pneumatic tires

Abstract

Pneumatic tire (1) rotating about a rotational axis (AX), comprising: a tread section (2) comprising a tread rubber (8); and Side sections (3) provided on both sides in a transverse direction of the tread section (2), each comprising a side rubber (9); wherein the tread section (2) further comprises a plurality of main circumferential grooves (10) provided in the transverse direction of the tire, each extending in a circumferential direction of the tire, and a plurality of rib sections (20) defined by the main circumferential grooves (10) and comprising a ground contact surface (30) that comes into contact with a road surface; wherein the rib sections (20) comprise a shoulder rib section (23) which is arranged outside a main shoulder groove (12) which is located under the majority of the main circumferential grooves (10) closest to a ground contact edge (T) of the tread section (2) in the transverse direction of the tire, and which comprises the ground contact edge (T); wherein the shoulder rib section (23) outside the ground contact edge (T) in the tire transverse direction comprises a surface (34) which is connected to a surface of the side section (3); wherein defined in a meridional cross-section of the running surface section (2) which passes through the axis of rotation (AX): a first imaginary line (VL1) passing through the ground contact surface (30); a second imaginary line (VL2) that passes through a floor section (12B) of the main scapular groove (12) and is parallel to the first imaginary line (VL1); an intersection point (P) between the second imaginary line (VL2) and a surface of the shoulder rib section (23) outside the ground contact edge (T) in the tire transverse direction; and an equatorial plane (CL) of the tire that is perpendicular to the axis of rotation (AX) and passes through a center of the tread section (2) in the transverse direction of the tire; The condition 0.80 ≤ (B+C) / A ≤ 1.15 is satisfied, where A is a distance in the tire transverse direction between the intersection point (P) and the equatorial plane (CL) of the tire, B is a groove depth of the main shoulder groove (12), which is a distance between an opening end section (12Ka) inside the main shoulder groove (12) or an opening end section (12Kb) outside the main shoulder groove (12) and the ground section (12B) in a tire radial direction when the pneumatic tire (1) is mounted on a rim, inflated to a prescribed air pressure, statically positioned perpendicular to a flat plate and loaded with a load corresponding to the prescribed weight, and C is a distance in the tire transverse direction between the ground contact edge (T) and the equatorial plane (CL) of the tire, which is a distance between the equatorial plane (CL) and the ground contact edge (T) when the pneumatic tire (1) is mounted on the suitable Rim mounted,inflated to the prescribed air pressure and in an unloaded state; wherein , a tire outer diameter in the tire equatorial plane (CL) is defined as a tire outer diameter J, a tire outer diameter at the opening end section (12Ka) within the shoulder main groove (12) in the tire transverse direction is defined as a tire outer diameter K, and a tire outer diameter at the ground contact edge (T) is defined as a tire outer diameter L, wherein the following conditions J > K, J > L and 0.05 ≤ (K - L) / (JL) ≤ 0.85 are satisfied; wherein the condition 0.76 ≤ C / H ≤ 0.96 is satisfied, where H is given as a distance in the tire transverse direction between the equatorial plane (CL) of the tire and an outermost section of the side section (3) in the tire transverse direction; furthermore, in the meridian cross-section, a third imaginary line (VL3) is defined, passing through the ground contact edge (T) and the intersection point (P), and a fourth imaginary line (VL4) is defined, which is parallel to the equatorial plane (CL) of the tire and passes through the intersection point (P); and the condition 20° ≤ θa ≤ 50° is satisfied, where θa is given as an angle formed by the third imaginary line (VL3) and the fourth imaginary line (VL4).

Description

Technical area

[0001] The present invention relates to a pneumatic tire. State of the art

[0002] In a pneumatic tire, a tread pattern is formed that includes grooves and land portions defined by the grooves. The tread pattern is formed in a tread rubber. The grooves of the tread pattern include a main circumferential groove extending in a tire circumferential direction and a lug groove extending at least partially in a tire transverse direction. A land portion defined by a plurality of main circumferential grooves is called a rib or block row. A rib is a continuous land portion not separated by a lug groove. A block row is a discontinuous land portion separated by a lug groove.

[0003] In a heavy-duty pneumatic tire mounted on a truck or bus, the performance of the pneumatic tire can be improved by defining a groove depth of a shoulder rib groove and the like (see JP H02-270608 A). Other tires are known from DE 11 2014 002 102 T5 and US 2010 / 0 269 967 A1. Brief description of the inventionTechnical problem

[0004] When a heavy-duty pneumatic tire rotates or hits a curb, the land portion may be damaged or excessively deformed. If the land portion is excessively deformed, cracks may appear on the inner surface of the main circumferential groove, and the tread rubber may partially peel off.

[0005] Furthermore, heavy-duty pneumatic tires require a reduction in rolling resistance. One known method for reducing rolling resistance is to reduce the volume of the tread rubber. However, reducing the volume of the tread rubber will reduce the abrasion resistance performance of the pneumatic tire.

[0006] An object of one aspect of the present invention is to provide a pneumatic tire capable of preventing damage to a tread rubber and capable of reducing rolling resistance while suppressing a reduction in abrasion resistance performance. Solution to the problem

[0007] According to one aspect of the present invention, a pneumatic tire that rotates around a rotation axis includes a tread portion including a tread rubber, and side portions provided on both sides in a tire transverse direction of the tread portion, each of which includes a side rubber. The tread portion includes a plurality of circumferential main grooves provided in the tire transverse direction, each extending in a tire circumferential direction, and a plurality of land portions defined by the circumferential main grooves and including a ground contact surface that comes into contact with a road surface.The land portions include a shoulder land portion located outside a shoulder main groove that is closest to a ground contact edge of the tread portion in the tire transverse direction among the plurality of circumferential main grooves and encloses the ground contact edge. The shoulder land portion outside the ground contact edge in the tire transverse direction includes a surface connected to a surface of the side portion.In a meridian cross section of the tread portion passing through the rotation axis, a first imaginary line passing through the ground contact surface, a second imaginary line passing through a bottom portion of the shoulder main groove and being parallel to the first imaginary line, an intersection point between the second imaginary line and a surface of the shoulder land portion outside the ground contact edge in the tire transverse direction, and an equatorial plane of the tire that is perpendicular to the rotation axis and passes through a center of the tread portion in the tire transverse direction are defined.The condition 0.80 ≤ (B + C) / A ≤ 1.15 is satisfied, where A is a distance in the tire transverse direction between the intersection point and the equatorial plane of the tire, B is a groove depth of the shoulder main groove, which is a distance between an opening end portion inside the shoulder main groove or an opening end portion outside the shoulder main groove and the ground portion in a tire radial direction when the pneumatic tire is mounted on a rim, inflated to a prescribed air pressure, statically placed perpendicular to a flat plate, and loaded with a load equal to the prescribed weight, and C is a distance in the tire transverse direction between the ground contact edge and the equatorial plane of the tire, which is a distance between the equatorial plane and the ground contact edge when the pneumatic tire is mounted on the appropriate rim, inflated to the prescribed air pressure, and in an unloaded state.A tire outer diameter in the tire equatorial plane is defined as a tire outer diameter J, a tire outer diameter at the opening end portion inside the shoulder main groove in the tire transverse direction is defined as a tire outer diameter K, and a tire outer diameter at the ground contact edge is defined as a tire outer diameter L, wherein the following conditions J > K, J > L and 0.05 ≤ (K - L) / (JL) ≤ 0.85 are satisfied. Further, in the meridian cross section, a third imaginary line passing through the ground contact edge and the intersection point and a fourth imaginary line parallel to the tire equatorial plane and passing through the intersection point are defined, and the condition 20° ≤ θ a ≤ 50° is satisfied, where θ a is given as an angle formed by the third imaginary line and the fourth imaginary line.

[0008] The condition 0.76 ≤ C / H ≤ 0.96 is satisfied, where H is given as a distance in the tire transverse direction between the equatorial plane of the tire and an outermost portion of the side portion.

[0009] From one aspect of the present invention, the pneumatic tire preferably further includes a carcass and a belt layer disposed outside the carcass in the tire radial direction. The tread rubber having the circumferential main grooves and the land portions formed therein is disposed outside the belt layer in the tire radial direction, and the condition of 0.10 ≤ M / B ≤ 0.75 is satisfied, where M is a distance in the tire radial direction between a bottom portion of the shoulder main groove and the belt layer.

[0010] In one aspect of the invention, the belt layer preferably includes a plurality of belt plies arranged in the tire radial direction, wherein two of the plurality of belt plies adjacent to each other in the tire radial direction form a cross-ply belt layer. The condition 0.75 ≤ Q / C ≤ 0.95 is satisfied, where Q is a distance in the tire transverse direction between the equatorial plane of the tire and an end portion of the belt ply among the two belt plies having the shortest dimension in the tire transverse direction.

[0011] Preferably, the conditions 60 ≤ Hs and 0.23 ≥ tan δ are satisfied, where Hs is given as a hardness of the tread rubber at room temperature and tan δ is given as a loss coefficient indicating a relationship between a storage shear modulus and a loss shear modulus of the tread rubber at 60°C.

[0012] From one aspect of the present invention, the condition D / C ≤ 0.80 is preferably satisfied, where D is given as a distance between the tire equatorial plane in the tire transverse direction and the opening end portion outside the shoulder main groove in the tire transverse direction.

[0013] In one aspect of the present invention, the pneumatic tire is preferably a heavy-duty tire mounted on a truck or a bus. Advantageous effects of the invention

[0014] According to an object of the present invention, it is possible to provide a pneumatic tire capable of preventing damage to a tread rubber and capable of reducing rolling resistance while suppressing a reduction in abrasion resistance performance. Brief description of the drawings Fig.1 is a meridian plane view of an example of a tire according to the present embodiment. Fig. 2 is a meridian cross-sectional view of a tread portion according to the present embodiment. Fig. 3 is an enlarged view of a section of Fig. 2. Fig. 4 is a perspective view illustrating a portion of the tire according to the present embodiment. Fig. 5 is a schematic drawing in which a portion of the tire according to the present embodiment is partially cut away. Fig. 6 is a schematic view for explaining the warping of the tire according to the present embodiment. Fig. 7 is a graph illustrating a relationship between tire warpage and features according to the present embodiment. Fig.8 is a table showing evaluation test results of the tire according to the present embodiment. Fig. 9 is a perspective view illustrating a modified example of a shoulder land portion according to an embodiment. Fig. 10 is a side view of the Fig. 9 illustrated shoulder bar section. Description of embodimentsTire overview

[0015] Fig.1 is a cross-sectional view illustrating an example of a tire 1 according to the present embodiment. The tire 1 is a pneumatic tire. The tire 1 is a heavy-duty tire mounted on a truck or a bus. A tire for a truck or a bus (a heavy-duty tire) is a tire specified in Chapter C of the JATMA Yearbook published by the Japan Automobile Tire Manufacturers Association, Inc. (JATMA). Note that the tire 1 can be mounted on a passenger car or a light truck.

[0016] The tire 1 rotates about the rotation axis AX and runs on a road surface while mounted on the vehicle, such as a truck or a bus.

[0017] In the following description, a direction parallel to the rotation axis AX of the tire 1 is appropriately referred to as a tire transverse direction, a radiation direction with respect to the rotation axis AX of the tire 1 is appropriately referred to as a tire radial direction, and a rotation direction around the rotation axis AX of the tire 1 is appropriately referred to as a tire circumferential direction.

[0018] Furthermore, in the following description, a flat plane perpendicular to the rotation axis AX and passing through a center in the tire transverse direction of the tire 1 is appropriately referred to as a tire equatorial plane CL. Furthermore, a center line where the tire equatorial plane CL and a surface of a tread portion 2 of the tire 1 intersect is appropriately referred to as a tire equator line.

[0019] Furthermore, in the following description, a position or a direction away from the tire equatorial plane CL in the tire transverse direction is appropriately referred to as outward in the tire transverse direction, a position near or in a direction approaching the tire equatorial plane CL in the tire transverse direction is appropriately referred to as inward in the tire transverse direction, a position or a direction away from the rotational axis AX in the tire radial direction is appropriately referred to as outward in the tire radial direction, and a position near or in a direction approaching the rotational axis AX in the tire radial direction is appropriately referred to as inward in the tire radial direction.

[0020] Furthermore, in the following description, an inner side in a vehicle lateral direction is appropriately referred to as a vehicle inner side, and an outer side in a vehicle lateral direction is appropriately referred to as a vehicle outer side. The vehicle inner side refers to a position near or a direction approaching a center of the vehicle in the vehicle lateral direction. The vehicle outer side refers to a position or a direction away from the center of the vehicle in the vehicle lateral direction.

[0021] Fig. 1 shows a meridian cross-section passing through the rotation axis AX of tire 1. Fig. Figure 1 shows a cross-section of tire 1 on a first side of the tire equatorial plane CL in the tire transverse direction. Tire 1 has a structure and shape that are symmetrical to the tire equatorial plane CL in the tire transverse direction.

[0022] As in Fig.As shown in Figure 1, the tire 1 includes the tread portion 2 on which a tread pattern is formed, side portions 3 provided on both sides in the tire transverse direction of the tread portion 2, and bead portions 4 connected to the side portions 3. During driving, the tread portion 2 of the tire 1 comes into contact with a road surface.

[0023] Furthermore, the tire 1 includes a carcass 5, a belt layer 6 arranged outside the carcass 5 in the tire radial direction, and a bead core 7. The carcass 5, the belt layer 6, and the bead core 7 function as a reinforcing member (frame member) of the tire 1.

[0024] Furthermore, the tire 1 includes a tread rubber 8 and a side rubber 9. The tread portion 2 includes the tread rubber 8. The side portion 3 includes the side rubber 9. The tread rubber 8 is arranged outside the belt layer 6 in the tire radial direction.

[0025] The carcass 5 is a reinforcing member that forms a framework of the tire 1. The carcass 5 functions as a pressure vessel when the tire 1 is inflated with air. The carcass 5 includes a plurality of carcass cords made of organic fibers or steel fibers, and a carcass rubber covering the carcass cords. The carcass 5 is supported by the tire bead core 7 of the bead portion 4. The bead core 7 is arranged on a first side and a second side of the carcass 5 in the tire transverse direction. The carcass 5 is folded back at the bead core 7.

[0026] The belt layer 6 is a reinforcing member that maintains the shape of the tire 1. The belt layer 6 is disposed between the carcass 5 and the tread rubber 8 in the tire radial direction. The belt layer 6 tightens the carcass 5. The rigidity of the carcass 5 is increased by the tightening force applied to the belt layer 6. Furthermore, the belt layer 6 absorbs the impact of the tire 1 traveling, thereby protecting the carcass 5. For example, even if the tread portion 2 is damaged, the belt layer 6 prevents damage to the carcass 5.

[0027] The belt layer 6 includes a plurality of belt plies arranged in the tire radial direction. In the present embodiment, the belt layer 6 is a so-called four-ply belt and includes four belt plies. Each belt ply includes a first belt ply 61 arranged innermost in the tire radial direction, a second belt ply 62 arranged innermost in the tire radial direction following the first belt ply 61, a third belt layer 63 arranged innermost in the tire radial direction following the second belt ply 62, and a fourth belt layer 64 arranged outermost in the tire radial direction. The first belt ply 61 and the second belt ply 62 are adjacent to each other. The second belt ply 62 and the third belt ply 63 are adjacent to each other. The third belt ply 63 and the second belt ply 64 are adjacent to each other.

[0028] The dimensions of the belt layers 61, 62, 63, and 64 in the tire transverse direction are different. In the tire transverse direction, the dimension of the second belt layer 62 is the largest, the dimension of the third belt layer 63 is the next largest after the second belt layer 62, the dimension of the first belt layer 61 is the next largest after the third belt layer 63, and the dimension of the fourth belt layer 64 is the smallest.

[0029] The belt plies 61, 62, 63, 64 include a plurality of belt cords made of metal fibers and a belt rubber covering the belt cords. The second belt ply 62 and the third belt ply 63, which are adjacent to each other in the tire radial direction, form a cross-ply belt layer. The second belt ply 62 and the third belt ply 63 are arranged such that the belt cords of the second belt ply 62 and the belt cords of the third belt ply 63 intersect.

[0030] The bead portions 4 are reinforcing members that secure both ends of the carcass 5. The tire bead core 7 supports the carcass 5, to which tension is applied by an internal pressure of the tire 1. The bead portion 4 includes the tire bead core 7 and a bead filler rubber 7F. The tire bead core 7 is a member formed into a ring shape by winding a tire bead wire 7W. The tire bead wire 7W is a steel wire.

[0031] The bead filler rubber 7F fixes the carcass 5 to the tire bead core 7. Furthermore, the bead filler rubber 7F determines the shape of the bead portion 4 and increases the rigidity of the bead portion 4. The bead filler rubber 7F is arranged in a space formed by the carcass 5 to the tire bead core 7. The bead filler rubber 7F is arranged in a space formed by folding back an end portion of the carcass 5 in the tire transverse direction at the position of the tire bead core 7. The tire bead core 7 and the bead filler rubber 7F are arranged in a space formed by folding back the carcass 5.

[0032] The tread rubber 8 protects the carcass 5. The tread rubber 8 includes an under-tread rubber 81 and a cap tread rubber 82. The under-tread rubber 81 is arranged outside the belt layer 6 in the tire radial direction. The cap tread rubber 82 is arranged outside the under-tread rubber 81 in the tire radial direction. The tread pattern is formed in the cap tread rubber 82.

[0033] The side rubber 9 protects the carcass 5. The side rubber 9 is connected to the closure tread rubber 82.

[0034] The tread portion 2 includes a plurality of circumferential main grooves 10 in the tire transverse direction, each extending in the tire circumferential direction, and a plurality of land portions 20 defined by the circumferential main grooves 10 and including a ground contact surface that comes into contact with the road surface. The circumferential main grooves 10 and the land portions 20 are formed in the closure tread rubber 82 of the tread rubber 8. The land portion 20 includes a ground contact surface 30 that can be in contact with the road surface during travel of the tire 1.

[0035] The circumferential main groove 10 extends in the tire circumferential direction. The circumferential main groove 10 is substantially parallel to the tire equator line. The circumferential main groove 10 extends linearly in the tire circumferential direction. Note that the circumferential main groove 10 can be provided in a wave-like shape or a zigzag shape in the tire circumferential direction.

[0036] Four of the circumferential main grooves 10 are provided in the tire transverse direction. The circumferential main groove 10 includes a central main groove 11, one of which is arranged on each of the two sides in the tire transverse direction relative to the tire equatorial plane CL, and shoulder main grooves 12, each provided outside the central main groove 11 in the tire transverse direction.

[0037] Five land portions 20 are provided in the tire transverse direction. The land portion 20 includes a central land portion 21 provided between a pair of the central main grooves 11, a second land portion 22 provided between the central main groove 11 and the shoulder main groove 12, and a shoulder land portion 23 provided outside the shoulder main groove 12 in the tire transverse direction.

[0038] The central land portion 21 encloses the tire equatorial plane CL. The tire equatorial plane CL (tire equator line) passes through the central land portion 21. The second land portion 22 is provided on both sides of the tire equatorial plane CL in the tire transverse direction, one on each side. The shoulder land portion 23 is provided on both sides of the tire equatorial plane CL in the tire transverse direction, one on each side.

[0039] The ground contact surface 30 of the web portion 20 that can come into contact with the road surface includes a ground contact surface 31 of the central web portion 21, a ground contact surface 32 of the second web portion 22, and a ground contact surface 33 of the shoulder web portion 23.

[0040] The fourth belt ply 64 is partially disposed directly below the central main groove 11. The fourth belt ply 64 is not disposed directly below the shoulder main groove 12. The third belt ply 63 is disposed directly below the shoulder main groove 12. Note that "directly below" refers to the same position in the tire transverse direction, inward in the tire radial direction. Definitions of terms

[0041] Next, the terminology used in this specification is defined with reference to Fig. 1 to 5 described. Fig.2 is a drawing illustrating the meridian cross-sectional view of the tread portion 2 according to the present embodiment. Fig. 3 is an enlarged view of a section of Fig. 2. Fig. 4 is a perspective view illustrating a portion of the tire 1 according to the present embodiment. Fig. 5 is a schematic diagram showing a portion of the tire 1 according to the present embodiment cut away. The meridian cross-section of the tread portion 2 refers to a cross-section passing through the rotation axis AX and parallel to the rotation axis AX. The tire equatorial plane CL passes through the center of the tread portion 2 in the tire transverse direction.

[0042] As defined in Chapter G of the JATMA Yearbook, an outer diameter of the tyre 1 refers to the outer diameter of the tyre 1 mounted on a suitable rim and inflated to a prescribed air pressure in an unloaded condition.

[0043] As defined in Chapter G of the JATMA Yearbook, the overall width of the tire 1 refers to a linear distance between the side portions, including the design, alphanumeric characters, and the like, of the side surface of the tire 1 mounted on a suitable rim and inflated to a prescribed air pressure in an unloaded state. That is, the overall width of the tire 1 refers to the distance between an area on the outermost side of the structure constituting the tire 1 located on a first side of the tire equatorial plane CL in the tire transverse direction and an area on the outermost side of the structure constituting the tire 1 located on a second side.

[0044] Further, as defined in Chapter G of the JATMA Yearbook, a tread width of the tread portion 2 refers to a linear distance between both ends of the tread design portion of the tire 1 mounted on a suitable rim and inflated to a prescribed air pressure in an unloaded condition.

[0045] Further, as defined in Chapter G of the JATMA Yearbook, a ground contact width of the tread portion 2 refers to a maximum linear distance in a tire axial direction (tire transverse direction) of the ground contact surface with a flat plate when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and statically positioned perpendicular to the flat plate. This means that the ground contact width of the tread portion 2 refers to a distance between a ground contact edge T of the tread portion 2 on a first side and the ground contact edge T of the tread portion 2 on a second side of the tire equatorial plane CL in the tire transverse direction.

[0046] The ground contact edge T of the tread portion 2 refers to an end portion in the tire transverse direction of an area that comes into contact with a flat plate when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, placed statically perpendicular to the flat plate, and loaded with a load corresponding to the prescribed weight.

[0047] The circumferential main groove 10 of the plurality of circumferential main grooves 10 closest to the ground contact edge T of the tread portion 2 is the shoulder main groove 12. The shoulder land portion 23 is located outside the shoulder main groove 12 in the tire transverse direction. The land portion 20 of the plurality of land portions 20 closest to the ground contact edge T of the tread portion 2 is the shoulder land portion 23. The shoulder land portion 23 encloses the ground contact edge T. This means that the ground contact edge T is provided in the shoulder land portion 23. The land portion 20 of the plurality of land portions 20 closest to the tire equatorial plane CL of the tread portion 2 is the central land portion 21. The central land portion 21 encloses the tire equatorial plane CL. The tire equatorial plane CL passes through the central land portion 21.

[0048] Note that the terms described below are defined under the conditions of a new tire 1 mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state. Furthermore, as described above, the ground contact width and the ground contact edge T are dimensions and positions measured when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, statically placed perpendicular to the flat plate, and loaded with a load equal to the prescribed weight. The ground contact edge T is measured when a load equal to the prescribed mass is applied, and the position of the measured ground contact edge T is on the surface of the tread portion 2 in an unloaded state.

[0049] The surface of the shoulder land portion 23 includes the ground contact surface 33 located inside the ground contact edge T in the tire transverse direction, and a side surface 34 located outside the ground contact edge T in the tire transverse direction. The ground contact surface 33 and the side surface 34 are located in the plug tread rubber 82 of the tread rubber 8. The ground contact surface 33 and the side surface 34 are connected via a corner portion formed in the plug tread rubber 82. The ground contact surface 33 is substantially parallel to the rotation axis AX (road surface). The side surface 34 intersects the axis parallel to the rotation axis AX. An angle formed by the road surface and the side surface 34 is substantially greater than 45°, and an angle formed by the ground contact surface 33 and the side surface 34 is substantially greater than 225°.The side surface 34 of the shoulder land portion 23 and the surface 35 of the side portion 3 are oriented substantially in the same direction. The side surface 34 of the shoulder land portion 23 outside the ground contact edge T in the tire transverse direction is connected to the surface 35 of the side portion 3.

[0050] The shoulder main groove 12 includes an inner surface. An opening end portion 12K is provided outside the inner surface of the shoulder main groove 12 in the tire radial direction. The opening end portion 12K is a boundary portion between the shoulder main groove 12 and the ground contact surface 30. The opening end portion 12K includes an opening end portion 12Ka inward in the tire transverse direction and an opening end portion 12Kb outward in the tire transverse direction.

[0051] The inner surface of the shoulder main groove 12 includes a bottom portion 12B and a sidewall portion 12S connecting the opening end portion 12K and the bottom portion 12B. The sidewall portion 12S of the shoulder main groove 12 includes a sidewall portion 12Sa inward in the tire transverse direction and a sidewall portion 12Sb outward in the tire transverse direction. The sidewall portion 12Sa connects the opening end portion 12Ka and the bottom portion 12B. The sidewall portion 12Sb connects the opening end portion 12Kb and the bottom portion 12B. The opening end portion 12Ka is a boundary portion between the sidewall portion 12Sa and the ground contact surface 32. The opening end portion 12Kb is a boundary portion between the sidewall portion 12Sb and the ground contact surface 33.

[0052] The bottom portion 12B of the shoulder main groove 12 refers to the area on the inner surface of the shoulder main groove 12 that is farthest from the opening end portion 12K of the shoulder main groove 12 in the tire radial direction. That is, the bottom portion 12B of the shoulder main groove 12 refers to the deepest area in the shoulder main groove 12. The bottom portion 12B may also be referred to as the area on the inner surface of the shoulder main groove 12 that is closest to the rotation axis AX.

[0053] As in Fig.As illustrated in Figure 2, the bottom portion 12B of the shoulder main groove 12 has an arcuate shape in the meridian cross-section of the tread portion 2. In the meridian cross-section of the tread portion 2, the sidewall portion 12Sa slopes inward in the tire transverse direction toward an outer side in the tire radial direction. The sidewall portion 12Sb slopes outward in the tire transverse direction toward an outer side in the tire radial direction.

[0054] As in Fig. As illustrated in Figure 2, in the meridian cross-section of the tread portion 2, an imaginary line passing through the ground contact surface 30 of the land portion 20 is defined as a first imaginary line VL1. The first imaginary line VL1 indicates a profile of the ground contact surface 30 of the tire 1 when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0055] As in Fig.2, in the meridian cross-section of the tread portion 2, an imaginary line passing through the bottom portion 12B of the shoulder main groove 12 and parallel to the first imaginary line VL1 is defined as a second imaginary line VL2. That is, the second imaginary line VL2 is an imaginary line obtained by moving the first imaginary line VL1 in parallel inward in the tire radial direction until the first imaginary line VL1 is located in the bottom portion 12B of the shoulder main groove 12, with the tire 1 mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0056] As in Fig.2, in the meridian cross-section of the tread portion 2, an intersection point of the second imaginary line VL2 and the side surface 34 of the shoulder land portion 23 outside the ground contact edge T in the tire transverse direction is defined as an intersection point P. The intersection point P is an intersection point of the second imaginary line VL2 and the side surface 34 when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0057] As in Fig. 2, in the meridian cross-section of the tread portion 2, a distance between the tire equatorial plane CL and the intersection point P in the tire transverse direction is defined as distance A. The distance A is a distance between the tire equatorial plane CL and the intersection point P when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0058] As in Fig.2, in the meridian cross-section of the tread portion 2, a groove depth of the shoulder main groove 12 is defined as a groove depth B. The groove depth B is a distance between the bottom portion 12B of the shoulder main groove 12 and the opening end portion 12K of the shoulder main groove 12 in the tire radial direction when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state. Note that when the opening end portion 12Ka and the opening end portion 12Kb of the shoulder main groove 12 differ in position in the tire radial direction, the distance between the opening end portion 12K of the two opening end portions 12Ka, 12Kb that is farther away from the rotation axis AX and the bottom portion 12B of the shoulder main groove 12 can be set as the groove depth B.Or, the distance between the opening end portion 12Kb outward in the tire radial direction and the bottom portion 12B of the shoulder main groove 12 may be set as the groove depth B. Or, an average value of the distance between the opening end portion 12Ka and the bottom portion 12B, and the distance between the opening end portion 12Kb and the bottom portion 12B in the tire radial direction may be set as the groove depth B. Note that when the positions of the opening end portion 12Ka and the opening end portion 12Kb in the tire radial direction are substantially the same, the distance between the opening end portion 12K of the two opening end portions 12Ka, 12Kb and the bottom portion 12B of the shoulder main groove 12 may be set as the groove depth B.

[0059] Note that the positions of the opening end portion 12Ka and the position of the opening end portion 12Kb in the tire radial direction are substantially the same when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, statically placed perpendicular to a flat plate, and loaded with a load corresponding to the prescribed weight. The distance between the opening end portion 12Ka or the opening end portion 12Kb and the land portion 12B in the tire radial direction when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, statically placed perpendicular to a flat plate, and loaded with a load corresponding to the prescribed weight is defined as the groove depth B.

[0060] As in Fig.As illustrated in Figure 2, in the meridian cross-section of the tread portion 2, a distance between the tire equatorial plane CL and the ground contact edge T in the tire transverse direction is defined as distance C. The position of the ground contact edge T is specified by measuring the position when a load corresponding to a predetermined weight is applied and positioning the measured position on the surface of the tread portion 2 in an unloaded state. The distance C is a distance between the tire equatorial plane CL and the indicated ground contact edge T when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state. The distance C is a value equal to half the ground contact width.

[0061] As in Fig.2, in the meridian cross-section of the tread portion 2, a distance between the tire equatorial plane CL in the tire transverse direction and the opening end portion 12Kb outside the shoulder main groove 12 in the tire transverse direction is defined as a distance D. The distance D is a distance between the tire equatorial plane CL and the opening end portion 12Kb when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0062] As in Fig.3, in the meridian cross-section of the tread portion 2, an imaginary line passing through the ground contact edge T and the intersection point P is defined as a third imaginary line VL3. The third imaginary line VL3 is a straight line passing through the ground contact edge T and the intersection point P when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0063] As in Fig. As illustrated in Figure 3, in the meridian cross-section of the tread portion 2, an imaginary line parallel to the tire equatorial plane CL and passing through the intersection point P is defined as a fourth imaginary line VL4. The fourth imaginary line VL4 is a straight line passing through the intersection point P when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0064] As in Fig. 3, in the meridian cross-section of the tread portion 2, an angle formed by the third imaginary line VL3 and the fourth imaginary line VL4 is defined as angle θa.

[0065] As in Fig. 2, in the meridian cross-section of the tread portion 2, a distance between the bottom portion 12B of the shoulder main groove 12 and the intersection point P in the tire transverse direction is defined as a distance E. The distance E is a distance between the bottom portion 12B and the intersection point P when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0066] As in Fig.As illustrated in Figure 2, in the meridian cross-section of the tread portion 2, an imaginary line passing through the sidewall portion 12Sb and parallel to the tire equatorial line CL is defined as a fifth imaginary line VL5. The fifth imaginary line VL5 is a straight line passing through the sidewall portion 12Sb when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0067] As in Fig. 2, in the meridian cross-section of the tread portion 2, the sidewall portion 12Sb slopes outward in the tire transverse direction toward an outer side in the tire radial direction with respect to the fifth imaginary line VL5. In the meridian cross-section of the tread portion 2, an angle formed by the fifth imaginary line VL5 and the sidewall portion 12Sb outside the shoulder main groove 12 in the tire transverse direction is referred to as angle θb.

[0068] As in Fig. As illustrated in Figure 2, in the meridian cross-section of the tread portion 2, a distance between the opening end portion 12Kb outside the shoulder main groove 12 in the tire transverse direction and the ground contact edge T in the tire transverse direction is defined as distance F. The distance F is the dimension of the ground contact surface 33 of the shoulder land portion 23 in the tire transverse direction. The distance F is a distance between the opening end portion 12Kb and the ground contact edge T when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0069] As in Fig.As illustrated in Figure 2, in the meridian cross-section of the tread portion 2, a dimension of the central land portion 21 in the tire transverse direction is defined as dimension G. The dimension G is a dimension of the central land portion 21 when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state. The dimension G is the measurement of the ground contact surface 31 of the central land portion 21 in the tire transverse direction.

[0070] As in Fig.As illustrated in Figure 1, in the meridian cross-section of the tread portion 2, a distance in the tire transverse direction between the tire equatorial plane CL and the outermost portion of the side portion 3 in the tire transverse direction is defined as distance H. The distance H is a distance between the tire equatorial plane CL and the outermost portion of the side portion 3 in the tire transverse direction when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state. The distance H is a value corresponding to half the total width.

[0071] As in Fig.1, in the meridian cross-section of the tread portion 2, a tire outer diameter in the tire equatorial plane CL is defined as a tire outer diameter J. The tire outer diameter J is a diameter of the tire 1 in the tire equatorial plane CL when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0072] As in Fig. 1, in the meridian cross-section of the tread portion 2, a tire outer diameter of the opening end portion 12Ka within the shoulder main groove 12 in the tire transverse direction is defined as a tire outer diameter K. The tire outer diameter K is the diameter of the tire 1 at the opening end portion 12Ka when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0073] As in Fig.1, in the meridian cross-section of the tread portion 2, a tire outer diameter at the ground contact edge T is defined as a tire outer diameter L. The tire outer diameter L is a diameter of the tire 1 at the ground contact edge T when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0074] As in Fig.2, in the meridian cross-section of the tread portion 2, a distance between the bottom portion 12B of the shoulder main groove 12 and the belt layer 6 in the tire radial direction is defined as a distance M. In the present embodiment, the third belt ply 63 is disposed directly below the bottom portion 12B of the shoulder main groove 12. The distance M is a distance between the bottom portion 12B of the shoulder main groove 12 and the third belt ply 63 disposed directly below the bottom portion 12B when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0075] As in Fig.2, in the meridian cross-section of the tread portion 2, a distance in the tire radial direction between the ground contact surface 33 of the shoulder land portion 23 and the end portion of the third belt ply 63 disposed under the second belt ply 62 and the third belt ply 63 constituting the cross-ply belt layer, outward in the tire radial direction is defined as a distance N. The distance N is a distance in the tire radial direction between the end portion of the third belt ply 63 in the tire transverse direction and a region of the ground contact surface 33 located directly above the end portion of the third belt ply 63 when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0076] As in Fig.2, in the meridian cross-section of the tread portion 2, a distance in the tire transverse direction between the tire equatorial plane CL and the end portion of the third belt ply 63, which has a short dimension in the tire transverse direction among the second belt ply 62 and the third belt ply 63 constituting the cross-ply belt layer, is defined as a distance Q. The distance Q is a distance in the tire transverse direction between the tire equatorial plane CL and the end portion of the third belt ply 63 in the tire transverse direction when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0077] As in Fig.2, in the meridian cross-section of the tread portion 2, a distance in the tire transverse direction between the tire equatorial plane CL and the end portion of the second belt ply 62 having the longest dimension among the plurality of belt plies 61, 62, 63, 64 is defined as a distance S in the tire transverse direction. The distance S is a distance between the tire equatorial plane CL and the end portion of the second belt ply 62 in the tire transverse direction when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state.

[0078] As in Fig.As illustrated in Figure 4, a plurality of depressed portions 40 are provided in the tire circumferential direction in the side surface 34 of the shoulder land portion 23 outside the ground contact edge T in the tire transverse direction. The depressed portions 40 are lug grooves formed in the side surface 34. The depressed portions 40 extend in the tire radial direction.

[0079] As in Fig. As illustrated in Figure 4, a dimension of the depressed portion 40 in the tire circumferential direction is defined as dimension U. The dimension U of the depressed portion 40 is a dimension when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state. The dimension of the depressed portion 40 in the tire circumferential direction is smaller than a dimension of the depressed portion 40 in the tire radial direction.

[0080] As in Fig.As illustrated in Figure 4, a dimension between the adjacent depressed portions 40 in the tire circumferential direction is defined as dimension V. The dimension V is a dimension of the space between adjacent depressed portions 40 when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state. The dimension V is larger than the dimension U.

[0081] As in Fig. As illustrated in Figure 4, a plurality of sipes 41 are provided in the tire circumferential direction on the side surface 34 of the shoulder land portion 23. The sipes 41 each have a groove depth smaller than that of the recessed portion 40 (lug groove) and a small groove width. The sipes 41 extend in the tire radial direction. A plurality of sipes 41 are provided between the recessed portions 40 adjacent to each other in the tire circumferential direction.

[0082] As in Fig. As illustrated in Figure 4, a dimension between the adjacent sipes 41 in the tire circumferential direction is defined as dimension W. The dimension W is a dimension of the space between the adjacent sipes 41 when the tire 1 is mounted on a suitable rim, inflated to a prescribed air pressure, and in an unloaded state. The dimension W is smaller than the dimension of the sipe 41 in the tire radial direction.

[0083] Note that the lug groove (recessed portion) 40 refers to a groove in which the groove opening is maintained even when the lug groove is considered to have come into contact with the ground. The sipe 41 refers to a groove in which the opening of the sipe 41 is blocked and not maintained when the sipe 41 is considered to have come into contact with the ground.

[0084] As in Fig. As illustrated in Figure 5, the inclination direction of the belt cords of the second belt ply 62 and the inclination direction of the belt cords of the third belt ply 63 are different with respect to the tire equator line. The belt cords of the second belt ply 62 incline toward a first side in the tire transverse direction toward a first side in the tire circumferential direction. The belt cords of the third belt ply 63 incline toward a second side in the tire transverse direction toward the first side in the tire circumferential direction.

[0085] The inclination angle of the belt cords of the second belt ply 62 with respect to the tire equator line is defined as angle θc. Furthermore, an inclination angle of the belt cords of the third belt ply 63 with respect to the tire equator line is defined as angle θd. Explanation of the features

[0086] Next, the features of the tire 1 according to the present embodiment will be described. The tire 1 has a plurality of features. Each feature will be described in turn. Feature 1

[0087] The following inventive condition is met: 0.80≤(B+C) / A≤1.15 More preferably, the following condition is met: 0.80≤(B+C) / A≤1.05

[0088] When the tire 1 rotates or hits a curb and deforms, with the shoulder main groove 12 widening and the shoulder land portion 23 shifting outward in the tire transverse direction, the value (B+C) approaches the value A in accordance with the groove depth B. Feature 1 defines the degree of closeness between the distance A and the sum of the groove depth B and the distance C when the shoulder land portion 23 shifts outward in the tire transverse direction. Feature 2

[0089] The following inventive condition is met: 20°≤θa≤50°

[0090] Feature 2 defines the degree of rise of the side surface 34 of the shoulder web section 23. Feature 3

[0091] The following condition is met: D / C≤0.80

[0092] Feature 3 specifies that the main circumferential groove 10 (shoulder main groove 12) is not located within 20% of the outer side of the distance C (half of the ground contact width). Feature 4

[0093] In the meridian cross-section of the tire 1, the bottom portion 12B of the shoulder main groove 12 has an arc shape. A radius of curvature R of the bottom portion 12B is 2.0 mm or more. This means that the following condition is satisfied: 2.0≤R More preferably, the following condition is met: 2.0≤R≤5.0

[0094] Feature 4 specifies that the bottom portion 12B of the shoulder main groove 12 is preferably not angular, and that the radius of curvature R is therefore large. Feature 5

[0095] The following condition is met: 2.0≤E / B≤5.0

[0096] Feature 5 defines the relationship between the groove depth B and the distance E. Feature 6

[0097] The following condition is met: 5°≤θb≤45° More preferably, the following condition is met: 5°≤θb≤20°

[0098] Feature 6 defines the degree of rise of the sidewall portion 12Sb outward in the tire transverse direction on the inner surface of the shoulder main groove 12. Feature 7

[0099] The following condition is met: 12mm≤W≤25mm More preferably, the following condition is met: 15mm≤W≤17mm

[0100] Feature 7 defines an absolute value of the groove depth B. Feature 8

[0101] The following condition is met: 0.80≤F / G≤1.30

[0102] Feature 8 defines the ratio of the dimension of the ground contact surface 31 of the central web portion 21 in the tire transverse direction to the dimension of the ground contact surface 33 of the shoulder web portion 23. Feature 9

[0103] The following condition is met: 1.5≤F / B≤4.0

[0104] Feature 9 defines the relationship between the dimension of the ground contact surface 33 of the shoulder land portion 23 in the tire transverse direction and the groove depth B. Feature 10

[0105] The following conditions according to the invention are met: J>K J>L and 0.05≤(K−L) / (J−L)≤0.85

[0106] Feature 10 defines a shoulder depression of the profile of the ground contact surface 30 of the tread portion 2. Feature 11

[0107] The following condition is met: 1.0≤N / B≤1.4

[0108] Feature 11 defines the relationship between the distance N between the ground contact surface 33 of the shoulder land portion 23 and the third belt ply 63, and the groove depth B of the shoulder main groove 12. Feature 12

[0109] The following conditions are satisfied, where Hs is given as a hardness indicating the buckling strength of the closure tread rubber 82 at room temperature (23 °C), and tan δ is given as a loss coefficient indicating a relationship between a storage shear modulus and a loss shear modulus of the closure tread rubber 82 at 60 °C: 60≤Hs and 0.23≥tanδ More preferably, the following conditions are met: 65≤Hs≤75 and 0.05≤tanδ≤0.23

[0110] Feature 12 defines the physical properties of the closure tread rubber 82 of the tread rubber 8 in which the main circumferential groove 10 and the land portion 20 are formed. Feature 13

[0111] The following condition is satisfied, where Md is given as the modulus at 300% elongation, which indicates a tensile stress required to elongate the closure tread rubber 82 by 300%: 9.0 MPa≤Md≤17.1 MPa

[0112] Furthermore, the following condition is satisfied, where TB is given as a tensile strength indicating the maximum tensile stress required to pull and tear the closure tread rubber 82 at 100 °C: 13.0 MPa≤TB≤23.3 MPa

[0113] Furthermore, the following condition is satisfied, where EB is given as a tensile elasticity indicating a stretch ratio at the breakage of the closure tread rubber 82 at 100 °C: 444 MPa≤EB≤653 MPa

[0114] Furthermore, the hardness Hs of the under-tread rubber 81 at room temperature is preferably lower than the hardness Hs of the closure tread rubber 82. Furthermore, the hardness Hs of the side rubber 9 at room temperature is preferably lower than the hardness Hs of the closure tread rubber 82 and the hardness Hs of the under-tread rubber 81.

[0115] Furthermore, the tan δ of the under-tread rubber 81 at 60 °C is preferably lower than the tan δ of the closure tread rubber 82. Furthermore, the tan δ of the side rubber 9 at 60 °C is preferably lower than the tan δ of the closure tread rubber 82.

[0116] Furthermore, the modulus MD at 300% elongation of the undertread rubber 81 is preferably less than or equal to the modulus Md at 300% elongation of the closure tread rubber 82. Furthermore, the modulus MD at 300% elongation of the side rubber 9 is preferably less than the modulus Md at 300% elongation of the closure tread rubber 82.

[0117] Furthermore, the tensile strength TB of the undertread rubber 81 at 100 °C is preferably lower than the tensile strength TB of the closure tread rubber 82. Furthermore, the tensile strength TB of the side rubber 9 at 100 °C is preferably lower than the tensile strength TB of the closure tread rubber 82.

[0118] Furthermore, the tensile elasticity EB of the undertread rubber 81 at 100 °C is preferably lower than the tensile elasticity EB of the closure tread rubber 82. Furthermore, the tensile elasticity EB of the side rubber 9 at 100 °C is preferably lower than the tensile elasticity EB of the undertread rubber 81.

[0119] The preferred values ​​for the hardness HS at room temperature, the modulus Md at 300% elongation, the tensile strength TB at 100 °C, the tensile elasticity EB at 100 °C, and the tan δ at 60 °C of the closure tread rubber 82, the undertread rubber 81, and the sidewall rubber 9 are shown in Table 1 below. That is, Table 1 summarizes Features 12 and 13. Note that the values ​​in parentheses in Table 1 indicate the actually produced values ​​of Tire 1. Table 1 Lock tread rubber Hardness Hs From 60 to 75 (65) inclusive Modulus Md at strain (MPa) From 9.0 to 17.1 (14.5) Tensile strength TB (MPa) From 13.0 to 23.3 (23.3) Tensile elasticity EB From 444 to 653 (600) tan δ From 0.05 to 0.23 (0.21) inclusive Undertread rubber Hardness Hs 60 (60) Modulus Md at strain (MPa) 14,4 (14,4) Tensile strength TB (MPa) From 20.1 to 21.3 inclusive (21.3) Tensile elasticity EB From 555 to 576 inclusive (555) tan δ 0,12 (0,12) Side rubber Hardness Hs From 52 to 58 (55) inclusive Modulus Md at strain (MPa) From 5.5 to 10.5 (7.5) Tensile strength TB (MPa) From 16.0 to 25.0 (20.0) inclusive Tensile elasticity EB From 500 to 700 (600) inclusive tan δ From 0.10 to 0.18 (0.14) inclusive Feature 14

[0120] The following condition is satisfied in each of the belt layers 61, 62, 63 and 64, where BP is given as the number of belt cords arranged per 50 mm: 20 cord threads≤BP≤30 cord threads Feature 15

[0121] The following condition is met, where Mbp is given as the modulus at 100% elongation, which indicates the tensile stress required to stretch the belt rubber of each of the belt plies 61, 62, 63, 64 in a new product: 5.5 MPa≤Mbp Feature 16

[0122] The following inventive condition is met: 0.76≤C / H≤0.96

[0123] Feature 16 defines the ratio of the value of half the ground contact width to the value of half the total width. Feature 17

[0124] The following conditions are met: 45°≤θc≤70° and 45°≤θd≤70° Note that, as described above, the inclination direction of the belt cords of the second belt layer 62 and the inclination direction of the belt cords of the third belt layer 63 are different.

[0125] The belt cords of the first belt ply 61 and the belt cords of the second belt ply 62 are inclined in the same direction. That is, the first belt ply 61 and the second belt ply 62 are layered such that the belt cords of the first belt ply 61 and the belt cords of the second belt ply 62 overlap. The following condition is satisfied, where θe is the inclination angle of the belt cords of the first belt ply 61 with respect to the tire equator line: 45°≤θe≤70° Feature 18

[0126] The following condition is met: 1.0≤F / U

[0127] Feature 18 defines the relationship between the dimension of the ground contact surface 33 of the shoulder land portion 23 in the tire transverse direction and the dimension of the depressed portion 40 provided in the side surface 34 of the shoulder land portion 23. Feature 19

[0128] The following condition is met: 0.10≤U / V≤0.60

[0129] Feature 19 defines the ratio of the dimension of the recessed portion 40 provided in the side surface 34 of the shoulder web portion 23 to the dimension of the gap of the recessed portion 40. Feature 20

[0130] The following condition is met: 5 mm≤U≤20 mm

[0131] Feature 20 defines an absolute value of the dimension of the recessed section 40. Feature 21

[0132] The following condition is met: 3≤F / W≤10

[0133] Feature 21 defines the relationship between the dimension of the ground contact surface 33 of the shoulder land portion 23 in the tire transverse direction to the dimension of the gap of the sipe 41 provided in the side surface 34 of the shoulder land portion 23. Feature 22

[0134] The following condition is met: 0.10≤M / B≤0.75

[0135] Feature 22 defines the relationship between the distance M of the tread rubber 8 directly below the shoulder main groove 12 to the groove depth B. Feature 23

[0136] The following condition is met: 0.75≤Q / C≤0.95

[0137] Feature 23 defines the ratio of the value of half the width of the third belt layer 63 and the value of half the ground contact width. Feature 24

[0138] The end portion of the belt layer 6 in the tire transverse direction is arranged inside or outside the shoulder land portion 23 in the tire transverse direction. That is, the end portions of the belt plies 61, 62, 63, 64 are not arranged directly below the shoulder main groove 12. In the present embodiment, the end portion of the fourth belt ply 64 in the tire transverse direction is arranged inside the opening end portion 12Ka in the tire transverse direction, with the opening end portion 12Ka being located inside the shoulder main groove 12 in the tire transverse direction. The end portions of the first, second, and third belt plies 61, 62, 63 in the tire transverse direction are arranged outside the opening end portion 12Kb in the tire transverse direction, with the opening end portion 12Kb being located outside the shoulder main groove 12 in the tire transverse direction. Measures and impacts

[0139] According to the present embodiment, satisfying at least feature 1 of the above-described features 1 to 24 suppresses excessive deformation of the shoulder land portion 23 when the tire 1 mounted on a vehicle rotates or hits a curb.

[0140] The inventors of the present invention prepared tires as evaluation test tires satisfying the above-described characteristics and tires not satisfying them, mounted the evaluation test tires on vehicles, and conducted the evaluation tests by driving the vehicles onto a curb. Fig. Figure 6 is a schematic diagram explaining the evaluation test. As shown in Fig.6, the shoulder land portion 23 on an outer side of the tire mounted on the vehicle for the evaluation test was allowed to drive onto a curb. For each evaluation test tire, a degree of deformation of the shoulder land portion 23 was measured when the shoulder land portion 23 on the outer side of the vehicle was driven onto a curb. As shown in Fig.As illustrated in Fig. 6, the shoulder land portion 23 deforms by rotating upward depending on the structure of the tire, and the ground contact surface 33 of the shoulder land portion 23 warps. As the degree of deformation of the shoulder land portion 23, a distance SH between an upper surface of the curb and the ground contact edge T of the warped ground contact surface 33 in the vertical direction was measured. Note that the upper surface of the curb is substantially parallel to the horizontal plane. In the following description, the distance SH between the upper surface of the curb and the ground contact edge T of the warped ground contact surface 33 in the vertical direction is referred to as a warpage amount SH.

[0141] A large value of the warpage amount SH means that the shoulder land portion 23 is excessively deformed. When the warpage amount SH is large, the likelihood of cracks in the inner surface of the shoulder main groove 12, damage to the shoulder land portion 23, and a phenomenon called rib cracking increases. A rib crack is a phenomenon in which a portion of the tread rubber 8 cracks or is damaged due to the application of an external force. From the perspective of suppressing cracks in the inner surface of the shoulder main groove 12, suppressing damage to the shoulder land portion 23, and suppressing the occurrence of rib cracks, a smaller warpage amount SH is preferable.

[0142] Fig. Figure 7 shows the test results of the tire deflection SH of each evaluation test. The horizontal axis of the graph in Fig. 7 indicates the value of feature 1. The vertical axis of the graph in Fig.Figure 7 indicates the warpage amount SH. If the warpage amount SH is greater than 6 mm, the possibility of cracks in the inner surface of the shoulder main groove 12, damage to the shoulder land portion 23, and the occurrence of rib cracks increases. If the warpage amount SH is 6 mm or less, the suppression of cracks in the inner surface of the shoulder main groove 12, the suppression of damage to the shoulder land portion 23, and the suppression of the occurrence of rib cracks can be expected.

[0143] As in Fig. As illustrated in Figure 7, the tire according to the prior art example does not satisfy the condition of Feature 1, and the value of (B+C) / A is greater than 1.15. The tire according to Examples A, B, C, D, and E satisfies the condition of Feature 1. The warpage amount SH of the tire according to the prior art example is more than 6 mm. The warpage amount SH of the tires according to Examples A, B, C, D, and E is less than 6 mm.

[0144] As mentioned with reference to Fig. As described in Fig. 6, when the tire rotates or hits a curb, causing the shoulder main groove 12 to widen, the inner surface of the shoulder main groove 12 comes into contact with the upper surface of the curb, and the shoulder land portion 23 is displaced outward in the tire transverse direction (on the vehicle outer side). If the groove depth B is too deep, the distance C (half of the ground contact width) is too large, or the distance A is too small, thereby increasing the value of (B+C) / A, it is considered that the shoulder land portion 23 is more likely to warp. The inventors of the present invention found that the warp of the shoulder land portion 23 can be suppressed by setting the value of (B+C) / A to 1.15 or less.

[0145] The tires according to Examples A, B and C satisfy the condition of characteristic 1, but they do not satisfy the conditions of characteristics 2 to 24. As can be seen from Examples A, B and C, the distortion SH decreases proportionally to the decrease in the value of (B+C) / A.

[0146] Example D is a tire that satisfies the conditions of Feature 1, Feature 2, and Feature 3. The value of (B+C) / A of the tire according to Example B and the value of (B+C) / A of the tire according to Example D are substantially the same. The warpage SH of the tire according to Example D is smaller than the warpage SH of the tire according to Example B.

[0147] Feature 2 defines the degree of rise of the side surface 34 of the shoulder land portion 23. Feature 3 specifies that the shoulder main groove 12 is not located within 20% of the outer side of the distance C (half the ground contact width). The fulfillment of the conditions 20°≤θa≤50° D / C≤0.80 corresponding to characteristics 2 and 3 makes it possible to suppress the distortion dimension SH of the tire.

[0148] Example E is a tire that satisfies the conditions of Feature 1, Feature 2, Feature 3, Feature 4, Feature 5, Feature 6, Feature 7, Feature 12, and Feature 13. The value of (B+C) / A of the tire according to Example B, the value of (B+C) / A of the tire according to Example D, and the value of (B+C) / A of the tire according to Example E are substantially the same. The warpage SH of the tire according to Example E is smaller than the warpage SH of the tire according to Example B and smaller than the warpage SH of the tire according to Example D.

[0149] When the condition of feature 4 is satisfied, the warpage of the shoulder land portion 23, the occurrence of cracks in the bottom portion 12B of the shoulder main groove 12, and the occurrence of rib cracks are suppressed.

[0150] Furthermore, when the condition of Feature 5 is satisfied, the warping of the shoulder land portion 23 during tire rotation is suppressed, and the steering stability performance is improved. When the E / B value is more than 5.0, the rigidity of the shoulder land portion 23 is greater than the rigidity of the center land portion 21, and the vehicle's steering behavior linearity deteriorates. When the E / B value is less than 2.0, the rigidity of the shoulder land portion 23 decreases extensively, and the possibility of warping of the shoulder land portion 23 during tire rotation increases. When the shoulder land portion 23 is warped, the steering stability performance during tire rotation decreases.

[0151] Furthermore, when the condition of feature 6 is satisfied, the occurrence of cracks on the inner surface of the shoulder main groove 12 and the occurrence of rib cracks are suppressed.

[0152] Furthermore, when the condition of feature 7 is also satisfied, the occurrence of cracks on the inner surface of the shoulder main groove 12 and the occurrence of rib cracks are suppressed.

[0153] Furthermore, the physical properties of the closure tread rubber 82, the under tread rubber 81 and the side rubber 9 are designed to satisfy the conditions of the features 12, 13, thereby suppressing the warpage of the shoulder land portion 23, the occurrence of cracks on the inner surface of the shoulder main groove 12, damage to the shoulder land portion 23 and the occurrence of rib cracks.

[0154] Furthermore, according to the present embodiment, the following condition is met: 0.80≤(B+C) / A≤1.15 which is feature 1, making it possible to prevent damage to the tread rubber 8 and reduce the rolling resistance of the tire 1, while suppressing a reduction in the abrasion resistance performance of the tire 1. A high (B+C) / A value means that the volume of the plug tread rubber 82 is large. A low (B+C) / A value means that the volume of the plug tread rubber 82 is small. Furthermore, when the volume of (B+C) / A is greater than 1.15, the volume of the plug tread rubber 82 becomes excessively large, which hinders the heat generation of the tread rubber 8 when the tire 1 is running. As a result, the rolling resistance of the tire 1 deteriorates. When the value of (B+C) / A is less than 0.80, the volume of the plug tread rubber 82 is extremely small. As a result, the abrasion resistance performance of the tire 1 deteriorates.By satisfying the condition of feature 1, it is possible to prevent damage to the tread rubber 8 and reduce the rolling resistance of the tire 1 while suppressing a reduction in the abrasion resistance performance of the tire 1.

[0155] Furthermore, when the condition of Feature 1 is satisfied, cracking and chipping of tread rubber 8 are suppressed even when the shoulder land portion 23 comes into contact with a curb. When the value of (B+C) / A is more than 1.15, the shoulder land portion 23 moves easily and cracks easily upon contact with a curb. When the value of (B+C) / A is less than 0.80, a ground contact pressure of the shoulder land portion 23 increases, and the shoulder land portion 23 chips easily upon contact with a curb. When the condition of Feature 1 is satisfied, cracking and chipping of tread rubber 8 are suppressed even when the shoulder land portion 23 comes into contact with a curb.

[0156] Furthermore, when the condition of Feature 2 is satisfied, cracking and chipping of tread rubber 8 are more effectively suppressed even when the shoulder land portion 23 comes into contact with a curb. When the angle θa is greater than 50°, a ground contact pressure of the shoulder land portion 23 increases, and the shoulder land portion 23 is easily chipped upon contact with a curb. When the angle θa is less than 20°, the shoulder land portion 23 moves easily and cracks upon contact with a curb. When the condition of Feature 2 is satisfied, cracking and chipping of tread rubber 8 are more effectively suppressed even when the shoulder land portion 23 comes into contact with a curb.

[0157] Furthermore, when the condition of feature 3 is satisfied, the shoulder main groove 12 is not arranged in the side of the outer 20% of the distance C, thereby suppressing excessive movement of the shoulder land portion 23.

[0158] Furthermore, according to the present embodiment, the following condition is met: 0.76≤C / H≤0.96 which is Feature 16. If the condition of Feature 16 is not met and the C / H value is more than 0.96 or the C / H value is less than 0.76, there is an increased possibility that the stability of the tread portion 2 will decrease and the tread rubber 8 and the side rubber 9 will move excessively when the tire 1 is running. If the tread rubber 8 and the side rubber 9 move excessively, a rolling resistance of the tire 1 will deteriorate. When the condition of Feature 16 is met, the behavior of the tread rubber 8 and the side rubber 9 stabilizes when the ground contact surface 30 of the tread portion 2 comes into contact with the road surface, and the ground contact surface 30 comes into contact with the road surface in a stable manner. Thus, the rolling resistance of the tire 1 decreases.

[0159] Furthermore, according to the present embodiment, the condition is satisfied: 0.10≤M / B≤0.75 This is Feature 22. A large M / B value means that the volume of the tread rubber 8 directly under the shoulder main groove 12 is excessively large. A small M / B value means that the volume of the tread rubber 8 directly under the shoulder main groove 12 is excessively small. If the M / B value is greater than 0.75, the heat buildup of the tread rubber 8 during the running of the tire 1 is hindered. As a result, the rolling resistance of the tire 1 deteriorates. If the M / B value is less than 0.10, the abrasion resistance performance of the tread portion 2 decreases, increasing the possibility of exposing the belt layer 6 in the final stages of abrasion of the tread portion 2. By satisfying the condition of Feature 22, it is possible to suppress a decrease in abrasion resistance performance and reduce tire rolling resistance.

[0160] Furthermore, according to the present embodiment, the condition is satisfied: 0.75≤Q / C≤0.95 which is Feature 23. A large Q / C value means that the end portion of the belt layer 6 is likely to move to an excessive extent when the tire 1 is running. A small Q / C value means that the rigidity of the shoulder land portion 23 decreases. If the Q / C value is greater than 0.95, the end portion of the belt layer 6 moves excessively, which increases the amount of deformation of the tread rubber 8, resulting in a deterioration in the rolling resistance of the tire 1. If the Q / C value is less than 0.75, the rigidity of the shoulder land portion 23 decreases, and when the tire 1 is running, the shoulder land portion 23 moves excessively, resulting in a deterioration in the rolling resistance of the tire 1. When the condition of Feature 23 is satisfied, the rolling resistance of the tire 1 can be reduced.

[0161] Furthermore, according to the present embodiment, the conditions are met: 60≥Hs 0.23≥tan δ which is Feature 12. When the hardness Hs is less than 60, the tread rubber 8 (lock tread rubber 82) moves excessively when the tire 1 runs, resulting in an increase in the rolling resistance of the tire 1. When tan δ is greater than 0.23, the rolling resistance of the tire 1 increases. When the condition of Feature 12 is satisfied, the rolling resistance of the tire 1 can be reduced.

[0162] Furthermore, when the condition of Feature 8 is satisfied, the stiffness difference between the central portion of the tread portion 2, including the central land portion 21, and the shoulder portion of the tread portion 2, including the shoulder land portion 23, decreases, thereby suppressing the occurrence of uneven wear in the shoulder portion. When the F / G value is more than 1.30, the stiffness of the shoulder portion becomes excessively large, and the shoulder wear resistance performance decreases. When the F / G value is less than 0.80, the stiffness of the shoulder portion becomes excessively small, and the shoulder wear resistance performance also decreases.

[0163] Furthermore, if the condition of Feature 9 is met, a decrease in shoulder abrasion resistance performance can be similarly suppressed. If the F / B value is more than 4.0, the rigidity of the shoulder web portion 23 becomes excessively large, and the shoulder abrasion resistance performance decreases. If the F / B value is less than 1.5, the rigidity of the shoulder portion becomes excessively small, and the shoulder abrasion resistance performance also decreases in this case.

[0164] Furthermore, according to the present invention, when the condition of feature 10 is satisfied, a decrease in shoulder abrasion resistance performance can be similarly prevented. When the value of (KL) / (JL) is more than 0.85, the stiffness of the shoulder portion becomes excessively small, and the shoulder abrasion resistance performance decreases. When the value of (KL) / (JL) is less than 0.05, the stiffness of the shoulder portion becomes excessively large, and the shoulder abrasion resistance performance also decreases.

[0165] Furthermore, when the condition of Feature 11 is satisfied, the durability of the belt layer 6 is improved. An N / B value of more than 1.4 means that the volume of the closure tread rubber 82 of the shoulder land portion 23 is excessively large. If the volume of the closure tread rubber 82 is excessively large, the heat generation of the closure tread rubber 8 is hindered, and thereby the durability of the belt layer 6 deteriorates. An N / B value of less than 1.0 means that the thickness of the closure tread rubber 82 of the shoulder land portion 23 is excessively thin. If the thickness of the closure tread rubber 82 is excessively thin, the end portion of the belt layer 6 of the tread portion 2 is exposed at the final abrasion stage, thereby deteriorating the durability of the belt layer 6.

[0166] Furthermore, when the condition of feature 14 is satisfied, a feeling of upward thrust when the tire 1 passes over a step on the road surface is suppressed. Accordingly, ride comfort is improved.

[0167] Furthermore, if the condition of feature 17 is met, ride comfort is similarly improved. Furthermore, the durability of belt layer 6 is improved.

[0168] Furthermore, when the condition of Feature 18 is satisfied, the warping of the shoulder land portion 23 is suppressed. A large dimension U of the depressed portion 40 and an F / U value less than 1.0 mean that the rigidity of the shoulder land portion 23 decreases. As a result, the shoulder land portion 23 warps easily when the tire 1 turns. Furthermore, when the dimension U of the depressed portion 40 is large, the shoulder land portion 23 warps and the ground contact surface becomes smaller, making it impossible to obtain sufficient cornering force. Furthermore, when the condition of Feature 18 is satisfied, the warping of the shoulder land portion 23 when the tire 1 turns is suppressed, and ride comfort is improved.

[0169] Furthermore, when the condition of feature 19 is satisfied, the deformation of the shoulder land portion 23 and the warping of the shoulder land portion 23 when the tire 1 turns or hits a curb are similarly suppressed.

[0170] Furthermore, when the condition of feature 21 is satisfied, the deformation of the shoulder land portion 23 and the warping of the shoulder land portion 23 when the tire 1 turns or hits a curb are similarly suppressed. Examples

[0171] Tires that met the above-described conditions of Feature 1, Feature 16, Feature 22, Feature 23, and Feature 12, and tires that did not meet them, were evaluated for (1) rolling resistance and (2) abrasion resistance performance. Test tires with a tire size of 295 / 80R22.5 were inflated to a maximum internal pressure defined by JATMA, mounted on a large bus, run at a vehicle speed of 80 km / h on a test track for a distance of 40,000 km, and measured for fuel economy and groove depth of the circumferential main groove after running. With the test tires mounted on the large bus, a load equivalent to 70% of the maximum load defined by JATMA was applied to the test tires.The evaluation was expressed by using the evaluation result of the tire according to the prior art example that does not satisfy any of the conditions of Feature 1, Feature 16, Feature 22, Feature 23, or Feature 12 as an index value of 100 (standard). In this evaluation, larger values ​​are preferred.

[0172] Fig. Figure 8 shows the results of the evaluation test. Non-inventive Examples 1, 2, and 3 are tires that satisfy the conditions of Feature 1, but do not satisfy the conditions of Feature 16, Feature 22, Feature 23, and Feature 12. In Examples 1, 2, and 3, the value of (B+C) / A varied within the range of Feature 1.

[0173] Examples 4, 5, and 6 are tires that meet the conditions of Feature 1 and Feature 16, but do not meet the conditions of Feature 22, Feature 23, and Feature 12. For Examples 4, 5, and 6, the value of C / H varied within the range of Feature 16. Note that for Examples 4, 5, and 6, the value of (B+C) / A was 1.00.

[0174] Examples 7, 8, and 9 are tires that satisfy the conditions of Feature 1, Feature 16, and Feature 22, but do not satisfy the conditions of Feature 23 and Feature 12. For Examples 7, 8, and 9, the M / B value varied within the range of Feature 22. Note that for Examples 7, 8, and 9, the value of (B+C) / A was 1.00, and the C / H value was 0.96.

[0175] Examples 10, 11, and 12 are tires that meet the conditions of Feature 1, Feature 16, Feature 22, and Feature 23, but do not meet the conditions of Feature 12. For Examples 10, 11, and 12, the Q / C value varied within the range of Feature 23. Note that for Examples 10, 11, and 12, the value of (B+C) / A was 1.00, the C / H value was 0.96, and the M / B value was 0.40.

[0176] Example 13 is a tire that satisfies conditions (12A) of Feature 1, Feature 16, Feature 22, Feature 23, and Feature 12, but does not satisfy condition (12B) of Feature 12. For Example 13, the value of (B+C) / A was 1.00, the C / H value was 0.96, the M / B value was 0.40, and the Q / C value was 0.85.

[0177] Example 14 is a tire that meets all the requirements of Feature 1, Feature 16, Feature 22, Feature 23, and Feature 12. For Example 14, the value of (B+C) / A was 1.00, the C / H value was 0.96, the M / B value was 0.40, and the Q / C value was 0.85.

[0178] As in Fig. 8, it can be confirmed that both rolling resistance and abrasion resistance performance improve proportionally with the increase in the number of features satisfied from Feature 1, Feature 16, Feature 22, Feature 23 and Feature 12. Other embodiments

[0179] Fig. 9 is a perspective view illustrating a modified example of a shoulder web portion 23. Fig. 10 is a side view of the Fig.9. In the above-described embodiment, the shoulder land portion 23 was a rib serving as a continuous land portion. In the present embodiment, a lug groove 42 connected to the depressed portion 40 is provided on the ground contact surface 33 of the shoulder land portion 23. In the above-described embodiment, with the lug groove 42 provided, the shoulder land portion 23 is a block row serving as a discontinuous land portion. Note that, although the sipe (41) is not provided on the side surface 34 in the present embodiment, the sipe (41) may be provided.

[0180] As in Fig.As illustrated in FIG. 10, the groove depth of the lug groove 42 is defined as groove depth X. The groove depth X of the lug groove 42 is a distance between an opening end portion of the lug groove 42 in the tire radial direction and a bottom portion of the lug groove 42.

[0181] Furthermore, the number of the recessed portions 40 provided in the tire circumferential direction is defined as number Y. Feature 25

[0182] The following condition is met: 2 mm≤X≤28 mm Feature 26

[0183] The following condition is met: 35≤Y≤60

[0184] In the present embodiment, it is also possible to provide the tire 1 capable of preventing damage to the tread rubber 8 and capable of reducing the rolling resistance while maintaining the abrasion resistance performance. List of reference symbols 1 tire (pneumatic tire) 2 Tread section 3 page section 4 bead section 5 Carcass 6 belt layer 7 Tire bead core 7F bead filler rubber 7W tire bead wire 8 Tread rubber 9 side rubber 10 Main circumferential groove 11 Central main groove 12 shoulder main groove 20 bridge section 21 Central bridge section 22 Second bridge section 23 shoulder bar section 30 Ground contact surface 31 Ground contact surface 32 Ground contact surface 33 Ground contact surface 34 side surface 35 Top 40 Recessed section (lug groove) 41 slats 42 lug groove 61 First belt layer 62 Second belt layer 63 Third belt layer 64 Fourth belt layer 81 Undertread rubber 82 Lock tread rubber A distance B Groove depth C Distance CL Tire equatorial plane D Distance E distance F Distance G Dimension H distance J Tire outer diameter K Tire outer diameter L Tire outer diameter M distance N distance Q Distance R radius of curvature S distance T Ground contact edge U dimension V Dimension VL1 First imaginary line VL2 Second imaginary line VL3 Third imaginary line VL4 Fourth imaginary line W Dimension X Groove depth θa angle θb angle θc angle θd angle

Claims

[1] Pneumatic tire (1) rotating about an axis of rotation (AX), comprising: a tread portion (2) comprising a tread rubber (8); and side portions (3) provided on both sides in a tire transverse direction of the tread portion (2), each comprising a side rubber (9); wherein the tread portion (2) further comprises a plurality of circumferential main grooves (10) provided in the tire transverse direction, each extending in a tire circumferential direction, and a plurality of land portions (20) defined by the circumferential main grooves (10) and comprising a ground contact surface (30) that come into contact with a road surface; wherein the land portions (20) comprise a shoulder land portion (23) arranged outside a shoulder main groove (12) which is closest to a ground contact edge (T) of the tread portion (2) in the tire transverse direction among the plurality of circumferential main grooves (10), and comprises the ground contact edge (T); wherein the shoulder web portion (23) comprises, outside the ground contact edge (T) in the tire transverse direction, a surface (34) which is connected to a surface of the side portion (3); wherein in a meridian cross-section of the tread section (2) passing through the axis of rotation (AX): a first imaginary line (VL1) passing through the ground contact surface (30); a second imaginary line (VL2) passing through a bottom portion (12B) of the shoulder main groove (12) and being parallel to the first imaginary line (VL1); an intersection point (P) between the second imaginary line (VL2) and a surface of the shoulder land portion (23) outside the ground contact edge (T) in the tire transverse direction; and an equatorial plane (CL) of the tire which is perpendicular to the axis of rotation (AX) and passes through a center of the tread portion (2) in the tire transverse direction; the condition 0.80 ≤ (B+C) / A ≤ 1.15 is satisfied, where A is a distance in the tire transverse direction between the intersection point (P) and the equatorial plane (CL) of the tire, B is a groove depth of the shoulder main groove (12), which is a distance between an opening end portion (12Ka) inside the shoulder main groove (12) or an opening end portion (12Kb) outside the shoulder main groove (12) and the land portion (12B) in a tire radial direction when the pneumatic tire (1) is mounted on a rim, inflated to a prescribed air pressure, statically placed perpendicular to a flat plate, and loaded with a load corresponding to the prescribed weight, and C is a distance in the tire transverse direction between the ground contact edge (T) and the equatorial plane (CL) of the tire, which is a distance between the equatorial plane (CL) and the ground contact edge (T) when the pneumatic tire (1) is on the mounted on a suitable rim,filled to the prescribed air pressure and in an unloaded condition; a tire outer diameter in the tire equatorial plane (CL) is defined as a tire outer diameter J, a tire outer diameter at the opening end portion (12Ka) within the shoulder main groove (12) in the tire transverse direction is defined as a tire outer diameter K, and a tire outer diameter at the ground contact edge (T) is defined as a tire outer diameter L, wherein the following conditions J > K, J > L and 0.05 ≤ (K - L) / (JL) ≤ 0.85 are satisfied; wherein the condition 0.76 ≤ C / H ≤ 0.96 is satisfied, where H is given as a distance in the tire transverse direction between the equatorial plane (CL) of the tire and an outermost portion of the side portion (3) in the tire transverse direction; wherein further in the meridian cross-section a third imaginary line (VL3) passing through the ground contact edge (T) and the intersection point (P) and a fourth imaginary line (VL4) parallel to the equatorial plane (CL) of the tyre and passing through the intersection point (P) are defined; and the condition 20° ≤ θa ≤ 50° is satisfied, where θa is given as an angle formed by the third imaginary line (VL3) and the fourth imaginary line (VL4). [2] Pneumatic tire (1) according to claim 1, further comprising: a carcass (5); and a belt layer (6) arranged outside the carcass (5) in the tire radial direction; wherein the tread rubber (8) with the main circumferential grooves (10) and the web portions (20) formed therein is arranged outside the belt layer (6) in the tire radial direction; and the condition 0.10 ≤ M / B ≤ 0.75 is satisfied, where M is given as a distance in the tire radial direction between a bottom portion (12B) of the shoulder main groove (12) and the belt layer (6). [3] Pneumatic tire (1) according to claim 2, wherein: the belt layer (6) comprises a plurality of belt plies (61, 62, 63, 64) arranged in the tire radial direction, wherein two of the plurality of belt plies (61, 62, 63, 64) adjacent to each other in the tire radial direction form a cross-ply belt layer (6); and the condition 0.75 ≤ Q / C ≤ 0.95 is satisfied, where Q is given as a distance in the tire transverse direction between the equatorial plane (CL) of the tire and an end portion of the belt ply (6) of the two belt plies having the shortest dimension in the tire transverse direction. [4] A pneumatic tire (1) according to any one of claims 1 to 3, wherein the conditions of 60 ≤ Hs and 0.23 ≥ tan δ are satisfied, where Hs is given as a hardness of the tread rubber (8) at room temperature and tan δ is given as a loss coefficient indicating a relationship between a storage shear modulus and a loss shear modulus of the tread rubber at 60°C. [5] A pneumatic tire according to any one of claims 1 to 4, wherein: the condition D / C ≤ 0.80 is satisfied, where D is given as a distance in the tire transverse direction between the equatorial plane (CL) of the tire and the opening end portion (12Kb) outside the shoulder main groove (12) in the tire transverse direction. [6] A pneumatic tire (1) according to any one of claims 1 to 5, wherein the pneumatic tire is a heavy-duty pneumatic tire mounted on a truck or a bus.

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