pneumatic tires

Abstract

Pneumatic tires (1), comprising: a plurality of main grooves (30) extending in a circumferential direction of the tire; a bridge section (20) comprising end sections in Tire width direction defined by the main grooves (30), wherein both sides of the rib section (3020) are defined in the tire width direction by the main grooves (30); a plurality of beveled lamellae (41) formed in the web section (20), each of the beveled lamellae (41) comprising a beveled section (42); and a plurality of non-beveled lamellae (46) formed in the web section (20), wherein none of the non-beveled lamellae (46) encompass the beveled section (42), wherein the beveled lamella (41) comprises one end connected to the main groove (30) defining the web section (20) and another end terminating within the web section (20), the chamfered sipes (41) and the non-chamfered sipes (46) are arranged alternately in the circumferential direction of the tire, wherein the majority of chamfered sipes (41) formed in the same web section (20) are connected to the same main groove (30), and the majority of non-chamfered sipes (46) are connected to only one of the main grooves (30), In the case of the non-beveled sipes (46) arranged in the circumferential direction of the tire on both sides of the beveled sipe (41), the ratio between a distance a and a distance b in the circumferential direction of the tire is in the range 1.5 ≤ (b / a) ≤ 12, wherein the distance a in the circumferential direction of the tire is a distance between the beveled sipe (41) and a nearby sipe (47), which is the non-beveled sipe (46) arranged on one side near the beveled sipe (41) in the circumferential direction of the tire, and the distance b in the tire circumference direction is a distance between the chamfered lamella (41) and the non-chamfered lamella (46), which is located on one side away from the beveled lamella (41) in the direction of the tire circumference.

Description

Technical area

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

[0002] In a pneumatic tire, a plurality of grooves are formed in a surface of a tread portion for the purpose of water drainage between the tread contact surface and the road surface when driving on a wet road surface. Furthermore, some known pneumatic tires provide improved drainage properties by designing the shape of so-called sipes, which are recesses formed in the tread portion. For example, pneumatic tires described in JP 2018111453 A and JP 6364781B2 provide improved wet performance, which is the running performance on wet road surfaces, by designing the arrangement of chamfered sipes, which are sipes including chamfered portions.In other words, in JP 2018111 453 A and JP 63 64781 B2, wet performance is improved by alternately arranging in the tire circumferential direction chamfered sipes connected to one main groove of two main grooves defining both sides in the tire width direction of a rib in which the chamfered sipes are formed, and chamfered sipes connected to the other main groove. Literature listPatent literature

[0003] JP 2018 111 452 A1 discloses a pneumatic tire having a tread portion with a plurality of main grooves extending in the tire circumferential direction. One land portion is configured on the inner side region of the tread portion with respect to the tire width direction, and another land portion is configured on the outer side region of the tread portion with respect to the tire width direction. A plurality of tapered sipes and a plurality of non-tapered sipes are formed in both the land portions of the inner and outer side regions of the tread portion. Tapered sipes and non-tapered sipes are alternately arranged in the tire circumferential direction formed in the land portion of the outer side region. Continuous non-tapered sipes are provided between two main grooves.

[0004] EP 3 401 125 A1 discloses a tread pattern of a vehicle tire with tread bands separated from each other by circumferential grooves. The sipes are formed within the land portions (tread bands). The fine sipes are formed with a first extension portion. Non-beveled sipes without beveled parts are configured on the left side of the land portions, and beveled sipes with a beveled part are configured on the right side of the land portions.

[0005] US 6,467,517 B1 discloses a tire with land portions formed between grooves. A land portion comprises an alternating non-beveled sipe followed by a beveled sipe in the direction of tire rotation. Continuous sipes are located between two main grooves. Brief description of the inventionTechnical problem

[0006] However, if the chamfered sipes connected to the different main grooves are arranged alternately in the tire circumferential direction, the rigidity of the rib in a portion between the chamfered sipes may deteriorate during initial use of the pneumatic tire, and thus a reduction in steering stability on dry road surfaces may easily occur during initial use.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide a pneumatic tire that can provide wet performance while suppressing a reduction in steering stability. Solution to the problem

[0008] In order to solve the problems described above and achieve the object, a pneumatic tire according to an embodiment of the present invention includes a plurality of main grooves extending in the tire circumferential direction, a land portion including end portions in the tire width direction defined by the main grooves, both sides of the land portion in the tire width direction being defined by the main grooves, a plurality of chamfered sipes formed in the land portion, each of the chamfered sipes including a chamfered portion, and a plurality of non-chamfered sipes formed in the land portion, none of the non-chamfered sipes including the chamfered portion. The chamfered sipe includes one end connected to the main groove defining the land portion, and the other end terminates within the land portion.The tapered sipes and the non-tapered sipes are arranged alternately in the tire circumferential direction. The plurality of tapered sipes formed in the same land portion are connected to the same main groove, and the plurality of non-tapered sipes are connected to only one of the main grooves.In the non-chamfered sipes arranged on both sides of the chamfered sipe in the tire circumferential direction, a ratio between a distance a and a distance b in the tire circumferential direction is in the range of 1.5 ≤ (b / a) ≤ 12, where the tire circumferential distance a is a distance between the chamfered sipe and a nearby sipe, which is the non-chamfered sipe arranged on a side close to the chamfered sipe in the tire circumferential direction, and the tire circumferential distance b is a distance between the chamfered sipe and the non-chamfered sipe arranged on a side away from the chamfered sipe in the tire circumferential direction.

[0009] Furthermore, in the pneumatic tire described above, a ratio between a length Lm of the chamfered sipe and a length Lp of the near sipe is preferably in the range 0.2 ≤ (Lm / Lp) ≤ 0.95.

[0010] Furthermore, in the pneumatic tire described above, of opposite wall surfaces of the tapered sipe, the wall surface located on a side near the near sipe is preferably provided with the tapered portion.

[0011] Furthermore, in the pneumatic tire described above, a ratio between an opening width Wm of the tapered sipe and an opening width Wp of the near sipe is preferably in the range of 1.2 ≤ (Wm / Wp) ≤ 6.0.

[0012] Furthermore, in the pneumatic tire described above, the chamfered sipe preferably has a ratio between an opening width Wm and a groove bottom width Wm1 in the range 0.1 ≤ (Wm1 / Wm) ≤ 0.85.

[0013] Further, in the pneumatic tire described above, both sides of the land portion in the tire width direction are preferably defined by the main grooves, and the near sipe is preferably connected to two of the main grooves defining the land portion.

[0014] Furthermore, in the pneumatic tire described above, a ratio between a groove depth Dm of the tapered sipe and a groove depth Dp of the near sipe is preferably in the range of 1.2 ≤ (Dp / Dm) ≤ 8.0.

[0015] Furthermore, in the pneumatic tire described above, the chamfered sipe preferably has a ratio between a groove depth Dm and a depth Dm1 of the chamfered portion in the range 0.1 ≤ (Dm1 / Dm) ≤ 0.85.

[0016] Furthermore, in the pneumatic tire described above, both sides of the land portion in the tire width direction are defined by the main grooves, and the plurality of tapered sipes formed in the same land portion are connected to the same main groove.

[0017] Furthermore, in the pneumatic tire described above, of the tapered sipe and the near sipe, the near sipe is preferably arranged on a front side in the tire rotation direction.

[0018] Furthermore, in the pneumatic tire described above, the land portion in which the tapered sipes are formed preferably includes a road contact surface that curves from a standard contour line of a tread pattern to a tire radially outer side in a tire meridian cross-sectional view. Advantageous effects of the invention

[0019] A pneumatic tire according to the present invention achieves the effect that can ensure wet performance while suppressing a reduction in steering stability. Brief description of the drawings Fig. 1 is a meridian cross-sectional view illustrating a main portion of a pneumatic tire according to a comparative example. Fig. 2 is a view along line AA of Fig. 1 in the direction of the arrow. Fig. 3 is a perspective view of a Fig. 2 illustrated bridge section. Fig. 4 is a cross-sectional view along BB of Fig. 2. Fig. 5 is a detailed view of a section C of Fig. 4. Fig. 6 is an explanatory view of a pneumatic tire according to an embodiment of the invention, illustrating a case where non-chamfered sipes are connected to only one main groove on one side. Fig. 7 is an explanatory view of a modified example of the pneumatic tire according to a comparative example, illustrating a case where chamfered portions are connected to different main grooves. Fig. 8 is an explanatory view of a modification example of the pneumatic tire according to a comparative example, illustrating a case where a land portion is formed by block molding. Fig. 9 is a schematic view of a modification example of a pneumatic tire according to an embodiment, illustrating the arrangement of sipes with respect to the rotation direction of the pneumatic tire. Fig. 10 is a schematic view of a modification example of a pneumatic tire according to an embodiment, illustrating a main portion of a curved land portion. Fig. 11A is a table showing the results of performance evaluation tests of pneumatic tires. Fig. Figure 11B is a table showing the results of performance evaluation tests of pneumatic tires. Fig. 11C is a table showing the results of performance evaluation tests of pneumatic tires. Fig. 11D is a table showing the results of performance evaluation tests of pneumatic tires. Description of comparative examples and embodiments

[0020] Pneumatic tires according to comparative examples and embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the embodiment. Components of the following embodiment include elements that are substantially identical, or can be easily replaced or devised by a person skilled in the art. [Comparative examples and embodiments]

[0021] In the following description, the term "tire radial direction" refers to a direction perpendicular to the tire rotation axis (not illustrated), which is a rotation axis of a pneumatic tire 1, the term "tire radial inner side" refers to a side toward the tire rotation axis in the tire radial direction, and the term "tire radial outer side" refers to a side away from the tire rotation axis in the tire radial direction. The term "tire circumferential direction" refers to a circumferential direction with the tire rotation axis as the center axis. In addition, the term "tire width direction" refers to a direction parallel to the tire rotation axis, the term "tire width direction inner side" refers to a side toward the tire equatorial plane (tire equator line) CL in the tire width direction, and the term "tire width direction outer side" refers to an equatorial plane of the tire CL in the tire width direction.The term "tire equatorial plane CL" refers to a plane perpendicular to the tire rotation axis and passing through the center of the tire width of the pneumatic tire 1. The tire equatorial plane CL is aligned at a position in the tire width direction on the center line in the tire width direction, which corresponds to the center position of the pneumatic tire 1 in the tire width direction. The tire width is the width in the tire width direction between portions located on the outermost sides in the tire width direction, or in other words, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The term "tire equator line" refers to a line in the tire circumferential direction of the pneumatic tire 1 that lies on the equatorial plane CL.

[0022] Fig. 1 is a meridian cross-sectional view illustrating a main portion of the pneumatic tire 1 according to a comparative example. In the pneumatic tire 1 according to the present comparative example, a tread portion 2 is arranged on a portion on the outermost side in the tire radial direction when viewed in a meridian cross-section, and the tread portion 2 includes a tread rubber layer 4 made of a rubber composition. A surface of the tread portion 2, that is, a portion that comes into contact with a road surface during travel of a vehicle (not illustrated) on which the pneumatic tires 1 are mounted, is formed as a road contact surface 3, and the road contact surface 3 constitutes a part of a contour of the pneumatic tire 1.

[0023] At the tread portion 2, a plurality of main grooves 30 are formed in the road contact surface 3, extending in the tire circumferential direction. The plurality of circumferential main grooves 30 are arranged adjacent to each other in the tire width direction. Furthermore, a plurality of land portions 20, including end portions in the tire width direction defined by the main grooves 30, are formed in the tread portion 2. In the present comparative example, three of the main grooves 30 are arranged adjacent to each other in the tire width direction, and accordingly, four rows of the land portions 20 are arranged in the tire width direction with the main grooves 30 therebetween. The four rows of land portions 20 are each formed in a rib shape extending in the tire circumferential direction.

[0024] Note that "main groove 30" refers to a vertical groove at least a portion of which extends in the tire circumferential direction. Generally, the main groove 30 has a groove width of 3.0 mm or more and a groove depth of 5.5 mm or more, and includes a treadwear indicator (tread mark) indicating the final stages of wear. The main groove 30 may extend linearly in the tire circumferential direction or may repeatedly oscillate in the tire width direction while extending in the tire circumferential direction, and thus be wave-shaped or zigzag-shaped.

[0025] Shoulder portions 5 are arranged at both ends on outer sides of the tread portion 2 in the tire width direction, and sidewall portions 8 are arranged on inner sides of the shoulder portions 5 in the tire radial direction. In other words, the shoulder portions 8 are arranged on both sides in the tire width direction of the tread portion 2. In other words, the sidewall portions 8 are arranged at two regions on both sides in the tire width direction of the pneumatic tire 1 and form portions exposed to the outermost sides of the pneumatic tire 1 in the tire width direction.

[0026] A bead portion 10 is located on an inner side in the tire radial direction of each of the sidewall portions 8 located on both sides in the tire width direction. Similar to the sidewall portions 8, the bead portions 10 are arranged on both sides of the equatorial plane of the tire CL. That is, a pair of the bead portions 10 are arranged on both sides in the tire width direction of the equatorial plane of the tire CL. Each bead portion 10 is provided with a bead core 11, and a bead filler 12 is provided on the outer side of the bead core 11 in the tire radial direction. The bead core 11 is an annular member formed by bundling tire bead wires, which are steel wires, into an annular shape, and the bead filler 12 is a rubber member arranged on the outer side of the bead core 11 in the tire radial direction.

[0027] Furthermore, a belt layer 14 is disposed in the tread portion 2. The belt layer 14 is formed by a multi-layer structure in which a plurality of belts 141, 142 are laminated, and the two layers of the belts 141, 142 are laminated in the present comparative example. The belts 141, 142 constituting the belt layer 14 are formed by covering a plurality of belt cords made of steel or an organic fiber material such as polyester, rayon, or nylon with coating rubber and subjecting the belt cords to a rolling process. A belt angle, defined as an inclination angle in the tire width direction of the belt cords with respect to the tire circumferential direction, is within a predetermined range (for example, from 20° or more and 55° or less). In addition, the belt angles of the two layers of the belts 141, 142 are different from each other.Accordingly, the belt layer 14 is configured as a so-called cross-ply structure in which the two layers of belts 141, 142 are laminated with the inclination directions of the belt cords intersecting each other. In other words, the two layers of belts 141, 142 are provided as so-called cross belts in which the belt cords provided with the respective belts 141, 142 are arranged in intersecting orientations. The tread rubber layer 4 of the tread portion 2 is arranged on the tire radially outer side of the belt layer 14 in the tread portion 2.

[0028] A carcass layer 13 containing the cords of radial plies is continuously provided on the inner side of the belt layer 14 in the tire radial direction and on a side of the sidewall portion 8 near the equatorial plane of the tire CL. Accordingly, the pneumatic tire 1 according to this comparative example is configured as a so-called radial tire. The carcass layer 13 has a single-layer structure of one carcass ply or a multi-layer structure of a plurality of laminated carcass plies and extends between the pair of bead portions 10 arranged on both sides in the tire width direction in a toroidal shape to form the frame structure of the tire.

[0029] Specifically, the carcass layer 13 is arranged to stretch from one bead portion 10 to the other bead portion 10 of the pair of bead portions 10 located on both sides in the tire width direction, and to bend back on the tire width-outer side along the bead cores 11 at the bead portions 10 so as to be wrapped around the bead cores 11 and the bead fillers 12. The bead filler 12 is a rubber member arranged in a space formed on the tire radially outer side of the bead core 11 when the carcass layer 13 is bent back at the bead portion 10. Moreover, the belt layer 14 is arranged on the tire radially outer side of a portion of the carcass layer 13 located in the tread portion 2, which is stretched between the pair of bead portions 10.Furthermore, the carcass ply of the carcass layer 13 is formed by covering a plurality of carcass cords made of steel or an organic fiber material such as aramid, nylon, polyester, or rayon with coating rubber, followed by rolling. A plurality of carcass cords constituting the carcass plies are arranged side by side at an angle in the tire circumferential direction, the angle following a tire meridian direction with respect to the tire circumferential direction.

[0030] At the tire bead portion 10, a rim cushion rubber 17 is disposed on an inner side in the tire radial direction and an outer side in the tire width direction of the bead core 11 and a bent-back portion of the carcass layer 13. The rim cushion rubber 17 forms a contact surface of the tire bead portion 10 with the rim flange. Additionally, an inner liner 16 is formed along the carcass layer 13 on the inner side of the carcass layer 13 or on the inner portion side of the carcass layer 13 in the pneumatic tire 1. The inner liner 16 forms a tire inner surface 18, which is a surface on the inner side of the pneumatic tire 1.

[0031] Fig. 2 is a view along line AA of Fig. 1 in the direction of the arrow. Fig. 3 is a perspective view of the Fig. 2 illustrated bridge section 20. It should be noted that Fig. 2 and Fig. 3 of the plurality of land portions 20 illustrate the land portion 20, both sides of which are defined in the tire width direction by the main grooves 30. As in Fig. 2 and Fig. As illustrated in Fig. 3, a plurality of sipes 40 are formed in the land portion 20. The sipes 40 described here are each formed in a narrow groove shape in the road contact surface 3, and in a state before the pneumatic tire 1 is mounted on a rim, a width between wall surfaces forming the narrow groove is less than 2 mm, and a depth of the narrow groove from the road contact surface 3 is 2 mm or more.

[0032] The plurality of sipes 40 includes a plurality of chamfered sipes 41, which are sipes 40 each including a chamfered portion 42, and a plurality of non-chamfered sipes 46, which are sipes 40 each not including the chamfered portion 42. The chamfered portion 42 in this case refers to a recessed portion obtained by cutting out a portion of an edge where the wall surface of the sipe 40 and the road contact surface 3 intersect, and the chamfered portion 42 may have a shape such as a rectangular shape or an inclination.

[0033] The plurality of tapered sipes 41 and the plurality of non-tapered sipes 46 are provided in the single land portion 20, and the plurality of tapered sipes 41 and the plurality of non-tapered sipes 46 are alternately arranged in the tire circumferential direction. In this case, the pitch of the tapered sipes 41 in the tire circumferential direction and the pitch of the non-tapered sipes 46 in the tire circumferential direction are equal to each other, and the tapered sipes 41 and the non-tapered sipes 46 are arranged so that their phases are offset in the tire circumferential direction.

[0034] In the sipes, one end of the chamfered sipe 41 is connected to the main groove 30 defining the land portion 20, and the other end of the chamfered sipe 41 terminates within the land portion 20. Furthermore, the chamfered sipes 41 are configured such that the plurality of chamfered sipes 41 formed in the same land portion 20 are connected to the same main groove 30 of the two main grooves 30 defining both sides in the tire width direction of the land portion 20. In other words, all of the plurality of chamfered sipes 41 formed in the single land portion 20 are connected to the same main groove 30.

[0035] The two ends in a longitudinal direction of the non-chamfered sipe 46, in turn, are connected to both of the two main grooves 30 defining the land portion 20. In other words, the non-chamfered sipe 46 extends in the tire width direction through the land portion 20 in which the non-chamfered sipe 46 is formed.

[0036] Accordingly, a length Lm of the tapered slat 41 and a length Lp of the non-tapered slat 46 have the relationship Lm < Lp, specifically in the range of 0.2 ≤ (Lm / Lp) ≤ 0.95. Note that the lengths Lm, Lp in this case are lengths in the extending direction of the tapered slat 41 and the non-tapered slat 46, that is, lengths in the direction along the shapes of the tapered slat 41 and the non-tapered slat 46. The ratio between the length Lm of the beveled slat 41 and the length Lp of the non-beveled slat 46 is preferably in the range of 0.3 ≤ (Lm / Lp) ≤ 0.8, and in particular, the length Lm of the beveled slat 41 is preferably in the range of 2 mm or more and 30 mm or less.

[0037] Since the chamfered sipes 41 and the non-chamfered sipes 46 are arranged alternately in the tire circumferential direction, the non-chamfered sipes 46 are located on both sides in the tire circumferential direction of the chamfered sipe 41. Since the chamfered sipes 41 and the non-chamfered sipes 46 are arranged so that their phases are offset in the tire circumferential direction, the two non-chamfered sipes 46 arranged on both sides in the tire circumferential direction of the chamfered sipe 41 have different distances from the chamfered sipe 41 in the tire circumferential direction.

[0038] Of the non-chamfered sipes 46 arranged at different distances from the chamfered sipe 41 on both sides in the tire circumferential direction of the chamfered sipe 41, the non-chamfered sipe 46 on the side of the smaller distance in the tire circumferential direction from the chamfered sipe 41 is a near sipe 47, and the non-chamfered sipe 46 on the side of the larger distance in the tire circumferential direction from the chamfered sipe 41 is a far sipe 48. Both the near sipe 47 and the far sipe 48 are connected to the two main grooves 30 defining the land portion 20 in which the near sipe 47 and the far sipe 48 are formed.In addition, since the near slat 47 is the non-beveled slat 46, compared to the lengths of the beveled slat 41 and the near slat 47, the ratio between the length Lm of the beveled slat 41 and the length Lp of the near slat 47 is in the range 0.2 ≤ (Lm / Lp) ≤ 0.95.

[0039] Note that the near slat 47 and the far slat 48 are defined based on the distances from the beveled slat 41 located between the two non-beveled slats 46 adjacent to the beveled slat 41 therebetween. Consequently, the slat 47 near the particular beveled slat 41 is treated as the far slat 48 with respect to the beveled slat 41 adjacent to the particular beveled slat 41 with the near slat 47 therebetween. Similarly, the slat 48 far from the particular beveled slat 41 is treated as the near slat 47 with respect to the beveled slat 41 adjacent to the particular beveled slat 41 with the far slat 48 therebetween.

[0040] The chamfered sipes 41, the near sipes 47 and the far sipes 48 defined as described above have a ratio between a distance a in the tire circumferential direction between the chamfered sipe 41 and the near sipe 47 and a distance b in the tire circumferential direction between the chamfered sipe 41 and the far sipe 48 in the range of 1.5 ≤ (b / a) ≤ 12.

[0041] Fig. 4 is a cross-sectional view along line BB of Fig. 2. The distance a between the chamfered sipe 41 and the near sipe 47 is the distance a in the tire circumferential direction at a position of the chamfered sipe 41 at which the distance from the chamfered sipe 41 including the chamfered portion 42 to the near sipe 47 is the shortest. Similarly, the distance b between the chamfered sipe 41 and the far sipe 48 is the distance b in the tire circumferential direction at a position of the chamfered sipe 41 at which the distance from the chamfered sipe 41 including the chamfered portion 42 to the far sipe 48 is the shortest.

[0042] Here, in the present comparative example, of the opposing wall surfaces 41a of the tapered sipe 41, the wall surfaces 41a located on a side close to the near sipe 47 are provided with the tapered portion 42. Therefore, in the present comparative example, the distance a between the tapered sipe 41 and the near sipe 47 is the shortest distance in the tire circumferential direction between a portion of the tapered portion 42 of the tapered sipe 41 closest to the near sipe 47 and a wall surface 47a of the near sipe 47 located on the tapered sipe 41 side.In addition, the distance b between the chamfered sipe 41 and the remote sipe 48 is the shortest distance in the tire circumferential direction between the wall surface 41a of the chamfered sipe 41 located on the remote sipe 48 side and a wall surface 48a of the remote sipe 48 located on the chamfered sipe 41 side.

[0043] The distance a between the beveled slat 41 and the near slat 47 defined as just described and the distance b between the beveled slat 41 and the far slat 48 defined as just described preferably have the relationship 1.5 ≤ (b / a) ≤ 5, and the relationship is more preferably in the range 3 ≤ (b / a) ≤ 5. Also, the distance a between the beveled slat 41 and the near slat 47 is preferably in the range of 3 mm or more and 6 mm or less.

[0044] Fig. 5 is a detailed view of section C of Fig. 4. The ratio between an opening width Wm of the tapered sipe 41 and an opening width Wp of the near sipe 47 is in the range of 1.2 ≤ (Wm / Wp) ≤ 6.0. The opening width Wm of the tapered sipe 41 in this case is a width of an opening portion of the tapered sipe 41 including the tapered portion 42 with respect to the road contact surface 3, and when the width of the opening portion changes, the width is a width at a position where the maximum width is reached. Similarly, the opening width Wp of the near sipe 47 is a width of an opening portion of the near sipe 47 with respect to the road contact surface 3, and when the width of the opening portion changes, the width is a width at a position where the maximum width is reached.

[0045] Note that the ratio between the opening width Wm of the tapered louver 41 and the opening width Wp of the near louver 47 is preferably in the range of 2.0 ≤ (Wm / Wp) ≤ 4.0. Furthermore, the opening width Wm of the tapered louver 41 is preferably in the range of 1.0 mm or more and 8.0 mm or less, and the opening width Wp of the near louver 47 is preferably in the range of 0.8 mm or more and 1.8 mm or less.

[0046] In addition, the tapered sipe 41 has a ratio between the opening width Wm and a groove bottom width Wm1 in the range of 0.1 ≤ (Wm1 / Wm) ≤ 0.85. The groove bottom width Wm1 of the tapered sipe 41 in this case is a width at a position where the groove width is largest at the position of a groove bottom 41b of the tapered sipe 41. Note that the ratio between the opening width Wm and the groove bottom width Wm1 of the tapered sipe 41 is preferably in the range of 0.3 ≤ (Wm1 / Wm) ≤ 0.6, and the groove bottom width Wm1 of the tapered sipe 41 is preferably in the range of 0.8 mm or more and 1.8 mm or less.

[0047] In addition, the ratio between the groove bottom width Wm1 of the tapered sipe 41 and a groove bottom width Wp1 of the near sipe 47 is in the range of 0.3 ≤ (Wm1 / Wp1) ≤ 3.0. The groove bottom width Wp1 in this case is a width at a position where the groove width is largest at the position of a groove bottom 47b of the near sipe 47. Note that the ratio between the groove bottom width Wm1 of the tapered sipe 41 and the groove bottom width Wp1 of the near sipe 47 is preferably in the range of 0.5 ≤ (Wm1 / Wp1) ≤ 2.0.

[0048] In addition, the ratio between a groove depth Dm of the tapered sipe 41 and a groove depth Dp of the near sipe 47 is in the range of 1.2 ≤ (Dp / Dm) ≤ 8.0. The groove depth Dm of the tapered sipe 41 and the groove depth Dp of the near sipe 47 in this case are a depth of each of the sipes 40 at a position where the depth from the opening portion with respect to the road contact surface 3 to the groove bottom is the greatest.

[0049] Note that the ratio between the groove depth Dm of the tapered sipe 41 and the groove depth Dp of the near sipe 47 is preferably in the range of 1.4 ≤ (Dp / Dm) ≤ 2.0. Further, the groove depth Dm of the tapered sipe 41 is preferably in the range of 2.0 mm or more and 5.0 mm or less, and the groove depth Dp of the near sipe 47 is preferably in the range of 2.4 mm or more and 6.0 mm or less.

[0050] In addition, the tapered sipe 41 has a ratio between the groove depth Dm and a tapered portion depth Dm1 of the tapered portion 42 in the range of 0.1 ≤ (Dm1 / Dm) ≤ 0.85. The tapered portion depth Dm1 in this case is a depth of the tapered portion 42 at a position where the depth in the depth direction of the tapered sipe 41 is greatest from the opening portion with respect to the road contact surface 3 to an end portion on the groove bottom 41b side of the tapered sipe 41.

[0051] In addition, in the chamfered sipe 41, the ratio between the groove depth Dm and the depth Dm1 of the chamfered portion is preferably in the range of 0.3 ≤ (Dm1 / Dm) ≤ 0.6, and the depth Dm1 of the chamfered portion is preferably in the range of 0.6 mm or more to 3.0 mm or less.

[0052] In the case of mounting the pneumatic tire 1 according to the present comparative example on a vehicle, the pneumatic tire 1 is mounted on a rim wheel, and inflated internally with air to an inflated state, and then mounted on the vehicle. When the vehicle on which the pneumatic tires 1 are mounted runs, all of the pneumatic tires 1 rotate while resting on the road contact surface 3 on the tread surface 2, and the road contact surface 3 comes into contact with the road surface. When running on dry road surfaces, the vehicle on which the pneumatic tires 1 are mounted runs mainly by transmitting driving force and braking force to the road surface and generating steering force by means of frictional force between the road contact surface 3 and the road surface.In addition, during driving on wet road surfaces, water enters between the road contact surface 3 and the road surface, for example, into the circumferential main grooves 30 and the sipes 40, and the vehicle travels while draining the water between the road contact surface 3 and the road surface through the main grooves 30 and the sipes 40. As a result, the road contact surface 3 is easily contacted with the road surface, and the vehicle can travel by the frictional force between the road contact surface 3 and the road surface.

[0053] In this case, a portion of the plurality of sipes 40 is formed as the tapered sipes 41, and each of the tapered sipes 41 includes the tapered portion 42, and thus drainage properties can be ensured by the tapered portion 42. In other words, even in a case where a portion located around the tapered sipe 41 in the road contact surface 3 of the land portion 20 in which the tapered sipes 41 are formed comes into contact with the road surface and is deformed in a direction in which the groove width decreases, the volume of the tapered sipe 41 can be ensured by the tapered portion 42. As a result, drainage properties of the tapered sipe 41 can be improved.On the other hand, since the tapered sipe 41 includes an end portion ending within the land portion 20, a reduction in the rigidity of the land portion 20 in which the tapered sipes 41 are formed can be suppressed, and thus the steering stability when the vehicle is running can be ensured.

[0054] Furthermore, in the sipes 40, the chamfered sipes 41 and the non-chamfered sipes 46 are alternately arranged in the tire circumferential direction, and the sipe 40 on one side in the tire circumferential direction of the chamfered sipe 41 is the near sipe 47, which is arranged at a relatively short distance from the chamfered sipe 41. Accordingly, when a portion of the road contact surface 3 of the land portion 20 arranged around the chamfered sipe 41 comes into contact with the ground, the land portion 20 can be deformed around the chamfered sipe 41 in a direction in which the groove width of the near sipe 47 decreases. This can prevent the chamfered sipe 41 from being significantly deformed in a direction in which the groove width of the chamfered sipe 41 decreases.In other words, when a portion of the road contact surface 3 of the land portion 20 disposed around the tapered sipe 41 comes into contact with the ground, the near sipe 47 is compressed, and thus, deformation of the land portion 20 can be absorbed by the near sipe 47, and compression of the tapered sipe 41 can be suppressed. Consequently, even if a portion disposed around the tapered sipe 41 comes into contact with the ground, the volume of the tapered sipe 41 including the tapered portion 42 can be more reliably ensured, and drainage properties of the tapered sipe 41 can be ensured.

[0055] Further, in the chamfered sipe 41 and the non-chamfered sipe 46, the ratio between the distance a between the chamfered sipe 41 and the near sipe 47 and the distance b between the chamfered sipe 41 and the far sipe 48 is in the range of 1.5 ≤ (b / a) ≤ 12. Consequently, while preventing a partial reduction in the rigidity of the web portion 20, the compression of the near sipe 47 can suppress compression of the chamfered sipe 41.

[0056] In other words, when the ratio between the distance a and the distance b (b / a) < 1.5, the distance a between the tapered sipe 41 and the near sipe 47 is too large. Consequently, when a portion of the land portion 20 disposed around the tapered sipe 41 comes into contact with the ground, the near sipe 47 is not easily compressed, or even if the near sipe 47 is compressed, it is difficult to suppress the compression of the tapered sipe 41.In other words, since the distance a between the chamfered sipe 41 and the near sipe 47 is too large, deformation of the near sipe 47 and deformation of the chamfered sipe 41 may not easily affect each other, and thus it is difficult to suppress compression of the chamfered sipe 41 when a portion of the land portion 20 arranged around the chamfered sipe 41 comes into contact with the ground, and in this case, it may be difficult to ensure the volume of the chamfered sipe 41 when a portion of the land portion 20 arranged around the chamfered sipe 41 comes into contact with the ground, and it may be difficult to ensure the wet performance, which is the mileage on wet road surfaces.In addition, if the ratio between the distance a and the distance b (b / a) > 12, the distance a between the chamfered sipe 41 and the near sipe 47 is too small. Consequently, the rigidity of a portion of the land portion 20 located between the chamfered sipe 41 and the near sipe 47 may be too low. In this case, the rigidity of the land portion 20 is partially reduced, and therefore, it may be difficult to ensure steering stability when driving the vehicle mainly on dry road surfaces.

[0057] On the other hand, when the ratio between the distance a and the distance b is in the range of 1.5 ≤ (b / a) ≤ 12, the rigidity of a portion of the land portion 20 located between the tapered sipe 41 and the near sipe 47 is prevented from being too low, and the deformation of the near sipe 47 and the deformation of the tapered sipe 41 are prevented from affecting each other. As a result, while preventing a partial reduction in the rigidity of the land portion 20, compression of the tapered sipe 41 by compression of the near sipe 47 can be suppressed when a portion of the land portion 20 located around the tapered sipe 41 comes into contact with the ground. As a result, wet performance can be ensured while suppressing a reduction in steering stability.

[0058] Furthermore, the ratio between the length Lm of the tapered sipe 41 and the length Lp of the near sipe 47 is in the range of 0.2 ≤ (Lm / Lp) ≤ 0.95. Therefore, by compressing the near sipe 47 over an appropriate length, compression of the tapered sipe 41 can be suppressed while preventing the rigidity of a portion of the web portion 20 located near the near sipe 47 from being too low.

[0059] In other words, if the ratio between the length Lm of the chamfered sipe 41 and the length Lp of the near sipe 47 (Lm / Lp) is < 0.2, the length Lp of the near sipe 47 is too long. Consequently, the rigidity of a portion of the land portion 20 located near the near sipe 47 may be too low. In this case, the rigidity of the land portion 20 is partially reduced, and therefore, it may be difficult to ensure steering stability when the vehicle is running. Furthermore, if the ratio between the length Lm of the chamfered sipe 41 and the length Lp of the near sipe 47 (Lm / Lp) is > 0.95, the length Lp of the near sipe 47 is too short. In this case, even if the near sipe 47 is compressed, the near sipes 47 are compressed over a short length when a portion of the land portion 20 arranged around the tapered sipe 41 comes into contact with the ground.Consequently, it may be difficult to suppress the compression of the beveled fin 41 by compression of the nearby fins 47, and it may be difficult to ensure the drainage properties of the beveled fin 41.

[0060] On the other hand, when the ratio between the length Lm of the tapered sipe 41 and the length Lp of the near sipe 47 is in the range of 0.2 ≤ (Lm / Lp) ≤ 0.95, the near sipe 47 is compressed over an appropriate length when a portion of the land portion 20 located around the tapered sipe 41 comes into contact with the ground, while preventing excessive rigidity of a portion of the land portion located near the near sipe 47, and therefore, the tapered sipe 41 can be prevented from being compressed. As a result, wet performance can be ensured while more reliably suppressing a reduction in steering stability.

[0061] Furthermore, of the opposite wall surfaces 41a of the tapered louver 41, the wall surface 41a located on one side close to the near louver 47 is provided with the tapered portion 42. Accordingly, a portion of the land portion 20 located around the tapered louver 41 comes into contact with the ground, the near louver 47 is compressed, and thus a portion of the tapered louver 41 located at or near the tapered portion 42 can be more reliably prevented from being compressed. Consequently, the volume of the tapered louver 41 can be more reliably secured by the tapered portion 42, and the drainage properties of the tapered louver 41 can be improved. As a result, the wet performance can be more reliably improved.

[0062] Furthermore, the ratio between the opening width Wm of the tapered slat 41 and the opening width Wp of the near slat 47 is in the range of 1.2 ≤ (Wm / Wp) ≤ 6.0, and thus, while ensuring the volume of the tapered slat 41, the rigidity of a portion of the web portion 20 arranged around the tapered slat 41 can be prevented from being too low. In other words, when the ratio between the opening width Wm of the tapered slat 41 and the opening width Wp of the near slat 47 is (Wm / Wp) < 1.2, the opening width Wm of the tapered slat 41 is too small, and therefore, it may be difficult to ensure the volume of the tapered slat 41. In this case, it is difficult to ensure drainage properties of the beveled slat 41, and the wet performance can hardly be ensured by the beveled slat 41.Also, when the ratio between the opening width Wm of the tapered sipe 41 and the opening width Wp of the near sipe 47 (Wm / Wp) is > 6.0, the opening width Wm of the tapered sipe 41 is too large, and thus the rigidity of a portion of the land portion 20 located around the tapered sipe 41 may be too low. In this case, the rigidity of the land portion 20 is partially reduced, and therefore, it may be difficult to ensure steering stability when driving the vehicle.

[0063] On the other hand, when the ratio between the opening width Wm of the tapered sipe 41 and the opening width Wp of the near sipe 47 is in the range of 1.2 ≤ (Wm / Wp) ≤ 6.0, the rigidity of a portion of the land portion 20 located around the tapered sipe 41 is prevented from being too low while ensuring the volume of the tapered sipe 41. As a result, wet performance can be ensured while more reliably suppressing a reduction in steering stability.

[0064] Furthermore, in the tapered sipe 41, the ratio between the opening width Wm and the groove bottom width Wm1 is in the range of 0.1 ≤ (Wm1 / Wm) ≤ 0.85, and thus, while ensuring the volume of the tapered sipe 41, the rigidity of a portion of the land portion 20 arranged around the tapered sipe 41 is prevented from being too low. In other words, when the ratio between the opening width Wm and the groove bottom width Wm1 of the tapered sipe 41 is (Wm1 / Wm) < 0.1, the groove bottom width Wm1 of the tapered sipe 41 is too small, and therefore, it may be difficult to ensure the volume of the tapered sipe 41. In this case, it is difficult to ensure drainage properties of the beveled slat 41, and the wet performance can hardly be ensured by the beveled slat 41.Also, when the ratio between the opening width Wm and the groove bottom width Wm1 of the tapered sipe 41 (Wm1 / Wm) is > 0.85, the groove bottom width Wm1 of the tapered sipe 41 is too large, and thus the rigidity of a portion of the land portion 20 located around the tapered sipe 41 may be too low. In this case, the rigidity of the land portion 20 is partially reduced, and therefore, it may be difficult to ensure steering stability when driving the vehicle.

[0065] On the other hand, when the ratio between the opening width Wm and the groove bottom width Wm1 of the tapered sipe 41 is in the range of 0.1 ≤ (Wm1 / Wm) ≤ 0.85, the rigidity of a portion of the land portion 20 located around the tapered sipe 41 can be prevented from being too low while ensuring the volume of the tapered sipe 41. As a result, wet performance can be ensured while more reliably suppressing a reduction in steering stability.

[0066] Furthermore, the near sipe 47 is connected to the two main grooves 30 defining the land portion 20, that is, it extends through the land portion 20 in the tire width direction, in which the near sipes 47 are formed. Thus, the circumferential rigidity of a portion of the land portion 20 in which the near sipe 47 is formed can be more reliably reduced. As a result, when a portion of the land portion 20 located around the tapered sipe 41 comes into contact with the ground, the near sipe 47 can be more reliably compressed. The near sipe 47 is compressed, and therefore, deformation of the land portion 20 can be absorbed by the near sipe 47.Accordingly, compression of the tapered fin 41 can be more reliably suppressed, and thus the volume of the tapered fin 41 can be ensured and the drainage properties of the tapered fin 41 can be improved. As a result, the wet performance can be more reliably improved.

[0067] Furthermore, the ratio between the groove depth Dm of the tapered sipe 41 and the groove depth Dp of the near sipe 47 is in the range of 1.2 ≤ (Dp / Dm) ≤ 8.0, and thus the rigidity of a portion of the land portion 20 located near the near sipe 47 is prevented from being too low, and compression of the tapered sipe 41 by compression of the near sipe 47 can be suppressed. In other words, when the ratio between the groove depth Dm of the tapered sipe 41 and the groove depth Dp of the near sipe 47 is (Dp / Dm) < 1.2, the groove depth Dp of the near sipe 47 is too small, and therefore it may be difficult to absorb deformation of the land portion 20 by compression of the near sipe 47.In this case, when a portion of the land portion 20 disposed around the chamfered sipe 41 comes into contact with the ground, compression of the chamfered sipe 41 is not easily suppressed, and it may be difficult to ensure drainage properties of the chamfered sipe 41. Also, when the ratio between the groove depth Dm of the chamfered sipe 41 and the groove depth Dp of the near sipe 47 (Dp / Dm) is > 8.0, the groove depth Dp of the near sipe 47 is too large, and thus the rigidity of a portion of the land portion 20 disposed around the near sipe 47 may be too low. In this case, the rigidity of the land portion 20 is partially reduced, and therefore, it may be difficult to ensure steering stability when driving the vehicle.

[0068] On the other hand, when the ratio between the groove depth Dm of the tapered sipe 41 and the groove depth Dp of the near sipe 47 is in the range of 1.2 ≤ (Dp / Dm) ≤ 8.0, while preventing the rigidity of a portion of the land portion 20 located near the near sipe 47 from becoming too low, compression of the tapered sipe 41 when a portion of the land portion 20 located around the tapered sipe 41 comes into contact with the ground can be suppressed by compression of the near sipe 47. As a result, wet performance can be ensured while more reliably suppressing a reduction in steering stability.

[0069] Furthermore, in the tapered sipe 41, the ratio between the groove depth Dm and the depth Dm1 of the tapered portion is in the range of 0.1 ≤ (Dm1 / Dm) ≤ 0.85, and thus the drainage characteristics of the tapered sipe 41 can be improved by the tapered portion 42 while suppressing a decrease in the rigidity of the land portion 20. In other words, when the ratio between the groove depth Dm and the depth Dm1 of the tapered portion of the tapered sipe 41 is (Dm1 / Dm) < 0.1, the depth Dm1 of the tapered portion of the tapered sipe 41 is too small, and therefore the drainage characteristics of the tapered sipe 41 are difficult to improve by the tapered portion 42 even though the tapered portion 42 is provided on the tapered sipe 41.Also, when the ratio between the groove depth Dm and the depth Dm1 of the tapered portion of the tapered sipe 41 (Dm1 / Dm) is > 0.85, the depth Dm1 of the tapered portion of the tapered sipe 41 is too large, and therefore the volume of a portion of the land portion 20 arranged around the tapered sipe 41 is small, and the rigidity of the land portion 20 in which the tapered sipes 41 are formed is likely to decrease.

[0070] On the other hand, when the ratio between the groove depth Dm and the chamfer depth Dm1 of the chamfered sipe 41 is in the range of 0.1 ≤ (Dm1 / Dm) ≤ 0.85, the drainage characteristics of the chamfered sipe 41 can be effectively improved by the chamfered portion 42 while preventing the rigidity of the land portion 20 in which the chamfered sipes 41 are formed from being low. As a result, wet performance can be ensured while more reliably suppressing a reduction in steering stability.

[0071] Furthermore, since the plurality of tapered sipes 41 formed in the same land portion 20 are connected to the same main groove 30, a rigidity difference may arise between an edge of the land portion 20 on the side defined by the main groove 30 to which the tapered sipe 41 is connected and an edge of the land portion 20 on the side defined by the main groove 30 on the opposite side. Accordingly, the rigidity of the land portion 20 on the side defined by the main groove 30 to which the tapered sipe 41 is connected is low, so the near sipe 47 is easily compressed, and compression of the tapered sipe 41 by compression of the near sipe 47 can be suppressed.Furthermore, the number of sipes 40 connected to the main groove 30 in the land portion 20 is small on the edge side defined by the main groove 30, which is located on the opposite side of the main groove 30 to which the tapered sipe 41 is connected, and the rigidity of the land portion 20 is ensured. Consequently, a rigidity feeling in an initial steering phase can be improved when the vehicle is running. As a result, wet performance can be ensured while a reduction in steering stability can be more reliably suppressed. Example

[0072] Furthermore, in the comparative example described above, the non-chamfered sipe 46 is connected to both of the two main grooves 30 defining the land portion 20, but the non-chamfered sipe 46 need not be connected to both of the two main grooves 30. Fig. Fig. 6 is an explanatory view of a pneumatic tire 1 according to an embodiment, illustrating a case where the non-chamfered sipe 46 is connected to only one of the main grooves 30. For example, as shown in Fig. 6, the non-chamfered sipe 46 is connected to only one of the main grooves 30 of the two main grooves 30 defining the two sides of the land portion 20 in the tire width direction, and the end portion on the opposite side of the end portion on the side connected to the main groove 30 may terminate within the land portion 20. In other words, the near sipe 47 and the far sipe 48 may have one end connected to the main groove 30, while the other end terminates within the land portion 20. In this case, as shown in Fig. 6 illustrates that, of the two main grooves 30 defining the land portion 20, the plurality of non-chamfered sipes 46 are preferably connected to the same main groove 30 as the main groove 30 to which the chamfered sipe 41 is connected. The ratio between the length Lm of the chamfered sipe 41 and the length Lp of the proximal sipe 47 is preferably in the range 0.2 ≤ (Lm / Lp) ≤ 0.95, as described above, even if the non-chamfered sipe 46 is connected to only one of the main grooves 30.

[0073] Furthermore, in the above-described embodiment, the plurality of tapered sipes 41 formed in the same land portion 20 are connected to the same main groove 30, but the plurality of tapered sipes 41 need not be connected to the same main groove 30. Fig. Fig. 7 is an explanatory view of a comparative example of the pneumatic tire 1, illustrating a case where the tapered sipes 41 are connected to different main grooves 30. As in Fig. 7, the chamfered sipes 41 formed in the same land portion 20 may be connected to different main grooves 30. In this case, the chamfered sipes 41 adjacent to each other in the tire circumferential direction with the non-chamfered sipe 46 therebetween may be alternately connected to the different main grooves 30. Alternatively, among the plurality of chamfered sipes 41 formed in the same land portion 20, chamfered sipes 41 adjacent to each other with the non-chamfered sipe 46 therebetween in the tire circumferential direction and connected to different main grooves 30 and chamfered sipes 41 adjacent to the non-chamfered sipe 46 therebetween in the tire circumferential direction and connected to the same main groove 30 may coexist.

[0074] Moreover, in the comparative example described above, the land portion 20 in which the sipes 40 are formed is formed in a rib shape, but the land portion 20 may be formed in a shape other than a rib shape. Fig. Fig. 8 is an explanatory view of a modification example of the pneumatic tire 1 according to a comparative example, illustrating a case where the land portion 20 is formed in a block shape. As in Fig. 8, the land portion 20 may be formed, for example, in a so-called block shape such that the two sides in the tire width direction are defined by the main grooves 30 and the two sides in the tire circumferential direction are defined by lug grooves 35. In other words, in addition to the main grooves 30 extending in the tire circumferential direction, a plurality of lug grooves 35 extending in the tire width direction may be formed in the road contact surface 3 of the tread portion 2, and the land portion 20 in which the sipes 40 are formed may be defined by the main grooves 30 and the lug grooves 35. In this case, the sipes 40 are preferably arranged such that the plurality of chamfered sipes 41 and the plurality of non-chamfered sipes 46 are arranged alternately in the tire circumferential direction in the single block-shaped land portion 20.As long as the sipes 40 are arranged such that the chamfered sipes 41 and the non-chamfered sipes 46 are arranged alternately in the tire circumferential direction, the land portion 20 in which the sipes 40 are formed may have any shape.

[0075] Also, in the comparative example described above, the rotation direction of the pneumatic tire 1 is not particularly specified, but the pneumatic tire 1 may be the pneumatic tire 1 having a designated rotation direction when mounted on a vehicle. In other words, the pneumatic tire 1 in which the sipes 40 are formed may be a pneumatic tire 1 to be mounted on a vehicle such that the tire rotates in the designated rotation direction around the rotation axis when the vehicle moves forward. The pneumatic tire 1 also includes a rotation direction indicating portion (not illustrated) that indicates the rotation direction. The rotation direction indicating portion is formed, for example, by a mark or recesses / projections provided on the sidewall portion 8 of the tire.

[0076] Fig. 9 is a schematic view of a modification example of the pneumatic tire 1 according to an embodiment, illustrating the arrangement of the sipes 40 with respect to the rotational direction of the pneumatic tire 1. The pneumatic tire 1 in which the chamfered sipes 41 and the non-chamfered sipes 46 are arranged alternately in the tire circumferential direction on the road contact surface 3 may be a pneumatic tire 1 whose rotational direction is provided upon mounting on a vehicle. In this case, as shown in Fig. 9, the near sipe 47 is preferably arranged on the front side in the tire rotation direction, and the beveled sipe 41 is preferably arranged on the rear side in the tire rotation direction.

[0077] In this case, the front side in the tire rotation direction is a rotation direction side when the pneumatic tire 1 rotates in the intended direction. When the pneumatic tire 1 is mounted on a vehicle and rotates and travels in the intended direction, the front side is the side that first comes into contact with a road surface 100 or first separates from the road surface 100. The rear side in the tire rotation direction, in turn, is the side opposite to the rotation direction when the pneumatic tire 1 rotates in the intended direction. When the pneumatic tire 1 is mounted on a vehicle and rotates and travels in the intended direction, the rear side is the side that comes into contact with the road surface 100 after a portion located on the front side comes into contact, or separates from the road surface 100 after a portion located on the front side separates.

[0078] With the chamfered sipe 41 and the near sipe 47 arranged side by side in the tire circumferential direction, the near sipe 47 is arranged on the front side in the tire rotation direction, and the near sipe 47 contacts the road surface 100 before the chamfered sipe 41. Accordingly, the near sipe 47 can further absorb deformation of the land portion 20. As a result, the compression of the chamfered sipe 41 can be more reliably suppressed, and wet performance can be more reliably improved.

[0079] In addition, the land portion 20 in which the sipes 40 are formed may be formed in such a shape that the road contact surface 3 curves toward an outer side in the tire radial direction. Fig. 10 is a schematic view of a modification example of the pneumatic tire 1 according to an embodiment, illustrating a main portion of the curved land portion 20. As shown in Fig. As illustrated in Figure 10, the land portion 20 in which the chamfered sipes 41 are formed may include the road contact surface 3 that curves from a standard contour line Pf of a tread pattern toward the tire radial direction outer side in a tire meridian cross-sectional view. The standard contour line Pf of the tread pattern in this case is a contour line serving as a reference for the shape of the road contact surface 3 of the land portion 20 in a state where there is no internal pressure due to inflation.More specifically, the standard contour line Pf of the tread pattern is a circular arc passing through at least three of four opening ends E of the two main grooves 30 adjacent to the two sides of the land portion 20 in the tire width direction in the tire meridian cross-sectional view in a state where there is no internal pressure due to inflation, and is drawn with a maximum radius of curvature, the center of the arc being located on an inner side of the road contact surface 3 in the tire radial direction.

[0080] The land portion 20, in which the tapered sipes 41 are formed, has a radius of curvature of the road contact surface 3 in the tire meridian cross-sectional view that is smaller than the radius of curvature of the standard contour line Pf of the tread pattern defined as described above. Accordingly, the shape of the road contact surface 3 in the tire meridian cross-sectional view is formed to curve from the standard contour line Pf of the tread pattern toward the outer side in the tire radial direction. In other words, the thickness of the land portion 20 is greater at the center position in the tire width direction than at the positions of both end portions in the tire width direction.

[0081] By forming the road contact surface 3 of the land portion 20 to curve toward the outer side in the tire radial direction further than the standard contour line Pf of the tread pattern as just described, water between the road contact surface 3 and the road surface can be guided to the main groove 30 defining the end portion of the land portion 20 in the tire width direction when driving on wet road surfaces. As a result, drainage properties can be more reliably improved, and wet performance can be more reliably improved.

[0082] Furthermore, in the above-described embodiment, the tapered sipe 41 and the non-tapered sipe 46 are illustrated in a shape extending straight in the tire width direction, but each of the sipes 40 may have a shape other than such a shape. The sipe 40 may be inclined in the tire width direction as it extends in the tire circumferential direction, or may be bent or curved in the tire circumferential direction as it extends in the tire width direction.

[0083] Furthermore, in the above-described embodiment, three main grooves 30 are formed, but the number of main grooves 30 may be other than three. The number of main grooves 30 formed in the tread portion 2 is preferably in a range of three or more and five or less. Furthermore, the main groove 30 may be formed in a shape other than a straight line as it extends in the tire circumferential direction. For example, the main groove 30 may be repeatedly bent or curved in the tire width direction as it extends in the tire circumferential direction. Examples

[0084] Fig. 11A to 11D are tables indicating the results of performance tests of pneumatic tires. With respect to the pneumatic tire 1 described above, performance evaluation tests conducted on a pneumatic tire according to a prior art example, on the pneumatic tires 1 according to comparative examples and embodiments of the present invention, and on pneumatic tires according to comparative examples for comparison with the pneumatic tires 1 according to embodiments of the present invention will be described. Performance evaluation tests were conducted on wet braking performance, which is braking performance on wet road surfaces, and steering stability.

[0085] The performance evaluation tests were conducted by mounting pneumatic tires 1 with a JATMA-specified nominal tire size of 195 / 65R15 91H on JATMA standard rim wheels with a rim size of 16 x 6.5J, setting the air pressure to 250 kPa, mounting the test tires on an evaluation vehicle, and then driving the evaluation vehicle.

[0086] In the evaluation procedure for each test item, for wet braking performance, the evaluation vehicle, fitted with test tires, was driven at an initial speed of 100 km / h on a water-sprinkled road surface of a test track, and a braking distance was measured. The reciprocal of the measured distance is expressed as an index value, with the prior art example described below being assigned a value of 100. Larger index values ​​indicate a shorter braking distance and superior wet braking performance.

[0087] In addition, steering stability was compared using sensory evaluation by a test driver, with the evaluation vehicle, fitted with the test tires, driven on a test track on dry road surfaces. Steering stability was evaluated by expressing the sensory evaluation by a test driver as an index value, with the prior art example described below being assigned a value of 100. Larger index values ​​indicate better steering stability. Note that the decrease in steering stability is suppressed starting at an index value of 98.

[0088] The performance evaluation tests were conducted on thirty-two types of pneumatic tires, which were a pneumatic tire of the prior art example as an example of a prior art pneumatic tire, pneumatic tires of Examples 1 to 17 corresponding to the pneumatic tire 1 according to an embodiment of the present invention, and pneumatic tires of Comparative Examples 1, 2 for comparison with the pneumatic tire 1 according to an embodiment of the present invention. Of the tires, the prior art example does not include the near sipe 47 near the chamfered sipe 41. Comparative Example 1 includes the near sipe 47 near the chamfered sipe 41, but the ratio of the distance b between the chamfered sipe 41 and the far sipe 48 to the distance a between the chamfered sipe 41 and the near sipe 47 is less than 1.5.Comparative Example 2 includes the near slat 47 in the same manner as Comparative Example 1, but the ratio of the distance b between the beveled slat 41 and the far slat 48 to the distance a between the beveled slat 41 and the near slat 47 is greater than 12.

[0089] In contrast, in all of Examples 1 to 17, each of which is an example of the pneumatic tire 1 according to an embodiment of the present invention, the ratio of the distance b between the chamfered sipe 41 and the far sipe 48 to the distance a between the chamfered sipe 41 and the near sipe 47 is in the range of 1.5 ≤ (b / a) ≤ 12. Furthermore, in the pneumatic tires 1 according to Examples 1 to 17, the ratio (Lm / Lp) of the length Lm of the chamfered sipe 41 to the length Lp of the near sipe 47, the direction in which the chamfered portion 42 of the chamfered sipe 41 is arranged, the ratio (Wm / Wp) of the opening width Wm of the chamfered sipe 41 to the opening width Wp of the near sipe 47, the ratio (Wm1 / Wm) of the Groove bottom width Wm1 to the opening width Wm of the beveled slat 41, the presence of a connection of the near slat 47 with the two main grooves 30 defining the web section 20,the ratio (Dp / Dm) of the groove depth Dp of the near sipe 47 to the groove depth Dm of the tapered sipe 41, the ratio (Dm1 / Dm) of the groove depth Dm1 of the tapered portion to the groove depth Dm of the tapered sipe 41, the main groove 30 to which the plurality of tapered sipes 41 formed in the same land portion 20 are connected, the sipe 40 located on the front side in the tire rotation direction, and the presence of the land portion 20 enclosing the road contact surface 3 bulging toward the outer side in the tire radial direction, are each different.

[0090] As a result of conducting the performance evaluation tests using these pneumatic tires 1 as shown in Fig.As shown in Figures 11A to 11D, it was found that the pneumatic tires 1 according to Examples 1 to 17 can improve wet braking performance while suppressing a reduction in steering stability as much as possible compared to the prior art example and Comparative Examples 1 and 2. In other words, the pneumatic tires 1 according to Examples 1 to 17 can improve wet performance while suppressing a reduction in steering stability. List of reference symbols 1 pneumatic tire 2 Tread section 3 Road contact surface 4 Tread rubber layer 5 shoulder section 8 Side wall section 10 bead section 11 Bead core 12 bead fillers 13 carcass layers 14 Belt layer 16 Inner core 17 Rim cushion rubber 18 Tire inner surface 20 bridge section 30 main groove 35 lug groove 40 slats 41 bevelled slats 41a, 47a, 48a wall surface 41b, 47b grooved bottom 42 bevelled section 46 non-beveled slats 47 near slat 48 removed slats

Claims

[1] Pneumatic tyre (1), comprising: a plurality of main grooves (30) extending in a tire circumferential direction; a web section (20) comprising end sections in Tire width direction defined by the main grooves (30), wherein both sides of the land portion (3020) in the tire width direction are defined by the main grooves (30); a plurality of beveled slats (41) formed in the web portion (20), each of the beveled slats (41) including a beveled portion (42); and a plurality of non-beveled sipes (46) formed in the land portion (20), none of the non-beveled sipes (46) comprising the beveled portion (42), the beveled sipe (41) having one end connected to the main groove (30) defining the land portion (20) and another end terminating within the land portion (20), the chamfered sipes (41) and the non-chamfered sipes (46) are arranged alternately in the tire circumferential direction, wherein the plurality of chamfered sipes (41) formed in the same land portion (20) is connected to the same main groove (30), and the plurality of non-chamfered sipes (46) is connected to only one of the main grooves (30), in the non-beveled sipes (46) arranged in the tire circumferential direction on both sides of the beveled sipe (41), a ratio between a distance a and a distance b in the tire circumferential direction is in the range 1.5 ≤ (b / a) ≤ 12, wherein the distance a in the tire circumferential direction is a distance between the beveled sipe (41) and a near sipe (47), which is the non-beveled sipe (46) arranged on a side near the beveled sipe (41) in the tire circumferential direction, and the distance b in the tyre circumferential direction is a distance between the bevelled sipe (41) and the non-bevelled sipe (46), which is arranged on a side remote from the beveled sipe (41) in the tire circumferential direction. [2] A pneumatic tire (1) according to claim 1, wherein a ratio between a length Lm of the chamfered sipe (41) and a length Lp of the proximal sipe (47) is in the range 0.2 ≤ (Lm / Lp) ≤ 0.

95. [3] A pneumatic tire (1) according to claim 1 or 2, wherein, of opposite wall surfaces (41a) of the tapered sipe (41), the wall surface (41a) located on a side near the near sipe (47) is provided with the tapered portion (42). [4] A pneumatic tire according to any one of claims 1 to 3, wherein a ratio between an opening width Wm of the tapered sipe (41) and an opening width Wp of the near sipe (47) is in the range of 1.2 ≤ (Wm / Wp) ≤ 6.

0. [5] A pneumatic tire (1) according to any one of claims 1 to 4, wherein the tapered sipe (41) has a ratio between an opening width Wm and a groove bottom width Wm1 which is in the range 0.1 ≤ (Wm1 / Wm) ≤ 0.

85. [6] Pneumatic tire (1) according to one of claims 1 to 5, wherein both sides of the web section (20) are defined in the tire width direction by the main grooves (30) and the near slat (47) is connected to two of the main grooves (30) defining the web portion (20). [7] A pneumatic tire (1) according to any one of claims 1 to 6, wherein a ratio between a groove depth Dm of the tapered sipe (41) and a groove depth Dp of the near sipe (47) is in the range 1.2 ≤ (Dp / Dm) ≤ 8.

0. [8] A pneumatic tire (1) according to any one of claims 1 to 7, wherein the tapered sipe (41) has a ratio between a groove depth Dm and a depth Dm1 of the tapered portion (42) which is in the range 0.1 ≤ (Dm1 / Dm) ≤ 0.

85. [9] A pneumatic tire (1) according to any one of claims 1 to 8, wherein, of the tapered sipe (41) and the near sipe (47), the near sipe (47) is arranged on a front side in the tire rotation direction. [10] A pneumatic tire (1) according to any one of claims 1 to 9, wherein the land portion (20) in which the tapered sipes (41) are formed includes a road contact surface (3) which curves from a standard contour line (pf) of a tread pattern to a tire radially outer side in a tire meridian cross-sectional view.

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