JP2016097785A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of making the handling stability during high-speed travel compatible with the durability during high-speed travel with a camber.SOLUTION: In a pneumatic tire 1, two or more columns of land parts are ribs consecutively extending in a tire peripheral direction, and project to the outer side of a tire radial direction relative to a contour line L of a tread surface 21 in a tire meridian cross section. An amount of projection G of a rib on one side in a tire width direction is greater than an amount of projection G of a rib 23 on the other side of the tire width direction (Gc<Gb<Ga). A rigidity of a belt cover in an area on one side demarcated by a tire equator surface CL is greater than the rigidity of a belt cover in an area on the other side.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can achieve both steering stability at high speed running and durability at high speed running with a camber.

  Conventionally, for example, in Patent Document 1, for the purpose of ensuring straight running stability, a land portion is defined by a groove that intersects the tread width direction cross section in the tread portion, and the ground surface of the land portion is crossed in the tread width direction cross section. A curved shape that protrudes outward in the radial direction, and the top portion closest to the tread tread outline over the entire tread width of the ground contact surface is landed to one side edge side of the land portion with respect to the width center of the land portion. A pneumatic tire is shown that is biased in the range of 0.1 to 0.4 times the part width.

JP 2002-29216 A

  In recent years, with the improvement in performance of vehicles, there is a demand for achieving both handling stability at high speeds and durability at high speeds with a camber. Here, as shown in Patent Document 1, the steering stability is ensured by the contour of the rib meridian section of the rib rather than the contour of the tread surface so as to improve the ground contact property of the rib (land portion) formed in the tread portion. It is effective to protrude the tire radially outward. However, in the case of application to a vehicle with a camber, for example, in a negative camber, the inner rib from the tire equatorial plane when the vehicle is mounted has a longer ground contact length than the outer rib, so durability at high speeds Tends to decrease. For this reason, there is a problem that it is difficult to achieve both handling stability at high speed and durability at high speed with camber.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire that can achieve both steering stability at high speed running and durability at high speed running with a camber.

  In order to achieve the above object, a pneumatic tire according to the present invention is disposed on a carcass layer, a pair of cross belts disposed on the outer side in the tire radial direction of the carcass layer, and on the outer side in the tire radial direction of the cross belt. A pneumatic tire comprising a belt cover and having at least three circumferential grooves extending in the tire circumferential direction and at least four rows of land portions defined by the circumferential grooves on a tread surface. The two or more rows of the land portions are ribs extending continuously in the tire circumferential direction, projecting outward in the tire radial direction from the contour line of the tread surface in the tire meridional section, and on one side in the tire width direction And the rigidity of the belt cover in the region on the one side with the tire equatorial plane as a boundary is larger than the protruding amount of the rib on the other side in the tire width direction. Wherein the at areas greater than the stiffness of the belt cover.

  A pneumatic tire according to the present invention includes a carcass layer, a pair of cross belts arranged on the outer side in the tire radial direction of the carcass layer, and a pair of belt edge covers arranged on the outer side in the tire radial direction of the cross belt. And a tread surface including at least three circumferential grooves extending in the tire circumferential direction and at least four rows of land portions defined by the circumferential grooves, Two or more rows of the land portions are ribs extending continuously in the tire circumferential direction, projecting outward in the tire radial direction from the contour line of the tread surface in the tire meridional section, and being on one side in the tire width direction. The protruding amount of the rib is larger than the protruding amount of the rib on the other side in the tire width direction, and the rigidity of the belt edge cover in the one side region with the tire equatorial plane as a boundary is the other Wherein the at areas greater than the stiffness of the belt edge cover.

  In the pneumatic tire according to the present invention, since the protruding amount of the rib on one side in the tire width direction is larger than the protruding amount of the rib on the other side in the tire width direction, the grounding property on the dry road surface is ensured, Steering stability during high-speed driving is ensured. At the same time, when the tire is mounted on a vehicle having a large camber angle, the ground contact length of the rib in the entire tread is made uniform, and durability during high-speed traveling is ensured. As a result, there is an advantage that the handling stability at high speed and the durability at high speed with camber are compatible.

FIG. 1 is a meridional sectional view showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a meridional sectional view of the tread portion of the pneumatic tire depicted in FIG. 1. FIG. 3 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. FIG. 4 is an enlarged meridian cross-sectional view of the tread portion shown in FIG. 1. FIG. 5 is an enlarged meridian cross-sectional view of the tread portion illustrated in FIG. 1. FIG. 6 is an enlarged meridian cross-sectional view of the tread portion illustrated in FIG. 1. FIG. 7 is an explanatory view showing the structure of the belt cover and the belt edge cover shown in FIG. FIG. 8 is an explanatory view showing the structure of the belt cover and the belt edge cover shown in FIG. FIG. 9 is an explanatory view showing the structure of the belt cover and the belt edge cover shown in FIG. FIG. 10 is an explanatory view showing the structure of the belt cover and the belt edge cover shown in FIG. FIG. 11 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. FIG. 12 is a chart showing the results of the performance test of the pneumatic tire according to this embodiment. FIG. 13 is a chart showing the results of the performance test of the pneumatic tire according to this embodiment. FIG. 14 is a chart showing the results of the performance test of the pneumatic tire according to this embodiment. FIG. 15 is a chart showing the results of the performance test of the pneumatic tire according to this embodiment.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Pneumatic tire]
FIG. 1 is a meridional sectional view showing a pneumatic tire according to an embodiment of the present invention. The same figure has shown sectional drawing of the one-side area | region of a tire radial direction. The figure shows a radial tire for a passenger car as an example of a pneumatic tire.

  In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial direction inner side refers to the side toward the rotation axis in the tire radial direction, the tire radial direction outer side. Means the side away from the rotation axis in the tire radial direction. Further, the tire circumferential direction refers to a direction around the rotation axis as a central axis. Further, the tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction means the side toward the tire equator plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction means the tire width direction. Is the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equator line is a line along the tire circumferential direction of the pneumatic tire 1 on the tire equator plane CL. In the present embodiment, the same sign “CL” as that of the tire equator plane is attached to the tire equator line.

  In the pneumatic tire 1 of the present embodiment, as shown in FIG. 1, the tread portion 2 is made of a rubber material (tread rubber 15), exposed at the outermost side in the tire radial direction of the pneumatic tire 1, and the surface thereof. The contour of the pneumatic tire 1 is obtained. A tread surface 21 is formed on the outer peripheral surface of the tread portion 2, that is, on the tread surface that contacts the road surface during traveling. The tread portion 2 is provided with a circumferential groove 22 that opens in the tread surface 21. The circumferential groove 22 has a groove depth of 5 mm or more from the tread surface 21 to the groove bottom, extends along the tire circumferential direction, and is arranged in a plurality (four in FIG. 1) in the tire width direction. Is provided. In the tread portion 2, a plurality of ribs 23 (five in FIG. 1) extending in the tire width direction are partitioned and formed by the plurality of circumferential grooves 22. Further, the tread portion 2 is formed with lug grooves 24 that extend in a direction intersecting the circumferential groove 22 and are arranged in the tire circumferential direction in each rib 23. In FIG. 1, the lug grooves 24 are provided only on the outermost ribs 23 in the tire width direction, but may be provided on other ribs 23. The lug groove 24 may be either in a form communicating with the circumferential groove 22 or in a form not communicating with the circumferential groove 22. Further, when the lug groove 24 is provided in the outermost rib 23 in the tire width direction, the lug groove 24 is formed to open to the outer side in the tire width direction. In addition, when the rib 23 is formed on the tire equator plane CL as shown in FIG. 1, a groove extending along the tire circumferential direction on the tire equator plane CL and having a groove depth of 5 mm or more. However, this groove is not included in the circumferential groove 22.

  In addition, as shown in FIG. 1, the pneumatic tire 1 is a tire in the pneumatic tire 1 that is continuously disposed on a portion of the tread portion 2 that is continuously located on both outer sides in the tire width direction, and that is continuously on each shoulder portion. A sidewall portion exposed at the outermost side in the width direction and a bead portion engaged with the rim continuously with each sidewall portion. In the figure, reference numeral 15 is a tread rubber, reference numeral 16 is a side wall rubber, and reference numeral 17 is a rim cushion rubber. The pneumatic tire 1 is provided with a bead core 11 formed by winding a bead wire, which is a steel wire, in a ring shape in the tire circumferential direction inside each bead portion. The pneumatic tire 1 also includes a pair of bead fillers 12 and 12 disposed on the outer periphery in the tire radial direction of the pair of bead cores 11 and 11, respectively. The pneumatic tire 1 is folded by a pair of bead cores 11 and 11 from the inner side in the tire width direction to the outer side in the tire width direction and is wound around in a toroidal shape in the tire circumferential direction so as to constitute a tire skeleton. 13 is provided. Further, the pneumatic tire 1 is provided inside the tread portion 2 on the outer side in the tire radial direction, which is the outer periphery of the carcass layer 13, and is provided with a belt layer 14 having a multilayer structure in which at least two belts are laminated.

  The belt layer 14 is formed by laminating a pair of cross belts 141 and 142, a belt cover 143, and a pair of belt edge covers 144_R and 144_L, and is arranged around the outer periphery of the carcass layer 13.

  The pair of cross belts 141 and 142 is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and has an absolute value of a belt angle of 20 [deg] or more and 55 [deg] or less. Have. Further, the pair of cross belts 141 and 142 have belt angles with different signs from each other (inclination angle of the fiber direction of the belt cord with respect to the tire circumferential direction), and are laminated so that the fiber directions of the belt cords cross each other. (Cross ply structure).

  The belt cover 143 and the pair of belt edge covers 144_R and 144_L are configured by coating a belt cord made of steel or an organic fiber material with a coat rubber, and have a belt angle of 0 [deg] or more and 10 [deg] or less in absolute value. . The belt cover 143 and the pair of belt edge covers 144_R and 144_L are formed of, for example, (A) a sheet-like member formed by rolling a plurality of belt cords with a coat rubber, and intersecting belts 141 and 142. Or (B) a strip material formed by coating one or a plurality of belt cords with a coat rubber, and this strip material is used as a tire of the cross belts 141 and 142. It may be configured to be wound in a spiral shape a plurality of times in the radially outer side and in the tire circumferential direction. The belt cover 143 is disposed so as to cover the entire area of the cross belts 141 and 142, the pair of belt edge covers 144_R and 144_L are separated from each other in the tire width direction, and the left and right edges of the cross belts 141 and 142 It is arranged so as to cover each part.

  In the configuration of FIG. 1, the belt layer 14 includes both a belt cover 143 and a pair of belt edge covers 144_R and 144_L. However, the present invention is not limited to this, and the belt layer 14 may include only one of the belt cover 143 and the pair of belt edge covers 144_R and 144_L, and the other may be omitted (not shown).

[Rib protrusion]
FIG. 2 is a meridional sectional view of the tread portion of the pneumatic tire depicted in FIG. 1. FIG. 3 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. 4 to 6 are enlarged meridian cross-sectional views of the tread portion shown in FIG. 2 and 3 show the relationship between the tread profile and the belt cover 143 and the belt edge covers 144_R and 144_L. FIG. 4 shows the profile of the rib 23 in the tread portion center region, and FIG. 5 shows the profile of the rib 23 in the tread portion shoulder region. FIG. 6 shows a modification of the rib described in FIG.

  In such a pneumatic tire 1, when new, as shown in FIGS. 2 and 3, at least two ribs 23 are formed so as to protrude outward in the tire radial direction from the contour line L of the tread surface 21. . The protruding ribs G are formed so that the protruding amount G is gradually reduced from one side to the other side in the tire width direction. In FIG. 2, the outermost rib 23 in the tire width direction is not formed so as to protrude, and three ribs sandwiched between the circumferential grooves 22 are formed so as to protrude from the contour line L. In this example, the projecting amount G is in a relationship of Ga> Gb> Gc from the other side to the other side. In FIG. 3, all (four) ribs 23 are formed so as to protrude from the contour line L, and the protrusion amount G is in a relationship of Gd> Ge> Gf> Gg from one side to the other side. ing.

  The at least two ribs 23 protruding from the contour line L may not be adjacent to each other with the circumferential groove 22 interposed therebetween, and between the ribs 23 protruding from the contour line L between the tire width directions. There may be a rib 23 that does not protrude from the contour line L.

  Here, as shown in FIG. 4, in the case of the ribs 23 sandwiched between the circumferential grooves 22, the contour line L is two adjacent to both sides in the tire width direction of the ribs 23 in the meridional section. An arc that passes through at least three of the four open ends P in the circumferential groove 22 and can be drawn with a maximum curvature radius centered on the inner side of the tread surface 21 in the tire radial direction.

  Further, as shown in FIG. 5, in the case of the outermost rib 23 in the tire width direction, the contour line L has a grounding end T on the rib 23 in the meridian cross section, and the grounding end T is P1. When the opening end on the outer side in the tire width direction of the circumferential groove 22 adjacent to the rib 23 is P2, and the opening end on the inner side in the tire width direction of the circumferential groove 22 is P3, it passes through P1, P2, P3, An arc having a radius of curvature centered on the inner side of the tread surface 21 in the tire radial direction.

  In addition, as shown in FIG. 6, when the chamfering C is given to the opening end of the circumferential groove 22, the contour line L is defined as described above with the end point located on the outermost side in the tire radial direction being the opening end. In FIG. 6, the ribs 23 disposed between the circumferential grooves 22 are shown, but the same applies to the outermost ribs 23 in the tire width direction.

  Further, the ground contact end T means that when the pneumatic tire 1 is assembled to a regular rim and filled with a regular internal pressure and a regular load is applied, the tread surface 21 of the tread portion 2 of the pneumatic tire 1 is a road surface. In the contact area, both outermost ends in the tire width direction are continuous in the tire circumferential direction.

  The regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “maximum air pressure” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The normal load is “maximum load capacity” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO.

  As described above, the pneumatic tire 1 of the present embodiment includes at least four circumferential grooves 22 that extend along the tire circumferential direction in the tread portion 2 and at least four that extend along the tire circumferential direction. In the pneumatic tire 1 in which the ribs 23 are defined, at least two ribs 23 protrude outward in the tire radial direction from the contour line L of the tread surface in the meridional section, and the protruding amount G is in the tire width direction. The size is gradually reduced from one side to the other side.

  According to this pneumatic tire 1, at least two ribs 23 protruding from the contour line L are formed so that the protruding amount G is sequentially reduced from one side to the other side, thereby providing a negative camber. In the case where one side is the outside of the vehicle and the other side is the inside of the vehicle, while the positive camber is attached, the one side is the inside of the vehicle and the other side is the outside of the vehicle. Since the ground contact property is improved, it is possible to improve the handling stability during high speed traveling. Moreover, when equipped with a negative camber, it is mounted on the vehicle with one side being the vehicle outer side and the other side being the vehicle inner side, while when equipped with a positive camber, it is mounted on the vehicle with the one side being the vehicle inner side and the other side being the vehicle outer side. As a result, excessive contact in the tire width direction is alleviated, so that the contact length between the ribs 23 (the length in the tire circumferential direction in the region where the tread surface 21 contacts the road surface) is made uniform, and the camber can be operated at high speed. It becomes possible to improve durability. As a result, it is possible to achieve both handling stability at high speed and durability at high speed with camber.

  Moreover, in the pneumatic tire 1 of this embodiment, it is preferable that the protrusion amount G of the rib 23 from the outline L is 0.05 mm or more and 2.0 mm or less.

  If the protruding amount G of the rib 23 is less than 0.05 mm, the protruding amount G of the rib 23 becomes small, and it becomes difficult to obtain the effect of improving the ground contact property and the uniform effect of the contact length. On the other hand, when the protruding amount G of the rib 23 exceeds 2.0 mm, the protruding amount G of the rib 23 increases, and it becomes difficult to obtain the effect of improving the ground contact and the uniform effect of the contact length. For this reason, by making the protrusion amount G of the rib 23 0.05 mm or more and 2.0 mm or less, it is possible to obtain a remarkable effect of achieving both steering stability at high speed running and durability at high speed running with a camber. . In order to obtain the effect of achieving both the steering stability at high speed and the durability at high speed with camber, the protrusion amount G of the rib 23 from the contour line L is 0.2 mm or more and 0.6 mm. The following is preferable.

  Further, in the pneumatic tire 1 of the present embodiment, the direction inside and outside the vehicle when the vehicle is mounted is specified, and the protruding amount G of the rib 23 is formed so as to gradually decrease from the vehicle outer side toward the vehicle inner side. Is preferred.

  In such a pneumatic tire 1, for example, the inside / outside direction of the vehicle is designated by the indication provided on the side wall portion indicating the inside / outside direction of the vehicle when the vehicle is mounted. In addition, designation | designated of a vehicle inner side and a vehicle outer side is not restricted to the case where it mounts | wears with a vehicle. For example, when the rim is assembled, the direction of the rim with respect to the inside and outside of the vehicle is determined in the tire width direction. For this reason, when the pneumatic tire 1 is assembled with a rim, the orientation with respect to the vehicle inner side and the vehicle outer side is designated in the tire width direction.

  According to this pneumatic tire 1, it is preferable to have a negative camber in order to improve steering stability when dealing with high speed running. Therefore, by forming the protrusion amount G of the rib 23 gradually smaller from the outside of the vehicle toward the inside of the vehicle, the effect of improving the grounding property and the uniform effect of the grounding length can be significantly obtained when the negative camber is provided. As a result, it is possible to remarkably obtain the effect of achieving both steering stability at high speed and durability at high speed with a negative camber.

  Further, in the pneumatic tire 1 of the present embodiment, the rib 23 protruding from the contour line L is provided adjacent to the circumferential groove 22, and the difference ΔG in the protruding amount G of each adjacent rib 23 is provided. (Ga-Gb and Gb-Gc in FIG. 2, Gd-Ge, Ge-Gf and Gf-Gg in FIG. 3) are preferably in the range of 0.1 mm ≦ ΔG ≦ 0.8 mm, and 0.2 mm ≦ More preferably, it is in the range of ΔG ≦ 0.5 mm.

  If the difference ΔG between the protruding amounts G of the adjacent ribs 23 is less than 0.1 mm, the difference in the protruding amount G between the ribs 23 is too small, and it is difficult to obtain the effect of improving the ground contact property and the uniform effect of the contact length. It becomes a trend. On the other hand, if the difference ΔG between the protruding amounts G of the adjacent ribs 23 exceeds 0.8 mm, the difference in the protruding amount G between the ribs 23 is too large, and the effect of improving the ground contact property and the uniform effect of the contact length are obtained. It tends to be difficult to obtain. For this reason, by making the difference ΔG between the protruding amounts G of the adjacent ribs 23 to be 0.1 mm or more and 0.8 mm or less, it is possible to achieve both the steering stability at high speed running and the durability at high speed running with camber. Remarkably can be obtained.

  Further, the difference ΣG_R between the total sum ΣG_R of the protruding amount of each rib 23 in one region in the tire width direction with the tire equator plane CL as a boundary and the total sum ΣG_L of the protruding amount of the rib 23 arranged in the other region. −ΣG_L is preferably in the range of 0.4 [mm] ≦ ΣG_R−ΣG_L ≦ 0.9 [mm], and is in the range of 0.5 [mm] ≦ ΣG_R−ΣG_L ≦ 0.7 [mm]. It is more preferable. In addition, the protrusion amount of the rib 23 on the tire equatorial plane CL is excluded from the above-described comparison target.

  Moreover, in the pneumatic tire 1 of this embodiment, it is preferable that the rib 23 protruding from the contour line L is provided between the circumferential grooves 22.

  That is, as shown in FIG. 2, the rib 23 protruding from the contour line L is provided between the circumferential grooves 22, and the tire width excluding the outermost rib 23 in the tire width direction (shoulder side). It is each rib 23 inside a direction. Each of the ribs 23 on the inner side in the tire width direction protrudes outward in the tire radial direction from the contour line L, and the protruding amount G is formed to be gradually decreased from one side to the other side in the tire width direction. This greatly contributes to the improvement effect and the uniform effect of the contact length. Therefore, it is possible to remarkably obtain the effect of achieving both the steering stability at high speed running and the durability at high speed running with camber.

[Asymmetric structure of belt cover / belt edge cover]
As described above, in this pneumatic tire 1, two or more rows of ribs 23 protrude outward in the tire radial direction from the contour line L of the tread surface 21 in the tire meridional section and are on one side in the tire width direction. The protruding amount G of the rib 23 is larger than the protruding amount G of the rib on the other side in the tire width direction (Gc <Gb <Ga in FIG. 2, Gg <Gf <Ge <Gd in FIG. 3). With such a configuration, the grounding property on the dry road surface is ensured, and the steering stability during high speed traveling is ensured. At the same time, when the tire is mounted on a vehicle having a large camber angle, the ground contact length of the rib in the entire tread is made uniform, and durability during high-speed traveling is ensured. Thereby, the handling stability at high speed and the durability at high speed with camber are compatible.

  By the way, in said structure, since the shape of a tread surface becomes asymmetrical in the area | region on either side which makes tire equatorial plane CL a boundary, there exists a possibility that a conicity may deteriorate.

  In view of this, the pneumatic tire 1 employs the following configuration in order to secure conicity while achieving both handling stability at high speed and durability at high speed with a camber.

  That is, in FIGS. 2 and 3, the rigidity of the belt cover 143 in the region on one side in the tire width direction with the tire equatorial plane CL as a boundary is larger than the rigidity of the belt cover 143 in the other region in the tire width direction. . Alternatively, the rigidity of the belt edge cover 144_R in the region on one side in the tire width direction is larger than the rigidity of the belt edge cover 144_L in the region on the other side in the tire width direction. That is, the rigidity of the belt cover 143 or the pair of belt edge covers 144_R and 144_L is configured asymmetrically in the left and right regions with the tire equatorial plane CL as a boundary.

  In such a configuration, the rigidity of the belt cover 143 or the belt edge cover 144_R in the one side region with the tire equatorial plane CL as a boundary is set to be large, so that the tire diameter growth in the inflated state in the one side region is increased. It is suppressed. Then, the unbalance of the tire left and right regions caused by the protrusion amount G of the rib 23 being asymmetric in the tire left and right regions is alleviated as a whole tire. As a result, the ground contact shapes in the left and right regions of the tire are made uniform, and conicity is ensured.

  In this embodiment, description will be made assuming that only one of the belt cover 143 and the pair of belt edge covers 144_R and 144_L has a left-right asymmetric structure. However, the present invention is not limited to this, and both the belt cover 143 and the pair of belt edge covers 144_R and 144_L may have asymmetric structures. The various asymmetric structures that the belt cover 143 and the pair of belt edge covers 144_R and 144_L can take can be arbitrarily combined within the scope of those skilled in the art.

[Specific example of asymmetric structure]
Specifically, the belt cover 143 or the belt edge cover 144_R, 144_L has the following asymmetric structure, so that the rigidity of the belt cover 143 or the belt edge cover 144_R in the one side region with the tire equatorial plane CL as a boundary is increased. It is set large. In addition, the specific examples of the following asymmetric structures can be arbitrarily combined within the scope obvious to those skilled in the art.

  For example, the number N1_R of belt cords of the belt cover 143 in the one side region and the number N1_L of belt cords of the belt cover 143 in the other side region have a relationship of N1_L <N1_R. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the number of belt cords N1_R and N1_L is preferably in the ranges of 20 [lines] ≦ N1_R ≦ 210 [lines] and 2 [lines] ≦ N1_L ≦ 40 [lines]. By satisfying 20 [lines] ≦ N1_R and 2 [lines] ≦ N1_L, the function of the belt cover 143 is appropriately ensured. In addition, since N1_R ≦ 210 [lines] and N1_L ≦ 40 [lines], an increase in tire weight due to excessive belt cords is suppressed.

  Further, the difference between the numbers N1_R and N1_L of the belt cords is preferably in the range of 4 [lines] ≦ N1_R−N1_L ≦ 30 [lines], and in the range of 10 [lines] ≦ N1_R−N1_L ≦ 20 [lines]. More preferably. By the above lower limit, the difference in rigidity between the left and right tire areas is ensured appropriately. Further, the above upper limit suppresses deterioration of uniformity due to an excessive difference in rigidity between the tire left and right regions.

  Further, the number N2_R of belt cords of the belt edge cover 144_R in the one side region and the number N2_L of belt cords of the belt edge cover 144_L in the other side region have a relationship of N2_L <N2_R. As a result, a difference in rigidity between the left and right tire regions is formed. The number N2_R and N2_L of the belt cords is preferably in the ranges of 20 [lines] ≦ N2_R ≦ 210 [lines] and 2 [lines] ≦ N2_L ≦ 40 [lines]. Further, the difference between the numbers N2_R and N2_L of the belt cords is preferably in the range of 4 [lines] ≦ N2_R−N2_L ≦ 30 [lines].

  The number N2_R and N2_L of the belt cords is preferably in the ranges of 20 [lines] ≦ N2_R ≦ 210 [lines] and 2 [lines] ≦ N2_L ≦ 40 [lines]. By satisfying 20 [lines] ≦ N2_R and 2 [lines] ≦ N2_L, the functions of the belt edge covers 144_R and 144_L are appropriately secured. In addition, since N2_R ≦ 210 [lines] and N2_L ≦ 40 [lines], an increase in tire weight due to excessive belt cords is suppressed.

  Further, the difference between the numbers N2_R and N2_L of the belt cords is preferably in the range of 4 [lines] ≦ N2_R−N2_L ≦ 30 [lines], and in the range of 10 [lines] ≦ N2_R−N2_L ≦ 20 [lines]. More preferably. By the above lower limit, the difference in rigidity between the left and right tire areas is ensured appropriately. Further, the above upper limit suppresses deterioration of uniformity due to an excessive difference in rigidity between the tire left and right regions.

  The number of belt cords (N1_R, N1_L, N2_R, N2_L) is defined as the apparent number of belt cords in the tire meridian section. That is, the number of belt cords is counted as the total number of belt cord cross sections in one region and the other region with the tire equatorial plane CL as a boundary in the tire meridian cross section. Accordingly, the belt cover 143 or the belt edge covers 144_R and 144_L are composed of (A) a sheet-like member formed by rolling a plurality of belt cords with a coat rubber, and the cross belts 141 and 142 in the tire radial direction. A configuration (not shown) that is laminated on the outside, and (B) a strip material formed by coating one or a plurality of belt cords with a coat rubber, and this strip material is used as a tire of the cross belts 141 and 142 The number of belt cords is similarly defined in any case of a structure (see FIGS. 7 to 10 to be described later) that is formed by winding a plurality of times in the radial direction and in the tire circumferential direction. The belt cord on the tire equatorial plane CL is excluded from the above count.

  Further, the number of belt cords can be adjusted by the number of stacked belt covers 143 or belt edge covers 144_R and 144_L, the number of belt cord ends or the winding interval, as will be described later.

  7-10 is explanatory drawing which shows the structure of the belt cover and belt edge cover which were described in FIG. The figure shows the structure of the belt edge cover 144 (144_L, 144_R) as an example. The structure shown in the figure can be similarly applied to the belt cover 143.

  In the configuration of FIG. 7, the belt edge cover 144 is made of a strip material in which one belt cord 1441 is covered with a coat rubber 1442, and this strip material is arranged on the outer side in the tire radial direction of the cross belts 141 and 142 and in the tire circumferential direction. It is configured to be wound multiple times and spirally in a single winding. In such a configuration, the tagging effect acts on the cross belts 141 and 142, and the tire diameter growth during inflation is suppressed. Thereby, the ground contact shape of a tire is ensured appropriately.

  In the configuration of FIG. 8, the belt edge cover 144 is made of a strip material formed by coating a plurality of (two in FIG. 8) belt cords 1441 and 1441 with a coat rubber 1442, and these strip materials are crossed belts 141 and 142. The tire is wound a plurality of times and spirally in the tire radial direction outside and in the tire circumferential direction. At this time, a plurality of belt cords 1441, 1441 are arranged in parallel in the tire width direction (so-called lateral placement) and wound around the outer circumferences of the cross belts 141, 142. Even with such a configuration, the function of the belt edge cover 144 is appropriately secured.

  In the configuration of FIG. 9, the belt edge cover 144 is made of a strip material in which one belt cord 1441 is covered with a coat rubber 1442, and this strip material is arranged on the outer side in the tire radial direction of the cross belts 141 and 142 and in the tire circumferential direction. It is configured by winding a plurality of times in a spiral manner. Further, the belt edge cover 144 has a multilayer structure by winding the strip material by multiple winding (double winding in FIG. 9). In the configuration in which the belt edge cover 144 is formed of a sheet-like member (not shown), a plurality of sheet-like members are stacked to form a multilayer structure of the belt edge cover 144.

  In the configuration of FIG. 10, the belt edge cover 144 is made of a strip material formed by coating a plurality (two in FIG. 10) of belt cords 1441 and 1441 with a coat rubber 1442, and the strip material is crossed belts 141 and 142. The tire is wound a plurality of times and spirally in the tire radial direction outside and in the tire circumferential direction. At this time, a plurality of belt cords 1441, 1441 are arranged in parallel in the tire radial direction (so-called vertical placement) and wound around the outer circumferences of the cross belts 141, 142. Even in such a configuration, a multilayer structure of the belt edge cover 144 is formed.

  2 and 3, the width W1_R of the belt cover 143 in one region and the width W1_L of the belt cover 143 in the other region may have a relationship of W1_L <W1_R. As a result, a difference in rigidity between the left and right tire regions is formed.

  In addition, the widths W1_R and W1_L in each region of the belt cover 143 are set to sizes that allow the belt cover 143 to cover the entire cross belts 141 and 142. For this reason, the widths W1_R and W1_L depend on the widths of the cross belts 141 and 142.

  The difference between the widths W1_R and W1_L of the belt cover 143 is preferably in the range of 5 [mm] ≦ W1_R−W1_L ≦ 30 [mm], and in the range of 10 [mm] ≦ W1_R−W1_L ≦ 20 [mm]. More preferably. By the above lower limit, the difference in rigidity between the left and right tire areas is ensured appropriately. Further, the above upper limit suppresses deterioration of uniformity due to an excessive difference in rigidity between the tire left and right regions.

  The widths W1_R and W1_L of the belt cover 143 are measured as the distance between the tire equatorial plane CL and the belt cord at the end of the belt cover 143 in the tire meridian cross section.

  2 and 3, the width W2_R of the belt edge cover 144_R in the one side region and the width W2_L of the belt edge cover 144_L in the other side region may have a relationship of W2_L <W2_R. As a result, a difference in rigidity between the left and right tire regions is formed.

  The widths W2_R and W2_L of the belt edge covers 144_R and 144_L are preferably in the ranges of 20 [mm] ≦ W2_R ≦ 50 [mm] and 5 [mm] ≦ W2_L ≦ 20 [mm]. By the above lower limit, the functions of the belt edge covers 144_R and 144_L are appropriately secured. In addition, the upper limit described above suppresses an increase in tire weight caused by the belt edge covers 144_R and 144_L becoming excessively wide.

  The difference between the widths W2_R and W2_L of the belt edge covers 144_R and 144_L is preferably in the range of 5 [mm] ≦ W2_R−W2_L ≦ 30 [mm], and 10 [mm] ≦ W2_R−W2_L ≦ 20 [mm]. ] Is more preferable. By the above lower limit, the difference in rigidity between the left and right tire areas is ensured appropriately. Further, the above upper limit suppresses deterioration of uniformity due to an excessive difference in rigidity between the tire left and right regions.

  The widths W2_R and W2_L of the belt edge covers 144_R and 144_L are measured as distances between the belt cords at both ends of each belt edge cover 144_R and 144_L in the tire meridian cross section.

  2 and 3, the number of belt covers 143 stacked in one region may be larger than the number of belt covers 143 stacked in the other region. (Not shown). For example, in FIGS. 2 and 3, the belt cover 143 in one region may have a multilayer structure, and the belt cover 143 in the other region may have a single layer structure. Specifically, the strip material constituting the belt cover 143 is formed of a strip material obtained by coating one belt cord 1441 with a coat rubber 1442, and this strip material is formed in a single winding as shown in FIG. It arrange | positions and it arrange | positions by the double winding shown in FIG. 9 in the area | region of the other side. Alternatively, the strip material constituting the belt cover 143 is made of a strip material formed by coating two belt cords 1441 and 1441 with a coat rubber 1442, and this strip material is arranged in a horizontal position as shown in FIG. And arranged in the vertical direction shown in FIG. As a result, the number of layers on one side of the belt cover 143 is different from the number of layers on the other side of the belt cover 143, thereby forming a difference in rigidity between the left and right regions of the tire.

  In addition, it is preferable that the number of stacked belt covers 143 in one region is 2 or more and 3 or less, and the number of stacked belt covers 143 in the other region is 1 or more and 2 or less. By the above lower limit, the number of stacked belt covers 143 is secured, and the function of the belt cover 143 is secured. With the above upper limit, an increase in tire weight due to an excessive number of stacked belt covers 143 is suppressed.

  Moreover, it is preferable that the difference between the number of stacked belt covers 143 in one region and the number of stacked belt covers 143 in the other region is one layer. As a result, the difference in rigidity between the left and right tire areas is optimized.

  2 and 3, the number of belt edge covers 144_R stacked in one region may be larger than the number of belt edge covers 144_L stacked in the other region (not shown). For example, in FIGS. 2 and 3, the belt edge cover 144_R in one region may have a multilayer structure, and the belt edge cover 144_L in the other region may have a single layer structure. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, it is preferable that the number of stacked belt edge covers 144_R in one region is 2 or more and 3 or less, and the number of stacked belt edge covers 144_L in the other region is 1 or more and 2 or less. . By the above lower limit, the number of stacked belt edge covers 144_R and 144_L is secured, and the functions of the belt edge covers 144_R and 144_L are secured. With the above upper limit, an increase in tire weight due to an excessive number of stacked belt edge covers 144_R and 144_L is suppressed.

  Further, it is preferable that the difference between the number of stacked belt edge covers 144_R in one region and the number of stacked belt edge covers 144_L in the other region is one layer. As a result, the difference in rigidity between the left and right tire areas is optimized.

  2 and 3, the end number NE1_R of the belt cover 143 in the one side region and the end number NE1_L of the belt cover 143 in the other side region may have a relationship of NE1_L <NE1_R. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the end number NE1_R of the belt cover 143 in the one region is in the range of 30 [lines / 50 mm] ≦ NE1_R ≦ 70 [50/50 mm], and the end number NE1_L of the belt cover 143 in the other region. However, it is preferable that it is in the range of 20 [lines / 50 mm] ≦ NE1_L ≦ 50 [lines / 50 mm]. By the above lower limit, the number of ends of the belt cover 143 is secured, and the function of the belt cover 143 is secured. Due to the above upper limit, an increase in tire weight due to an excessive number of ends of the belt cover 143 is suppressed.

  Further, the difference between the number of ends NE1_R of the belt cover 143 in the one side region and the number of ends NE1_L of the belt cover 143 in the other region is 5 [lines / 50 mm] ≦ NE1_R−NE1_L ≦ 30 [lines / 50 mm]. It is preferably in the range, and more preferably in the range of 10 [lines / 50 mm] ≦ NE1_R−NE1_L ≦ 20 [lines / 50 mm]. By the above lower limit, the difference in rigidity between the left and right tire areas is ensured appropriately. Further, the above upper limit suppresses deterioration of uniformity due to an excessive difference in rigidity between the tire left and right regions.

  2 and 3, the end number NE2_R of the belt edge cover 144_R in the one side region and the end number NE2_L of the belt edge cover 144_L in the other side region may have a relationship of NE2_L <NE2_R. good. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the end number NE2_R of the belt edge cover 144_R in the one side region is in a range of 30 [lines / 50 mm] ≦ NE2_R ≦ 70 [lines / 50 mm], and the end of the belt edge cover 144_L in the other region. The number NE2_L is preferably in the range of 20 [lines / 50 mm] ≦ NE2_L ≦ 50 [lines / 50 mm]. By the above lower limit, the end numbers of the belt edge covers 144_R and 144_L are secured, and the functions of the belt edge covers 144_R and 144_L are secured. With the above upper limit, an increase in tire weight due to an excessive number of ends of the belt edge covers 144_R and 144_L is suppressed.

  Further, the difference between the number of ends NE2_R of the belt edge cover 144_R in one region and the number of ends NE2_L of the belt edge cover 144_L in the other region is 5 [lines / 50 mm] ≦ NE2_R−NE2_L ≦ 30 [lines / 50 mm. ], Preferably 10 [lines / 50 mm] ≦ NE2_R−NE2_L ≦ 20 [lines / 50 mm]. By the above lower limit, the difference in rigidity between the left and right tire areas is ensured appropriately. Further, the above upper limit suppresses deterioration of uniformity due to an excessive difference in rigidity between the tire left and right regions.

  The number of ends can be adjusted, for example, by changing the winding interval P of the strip material of the belt cover 143 or each belt edge cover 144_R, 144_L in the configurations of FIGS.

  FIG. 11 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. This figure shows the relationship between the tread profile and the belt cover 143 and the belt edge covers 144_R and 144_L.

  2 and 3, the belt cover 143 has a single structure and is disposed so as to cover the entire area of the cross belts 141 and 142. Specifically, for example, (A) the belt cover 143 is formed of a single sheet-like member formed by rolling a plurality of belt cords with a coat rubber covered with a coat rubber, and the sheet-like member is a cross belt 141, 142, or (B) the belt cover 143 is made of a strip material in which one or a plurality of belt cords are coated with a coat rubber, and this strip material is made up of the cross belts 141 and 142. The structure wound continuously over the whole region may be employ | adopted.

  On the other hand, in the configuration of FIG. 11, the pair of belt covers 143_R and 143_L are arranged in parallel in the tire width direction and cover the entire area of the cross belts 141 and 142. At this time, the splice portions of the pair of belt covers 143_R and 143_L may be arranged on the tire equatorial plane CL (see FIG. 11), or may be arranged at positions away from the tire equatorial plane CL (not shown). . Two or more belt covers may be arranged in parallel in the tire width direction to cover the entire area of the cross belts 141 and 142 (not shown). As described above, in the configuration in which the plurality of belt covers 143_R and 143_L are used, a difference in rigidity between the left and right tire regions can be formed by making the structures or physical properties of the belt covers 143_R and 143_L different.

  For example, in FIG. 11, the belt cord 143_R belt cord twist number TC1_R in one side region and the belt cord 143_L belt cord twist number TC1_L in the other region have a relationship of TC1_L <TC1_R. Also good.

  Further, the belt cord twist number TC1_R of the belt cover 143_R in the one side region is in the range of 2 [lines] ≦ TC1_R ≦ 4 [number], and the belt cord twist number TC1_L of the belt cover 143_L in the other side region. Is preferably in the range of 1 [book] ≦ TC1_L ≦ 3 [book]. By the above lower limit, goodness of having a belt cord in a stranded wire structure is secured. With the above upper limit, a decrease in the function of the belt cord due to an excessive number of twists of the belt cord is suppressed.

  The difference between the number TC1_R of the belt cord 143 of the belt cover 143_R in the one side region and the number TC1_L of the belt cord 143_L of the belt cover 143_L in the other region is preferably 1 [piece]. As a result, the difference in rigidity between the left and right tire areas is optimized.

  2, 3 and 11, the number TC2_R of the belt cord twist of the belt edge cover 144_R in the one side region and the number TC2_L of the belt cord twist of the belt edge cover 144_L in the other side region are TC2_L. <TC2_R may be satisfied. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the belt cord twist number TC2_R of the belt edge cover 144_R in the one side region is in the range of 2 [lines] ≦ TC2_R ≦ 4 [lines], and the belt cord twist of the belt edge cover 144_L in the other side region. The number TC2_L is preferably in the range of 1 [book] ≦ TC2_L ≦ 3 [book]. By the above lower limit, goodness of having a belt cord in a stranded wire structure is secured. With the above upper limit, a decrease in the function of the belt cord due to an excessive number of twists of the belt cord is suppressed.

  Further, it is preferable that the difference between the number TC2_R of the belt cord twist of the belt edge cover 144_R in the one side region and the number TC2_L of the belt cord twist of the belt edge cover 144_L in the other region is one. As a result, the difference in rigidity between the left and right tire areas is optimized.

  2, 3 and 11, the intermediate elongation E1_R of the belt cords of the belt covers 143 and 143_R in one region and the intermediate elongation E1_L of the belt cords of the belt covers 143 and 143_L in the other region. May have a relationship of E1_R <E1_L. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the intermediate elongation E1_R of the belt cords of the belt covers 143 and 143_R in the one side region is in the range of 2 [%] ≦ E1_R ≦ 7 [%], and the belt covers 143 and 143_L in the other side region The intermediate elongation E1_L of the belt cord is preferably in the range of 5 [%] ≦ E1_L ≦ 10 [%]. Thereby, the intermediate | middle elongation of a belt cord is optimized and the function of a belt cover is ensured.

  Further, the difference between the intermediate elongation E1_R of the belt cords of the belt covers 143 and 143_R in the one region and the intermediate elongation E1_L of the belt cords of the belt covers 143 and 143_L in the other region is 1 [%] ≦ E1_L. It is preferable to be in the range of −E1_R ≦ 3 [%]. By the above lower limit, a difference in intermediate elongation of the belt cord is ensured, and a difference in rigidity between the left and right regions of the tire is ensured. Further, the above upper limit suppresses the deterioration of uniformity due to the excessive difference in the intermediate elongation of the belt cords.

  2, 3, and 11, the intermediate elongation E2_R of the belt cord of the belt edge cover 144_R in one region and the intermediate elongation E2_L of the belt cord of the belt edge cover 144_L in the other region. , E2_R <E2_L.

  Further, the intermediate elongation E2_R of the belt cord of the belt edge cover 144_R in the one side region is in a range of 2 [%] ≦ E2_R ≦ 7 [%], and the belt cord of the belt edge cover 144_L in the other region. The intermediate elongation E2_L is preferably in the range of 5 [%] ≦ E2_L ≦ 10 [%]. Thereby, the intermediate | middle elongation of a belt cord is optimized and the function of a belt edge cover is ensured.

  Further, the difference between the intermediate elongation E2_R of the belt cord of the belt edge cover 144_R in the one side region and the intermediate elongation E2_L of the belt cord of the belt edge cover 144_L in the other region is 1 [%] ≦ E2_L−E2_R. It is preferable to be in the range of ≦ 3 [%]. By the above lower limit, a difference in intermediate elongation of the belt cord is ensured, and a difference in rigidity between the left and right regions of the tire is ensured. Further, the above upper limit suppresses the deterioration of uniformity due to the excessive difference in the intermediate elongation of the belt cords.

  The intermediate elongation of the belt cord is measured as the elongation percentage of the cord material when a load of 2.0 [cN / dtex] is applied to a single cord material under the conditions of JIS-L1017. .

  In FIGS. 2, 3 and 11, the belt cord weight DT1_R of the belt covers 143 and 143_R in the one side region and the belt cord weight DT1_L of the belt covers 143 and 143_L in the other side region are DT1_L. <DT1_R may be satisfied. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the belt cord DT1_R of the belt covers 143 and 143_R in the one side region is in the range of 900 [dTex] ≦ DT1_R ≦ 1700 [dTex], and the belt cords 143 and 143_L in the other side region. The weight DT1_L is preferably in the range of 700 [dTex] ≦ DT1_L ≦ 1000 [dTex]. By the above upper limit, the weight of the belt cord is secured, and the function of the belt cover is secured. By the above lower limit, an increase in tire weight due to excessive weight of the belt cord is suppressed.

  Further, the difference between the belt cord weights DT1_R of the belt covers 143 and 143_R in one region and the belt cord weights DT1_L of the belt covers 143 and 143_L in the other region is 200 [dTex] ≦ DT1_R−DT1_L ≦ 500. It is preferably in the range of [dTex]. Due to the above upper limit, a difference in rigidity between the left and right tires is ensured appropriately. By the above lower limit, deterioration of uniformity due to excessive weight difference of the belt cord is suppressed.

  2, 3 and 11, the weight DT2_R of the belt cord of the belt edge cover 144_R in one region and the weight DT2_L of the belt cord of the belt edge cover 144_L in the other region are represented by DT2_L <DT2_R. It may have the relationship. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the belt cord weight DT2_R of the belt edge cover 144_R in the one region is in the range of 900 [dTex] ≦ DT2_R ≦ 1700 [dTex], and the belt cord weight of the belt edge cover 144_L in the other region. DT2_L is preferably in the range of 700 [dTex] ≦ DT2_L ≦ 1000 [dTex]. With the above upper limit, the weight of the belt cord is secured, and the function of the belt edge cover is secured. By the above lower limit, an increase in tire weight due to excessive weight of the belt cord is suppressed.

  Also, the difference between the belt cord weight DT2_R of the belt edge cover 144_R in the one side region and the belt cord weight DT2_L of the belt edge cover 144_L in the other region is 200 [dTex] ≦ DT2_R−DT2_L ≦ 500 [dTex. ] Is preferable. By the above lower limit, the difference in rigidity between the left and right tires is ensured appropriately. By the above upper limit, deterioration of uniformity due to excessive weight difference of the belt cord is suppressed.

  2, 3, and 11, the thermal contraction rate TS1_R of the belt cord of the belt cover 143_R 143 in the one side region and the thermal contraction rate TS1_L of the belt cord of the belt 143 and the belt cover 143_L in the other side region. May have a relationship of TS1_L <TS1_R. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the thermal contraction rate TS1_R of the belt cords of the belt covers 143 and 143_R in the one side region is in the range of 2 [%] ≦ TS1_R ≦ 7 [%], and the 143 and the belt cover 143_L in the other side region The thermal contraction rate TS1_L of the belt cord is preferably in the range of 1 [%] ≦ TS1_L ≦ 5 [%]. Thereby, the thermal contraction rate of a belt cord is optimized and the function of a belt cover is ensured appropriately.

  Further, the difference between the thermal contraction rate TS1_R of the belt cords of the belt covers 143 and 143_R in the one side region and the thermal contraction rate TS1_L of the belt cords of the belt covers 143 and 143_L in the other side region is 1 [%] ≦ TS1_R. -TS1_L ≦ 3 [%] is preferable. By the above lower limit, the difference in rigidity between the left and right tires is ensured appropriately. Further, the above upper limit suppresses deterioration of uniformity due to an excessive difference in the thermal contraction rate of the belt cord.

  2, 3, and 11, the belt cord thermal contraction rate TS2_R of the belt edge cover 144_R in one region and the belt cord thermal contraction rate TS2_L of the belt edge cover 144_L in the other region , TS2_L <TS2_R. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the thermal contraction rate TS2_R of the belt cord of the belt edge cover 144_R in the one side region is in the range of 2 [%] ≦ TS2_R ≦ 7 [%], and the belt cord of the belt edge cover 144_L in the other side region. It is preferable that the thermal shrinkage rate TS2_L is in the range of 1 [%] ≦ TS2_L ≦ 5 [%]. Thereby, the thermal contraction rate of a belt cord is optimized and the function of a belt edge cover is ensured appropriately.

  Further, the difference between the thermal contraction rate TS2_R of the belt cord of the belt edge cover 144_R in one region and the thermal contraction rate TS2_L of the belt cord of the belt edge cover 144_L in the other region is 1 [%] ≦ TS2_R−TS2_L. It is preferable to be in the range of ≦ 3 [%]. By the above lower limit, the difference in rigidity between the left and right tires is ensured appropriately. Further, the above upper limit suppresses deterioration of uniformity due to an excessive difference in the thermal contraction rate of the belt cord.

  The heat shrinkage rate of the belt cord is determined according to the dry heat shrinkage rate during heating (Method A) in section a) of 8.10 dry heat shrinkage rate of JIS L1017. The elongation rate under load was measured under the load condition of 2.3 cN / dtex in accordance with the standard time test of the item a) in the 8.7 constant load elongation rate of JIS L1017.

  2, 3 and 11, the cord diameter D1_R of the belt cords of the belt covers 143 and 143_R in the one side region and the cord diameter D1_L of the belt cords of the belt covers 143 and 143_L in the other side region. , D1_L <D1_R. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the ratio of the cord diameter D1_R of the belt cords of the belt covers 143 and 143_R in the one side region to the cord diameter D1_L of the belt cords of the belt covers 143 and 143_L in the other region is 1.1 ≦ D1_R / D1_L ≦. It is preferable to have a relationship of 2.0, and it is more preferable to have a relationship of 1.1 ≦ D1_R / D1_L ≦ 1.3. By the above lower limit, the difference in rigidity between the left and right tires is ensured appropriately. Further, the above upper limit suppresses deterioration of uniformity due to an excessive difference in the cord diameters of the belt cords.

  2, 3 and 11, the cord diameter D2_R of the belt cord of the belt edge cover 144_R in one region and the cord diameter D2_L of the belt cord of the belt edge cover 144_L in the other region are D2_L. <D2_R may be satisfied. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the ratio of the cord diameter D2_R of the belt cord of the belt edge cover 144_R in the one side region to the cord diameter D2_L of the belt cord of the belt edge cover 144_L in the other side region is 1.1 ≦ D2_R / D2_L ≦ 2. It is preferable to have a relationship of 0, and it is more preferable to have a relationship of 1.1 ≦ D2_R / D2_L ≦ 1.3. By the above lower limit, the difference in rigidity between the left and right tires is ensured appropriately. Further, the above upper limit suppresses deterioration of uniformity due to an excessive difference in the cord diameters of the belt cords.

  The cord diameter of the belt cord is measured as the outer diameter of the belt cord as indicated by the dimension symbol D in FIGS. Further, in the configuration including a plurality of filaments in which the cords are twisted, the cord diameter is measured as the diameter of the circumscribed circle in the radial sectional view of the belt cord.

  2, 3 and 11, the thickness T1_R of the belt rubber 143, 143_R in the one side region and the thickness T1_L of the belt rubber 143, 143_L in the other region are T1_L. <T1_R may be satisfied. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the thickness T1_R of the coated rubber of the belt covers 143 and 143_R in the region on one side and the thickness T1_L of the coated rubber of the belt covers 143 and 143_L in the region on the other side satisfy 1.2 ≦ T1_R / T1_L ≦ 2.0. It is preferable to have a relationship, and it is more preferable to have a relationship of 1.3 ≦ T1_R / T1_L ≦ 1.5. By the above lower limit, the difference in rigidity between the left and right tires is ensured appropriately. Further, the above upper limit suppresses the deterioration of uniformity due to an excessive difference in the thickness of the coat rubber.

  Further, in FIGS. 2, 3 and 11, the thickness T2_R of the coating rubber of the belt edge cover 144_R in one region and the thickness T2_L of the coating rubber of the belt edge cover 144_L in the other region are T2_L <T2_R. It may have the relationship. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the thickness T2_R of the coated rubber of the belt edge cover 144_R in the one side region and the thickness T2_L of the coated rubber of the belt edge cover 144_L in the other side region have a relationship of 1.2 ≦ T2_R / T2_L ≦ 2.0. Preferably, it has a relationship of 1.3 ≦ T2_R / T2_L ≦ 1.5. By the above lower limit, the difference in rigidity between the left and right tires is ensured appropriately. Further, the above upper limit suppresses the deterioration of uniformity due to an excessive difference in the thickness of the coat rubber.

  The thickness of the coat rubber is measured as the thickness of the coat rubber in the tire radial direction in the entire belt cover or belt edge cover, as indicated by the dimension symbol T in FIGS. For example, the thickness of the coat rubber increases in the configuration in which the strip material is wound in a multiple manner as shown in FIG. 9 or the configuration in which the strip material is placed vertically as shown in FIG.

  2, 3 and 11, the hardness Hs1_R of the coated rubber of the belt covers 143 and 143_R in one region and the hardness Hs1_L of the coated rubber of the belt covers 143 and 143_L in the other region are Hs1_L <Hs1_R. It may have the relationship. As a result, a difference in rigidity between the left and right tire regions is formed.

  Further, the difference between the hardness Hs1_R of the coated rubber of the belt covers 143 and 143_R in the one region and the hardness Hs1_L of the coated rubber of the belt covers 143 and 143_L in the other region is in the range of 3 ≦ Hs1_R−Hs1_L ≦ 10. Is preferable, and is more preferably in a range of 4 ≦ Hs1_R−Hs1_L ≦ 5. By the above lower limit, the difference in rigidity between the left and right tires is ensured appropriately. Further, the above upper limit suppresses deterioration of uniformity due to the excessive hardness difference of the coat rubber.

  In addition, in FIGS. 2, 3 and 11, the hardness Hs2_R of the coated rubber of the belt edge cover 144_R in one region and the hardness Hs2_L of the coated rubber of the belt edge cover 144_L in the other region are in a relationship of Hs2_L <Hs2_R. You may have. As a result, a difference in rigidity between the left and right tire regions is formed.

  The difference between the hardness Hs2_R of the coated rubber of the belt edge cover 144_R in the one side region and the hardness Hs2_L of the coated rubber of the belt edge cover 144_L in the other side region is preferably in the range of 3 ≦ Hs2_R−Hs2_L ≦ 10. 4 ≦ Hs2_R−Hs2_L ≦ 5 is preferable. By the above lower limit, the difference in rigidity between the left and right tires is ensured appropriately. Further, the above upper limit suppresses deterioration of uniformity due to the excessive hardness difference of the coat rubber.

  The rubber hardness Hs is measured as JIS-A hardness according to JIS-K6253.

[effect]
As described above, the pneumatic tire 1 includes the carcass layer 13, the pair of cross belts 141 and 142 disposed on the outer side in the tire radial direction of the carcass layer 13, and the outer side in the tire radial direction of the cross belts 141 and 142. And a belt cover 143 to be disposed (see FIG. 1). The tread surface 21 includes at least three circumferential grooves 22 extending in the tire circumferential direction and at least four rows of land portions 23 defined by the circumferential grooves 22. Also, two or more rows of land portions 23 are ribs extending continuously in the tire circumferential direction, and protrude outward in the tire radial direction from the contour line L of the tread surface 21 in the tire meridional section (see FIG. 2 and FIG. 2). (See FIG. 3). Further, the protruding amount G of the rib 23 on one side in the tire width direction is larger than the protruding amount G of the rib 23 on the other side in the tire width direction (in FIG. 2, Gc <Gb <Ga, in FIG. Gg <Gf <Ge <Gd). In addition, the rigidity of the belt cover 143 in one side region with the tire equatorial plane CL as a boundary is larger than the rigidity of the belt cover 143 in the other side region.

  In such a configuration, (1) since the protruding amount G of the rib 23 on one side in the tire width direction is larger than the protruding amount G of the rib 23 on the other side in the tire width direction, the grounding property on the dry road surface is ensured. Therefore, the handling stability at high speed is ensured. At the same time, when the tire is mounted on a vehicle having a large camber angle, the ground contact length of the rib in the entire tread is made uniform, and durability during high-speed traveling is ensured. As a result, there is an advantage that the handling stability at high speed and the durability at high speed with camber are compatible.

  In addition, (2) since the rigidity of the belt cover 143 in the one side region with the tire equatorial plane CL as a boundary is set large, the tire diameter growth in the inflated state in the one side region is suppressed. Then, the unbalance of the tire left and right regions caused by the protrusion amount G of the rib 23 being asymmetric in the tire left and right regions is alleviated as a whole tire. Thereby, there is an advantage that the ground contact shape in the left and right regions of the tire is made uniform and conicity is ensured.

  Further, in the pneumatic tire 1, the number N1_R of belt cords of the belt cover 143 in one region and the number N1_L of belt cords of the belt cover 143 in the other region have a relationship of N1_L <N1_R. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in the pneumatic tire 1, the width W1_R of the belt cover 143 in the one side region and the width W1_L of the belt cover 143 in the other side region have a relationship of W1_L <W1_R (see FIGS. 2 and 3). ). Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  In the pneumatic tire 1, the number of belt covers 143 stacked in one region is greater than the number of belt covers 143 stacked in the other region. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in the pneumatic tire 1, the number of ends NE1_R of the belt cover 143 in one region and the number of ends NE1_L of the belt cover 143 in the other region have a relationship of NE1_L <NE1_R. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in this pneumatic tire 1, the belt cord 143 twist number TC1_R in the one side region and the belt cord 143 twist number TC1_L in the other region have a relationship of TC1_L <TC1_R. Have. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in this pneumatic tire 1, the intermediate elongation E1_R of the belt cord of the belt cover 143 in one region and the intermediate elongation E1_L of the belt cord of the belt cover 143 in the other region satisfy E1_R <E1_L. Have a relationship. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  In the pneumatic tire 1, the weight DT1_R of the belt cord of the belt cover 143 in one region and the weight DT1_L of the belt cord of the belt cover 143 in the other region have a relationship of DT1_L <DT1_R. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in the pneumatic tire 1, the heat contraction rate TS1_R of the belt cord of the belt cover 143 in one region and the heat contraction rate TS1_L of the belt cord of the belt cover 143 in the other region satisfy TS1_L <TS1_R. Have a relationship. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in the pneumatic tire 1, the cord diameter D1_R of the belt cord of the belt cover 143 in the one side region and the cord diameter D1_L of the belt cord of the belt cover 143 in the other side region have a relationship of D1_L <D1_R. Have. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in this pneumatic tire 1, the thickness T1_R of the coat rubber of the belt cover 143 in one region and the thickness T1_L of the coat rubber of the belt cover 143 in the other region have a relationship of T1_L <T1_R. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in the pneumatic tire 1, the hardness Hs1_R of the coat rubber of the belt cover 143 in one region and the hardness Hs1_L of the coat rubber of the belt cover 143 in the other region have a relationship of Hs1_L <Hs1_R. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  The pneumatic tire 1 includes a carcass layer 13, a pair of cross belts 141 and 142 disposed on the outer side in the tire radial direction of the carcass layer 13, and a pair disposed on the outer side in the tire radial direction of the cross belts 141 and 142. Belt edge covers 144_R and 144_L (see FIG. 1). The tread surface 21 includes at least three circumferential grooves 22 extending in the tire circumferential direction and at least four rows of land portions 23 defined by the circumferential grooves 22. Also, two or more rows of land portions 23 are ribs extending continuously in the tire circumferential direction, and protrude outward in the tire radial direction from the contour line L of the tread surface 21 in the tire meridional section (see FIG. 2 and FIG. 2). (See FIG. 3). Further, the protruding amount G of the rib 23 on one side in the tire width direction is larger than the protruding amount G of the rib 23 on the other side in the tire width direction (in FIG. 2, Gc <Gb <Ga, in FIG. Gg <Gf <Ge <Gd). Further, the rigidity of the belt edge cover 144_R in the one side region with the tire equatorial plane CL as a boundary is larger than the rigidity of the belt edge cover 144_L in the other side region.

  In such a configuration, (1) since the protruding amount G of the rib 23 on one side in the tire width direction is larger than the protruding amount G of the rib 23 on the other side in the tire width direction, the grounding property on the dry road surface is ensured. Therefore, the handling stability at high speed is ensured. At the same time, when the tire is mounted on a vehicle having a large camber angle, the ground contact length of the rib in the entire tread is made uniform, and durability during high-speed traveling is ensured. As a result, there is an advantage that the handling stability at high speed and the durability at high speed with camber are compatible.

  In addition, (2) the rigidity of the belt edge cover 144_R in the region on one side with the tire equatorial plane CL as a boundary is set large. As a result, the rigidity unbalance caused by the protrusion amount G of the rib 23 being asymmetric in the left and right regions of the tire is alleviated. As a result, there is an advantage that the rigidity of the left and right regions with the tire equator plane CL as a boundary is made uniform, and conicity is ensured.

  Further, in this pneumatic tire 1, the number N2_R of belt cords of the belt edge cover 144_R in one region and the number N2_L of belt cords of the belt edge cover 144_L in the other region have a relationship of N2_L <N2_R. Have. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in this pneumatic tire 1, the width W2_R of the belt edge cover 144_R in one region and the width W2_L of the belt edge cover 144_L in the other region have a relationship of W2_L <W2_R (FIG. 2 and FIG. 2). 3). Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  In the pneumatic tire 1, the number of stacked belt edge covers 144_R in one region is larger than the number of stacked belt edge covers 144_L in the other region. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in the pneumatic tire 1, the number NE2_R of the belt edge cover 144_R in the one region and the number NE2_L of the belt edge cover 144_L in the other region have a relationship of NE2_L <NE2_R. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in this pneumatic tire 1, the number TC2_R of the belt cord twist of the belt edge cover 144_R in the one side region and the number TC2_L of the belt cord twist of the belt edge cover 144_L in the other side region satisfy TC2_L <TC2_R. Have a relationship. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in this pneumatic tire 1, the intermediate elongation E2_R of the belt cord of the belt edge cover 144_R in one region and the intermediate elongation E2_L of the belt cord of the belt edge cover 144_L in the other region are E2_R < E2_L relationship. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in this pneumatic tire 1, the weight DT2_R of the belt cord of the belt edge cover 144_R in the one side region and the weight DT2_L of the belt cord of the belt edge cover 144_L in the other side region have a relationship of DT2_L <DT2_R. Have. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in the pneumatic tire 1, the thermal contraction rate TS2_R of the belt cord of the belt edge cover 144_R in one region and the thermal contraction rate TS2_L of the belt cord of the belt edge cover 144_L in the other region are TS2_L < It has a relationship of TS2_R. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in this pneumatic tire 1, the cord diameter D2_R of the belt cord of the belt edge cover 144_R in one region and the cord diameter D2_L of the belt cord of the belt edge cover 144_L in the other region satisfy D2_L <D2_R. Have a relationship. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  In this pneumatic tire 1, the thickness T2_R of the belt rubber of the belt edge cover 144_R in one region and the thickness T2_L of the rubber coating of the belt edge cover 144_L in the other region have a relationship of T2_L <T2_R. Have. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Further, in the pneumatic tire 1, the hardness Hs2_R of the coated rubber of the belt edge cover 144_R in one region and the hardness Hs2_L of the coated rubber of the belt edge cover 144_L in the other region have a relationship of Hs2_L <Hs2_R. Thereby, there exists an advantage by which the rigidity difference of the area | region on the right and left of a tire is formed.

  Moreover, in this pneumatic tire 1, the protruding amount G (Ga to Gg) of the rib 23 is in the range of 0.05 [mm] ≦ G ≦ 2.0 [mm] (see FIGS. 2 and 3). Thereby, the protrusion amount G of the rib 23 is optimized, and there is an advantage that the effect of improving the ground contact property and the effect of equalizing the contact length by the protrusion amount G of the rib 23 are ensured.

  Further, in this pneumatic tire 1, the difference ΔG between the protrusion amounts G (Ga to Gg) of the adjacent ribs 23 is in the range of 0.1 [mm] ≦ ΔG ≦ 0.8 [mm] (FIG. 2 and FIG. 2). (See FIG. 3). Thereby, the protrusion amount G of the rib 23 is optimized, and there is an advantage that the effect of improving the ground contact property and the effect of equalizing the contact length by the protrusion amount G of the rib 23 are ensured.

  Further, in this pneumatic tire 1, the sum total ΣG_R of the protrusion amounts of the ribs 23 arranged in the one side region with the tire equator plane CL as the boundary and the sum total ΣG_L of the protrusion amount of the ribs 23 arranged in the other region. ΣG_R−ΣG_L is in the range of 0.4 [mm] ≦ ΣG_R−ΣG_L ≦ 0.9 [mm] (see FIGS. 2 and 3). Thereby, the protrusion amount G of the rib 23 is optimized, and there is an advantage that the effect of improving the ground contact property and the effect of equalizing the contact length by the protrusion amount G of the rib 23 are ensured.

[Specify mounting direction]
The pneumatic tire 1 also includes a mounting direction designating unit that designates that one side (see FIGS. 2 and 3) should be mounted on the vehicle with the vehicle width direction outside. When the tire is mounted on a vehicle having a negative camber, the contact length of the rib on the inner side in the vehicle width direction is generally longer than the contact length of the rib on the outer side in the vehicle width direction. There is a tendency for durability during running to decrease. Therefore, there is an advantage that the effect of improving the durability in high-speed traveling can be remarkably obtained by making one side having the protruding amount G of the large rib 23 outside in the vehicle width direction. Note that the mounting direction designating part is constituted by, for example, marks or irregularities attached to the sidewall part of the tire.

  12 to 15 are charts showing the results of the performance test of the pneumatic tire according to this embodiment. In these drawings, FIGS. 12 and 13 show the results of performance tests when the belt cover 143 has a left-right asymmetric structure, and FIGS. 14 and 15 show the belt edge covers 144_R, 144_L having a left-right asymmetric structure. The result of the performance test when it has is shown.

  In this example, performance tests on high speed maneuverability (steering stability at high speed driving), high speed durability with camber (durability at high speed driving with camber), and conicity for multiple types of pneumatic tires with different conditions. Was done.

  In this test, a pneumatic tire having a tire size of 295 / 35R21 was used as a test tire.

  The method for evaluating high-speed safety is to assemble the test tire on a rim of 21 x 10 J, fill it with air pressure of 260 kPa, mount it on a test vehicle (passenger vehicle with a displacement of 4800 cc), and run on a dry road test course. The steering performance at the time of lane change and cornering and the stability at the time of going straight are performed by sensory evaluation by one skilled test driver. This sensory evaluation is indicated by an index based on a conventional pneumatic tire as a reference (100), and the higher this index is, the better the steering stability is.

  The high-speed durability evaluation method with a camber is as follows. The test tire is assembled on a rim of 21 × 10 J, filled with air pressure of 340 kPa, applied with a load of 7.65 kN, and a camber angle of −2.7 degrees (one side on the outside of the vehicle) Or equivalent to when installed on the vehicle with the other side inside the vehicle) or +2.7 degrees (equivalent to mounting on the vehicle with one side inside the vehicle and the other side outside the vehicle). The vehicle was taken on the step and traveled, and the speed when the testing machine detected a tire failure was measured. Then, using the conventional pneumatic tire as a reference, it was evaluated how many steps were improved or how many steps were reduced. Here, +1 step indicates that the vehicle can travel for 20 minutes at +10 km / h, and +0.5 step indicates that the vehicle can travel for 10 minutes at +10 km / h.

・ Step0 ... Running time 0min ... Speed 0km / h
・ Step1 ... Running time 1min ... Speed 0-190km / h
・ Step2 ... Running time 5min ... Speed 190km / h
・ Step3 ... Running time 5min ... Speed 240km / h
・ Step4 ... Running time 10min ... Speed 250km / h
・ Step5: Travel time 10min ... Speed 260km / h
Step 6: Traveling time 10 min ... Speed 270 km / h
Step 7: Traveling time 20 min ... Speed 280 km / h
・ Step8 ... Running time 20min ... Speed 290km / h
・ Step9 ... Running time 20min ... Speed 300km / h
・ Step 10: Traveling time 20 min ... Speed 310 km / h
Thereafter, the speed is increased by +1 step (+10 km / h, 20 min running) until failure

  Conicity is evaluated by assembling the above test tire on a rim of 21 × 10 J, filling it with air pressure of 200 kPa, applying a load of 6.30 kN, and using a force variation tester, RFV (longitudinal direction) based on the JASO C607 standard. Rigidity balance), and the average value of the lateral force generated in the axial direction of the tire was measured. And it shows with the index | exponent which used the pneumatic tire of the prior art example as the reference | standard (100), and has shown that the conicity is excellent, so that an index | exponent is small.

  The test tires of Examples 1 to 23 have the structure of FIG. 3 and include three circumferential grooves 22 and four rows of ribs 23. Further, the belt cover 143 and the pair of belt edge covers 144_R and 144_L are configured by spirally winding one belt cord around the cross belts 141 and 142 (see FIGS. 7 and 9). The belt cover 143 has a left-right asymmetric structure. On the other hand, the pair of belt edge covers 144_R and 144_L have a symmetrical structure. Further, the outer diameter D1_L of the belt cord of the belt cover 143 in the other region is D1_L = 0.55 [mm], the thickness T1_L of the cord rubber is T1_L = 0.8 [mm], and the cord The rubber hardness Hs1_L is Hs1_L = 61.

  The test tires of Examples 24 to 47 have the structure shown in FIG. 3 and include three circumferential grooves 22 and four rows of ribs 23. Further, the belt cover 143 and the pair of belt edge covers 144_R and 144_L are configured by spirally winding one belt cord around the cross belts 141 and 142 (see FIGS. 7 and 9). Further, the belt cover 143 has a symmetrical structure. On the other hand, the pair of belt edge covers 144_R and 144_L have a left-right asymmetric structure. Further, the outer diameter D2_L of the belt cord of the belt cover 143 in the other region is D2_L = 0.55 [mm], the thickness T2_L of the cord rubber is T2_L = 0.8 [mm], and the cord The rubber hardness Hs2_L is Hs2_L = 61.

  In the test tire of the conventional example, the protruding amount G of all the ribs 23 is G = 0 [mm] in the configuration of Example 1, and the belt cover 143 and the pair of belt edge covers 144_R and 144_L are both. It has a symmetrical structure. In the test tire of Comparative Example 1, in the configuration of Example 1, the belt cover 143 and the pair of belt edge covers 144_R and 144_L both have a bilaterally symmetric structure.

  As shown in the test results, it can be seen that in the test tires of Examples 1 to 47, high-speed steering stability and high-speed durability with camber are compatible, and conicity is improved.

  1: pneumatic tire, 2: tread portion, 21: tread surface, 22: circumferential groove, 23: rib (land portion), 24: lug groove, 11: bead core, 12: bead filler, 13: carcass layer, 14 : Belt layer, 141, 142: cross belt, 143: belt cover, 144: belt edge cover, 1441: belt cord, 1442: coat rubber, 15: tread rubber

Claims (28)

A carcass layer; a pair of cross belts arranged on the outer side in the tire radial direction of the carcass layer; and a belt cover arranged on the outer side in the tire radial direction of the cross belt, and at least extending in the tire circumferential direction A pneumatic tire provided with three circumferential grooves and at least four rows of land portions defined by the circumferential grooves on a tread surface,
Two or more rows of the land portions are ribs extending continuously in the tire circumferential direction, and protrude outward in the tire radial direction from the contour line of the tread surface in the tire meridional section,
The protruding amount of the rib on one side in the tire width direction is larger than the protruding amount of the rib on the other side in the tire width direction, and
The pneumatic tire according to claim 1, wherein a rigidity of the belt cover in the region on the one side with the tire equatorial plane as a boundary is larger than a rigidity of the belt cover in the region on the other side.   2. The pneumatic according to claim 1, wherein the number N1_R of belt cords of the belt cover in the one side region and the number N1_L of belt cords of the belt cover in the other side region have a relationship of N1_L <N1_R. tire.   The pneumatic tire according to claim 1, wherein a width W1_R of the belt cover in the one side region and a width W1_L of the belt cover in the other side region have a relationship of W1_L <W1_R.   The pneumatic tire according to any one of claims 1 to 3, wherein the number of the belt covers stacked in the one side region is larger than the number of the belt covers stacked in the other side region.   5. The belt cover end number NE1_R in the one-side region and the belt cover end number NE1_L in the other-side region have a relationship of NE1_L <NE1_R. Pneumatic tires.   The number of twists TC1_R of the belt cord of the belt cover in the one side region and the number of twists TC1_L of the belt cord of the belt cover in the other region have a relationship of TC1_L <TC1_R. The pneumatic tire according to any one of the above.   The intermediate elongation E1_R of the belt cord of the belt cover in the one side region and the intermediate elongation E1_L of the belt cord of the belt cover in the other region have a relationship of E1_R <E1_L. The pneumatic tire according to any one of 6.   The weight DT1_R of the belt cord of the belt cover in the one side region and the weight DT1_L of the belt cord of the belt cover in the other side region have a relationship of DT1_L <DT1_R. The pneumatic tire according to one.   The thermal contraction rate TS1_R of the belt cord of the belt cover in the one side region and the thermal contraction rate TS1_L of the belt cord of the belt cover in the other side region have a relationship of TS1_L <TS1_R. The pneumatic tire according to any one of 8.   The cord diameter D1_R of the belt cord of the belt cover in the one side region and the cord diameter D1_L of the belt cord of the belt cover in the other region have a relationship of D1_L <D1_R. The pneumatic tire according to any one of the above.   The thickness T1_R of the belt cover coat rubber in the one side region and the thickness T1_L of the belt cover coat rubber in the other side region have a relationship of T1_L <T1_R. The pneumatic tire according to one.   The hardness Hs1_R of the coated rubber of the belt cover in the one side region and the hardness Hs1_L of the coated rubber of the belt cover in the other side region have a relationship of Hs1_L <Hs1_R. Pneumatic tire described in 2. A carcass layer, a pair of cross belts disposed on the outer side in the tire radial direction of the carcass layer, and a pair of belt edge covers disposed on the outer side in the tire radial direction of the cross belt, and extending in the tire circumferential direction. A pneumatic tire comprising at least three circumferential grooves present and at least four rows of land portions defined by the circumferential grooves on a tread surface,
Two or more rows of the land portions are ribs extending continuously in the tire circumferential direction, and protrude outward in the tire radial direction from the contour line of the tread surface in the tire meridional section,
The protruding amount of the rib on one side in the tire width direction is larger than the protruding amount of the rib on the other side in the tire width direction, and
The pneumatic tire according to claim 1, wherein a rigidity of the belt edge cover in the region on the one side with the tire equator plane as a boundary is larger than a rigidity of the belt edge cover in the region on the other side.   The number N2_R of belt cords of the belt edge cover in the one side region and the number N2_L of belt cords of the belt edge cover in the other side region have a relationship of N2_L <N2_R. Pneumatic tire.   The pneumatic tire according to claim 13 or 14, wherein a width W2_R of the belt edge cover in the one side region and a width W2_L of the belt edge cover in the other side region have a relationship of W2_L <W2_R.   The pneumatic tire according to any one of claims 13 to 15, wherein the number of the belt edge covers stacked in the one side region is larger than the number of the belt edge covers stacked in the other side region.   The number of ends NE2_R of the belt edge cover in the one side region and the number of ends NE2_L of the belt edge cover in the other side region have a relationship of NE2_L <NE2_R. Pneumatic tire described in 2.   The belt cord twist number TC2_R of the belt edge cover in the one side region and the belt cord twist number TC2_L of the belt edge cover in the other side region have a relationship of TC2_L <TC2_R. The pneumatic tire according to any one of 17.   The intermediate elongation E2_R of the belt cord of the belt edge cover in the one side region and the intermediate elongation E2_L of the belt cord of the belt edge cover in the other region have a relationship of E2_R <E2_L. The pneumatic tire according to any one of 13 to 18.   The weight DT2_R of the belt cord of the belt edge cover in the one side region and the weight DT2_L of the belt cord of the belt edge cover in the other side region have a relationship of DT2_L <DT2_R. The pneumatic tire according to any one of the above.   The thermal contraction rate TS2_R of the belt cord of the belt edge cover in the one side region and the thermal contraction rate TS2_L of the belt cord of the belt edge cover in the other side region have a relationship of TS2_L <TS2_R. The pneumatic tire according to any one of 13 to 20.   The cord diameter D2_R of the belt cord of the belt edge cover in the one side region and the cord diameter D2_L of the belt cord of the belt edge cover in the other side region have a relationship of D2_L <D2_R. 21. The pneumatic tire according to any one of 21.   The thickness T2_R of the belt edge cover coat rubber in the one side region and the thickness T2_L of the belt edge cover coat rubber in the other side region have a relationship of T2_L <T2_R. The pneumatic tire according to any one of the above.   The hardness Hs2_R of the belt edge cover coat rubber in the one side region and the hardness Hs2_L of the belt edge cover coat rubber in the other side region have a relationship of Hs2_L <Hs2_R. The pneumatic tire according to one.   The pneumatic tire according to any one of claims 1 to 24, wherein a protruding amount G of the rib is in a range of 0.05 [mm]? G? 2.0 [mm].   The pneumatic tire according to any one of claims 1 to 25, wherein a difference ΔG in the protruding amount of the adjacent ribs is in a range of 0.1 [mm] ≦ ΔG ≦ 0.8 [mm].   The difference ΣG_R−ΣG_L between the sum ΣG_R of the protruding amounts of the ribs arranged in the one side region with the tire equator plane as a boundary and the total amount ΣG_L of the protruding amounts of the ribs arranged in the other side region is The pneumatic tire according to any one of claims 1 to 26, which is in a range of 0.4 [mm] ≤ ΣG_R-ΣG_L ≤ 0.9 [mm].   The pneumatic tire according to any one of claims 1 to 27, further comprising a mounting direction specifying portion that specifies that the one side is to be mounted on the vehicle with the one side being in the vehicle width direction outside.

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