90b, as indicated by arrow D. If the tire 91 is a conventional tire with the same shape on both the serial and anti-serial sides, as shown in FIG. 7, when turbulence occurs on the vehicle 90a side (IN side) of the tire 91, this turbulence receives force from below the vehicle 90a, generating a vortex as indicated by arrow E. This vortex then flows in the same direction as the tire's traveling direction on the tire side, pushing the tire 91 in the traveling direction, thereby generating propulsive force. On the other hand, on the outside (OUT side) where the vehicle 90a is not present, there is no object that applies a forward force to the turbulent flow, and therefore, when turbulence as indicated by arrow F occurs, air resistance increases. Furthermore, when the vehicle 90a is traveling at high speed or cornering, centrifugal force on the serial side (OUT side) causes the second buttress 91a to rise, making it more susceptible to collision with air from the front. This makes it easier for air to flow, further increasing air resistance.

[0040] In contrast, if the tire 1 is the tire 1 of this embodiment and the thickness of the serial-side second buttress 11b is greater than the thickness of the anti-serial-side first buttress 11a, the rigidity of the serial-side second buttress 11b can be increased. This prevents the second buttress 11b on the outer side of the vehicle from rising upward during vehicle travel, particularly during cornering or high-speed travel where large centrifugal forces are applied. As a result, as shown in FIG. 8 , the second buttress 11b is more likely to maintain its round shape during vehicle travel, which makes it possible to smooth the airflow on the outer side of the vehicle 90b during vehicle travel, as indicated by arrow G, and reduces the air resistance experienced by the second buttress 11b during vehicle travel. As a result, the air resistance of the second buttress 11b, which significantly affects the overall air resistance of the tire 1, can be reduced, thereby efficiently reducing the overall air resistance of the tire 1 and improving vehicle fuel economy.

[0041] Furthermore, in this embodiment, simply by making the thickness of the second buttress 11b thicker than the thickness of the first buttress 11a, it is possible to effectively prevent the second buttress 11b from rising up when centrifugal force is applied, and it is possible to efficiently reduce the air resistance of the tire 1 without placing an additional reinforcing member in the second buttress 11b. Therefore, there is no deterioration in the rubber flow near the ends of the member, which may occur when an additional reinforcing member is placed in the second buttress 11b, and no defects resulting from this occur in the manufacturing process.

[0042] [Configurations and Effects Preferable to be Adopted in Tires of the Present Disclosure] It is preferable that the tire 1 comprises a cap ply 17a extending in the width direction from the radially inner side of the first buttress 11a to the radially inner side of the second buttress 11b, two first edge plies 17b, 17c arranged in two layers on the radially inner side of the first buttress 11a, and two second edge plies 17d, 17e arranged in two layers on the radially inner side of the second buttress 11b.

[0043] According to this configuration, two edge plies 17b, 17c, 17d, and 17e are arranged inside the buttresses 11a and 11b, thereby increasing the rigidity of the buttresses 11a and 11b. This makes it possible to more effectively prevent the buttresses 11a and 11b from rising when centrifugal force is applied. This makes it easier to more effectively maintain the round shape of the second buttress 11b when centrifugal force is applied, and greatly reduces air resistance.

[0044] It is also preferable that 1 mm≦(second thickness Ho−first thickness Hi)≦2 mm be satisfied.

[0045] If the difference between the second thickness Ho and the first thickness Hi is too large, the difference in stiffness between the inner and outer sides of the tire will be large, which will increase the difference in tire flex between the inner and outer sides of the tire when the vehicle corners, making it difficult to corner smoothly and affecting ride comfort. Also, uneven wear will be more likely to occur, and tire uniformity will be more likely to deteriorate. On the other hand, if the difference between the second thickness Ho and the first thickness Hi is too small, it will be difficult to achieve the effects of the present disclosure.

[0046] In contrast, with this configuration, (second thickness Ho - first thickness Hi) ≦ 2 mm, so the difference in stiffness between the inner and outer sides of the tire does not become excessively large, and it is possible to suppress differences in tire flex between the inner and outer sides of the tire when the vehicle corners. This makes it easier to corner smoothly and improves ride comfort. It also makes it less likely for uneven wear to occur and makes it easier to achieve good tire uniformity. Furthermore, since 1 mm ≦ (second thickness Ho - first thickness Hi), it is easy to significantly reduce the air resistance of the tire 1 when the vehicle is running, and it is possible to reliably improve the vehicle's fuel efficiency. [Explanation of symbols]

[0047] 1 tire, 10 tread, 10a contact surface, 11a first buttress, 11b second buttress, 12a first sidewall, 12b second sidewall, 13a first bead, 13b second bead, 15 carcass, 15a first carcass ply, 15b second carcass ply, 16 belt, 16a, 16b steel belt, 17 belt reinforcement, 17a cap ply, 17b, 17c first edge ply, 17d, 17e second edge ply, 18 inner liner, 26a first bead core, 26b second bead core, 27a first bead filler, 27b second bead filler, 30 mold, 31 sector mold, 32a first side mold, 32b second side mold, 33 Cavity, 36a first side plate, 36b second side plate, 38a first bead ring, 38b second bead ring, 41a first annular recess, 41b second annular recess, 51a first rib, 51b second rib, 90a, 90b vehicle, Hi rubber thickness of first buttress, Ho rubber thickness of second buttress.

Claims

1. a tread having a contact surface; a first buttress disposed on an inner side of the tread; a second buttress disposed on an outer side of the tread, the first buttress has a first rib; the second buttress has a second rib; a first thickness of the first buttress, which is the thickness of the first rib at a location thereof, is thinner than a second thickness of the second buttress, which is the thickness of the second buttress at a location thereof.

2. a cap ply extending in the tire width direction from the radially inner side of the first buttress to the radially inner side of the second buttress; two first edge plies arranged in two layers on the radially inner side of the first buttress; two second edge plies arranged in two layers on the radially inner side of the second buttress; The pneumatic tire of claim 1 , comprising:

3. The pneumatic tire according to claim 1 or 2, wherein 1 mm≦(the second thickness−the first thickness)≦2 mm is satisfied.

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