pneumatic tires

Abstract

Pneumatic tires with an asymmetric tread pattern on both sides of a tire centerline (CL) and a marked vehicle mounting direction, wherein the pneumatic tire comprises the following: in a running surface section (1) a plurality of main grooves (9) running in a circumferential direction of the tire; Ribs (10) defined by the main grooves (9); and Sipes (11) which run in a transverse direction in the ribs (10) of the tire; wherein the ribs (10) comprise a central rib (100A) located on the tire centerline CL, a pair of intermediate ribs (100B, 100C) arranged transversely to the outside from the central rib (100A), and include a pair of shoulder ribs (100D, 100E) that are arranged outwards in the transverse direction of the tire from the intermediate ribs (100B and 100C, respectively); wherein the lamellae (11), each enclosing a pair of beveled sections (12), are formed in the central rib (100A) and in the intermediate ribs (100B, 100C); wherein the lamellae (11) comprise a front edge (11A) and a rear edge (11B), each of which is provided with a chamfered section (12) that is shorter than a length of the lamellae (11) and a non-chamfered area (13) in which no further chamfered sections are present and which is located in an area opposite the chamfered section (12); wherein the lamellae (11) have a maximum depth x (mm) and the beveled section (12) has a maximum depth y (mm) satisfying a relationship represented by formula (1); wherein the sipes (11) have a constant width in a region from an end section of the chamfered section arranged inwards in a tire radial direction to a groove bottom (E) of the sipes (11); and wherein the lamellae (11) are configured such that a groove area of ​​the beveled sections (12) and the lamellae (11) enclosed in a ground contact area (E) on a vehicle mounting inside is larger than a groove area of ​​the beveled sections (12) and the lamellae (11) enclosed in a ground contact area (E) on a vehicle mounting outside; x × 0.1 ≤ y ≤ x × 0.3 + 1.0

Description

Technical area

[0001] The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having an asymmetric tread pattern and a designated vehicle mounting direction, wherein a chamfer shape of a sipe is designed to provide improvement in steering stability performance on both dry and wet road surfaces in a mutually compatible manner. State of the art

[0002] In the prior art, tread patterns of pneumatic tires feature a plurality of sipes formed in ribs defined by a plurality of main grooves. By providing such sipes, drainage properties are ensured, and thus the pneumatic tire exhibits good steering stability performance on wet road surfaces. However, when a plurality of sipes are arranged in a tread portion to improve steering stability performance on wet road surfaces, the rib rigidity decreases, resulting in the disadvantage of a decrease in uneven wear resistance and steering stability performance on dry road surfaces.

[0003] Furthermore, various pneumatic tires have been proposed in which sipes are formed and chamfered in the tread pattern (see, for example, Patent Document 1). When sipes are formed and chamfered, the chamfer shape may result in a loss of edge effect, and the chamfer dimensions may result in inadequacies in improving steering stability performance on dry road surfaces or improving steering stability performance on wet road surfaces. Patent Document 2 describes a pneumatic tire that has good dry performance and good wet performance. The pneumatic tire includes sipes formed in a tread rubber and having an opening extending in a first direction in a surface of the tread rubber.The opening is provided between a first edge of the tread rubber extending in the first direction and a second edge of the tread rubber adjacent to the first edge in a second direction perpendicular to the first direction. Patent Document 3 describes a pneumatic tire that has both good steering stability on snow and good steering stability on a dry road surface during cornering. In the pneumatic tire, land portions are formed adjacent to shoulder land regions, each of which is arranged on both sides of the tire in a tire width direction, and sipes are formed in the land portions. Patent Document 4 describes a pneumatic tire capable of improving both braking performance on ice and dry steering stability.The pneumatic tire has sipes extending in a width direction of the pneumatic tire, the sipes having a plurality of wide portions. Patent Document 5 describes a pneumatic tire that can effectively prevent damage to the sipe bottom and uneven tread wear around the sipe ends, improving the tire's durability and maneuverability. List of citationsPatent literature Patent document 1: JP 2013 - 537 134 A Patent document 2: EP 3 418 075 A1 Patent document 3: DE 10 2015 215 015 A1 Patent document 4: US 2010 / 0 084 062 A1 Patent document 5: EP 0 844 107 A2 Summary of the inventionTechnical problem

[0004] An object of the present invention is to provide a pneumatic tire having an asymmetric tread pattern and a designated vehicle mounting direction, wherein a chamfer shape of a sipe is designed to provide improvement in steering stability performance on both dry and wet road surfaces in a mutually compatible manner. Solution to the problem

[0005] A pneumatic tire according to the invention for achieving the above-described object is a pneumatic tire having an asymmetric tread pattern on both sides of a tire centerline and a designated vehicle mounting direction. The pneumatic tire includes, in a tread portion, a plurality of main grooves extending in a tire circumferential direction, ribs defined by the main grooves, and sipes extending in a tire transverse direction in the ribs. The ribs include a center rib disposed on the tire centerline, a pair of intermediate ribs disposed outward in the tire transverse direction from the center rib, and a pair of shoulder ribs disposed outward in the tire transverse direction from the intermediate ribs. The sipes each include a pair of chamfered portions formed in the center rib and the intermediate ribs.The sipes include a leading edge and a trailing edge, each provided with a chamfered portion shorter than a length of the sipes and a non-chamfered portion in which further chamfered portions are not present and located in a region opposite to the chamfered portion. The sipes have a maximum depth x (mm) and the chamfered portion has a maximum depth y (mm), which satisfy a relationship represented by formula (1) below. The sipes have a constant width in a region from an end portion of the chamfered portion located inward in a tire radial direction to a groove bottom of the sipes.The sipes are configured such that a groove area of ​​the chamfered portions and the sipes enclosed within a ground contact area on a vehicle mounting inside is larger than a groove area of ​​the chamfered portions and the sipes enclosed within a ground contact area on a vehicle mounting outside. x×0.1≤y≤x×0.3+1.0 Advantageous effects of the invention

[0006] According to the present invention, in the pneumatic tire having an asymmetric tread pattern on both sides of the tire center line and a designated vehicle mounting direction, and including the sipes extending in the tire transverse direction in the ribs defined by the main grooves, the chamfered portions shorter than the length of the sipes are provided at the leading edge and trailing edge of the sipes, and the non-chamfered portions where further chamfered portions are not present are provided in portions of the sipes opposite to the chamfered portions, whereby it is possible to enhance the drainage effect based on the chamfered portions and simultaneously effectively remove a water film by the edge effect in the non-chamfered portions. Therefore, it is possible to significantly improve the steering stability performance on wet road surfaces.Furthermore, by providing the chamfered portions and the non-chamfered areas both at the front and rear edges, it is possible to maximize the wet performance improvement effect described above during braking and driving. Furthermore, a chamfered surface can be minimized compared to that of a chamfered sipe in the prior art, making it possible to improve the steering stability performance on dry road surfaces. This makes it possible to improve the steering stability performance on both dry and wet road surfaces in a mutually compatible manner.Furthermore, the groove area of ​​the chamfered portions and the sipes included in the ground contact area on the vehicle mounting inside is larger than the groove area of ​​the chamfered portions and the sipes included in the ground contact area on the vehicle mounting outside, thereby making it possible to more effectively improve the steering stability performance on dry road surfaces and the steering stability performance on wet road surfaces.

[0007] According to the invention, the groove area ratio of the chamfered portions and the sipes in the ground contact area on the vehicle mounting inner side is preferably 3 to 15% larger than the groove area ratio of the chamfered portions and the sipes in the ground contact area on the vehicle mounting outer side. This makes it possible to effectively improve steering stability performance on both dry road surfaces and wet road surfaces in a mutually compatible manner. More preferably, the groove area ratio is 5 to 10%.

[0008] According to the invention, the groove area ratio in the ground contact area on the vehicle mounting inside is preferably 5 to 20% larger than the groove area ratio in the ground contact area on the vehicle mounting outside. This makes it possible to effectively improve steering stability performance on both dry road surfaces and wet road surfaces in a mutually compatible manner. More preferably, the groove area ratio is 8 to 15%.

[0009] According to the invention, the number of pitches of groove elements extending in the tire transverse direction in the ground contact area on the vehicle mounting inner side is preferably larger than the number of pitches of groove elements extending in the tire transverse direction in the ground contact area on the vehicle mounting outer side. Thus, the size of a block on the vehicle mounting outer side can be increased, making it possible to effectively improve steering stability performance on dry road surfaces.

[0010] According to the invention, the number of pitches of the groove elements extending in the tire transverse direction in the ground contact area on the vehicle mounting outer side is preferably 0.5 to 0.9 times the number of pitches of the groove elements extending in the tire transverse direction in the ground contact area on the vehicle mounting inner side. This makes it possible to effectively improve the steering stability performance on both dry road surfaces and wet road surfaces in a mutually compatible manner. More preferably, the number of pitches is 0.6 to 0.8 times.

[0011] According to the invention, the sipe is preferably inclined relative to the tire circumferential direction. With such an inclination of the sipe, it is possible to improve the pattern stiffness and thus further enhance the steering stability performance on dry road surfaces.

[0012] According to the invention, the inclination angle of the sipe on an acute-angle side relative to the tire circumferential direction is preferably between 40° and 80°. By setting the inclination angle of the sipe on the acute-angle side in the tire circumferential direction in this way, it is possible to more effectively improve steering stability performance on dry road surfaces. More preferably, the inclination angle is between 50° and 70°.

[0013] According to the invention, the chamfered portion is preferably arranged on the acute-angled side of the sipe. This makes it possible to further improve the resistance to uneven wear. Alternatively, the chamfered portion is preferably arranged on an obtuse-angled side of the sipe. This makes it possible to increase the edge effect and further improve the steering stability performance on wet road surfaces.

[0014] According to the invention, the sipe is preferably at least partially curved or bent in plan view. By at least partially forming the sipe in this way, the overall circumference of the edge of each sipe increases, thereby making it possible to improve steering stability performance on wet road surfaces. The sipe as a whole may have an arcuate shape.

[0015] According to the invention, the chamfered portion preferably opens toward the main groove. This makes it possible to further improve steering stability performance on wet road surfaces. Alternatively, the chamfered portion preferably ends blindly in the rib. This makes it possible to further improve steering stability performance on dry road surfaces.

[0016] According to the invention, the overlap length of the chamfered portion formed at the front edge of the sipe and the chamfered portion formed at the rear edge of the sipe is preferably from -30% to 30% of a sipe length. By appropriately setting the overlap length of the chamfered portions with respect to the sipe length in this way, it is possible to improve the steering stability performance on both dry and wet road surfaces in a mutually compatible manner. More preferably, the overlap length is from -15% to 15%.

[0017] According to the invention, the chamfered portion is arranged at one location on the front edge and one location on the rear edge of the sipe. By arranging the chamfered portion in this way, it is possible to improve the resistance to uneven wear.

[0018] According to the invention, the chamfered portion preferably has a maximum width of 0.8 to 5.0 times the sipe width. By appropriately setting the maximum width of the chamfered portion relative to the sipe width, it is possible to improve steering stability performance on both dry and wet road surfaces in a mutually compatible manner. More preferably, the maximum width is 1.2 to 3.0 times.

[0019] According to the invention, the chamfered portion preferably runs parallel to the sipe. This makes it possible to improve the resistance to uneven wear and to improve the steering stability performance on both dry and wet road surfaces in a mutually compatible manner.

[0020] According to the invention, the sipe preferably further includes a raised bottom portion. This makes it possible to improve steering stability performance on both dry and wet road surfaces in a mutually compatible manner. The bottom of the sipe may be raised at an end portion of the sipe or in a region other than an end portion.

[0021] According to the invention, the raised land portion located in a region other than an end portion of the sipe preferably has a height of 0.2 to 0.5 times the maximum depth x of the sipe. By setting the height of the raised land portion located in a region other than an end portion of the sipe to an appropriate height, it is possible to improve block rigidity and maintain a drainage effect, thus improving steering stability performance on wet road surfaces. More preferably, the height is 0.3 to 0.4 times.

[0022] According to the invention, the raised land portion located on an end portion of the sipe preferably has a height of 0.6 to 0.9 times the maximum depth x of the sipe. By setting the height of the raised land portion located on an end portion of the sipe to a suitable height, it is possible to improve block rigidity and improve steering stability performance on dry road surfaces. More preferably, the height is 0.7 to 0.8 times.

[0023] According to the invention, the raised bottom portion preferably has a height of 0.3 to 0.7 times the sipe length. By appropriately setting the length of the raised bottom portion, it is possible to improve block rigidity and enhance steering stability performance on dry road surfaces.

[0024] It should be noted that in the present invention, “ground contact area” refers to the area in the tire transverse direction corresponding to a maximum linear distance (tire ground contact width) in the tire transverse direction of the ground contact surface formed on a flat plate after a tire is inflated to an air pressure corresponding to the maximum load capacity defined by standards (such as those of the Japan Automobile Tire Manufacturers Association Inc. (JATMA), the Tire and Rim Association, Inc. (TRA), or the European Tire and Rim Technical Organization (ETRTO), placed vertically on the flat plate in a static state, and loaded with a load corresponding to 80% of the maximum load capacity.Further, “groove area ratio of the chamfered portions and the sipes in the ground contact area on the vehicle mounting outer side” refers to a percentage (%) of a total area of ​​the chamfered portions and the sipes included in the ground contact area on the vehicle mounting outer side of the tread portion with respect to the total area of ​​the ground contact area on the vehicle mounting outer side of the tread portion, and the “groove area ratio of the chamfered portions and the sipes in the ground contact area on the vehicle mounting inner side” refers to a percentage (%) of a total area of ​​the chamfered portions and the sipes included in the ground contact area on the vehicle mounting inner side of the tread portion with respect to the total area of ​​the ground contact area on the vehicle mounting inner side of the tread portion.Further, “groove area ratio in the ground contact area on the vehicle mounting outer side” refers to a percentage (%) of a total area of ​​the groove portion included in the ground contact area on the vehicle mounting outer side of the tread portion with respect to the total area of ​​the ground contact area on the vehicle mounting outer side of the tread portion, and the “groove area ratio in the ground contact area on the vehicle mounting inner side” refers to a percentage (%) of a total area of ​​the groove portion included in the ground contact area on the vehicle mounting inner side of the tread portion with respect to the total area of ​​the ground contact area on the vehicle mounting inner side of the tread portion. Brief description of the drawings Fig. 1 is a cross-sectional meridian view showing a pneumatic tire according to an embodiment of the present invention. Fig. 2 is a plan view showing an example of a tread portion of the pneumatic tire according to an embodiment of the present invention. Fig. 3 is a perspective view showing a portion of the tread portion of the pneumatic tire according to the invention. Fig. 4 is a plan view showing a portion of a tread portion of the pneumatic tire according to the invention. Fig. 5 is a plan view showing a sipe and chamfered portions thereof formed in the tread portion of Fig. 4 are formed. Fig. 6 is a cross-sectional view along the arrow line XX of Fig. 4. Fig. 7 is a plan view showing the sipe and the chamfered portions thereof formed in the tread portion of the pneumatic tire according to the present invention. Fig. 8A and Fig.8B show modified examples of the sipe and the chamfered portions thereof of the pneumatic tire according to the invention, each as a plan view of the corresponding modified example. Fig. 9 is a cross-sectional view along the arrow line YY of Fig. 4. Fig. 10A to 10E show other modified examples of the sipe and the chamfered portions thereof of the pneumatic tire according to the invention, each as a plan view of the corresponding modified example. Description of embodiments

[0025] Configurations of embodiments according to the invention will be described in detail below with reference to the accompanying drawings. It should be noted that in Fig. 1 and Fig. 2 CL denotes a tire center line.

[0026] As in Fig.1, a pneumatic tire of one embodiment of the present invention has a designated mounting direction with respect to a vehicle. "INSIDE" refers to a vehicle side inward of the tire center line CL when the tire is mounted on the vehicle (hereinafter referred to as "vehicle mounting inside"), and "OUTSIDE" refers to a vehicle side outward of the tire center line CL when the tire is mounted on the vehicle (hereinafter referred to as "vehicle mounting outside"). The tire shown in Fig. 1 includes an annular tread portion 1 extending in a tire circumferential direction, a pair of sidewall portions 2, 2 arranged on both sides of the tread portion 1, and a pair of bead portions 3, 3 arranged inwardly in a tire radial direction from the sidewall portions 2.

[0027] A carcass layer 4 is disposed between the pair of bead portions 3, 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction and is folded back from a tire inner side to a tire outer side around a bead core 5 disposed in each of the bead portions 3. A bead filler 6 having a triangular cross-sectional shape and formed from a rubber composition is disposed on the outer periphery of the bead core 5.

[0028] A plurality of belt layers 7 are embedded on an outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so that the directions of the reinforcing cords of the different layers intersect each other. In the belt layers 7, an inclination angle of the reinforcing cords with respect to the tire circumferential direction is in a range of, for example, 10° to 40°. Steel cords are preferably used as the reinforcing cords of the belt layers 7.To improve high-speed durability, at least one belt cover layer 8, formed by arranging reinforcing cords at an angle of, for example, not more than 5° with respect to the tire circumferential direction, is disposed on an outer peripheral side of the belt layers 7. Nylon, aramid, or similar organic glass fiber threads are preferably used as the reinforcing cords of the belt cover layer 8.

[0029] It should be noted that the tire internal structure described above is a typical example of a pneumatic tire, and the pneumatic tire is not limited to this.

[0030] Fig.2 is a plan view of the tread portion 1, where E denotes a ground contact edge. Four main grooves 9 extending in the tire circumferential direction are formed in the tread portion 1. The main grooves 9 include a pair of inner main grooves 9A, 9A adjacent to the tire center line CL, and a pair of outer main grooves 9B, 9B located at the outermost ends in the tire transverse direction. Ribs 10 are defined in the tread portion 1 by these four main grooves 9. The ribs 10 include a center rib 100A located on the tire center line CL, a pair of intermediate ribs 100B, 100C located outward in the tire transverse direction from the center rib 100A, and a pair of shoulder ribs 100D, 100E located outward in the tire transverse direction from the intermediate ribs 100B, 100C, respectively.

[0031] Slats 11, each including a pair of chamfered portions 12, are formed in the center rib 100A and the intermediate ribs 100B, 100C. The slats 11 include a slat 110A disposed in the center rib 100A, and slats 110B, 110C disposed in the intermediate ribs 100B, 100C, respectively. The chamfered portions 12 include a chamfered portion 120A formed in the slat 110A, a chamfered portion 120B formed in the slat 110B, and a chamfered portion 120C formed in the slat 110C.

[0032] A plurality of sipes 110A, which are inclined in the same direction with respect to the tire transverse direction, are formed in the center rib 100A at intervals in the tire circumferential direction. These sipes 110A are connected to the inner main groove 9A at a first end and terminate blindly in the center rib 100A at a second end. That is, the sipe 110A is a semi-closed sipe.

[0033] A plurality of sipes 110B, which are inclined in the same direction with respect to the tire transverse direction, are formed in the intermediate rib 100B at intervals in the tire circumferential direction. These sipes 110B are connected to the inner main groove 9A at a first end and are connected to the outer main groove 9B at a second end. That is, the sipe 110B is an open sipe. A plurality of sipes 110C, which are inclined in the same direction with respect to the tire transverse direction, are formed in the intermediate rib 100C at intervals in the tire circumferential direction. These sipes 110C terminate blindly in the intermediate rib 100C at a first end and are connected to the outer main groove 9B at a second end. That is, the sipe 110C is a semi-closed sipe.

[0034] A plurality of lug grooves 200 extending in the tire transverse direction, inclined in the ground contact area in the same direction with respect to the tire transverse direction, and not connected to the outer main groove 9B are formed in the shoulder ribs 100D, 100E at intervals in the tire circumferential direction. The lug grooves 200 include a lug groove 200A formed in the shoulder rib 100D and a lug groove 200B formed in the shoulder rib 100E.

[0035] The total sum of the projecting areas obtained by projecting, in the tire radial direction, the sipes 11 and the chamfered portions 12 included in the ground contact area on the vehicle mounting inside is defined as a groove area S Aand the total sum of the projecting areas obtained by projecting, in the tire radial direction, the sipes 11 and the chamfered portions 12 included in the ground contact area on the vehicle mounting outside is defined as a groove area S B This means that the groove area S A is the total sum of the groove areas of all the sipes 110A, chamfered portions 120A, sipes 110B, and chamfered portions 120B arranged in a region enclosed by the tire center line CL and the ground contact edge E on the vehicle mounting inside. On the other hand, the groove area S B the total sum of the groove areas of all sipes 110C and chamfered portions 120C arranged in an area enclosed by the tire center line CL and the ground contact edge E on the vehicle mounting outside. The groove area S Aon the vehicle mounting inside is larger than the groove area S B on the vehicle assembly exterior.

[0036] Fig. 3 to 5 each illustrate a section of the tread portion 1, where Tc denotes the tire circumferential direction and Tw denotes the tire transverse direction. As shown in Fig. As shown in Figure 3, the rib 10 includes a plurality of sipes 11 extending in the tire transverse direction and blocks 101 defined by the plurality of sipes 11. The plurality of blocks 101 are arranged adjacent to each other in the tire circumferential direction. The sipes 11 are narrow grooves with a groove width of 1.5 mm or less.

[0037] As in Fig.4, the sipes 11 each have a curved overall shape and are formed at intervals in the tire circumferential direction in the rib 10. Further, the sipes 11 each include an edge 11A on a front side with respect to a rotation direction R and an edge 11B on a rear side with respect to the rotation direction R. The chamfered portion 12 is formed on both the front side edge 11A and the rear side edge 11B.

[0038] The chamfered portions 12 each include a chamfered portion 12A on the front side with respect to the rotation direction R and a chamfered portion 12B on the rear side with respect to the rotation direction R. Non-chamfered regions 13, in which further chamfered portions are not present, are arranged in regions opposite to these chamfered portions 12. That is, there is a non-chamfered region 13B on the rear side with respect to the rotation direction R in the region opposite to the chamfered portion 12A, and there is a non-chamfered region 13A on the front side with respect to the rotation direction R in the region opposite to the chamfered portion 12B.The beveled portion 12 and the non-beveled region 13, in which further beveled portions are not present, are thus arranged such that they adjoin the front side edge 11A and the rear side edge 11B of the slat 11.

[0039] As in Fig. 5, in the sipe 11 and in the beveled sections 12A, 12B, the lengths in the tire transverse direction are respectively designated as a sipe length L and as bevel lengths L A , L B defined. The slat length L and the bevel lengths L A , L B are lengths in the tire transverse direction from a first end portion to a second end portion of the corresponding sipe 11 or the chamfered portion 12A, 12B. The chamfer lengths L A , L B the bevelled sections 12A, 12B are both less than the slat length L of the slat 11.

[0040] Fig.6 is a vertically sectioned cross-sectional view of the tread portion 1 perpendicular to the sipe 11. As in Fig.6, given x (mm) as a maximum depth of the sipe 11 and y (mm) as a maximum depth of the chamfered portion 12, the sipe 11 and the chamfered portion 12 are formed so that the maximum depth x (mm) and the maximum depth y (mm) satisfy the relationship of the following formula (1). The maximum depth x of the sipe 11 is preferably from 3 mm to 8 mm. A sipe width W of the sipe 11 is substantially constant in a range from an end portion 121 of the chamfered portion 12 disposed inward in the tire radial direction to a groove bottom of the sipe 11. The sipe width W is a substantially measured width of the sipe 11, which, for example, does not include a height of a protrusion when a protrusion is present in a groove wall of the sipe 11, or does not include a narrowed portion when the width of the sipe 11 gradually narrows along the groove bottom. x×0.1≤y≤x×0.3+1.0

[0041] In the pneumatic tire described above, the chamfered portions 12, which are shorter than the sipe length L of the sipe 11, are provided at the front side edge 11A and the rear side edge 11B of the sipe 11, and the non-chamfered regions 13, where further chamfered portions are not present, are arranged in the regions of the sipe 11 opposite to the chamfered portions 12. This makes it possible to improve the drainage effect based on the chamfered portions 12 and, at the same time, to effectively remove a water film by the edge effect through the non-chamfered regions 13 where the chamfered portions 12 are not provided. Therefore, it is possible to significantly improve the steering stability performance on wet road surfaces.Furthermore, by providing the chamfered portions 12 and the non-chamfered areas 13 where the chamfered portions 12 are not provided both at the front side edge 11A and the rear side edge 11B, it is possible to maximize such an effect of improving wet performance as described above during braking and driving. Furthermore, the groove area S is A of the chamfered sections 12 and the sipes 11 included in the ground contact area on the vehicle mounting inside, larger than the groove area S B the chamfered portions 12 and the sipes 11 incorporated into the ground contact area on the vehicle mounting outer side, whereby it is possible to more effectively improve the steering stability performance on dry road surfaces and the steering stability performance on wet road surfaces.

[0042] Furthermore, according to the pneumatic tire described above, the maximum depth x (mm) and the maximum depth y (mm) must satisfy the above-described relationship of formula (1). By providing the sipe 11 and the chamfered portion 12 so as to satisfy the above-described relationship of formula (1), a surface to be chamfered can be minimized compared to that of the prior art chamfered sipe, thereby making it possible to improve the steering stability performance on dry road surfaces. This makes it possible to improve the steering stability performance on both dry road surfaces and wet road surfaces in a mutually compatible manner. Here, when y < x × 0.1, the drainage effect based on the chamfered portions 12 is insufficient.Furthermore, conversely, when y > x × 0.3 + 1.0, the stiffness of the rib 10 decreases, resulting in a decrease in steering stability performance on dry road surfaces. In particular, satisfying the relationship y ≤ x × 0.3 + 0.5 is preferable.

[0043] A groove area ratio of the chamfered portions 12 and the sipes 11 in the ground contact area on the vehicle mounting inside is defined as M1 A and a groove area ratio of the chamfered portions 12 and the sipes 11 in the ground contact area on the vehicle mounting outside is defined as M1 B defined. The groove area ratio M1 A of the bevelled sections 12 and the sipes 11 in the ground contact area on the vehicle mounting inside is from 3 to 15% larger than the groove area ratio M1 B of the chamfered sections 12 and the sipes 11 in the ground contact area on the vehicle mounting outside. That is, the groove area ratio M1A is larger than the groove area ratio M1 B , and the difference between the groove area ratio M1 A and the groove area ratio M1 B is from 3 to 15%. In particular, the groove area ratio M1 A preferably 5 to 10% larger than the groove area ratio M1 B By adjusting the groove area ratio M1 A in relation to the groove area ratio M1 B is appropriately determined, it is possible to effectively improve the steering stability performance on both dry road surfaces and wet road surfaces in a mutually compatible manner.

[0044] Furthermore, a groove area ratio in the ground contact area on the vehicle mounting inside is specified as M2 A and a groove area ratio in the ground contact area on the vehicle mounting outside is defined as M2 B defined. The groove area ratio M2 Ain the ground contact area on the vehicle mounting inside is from 5 to 20% larger than the groove area ratio M2 B in the ground contact area on the vehicle mounting outside. That is, the groove area ratio M2 A is larger than the groove area ratio M2 B , and the difference between the groove area ratio M2 A and the groove area ratio M2 B is from 5 to 20%. In particular, the groove area ratio M2 A preferably 8 to 15% larger than the groove area ratio M2 B By adjusting the groove area ratio M2 A in relation to the groove area ratio M2 B is appropriately determined, it is possible to effectively improve the steering stability performance on both dry road surfaces and wet road surfaces in a mutually compatible manner.

[0045] Furthermore, a number of pitches of groove elements extending in the tire transverse direction in the ground contact area on the vehicle mounting inside, that is, the sipe 110A, the sipe 110B and the lug groove 200A, is designated as P A and a number of pitches of groove elements extending in the tire transverse direction in the ground contact area on the vehicle mounting outside, that is, the sipe 110C and the lug groove 200B, is defined as P B defined. The number of pitches P A of the groove elements running in the transverse direction of the tire in the ground contact area on the inside of the vehicle assembly is greater than the number of pitches P B of the groove elements that run in the tire's transverse direction in the ground contact area on the vehicle's outer side. By increasing the number of pitches P A in this way greater than the number of pitches P Bis set, a size of the block on the vehicle mounting outside can be increased, making it possible to effectively improve the steering stability performance on dry road surfaces.

[0046] In particular, the number of pitches P B preferably 0.5 to 0.9 times, more preferably 0.6 to 0.8 times, the number of pitches P A By increasing the number of pitches P B in relation to the number of pitches P A is appropriately determined, it is possible to effectively improve the steering stability performance on both dry road surfaces and wet road surfaces in a mutually compatible manner.

[0047] The sipe 11 is formed to have an inclination angle θ with respect to the tire circumferential direction as shown in Fig.7. This angle of inclination θ refers to an angle defined by an imaginary line (which is shown in Fig. 7) connecting both end portions of the slat 11 and a side surface of the block 101, and includes an inclination angle on an obtuse-angled side and an inclination angle on an acute-angled side. Fig.7 represents the inclination angle θ on the acute angle side. Furthermore, the inclination angle θ refers to the inclination angle θ of the sipe 11 at an inter-pitch distance in the rib 10. The inclination angle θ on the acute angle side is preferably from 40° to 80°, more preferably from 50° to 70°. By thus inclining the sipe 11 with respect to the tire circumferential direction, it is possible to improve the pattern rigidity and further enhance the steering stability performance on dry road surfaces. Here, if the inclination angle θ is less than 40°, the uneven wear resistance performance deteriorates. Furthermore, if the inclination angle θ exceeds 80°, the pattern rigidity cannot be sufficiently improved.

[0048] According to the invention, the side having an inclination angle θ on the acute-angled side of the sipe 11 is defined as the acute-angled side, and the side having the inclination angle θ on the obtuse-angled side of the sipe 11 is defined as the obtuse-angled side. The chamfered portions 12A, 12B formed on the edges 11A and 11B of the sipe 11, respectively, are formed on the acute-angled side of the sipe 11. By thus forming the chamfer on the acute-angled side of the sipe 11, it is possible to further improve the resistance performance to uneven wear. Alternatively, the chamfered portions 12A, 12B may be formed on the obtuse-angled side of the sipe 11. By forming the chamfered portions 12A, 12B on the obtuse-angle side in this manner, it is possible to increase the edge effect and further improve the steering stability performance on wet road surfaces.

[0049] According to the invention, while the steering stability performance on wet road surfaces can be improved by forming the above-described sipe 11 in a curved overall shape, the sipe 11 can have a shape that is partially curved or bent in a plan view. By forming the sipe 11 in this way, an overall circumference of the edges 11A, 11B of each sipe 11 increases, thereby making it possible to improve the steering stability performance on wet road surfaces.

[0050] The end portions of the tapered portions 12A, 12B arranged close to the main grooves 9 are respectively connected to the main grooves 9 arranged on both sides of the rib 10, as shown in Fig.7. By forming the chamfered portions 12A, 12B in this manner, it is possible to further improve the steering stability performance on wet road surfaces. Alternatively, the end portions of the chamfered portions 12A, 12B located near the main grooves 9 may blindly terminate in the rib 10 without connecting to the main grooves 9. By forming the chamfered portions 12A, 12B in this manner, it is possible to further improve the steering stability performance on dry road surfaces.

[0051] The bevelled section 12 is, as shown in Fig.7, the chamfered portions 12 are arranged at one location on the front side edge 11A and one location on the rear side edge 11B of the sipe 11. By arranging the chamfered portions 12 in this way, it is possible to improve the uneven wear resistance performance. If the chamfered portion 12 is formed at two or more locations on the front side edge 11A and the rear side edge 11B of the sipe 12, respectively, the number of joints increases, which tends to deteriorate the uneven wear resistance performance.

[0052] Further, a maximum value of the width of the chamfered portion 12, measured in a direction perpendicular to the sipe 11, is defined as width W1. The maximum width W1 of the chamfered portion 12 is preferably 0.8 to 5.0 times, more preferably 1.2 to 3.0 times, the sipe width W of the sipe 11. By appropriately setting the maximum width W1 of the chamfered portion 12 with respect to the sipe width W in this way, it is possible to improve the steering stability performance on both dry road surfaces and wet road surfaces in a mutually compatible manner. Here, if the maximum width W1 of the chamfered portion 12 is less than 0.8 times the sipe width W of the sipe 11, the improvement in the steering stability performance on wet road surfaces is insufficient.Furthermore, when the maximum width W1 of the chamfered portion 12 is more than 5.0 times the sipe width W of the sipe 11, the improvement of the steering stability performance on dry road surfaces is insufficient.

[0053] Furthermore, an outer edge portion of the chamfered portion 12 is formed in a longitudinal direction parallel to the extending direction of the sipe 11. By forming the chamfered portion 12 parallel to the sipe 11 in this way, it is possible to improve the uneven wear resistance performance and improve the steering stability performance on both dry road surfaces and wet road surfaces in a mutually compatible manner.

[0054] The beveled portion 12A and the beveled portion 12B, as shown in Fig.8A are formed to partially overlap in the center portion of the sipe 11. Here, a length in the tire transverse direction of an overlap portion, which is the portion where the chamfered portion 12 overlaps with the chamfered portion 12A, is defined as an overlap length L1. On the other hand, as shown in Fig.8B, when the chamfered portion 12A and the chamfered portion 12B do not partially overlap and are separated by a constant distance, a ratio of the overlap length L1 to the sipe length L is expressed as a negative value. The overlap length L1 of the overlapped portion is preferably from -30% to 30%, more preferably from -15% to 15%, of the sipe length L. By appropriately setting the overlap length L1 of the chamfered portions 12A, 12B with respect to the sipe length L in this way, it is possible to improve the steering stability performance on both dry road surfaces and wet road surfaces in a mutually compatible manner. Here, if the overlap length L1 is greater than 30%, the improvement in the steering stability performance on dry road surfaces is insufficient.Furthermore, when the overlap length L1 is less than -30%, the improvement of steering stability performance on wet road surfaces is insufficient.

[0055] As in Fig. As shown in Fig. 9, the sipe 11 further includes raised bottom portions 14 on portions thereof in the length direction. As the raised bottom portions 14, there are a raised bottom portion 14A located in a central portion of the sipe 11 and a raised bottom portion 14B located at both end portions of the sipe 11. By thus providing the raised bottom portions 14 of the sipe 11, it is possible to improve the steering stability performance on both dry road surfaces and wet road surfaces in a mutually compatible manner. The raised bottom portions 14 of the sipe 11 may be formed on an end portion of the sipe 11 and / or a region other than the end portion.

[0056] In the raised bottom portion 14A formed in a region other than an end portion of the sipe 11, a maximum value of a height from the groove bottom of the sipe 11 to an upper surface of the raised bottom portion 14A is defined as height H 14A This height H 14A is preferably 0.2 to 0.5 times, more preferably 0.3 to 0.4 times, the maximum depth x of the slat 11. By increasing the height H 14A of the raised bottom portion 14A, which is arranged in a region other than an end portion of the sipe 11, is thus set to a suitable height, it is possible to improve the rigidity of the block 101 and maintain the drainage effect, thereby making it possible to improve the steering stability performance on wet road surfaces. Here, if the height H 14Ais less than 0.2 times the maximum depth x of the slat 11, the rigidity of the block 101 cannot be sufficiently improved. Furthermore, if the height H 14A is more than 0.5 times the maximum depth x of the sipe 11, the steering stability performance on wet road surfaces cannot be sufficiently improved.

[0057] In the raised bottom portion 14B formed in both end portions of the slat 11, a maximum value of a height from the groove bottom of the slat 11 to an upper surface of the raised bottom portion 14B is defined as height H 14B This height H 14B is preferably 0.6 to 0.9 times, more preferably 0.7 to 0.8 times, the maximum depth x of the slat 11. By the height H 14Bof the raised bottom portion 14B formed on the end portions of the sipe 11 is thus set to a suitable height, it is possible to improve the rigidity of the block 101 and improve the steering stability performance on dry road surfaces. Here, if the height H 14B is less than 0.6 times the maximum depth x of the slat 11, the rigidity of the block 101 cannot be sufficiently improved. Furthermore, if the height H 14B is more than 0.9 times the maximum depth x of the sipe 11, the steering stability performance on wet road surfaces cannot be sufficiently improved.

[0058] Furthermore, in the raised bottom sections 14A, 14B of the sipe 11, projecting lengths in the tire transverse direction are designated as lengths L 14A , L 14B defined. The total sum of the lengths L 14A , L 14B of the respective raised floor sections 14A, 14B is defined as a length L 14of the raised floor sections 14. The length L 14 This raised base section 14 is preferably 0.3 to 0.7 times, more preferably 0.4 to 0.6 times, the slat length L. By the length L 14 of the raised floor sections 14 is thus appropriately determined, it is possible to improve the steering stability performance on both dry road surfaces and wet road surfaces in a mutually compatible manner. Here, if the length L 14 of the raised bottom portions 14 is less than 0.3 times the sipe length L of the sipe 11, the rigidity of the block 101 cannot be sufficiently improved. Furthermore, if the length L 14 is more than 0.7 times the sipe length L of the sipe 11, the steering stability performance on wet road surfaces cannot be sufficiently improved.

[0059] Examples of the chamfered portions 12A, 12B of the slat 11 include those shown in Fig. 2 to 5, 7, 8A and 8B, and when the obtuse-angled side of the slat 11 is bevelled, as in Fig. 10A when a portion of the slat 11 is bent as shown in Fig. 10B, and if end portions of the beveled portions 12A, 12B located close to the main grooves 9 end blindly in the rib 10 instead of opening toward the main grooves 9, as in Fig. 10C. Further, examples also include when the sipe 11 and the chamfered portions 12A, 12B are formed parallel to the tire transverse direction, as shown in Fig. 10D, and when a boundary line in the tire transverse direction between the chamfered portion 12A and the chamfered portion 12B is significantly shifted from the center of the sipe 11, as shown in Fig. 10E shown.

[0060] It should be noted that, while a slat 110A and a beveled portion 120A are provided in the embodiment described above ( Fig. 2) are not arranged on the tire center line CL, when the sipe 110A or the chamfered portion 120A is arranged on the tire center line CL, the groove surfaces S A , S B , the groove area ratios M1 A , M1 B and the groove area ratios M2 A , M2 B are respectively set for each section disposed on the vehicle mounting inside or the vehicle mounting outside of the slat 110A or the beveled section 120A. Examples

[0061] Using pneumatic tires with a tire size of 245 / 40R19, Prior Art Examples 1 and 2, Comparative Examples 1 and 2, and Examples 1 to 19 were manufactured. Each of these pneumatic tires includes a plurality of main grooves extending in the tire circumferential direction in the tread portion and sipes extending in the tire transverse direction in the ribs defined by the main grooves, and has a designated mounting direction on the vehicle and an asymmetric tread pattern on both sides of the tire centerline. For each pneumatic tire, the chamfer arrangement (both sides or one side), the aspect ratio between the sipe length L and the chamfer lengths L A , L B, the presence / absence of a chamfer in the area opposite the chamfered section, the maximum depth x (mm) of the sipe, the maximum depth y (mm) of the chamfered section, the size ratio between the groove area S A the bevelled sections and slats on the vehicle interior and the groove surface S Bof the chamfered sections and sipes on the vehicle outer side, the inclination angle of the sipe on the acute-angled side with respect to the tire circumferential direction, the chamfered position (obtuse-angled side or acute-angled side) of the sipe, the shape (linear or curved) of the sipe as a whole, the presence / absence of an opening in the chamfered section towards the main groove, the ratio of the overlap length L1 of the chamfered sections to the sipe length L, the number of chamfered positions (1 or 2), the maximum width W1 of the chamfered section with respect to the sipe width W (W1 / W), the chamfer shape (parallel or non-parallel), the presence / absence of a raised bottom portion of the sipe (center, end portion, or none), the height H 14 of the raised bottom section of the slat in relation to the maximum depth x of the slat (H 14 / x), the length L 14of the raised floor section in relation to the slat length L (L 14 / L), the difference between the groove area ratio M1 A the chamfered sections and the sipes on the vehicle interior and the groove area ratio M1 B the bevelled sections and the slats on the outside of the vehicle (M1 A - M1 B ), the difference between the groove area ratio M2 A on the vehicle interior and the groove area ratio M2 B on the outside of the vehicle (M2 A - M2 B ), the size ratio between the number of pitches P A on the vehicle interior and the number of pitches P B on the outside of the vehicle and the number of pitches P B on the outside of the vehicle in relation to the number of pitches P A on the inside of the vehicle (P B / P A) as shown in Tables 1 and 2.

[0062] It should be noted that in the tires of Prior Art Example 1, Comparative Examples 1 and 2, and Examples 1 to 19, the sipe width is constant in the range from the tire radially inward end portion of the chamfered portion to the groove bottom of the sipe.

[0063] For these test tires, a sensory evaluation of steering stability performance on dry road surfaces and steering stability performance on wet road surfaces by a test driver, as well as a visual evaluation of uneven wear resistance performance, were conducted, and the results are shown in Tables 1 and 2.

[0064] Sensory evaluation of steering stability performance on dry road surfaces and steering stability performance on wet road surfaces was conducted after mounting each test tire on a wheel with a rim size of 19 x 8.5 J and an air pressure of 260 kPa. The evaluation results are expressed as index values, with the results of Prior Art Example 1 assigned an index value of 100. Larger index values ​​indicate better steering stability performance on dry road surfaces and steering stability performance on wet road surfaces.

[0065] The sensory evaluation of uneven wear resistance performance was conducted by mounting each test tire on a wheel with a rim size of 19 x 8.5 J, driving the test tire for 4,000 km under an air pressure of 260 kPa, and visually evaluating the tire's external appearance. The evaluation results are expressed as index values, with the results of Prior Art Example 1 assigned an index value of 100. Larger index values ​​indicate better uneven wear resistance performance.

[0068] [Table 1-I] Example of the prior art 1 Example of the state of the art 2 Comparison example 1 Comparison example 2 Example 1 Example 2 Arrangement of the bevel (both sides or on one side) Both sides On one page Both sides Both sides Both sides Both sides Length ratio between the slat length L and the bevel lengths L A , L B L = L A , L B L = L A L > L A , L B L > L A , L B L > L A , L B L > L A , L B Bevel in area opposite beveled section? Yes No No No No No Maximum depth x of the slat (mm) 6 mm 6 mm 6 mm 6 mm 6 mm 6 mm Maximum depth y of the chamfered section (mm) 2 mm 5 mm 0.3 mm 4 mm 2 mm 2 mm Size ratio between groove area S A the bevelled sections and slats on the vehicle interior and groove surface S B the bevelled sections and slats on the vehicle exterior S A = S B S A = S B S A > S B S A > S B S A > S B S A > S B Angle of inclination of the sipe on the acute-angled side in relation to the tire circumferential direction 90° 90° 90° 90° 90° 85° Bevelled part of the slat (obtuse-angled side or acute-angled side) Obtuse-angled side Obtuse-angled side Obtuse-angled side Obtuse-angled side Obtuse-angled side Obtuse-angled side Overall shape of the slat (linear or curved) Linear Linear Linear Linear Linear Linear Opening of the beveled section to the main groove? Yes Yes Yes Yes Yes Yes Ratio of overlap length L1 of the bevelled sections to slat length L - - 0 % 0 % 0 % 0 % Number of beveled spots (1 or 2) 1 1 1 1 1 1 Maximum width W1 of the bevelled section to slat width W (W1 / W) 0,5 x 0,5 x 0,5 x 0,5 x 0,5 x 0,5 x Chamfer shape (parallel or non-parallel) Parallel Parallel Parallel Parallel Parallel Parallel Raised bottom section of the slat? (Middle, end section, or no) No No No No No No Height H 14 of the raised bottom section of the slat to maximum depth x of the slat (H 14 / x) - - - - - - Length L 14 of the raised floor section to slat length L (L 14 / L) - - - - - - Difference between groove area ratio M1 A of the bevelled sections and sipes on the vehicle interior and groove area ratio M1 B the bevelled sections and slats on the outside of the vehicle (M1 A - M1 B ) - - 2 % 2 % 2 % 2 % Difference between groove area ratio M2 A on the vehicle interior and groove area ratio M2 B on the outside of the vehicle (M2 A - M2 B ) - - 3 % 3 % 3 % 3 % Size ratio between number of pitches P A on the vehicle interior and number of pitches P B on the outside of the vehicle - - P A = P B P A = P B P A = P B P A = P B Number of pitches P B on the outside of the vehicle in relation to the number of pitches P A on the inside of the vehicle (P B / P A ) - - 1 x 1 x 1 x 1 x Steering stability performance on dry road surfaces 100 90 103 98 103 104 Steering stability performance on wet road surfaces 100 105 98 103 103 103 Resistance to uneven wear 100 100 100 100 104 104 [Table 1-II] Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Arrangement of the bevel (both sides or on one side) Both sides Both sides Both sides Both sides Both sides Both sides Length ratio between the slat length L and the bevel lengths L A , L B L > L A , L B L > L A , L B L > L A , L B L > L A , L B L > L A , L B L > L A , L B Bevel in area opposite beveled section? No No No No No No Maximum depth x of the slat (mm) 6 mm 6 mm 6 mm 6 mm 6 mm 6 mm Maximum depth y of the chamfered section (mm) 2 mm 2 mm 2 mm 2 mm 2 mm 2 mm Size ratio between groove area S A the bevelled sections and slats on the vehicle interior and groove surface S B the bevelled sections and slats on the vehicle exterior S A > S B S A > S B S A > S B S A > S B S A > S B S A > S B Angle of inclination of the sipe on the acute-angled side in relation to the tire circumferential direction 60° 60° 60° 60° 60° 60° Bevelled part of the slat (obtuse-angled side or acute-angled side) Obtuse-angled side Acute-angled side Acute-angled side Acute-angled side Acute-angled side Acute-angled side Overall shape of the slat (linear or curved) Linear Linear Curved Curved Curved Curved Opening of the beveled section to the main groove? Yes Yes Yes No Yes Yes Ratio of overlap length L1 of the bevelled sections to slat length L 0 % 0 % 0 % 0 % 10 % -10 % Number of beveled spots (1 or 2) 1 1 1 1 1 1 Maximum width W1 of the bevelled section to slat width W (W1 / W) 0,5 x 0,5 x 0,5 x 0,5 x 0,5 x 0,5 x Chamfer shape (parallel or non-parallel) Parallel Parallel Parallel Parallel Parallel Parallel Raised bottom section of the slat? (Middle, end section, or no) No No No No No No Height H 14 of the raised bottom section of the slat to maximum depth x of the slat (H 14 / x) - - - - - - Length L 14 of the raised floor section to slat length L (L 14 / L) - - - - - - Difference between groove area ratio M1 A of the bevelled sections and sipes on the vehicle interior and groove area ratio M1 B the bevelled sections and slats on the outside of the vehicle (M1 A - M1 B ) 2 % 2 % 2 % 2 % 2 % 2 % Difference between groove area ratio M2 A on the vehicle interior and groove area ratio M2 B on the outside of the vehicle (M2 A - M2 B ) 3 % 3 % 3 % 3 % 3 % 3 % Size ratio between number of pitches P A on the vehicle interior and number of pitches P B on the outside of the vehicle P A = P B P A = P B P A = P B P A = P B P A = P B P A = P B Number of pitches P B on the outside of the vehicle in relation to the number of pitches P A on the inside of the vehicle (P B / P A ) 1 x 1 x 1 x 1 x 1 x 1 x Steering stability performance on dry road surfaces 105 105 105 106 105 107 Steering stability performance on wet road surfaces 103 102 105 104 105 103 Resistance to uneven wear 104 107 107 107 107 107

[0069] [Table 2-I] Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Arrangement of the bevel (both sides or on one side) Both sides Both sides Both sides Both sides Both sides Both sides Length ratio between the slat length L and the bevel lengths L A , L B L > L A , L B L > L A , L B L > L A , L B L > L A , L B L > L A , L B L > L A , L B Bevel in area opposite beveled section? No No No No No No Maximum depth x of the slat (mm) 6 mm 6 mm 6 mm 6 mm 6 mm 6 mm Maximum depth y of the chamfered section (mm) 2 mm 2 mm 2 mm 2 mm 2 mm 2 mm Size ratio between groove area S A the bevelled sections and slats on the vehicle interior and groove surface S B the bevelled sections and slats on the vehicle exterior S A > S B S A > S B S A > S B S A > S B S A > S B S A > S B Angle of inclination of the sipe on the acute-angled side in relation to the tire circumferential direction 60° 60° 60° 60° 60° 60° Bevelled part of the slat (obtuse-angled side or acute-angled side) Acute-angled side Acute-angled side Acute-angled side Acute-angled side Acute-angled side Acute-angled side Overall shape of the slat (linear or curved) Curved Curved Curved Curved Curved Curved Opening of the beveled section to the main groove? Yes Yes Yes Yes Yes Yes Ratio of overlap length L1 of the bevelled sections to slat length L 0 % 0 % 0 % 0 % 0 % 0 % Number of beveled spots (1 or 2) 2 1 1 1 1 1 Maximum width W1 of the bevelled section to slat width W (W1 / W) 0,5 x 2 x 2 x 2 x 2 x 2 x Chamfer shape (parallel or non-parallel) Parallel Parallel Not parallel Parallel Parallel Parallel Raised bottom section of the slat? (Middle, end section, or no) No No No center center final section Height H 14 of the raised bottom section of the slat to maximum depth x of the slat (H 14 / x) - - - 0,6 x 0,3 x 0,8 x Length L 14 of the raised floor section to slat length L (L 14 / L) - - - 0,2 x 0,2 x 0,2 x Difference between groove area ratio M1 A of the bevelled sections and sipes on the vehicle interior and groove area ratio M1 B the bevelled sections and slats on the outside of the vehicle (M1 A - M1 B ) 2 % 2 % 2 % 2 % 2 % 2 % Difference between groove area ratio M2 A on the vehicle interior and groove area ratio M2 B on the outside of the vehicle (M2 A - M2 B ) 3 % 3 % 3 % 3 % 3 % 3 % Size ratio between number of pitches P A on the vehicle interior and number of pitches P B on the outside of the vehicle P A = P B P A = P B P A = P B P A = P B P A = P B P A = P B Number of pitches P B on the outside of the vehicle in relation to the number of pitches P A on the inside of the vehicle (P B / P A ) 1 x 1 x 1 x 1 x 1 x 1 x Steering stability performance on dry road surfaces 106 106 106 110 109 111 Steering stability performance on wet road surfaces 104 106 106 105 109 107 Resistance to uneven wear 105 109 106 109 109 109 [Table 2-II] Example 15 Example 16 Example 17 Example 18 Example 19 Arrangement of the bevel (both sides or on one side) Both sides Both sides Both sides Both sides Both sides Length ratio between the slat length L and the bevel lengths L A , L B L > L A , L B L > L A , L B L > L A , L B L > L A , L B L > L A , L B Bevel in area opposite beveled section? No No No No No Maximum depth x of the slat (mm) 6 mm 6 mm 6 mm 6 mm 6 mm Maximum depth y of the chamfered section (mm) 2 mm 2 mm 2 mm 2 mm 2 mm Size ratio between groove area S A the bevelled sections and slats on the vehicle interior and groove surface S B the bevelled sections and slats on the vehicle exterior S A > S B S A > S B S A > S B S A > S B S A > S B Angle of inclination of the sipe on the acute-angled side in relation to the tire circumferential direction 60° 60° 60° 60° 60° Bevelled part of the slat (obtuse-angled side or acute-angled side) Acute-angled side Acute-angled side Acute-angled side Acute-angled side Acute-angled side Overall shape of the slat (linear or curved) Curved Curved Curved Curved Curved Opening of the beveled section to the main groove? Yes Yes Yes Yes Yes Ratio of overlap length L1 of the bevelled sections to slat length L 0 % 0 % 0 % 0 % 0 % Number of beveled spots (1 or 2) 1 1 1 1 1 Maximum width W1 of the bevelled section to slat width W (W1 / W) 2 x 2 x 2 x 2 x 2 x Chamfer shape (parallel or non-parallel) Parallel Parallel Parallel Parallel Parallel Raised bottom section of the slat? (Middle, end section, or no) final section No No No No Height H 14 of the raised bottom section of the slat to maximum depth x of the slat (H 14 / x) 0,8 x - - - - Length L 14 of the raised floor section to slat length L (L 14 / L) 0,5 x - - - - Difference between groove area ratio M1 A of the bevelled sections and sipes on the vehicle interior and groove area ratio M1 B the bevelled sections and slats on the outside of the vehicle (M1 A - M1 B ) 2 % 8 % 8 % 8 % 8 % Difference between groove area ratio M2 A on the vehicle interior and groove area ratio M2 B on the outside of the vehicle (M2 A - M2 B ) 3 % 3 % 12 % 12 % 12 % Size ratio between number of pitches P A on the vehicle interior and number of pitches P B on the outside of the vehicle P A = P B P A = P B P A = P B P A > P B P A > P B Number of pitches P B on the outside of the vehicle in relation to the number of pitches P A on the inside of the vehicle (P B / P A ) 1 x 1 x 1 x 0,95 x 0,7 x Steering stability performance on dry road surfaces 113 107 108 109 110 Steering stability performance on wet road surfaces 106 107 108 109 110 Resistance to uneven wear 109 109 109 109 109

[0066] As shown in Tables 1 and 2, the test tires of Examples 1 to 19 with the thus-designed shape of the chamfered portions formed on the sipe achieved improved uneven wear resistance performance and simultaneous improvement in steering stability performance on both dry road surfaces and wet road surfaces.

[0067] In contrast, in Comparative Example 1, the maximum depth y of the chamfered portion is extremely small, and thus the effect of improving steering stability performance on wet road surfaces could not be achieved. Furthermore, in Comparative Example 2, the maximum depth y of the chamfered portion is extremely large, and thus the effect of improving steering stability performance on dry road surfaces could not be achieved. List of reference symbols 1 tread section 2 side wall section 3 bead section 9 main groove 9A Inner main groove 9B Outer main groove 10 ribs 100A midrib 100B, 100C Intercostal 100D, 100E shoulder rib 101 Block 11 slats 110A, 110B, 110C slat 11A Front edge 11B Rear margin 12 Bevelled section 12A Beveled front section 12B Beveled rear section 13 Non-beveled area 13A Non-beveled front section 13B Non-beveled rear section 14 Raised floor section 14A Raised floor section in area other than end section 14B Raised floor section in the end section

Claims

[1] A pneumatic tire having an asymmetric tread pattern on both sides of a tire centerline (CL) and a marked vehicle mounting direction, the pneumatic tire comprising: in a tread section (1) a plurality of main grooves (9) extending in a tire circumferential direction; ribs (10) defined by the main grooves (9); and sipes (11) extending in a tire transverse direction in the ribs (10); wherein the ribs (10) comprise a central rib (100A) arranged on the tire center line CL, a pair of intermediate ribs (100B, 100C) arranged outwardly in the tire transverse direction from the central rib (100A), and a pair of shoulder ribs (100D, 100E) arranged outwardly in the tire transverse direction from the intermediate ribs (100B and 100C, respectively); wherein the slats (11), each including a pair of chamfered portions (12), are formed in the central rib (100A) and in the intermediate ribs (100B, 100C); wherein the slats (11) comprise a front side edge (11A) and a rear side edge (11B), each provided with a beveled portion (12) which is shorter than a length of the slats (11) and a non-beveled region (13) in which further beveled portions are not present and which is arranged in a region opposite the beveled portion (12); wherein the slats (11) have a maximum depth x (mm) and the chamfered portion (12) has a maximum depth y (mm) satisfying a relationship represented by formula (1); wherein the sipes (11) have a constant width in a region from an end portion of the chamfered portion arranged inward in a tire radial direction to a groove bottom (E) of the sipes (11); and wherein the sipes (11) are configured such that a groove area of ​​the chamfered portions (12) and the sipes (11) included in a ground contact area (E) on a vehicle mounting inside is larger than a groove area of ​​the chamfered portions (12) and the sipes (11) included in a ground contact area (E) on a vehicle mounting outside; x×0.1≤y≤x×0.3+1.0 [2] A pneumatic tire according to claim 1, wherein a groove area ratio of the chamfered portions (12) and the sipes (E) in the ground contact area on the vehicle mounting inside is 3 to 15% larger than a groove area ratio of the chamfered portions (12) and the sipes (11) in the ground contact area (E) on the vehicle mounting outside. [3] A pneumatic tire according to claim 1, wherein a groove area ratio in the ground contact region (E) on the vehicle mounting inside is 5 to 20% larger than a groove area ratio in the ground contact region (E) on the vehicle mounting outside. [4] A pneumatic tire according to any one of claims 1 to 3, wherein a number of pitches of groove elements extending in the tire transverse direction in the ground contact area (E) on the vehicle mounting inside is larger than a number of pitches of groove elements extending in the tire transverse direction in the ground contact area (E) on the vehicle mounting outside. [5] A pneumatic tire according to claim 4, wherein the number of pitches of the groove elements extending in the tire transverse direction in the ground contact area (E) on the vehicle mounting outer side is 0.5 to 0.9 times the number of pitches of the groove elements extending in the tire transverse direction in the ground contact area (E) on the vehicle mounting inner side. [6] A pneumatic tire according to any one of claims 1 to 5, wherein the sipe is inclined with respect to the tire circumferential direction. [7] A pneumatic tire according to claim 6, wherein an inclination angle of the sipe (11) on an acute angle side with respect to the tire circumferential direction is from 40° to 80°. [8] A pneumatic tire according to claim 6 or 7, wherein the chamfered portion (12) is arranged on the acute-angled side of the sipe (11). [9] A pneumatic tire according to claim 6 or 7, wherein the chamfered portion (12) is arranged on an obtuse-angled side of the sipe (11). [10] A pneumatic tire according to any one of claims 1 to 9, wherein the sipe (11) is at least partially curved or bent in a plan view. [11] A pneumatic tire according to any one of claims 1 to 10, wherein the chamfered portion (12) opens toward the main groove (9). [12] A pneumatic tire according to any one of claims 1 to 10, wherein the chamfered portion (12) terminates blindly within the rib (10). [13] A pneumatic tire according to any one of claims 1 to 12, wherein an overlap length of the chamfered portion (12) formed at the front side edge (11A) of the sipe (11) and the chamfered portion (12) formed at the rear side edge (11B) of the sipe (11) is from -30% to 30% of the sipe length. [14] A pneumatic tire according to any one of claims 1 to 13, wherein the chamfered portion (12) is arranged at a position on the front side edge (11A) and a position on the rear side edge (11B) of the sipe (11). [15] A pneumatic tire according to any one of claims 1 to 14, wherein the chamfered portion (12) has a maximum width of 0.8 to 5.0 times a width of the sipe (11). [16] A pneumatic tire according to any one of claims 1 to 15, wherein the chamfered portion (12) extends parallel to the sipe (11). [17] A pneumatic tire according to any one of claims 1 to 16, wherein the sipe (11) further comprises a raised bottom portion (14). [18] A pneumatic tire according to claim 17, wherein the raised land portion (14A) located in a region other than an end portion of the sipe (11) has a height of 0.2 to 0.5 times the maximum depth x of the sipe (11). [19] A pneumatic tire according to claim 17 or 18, wherein the raised land portion (14B) disposed at an end portion of the sipe (11) has a height of 0.6 to 0.9 times the maximum depth x of the sipe (11). [20] A pneumatic tire according to any one of claims 17 to 19, wherein the raised land portion (14) has a length of 0.3 to 0.7 times the sipe length.

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