Tires

Abstract

Tire (10), comprising a tread pattern in a tread section (10T), wherein the tread pattern comprises: a first main circumferential groove (21) and a second main circumferential groove (22), which extend in the circumferential direction of the tire and are arranged at a distance in the direction of the tire width; a plurality of first sipes (51) extending in the tire width direction in a region of a first web section (71) between the first main circumferential groove (21) and the second main circumferential groove (22) and arranged at intervals in the tire circumferential direction; a first chamfered surface (81) with a tread surface of the first rib section (71) inclined towards the first main circumferential groove (21) in an end section in the tire width direction on a first main circumferential groove side of the first rib section (71), wherein the first chamfered surface (89) is provided in a plurality in the tire circumferential direction, and the first sipes (51) open towards the plurality of the first chamfered surfaces (89) without reaching a groove wall of the first main circumferential groove (21); a plurality of second sipes (53) extending in the tire width direction within a region of a second rib section (73) located on the opposite side of the region of the first rib section (71) with respect to the second main circumferential groove (22) and arranged at intervals in the tire circumferential direction; and a second chamfered surface (83) with a tread surface of the second rib section (73) which is inclined in the direction of the second main circumferential groove (22) in an end section in the tire width direction on a second main circumferential groove side (22) of the second rib section (73), wherein the second chamfered surface (83) in a PS:CZ:al The majority is provided in the tire circumferential direction, and the second sipes (53) open to the majority of the second chamfered surfaces (83) without reaching a groove wall of the second main circumferential groove (22); a length in the circumferential direction of the first chamfered surface (81) and a length in the circumferential direction of the second chamfered surface (83) are greater than a length in the width direction of the first chamfered surface (81) and a length in the width direction of the second chamfered surface (83), wherein the tread pattern includes a narrow circumferential groove (31, 33) extending in the circumferential direction of the tire in the region of the first rib section (71) and having a groove width that is smaller than the groove width of the first main circumferential groove (21) and the second main circumferential groove (22), and the first sipe (51) is arranged in an area between the first main circumferential groove (21) and the narrow circumferential groove (31, 33) and is connected to the narrow circumferential groove (31, 33), wherein the tread pattern has a third chamfered surface (89) with a surface inclined towards the narrow circumferential groove (31, 33) in an end section in the tire circumferential direction on one side of the narrow circumferential groove (31, 33) of an area comprising the first sipes (51), wherein the area is one of two areas of the first rib section (71) which are divided in the tire circumferential direction by the narrow circumferential groove (31, 33), the third chamfered surface (89) being provided in a plurality in the tire circumferential direction and the third chamfered surface (89) is provided in a plurality adjacent in the circumferential direction to connecting end sections of the first sipes (51) with the narrow circumferential groove (31, 33), wherein a length of the third chamfered surface (89) in the circumferential direction of the tire is smaller than the lengths of the first chamfered surface (81) and the second chamfered surface (83) in the circumferential direction of the tire.

Description

Technical area

[0001] The present invention relates to a tire having a tread pattern in a tread portion. State of the art

[0002] A well-known way to improve a tire's wet performance is to provide a main groove extending in the tire circumferential direction and a lug groove extending in the tire width direction in the tire's tread surface to ensure drainage properties. However, in a configuration where the lug groove has a large groove volume, a loud popping noise is generated during go-around, and tire noise reduction performance (hereinafter referred to as noise performance) is deteriorated.

[0003] From JP 2017-226 369 A, a tire without a groove having a width of 2 mm or more in a crown land portion or a center land portion in a tread portion of the tire is known. EP 3 208 111 A1 discloses a tire having a tread portion in which center chamfer portions, each formed at a corner between a ground contact surface of the first center land portion and a groove sidewall of the first shoulder main groove, are formed in a part of the area between a pair of center lug grooves adjacent in the tire circumferential direction. The center chamfer portions are arranged to overlap first shoulder chamfer portions of the first shoulder blocks in the tire circumferential direction, with both ends in the tire circumferential direction of the first shoulder chamfer portion terminating without being connected to first shoulder transverse grooves of the tire.EP 3 421 263 A1 discloses a tire with a tread portion having a land portion with axially spaced first and second ends, the land portion being provided with lateral grooves extending from a first end to ends terminating within the land portion, and first sipes each extending along a tire circumferential direction to connect a pair of lateral grooves arranged adjacent to each other in the tire circumferential direction, second sipes extending from the first end to the first sipes, and third sipes extending from the second end to the first sipes. The second sipes and the third sipes are arranged so as not to overlap the lateral grooves.WO 2019 / 159 564 A1 discloses a tire having a tread portion having five rows of land portions, wherein a groove opening portion of an inside shoulder main groove and a groove opening portion of an inside center main groove have edge portions of a straight shape, wherein a groove opening portion of an outside center main groove has an edge portion chamfered in a zigzag shape, and wherein a groove width Wg1 of the inside shoulder main groove, a groove width Wg2 of the inside center main groove, and a groove width Wg3 of the outside center main groove satisfy a relationship of Wg1 < Wg3 and Wg2 < Wg3. DE 11 2017 004 338 T5 discloses a tire having a tread portion including a chamfered portion and a non-chamfered portion, wherein the chamfered portion is shorter than a sipe length of a sipe and is formed in a front side edge and a rear side edge, respectively.Brief description of the invention. Technical problem

[0004] In a configuration where, in order to avoid deterioration of noise performance, a groove having a width of 2 mm or more is not provided in a crown land portion or a center land portion in a tread surface including a main groove and a lug groove, the groove volume decreases and thus the noise performance improves, but the drainage properties cannot be ensured due to a reduction in the groove volume, resulting in deterioration of wet performance.

[0005] An object of the present invention is to provide a tire that provides improved wet performance while suppressing degradation of noise performance. Solution to the problem

[0006] One aspect of the present invention is a tire including a tread pattern in a tread portion.

[0007] The tread pattern includes: a first circumferential main groove and a second circumferential main groove extending in the tire circumferential direction and arranged at a pitch in the tire width direction; a plurality of first sipes extending in the tire width direction in a region of a first land portion between the first circumferential main groove and the second circumferential main groove and arranged at pitches in the tire circumferential direction; a first tapered surface having a tread surface of the first land portion inclined toward the first circumferential main groove in an end portion in the tire width direction on a first circumferential main groove side of the first land portion, the first tapered surface being provided in a plurality in the tire circumferential direction, and the first sipes opening to the plurality of first tapered surfaces,without reaching a groove wall of the first circumferential main groove; a plurality of second sipes extending in the tire width direction within a range of a second land portion located on an opposite side of the range of the first land portion with respect to the second circumferential main groove and arranged at intervals in the tire circumferential direction; and a second tapered surface having a tread surface of the second land portion inclined toward the second circumferential main groove in an end portion in the tire width direction on a second circumferential main groove side of the second land portion, the second tapered surface being provided in a plurality in the tire circumferential direction, and the second sipes opening to the plurality of second tapered surfaces,without reaching a groove wall of the second circumferential main groove. A tire circumferential length of the first tapered surface and a tire circumferential length of the second tapered surface are greater than a tire widthwise length of the first tapered surface and a tire widthwise length of the second tapered surface. The tread pattern includes a narrow circumferential groove extending in the tire circumferential direction in the region of the first land portion and having a groove width smaller than a groove width of the first circumferential main groove and the second circumferential main groove, and the first sipe is arranged in a region between the first circumferential main groove and the narrow circumferential groove and connected to the narrow circumferential groove. The tread pattern has a third tapered surface,which has a tread surface inclined toward the narrow circumferential groove in an end portion in the tire width direction on one side of the narrow circumferential groove of a region including the first sipes, the region being one of two regions of the first land portion divided in the tire width direction by the narrow circumferential groove. The third tapered surface is provided in a plurality of adjacent, in the tire circumferential direction, connecting end portions of the first sipes with the narrow circumferential groove. A length of the third tapered surface in the tire circumferential direction is smaller than the lengths of the first tapered surface and the second tapered surface in the tire circumferential direction.

[0008] Preferably, the length of the tapered surface in the tire circumferential direction is 5 to 50% of the length of a distance between the sipes adjacent in the tire circumferential direction, the sipes opening towards the tapered surface.

[0009] Preferably, the ratio of the length of the chamfered surface in the tire circumferential direction to the length of the chamfered surface in the tire width direction is greater than 1 and 10 or less.

[0010] Preferably, the tire circumferential lengths of the first tapered surface and the second tapered surface are different from each other.

[0011] Preferably, the first tapered surface and the second tapered surface are arranged on one side of a tire width direction, and of the first tapered surface and the second tapered surface, the tire circumferential direction length of the one tapered surface farther from the tire center line is longer than the tire circumferential direction length of the one tapered surface closer to the tire center line.

[0012] Preferably, the positional ranges of the first beveled surface and the second beveled surface do not overlap in the tire circumferential direction.

[0013] Preferably, the maximum depth of the beveled surface is greater than the depth of the louvre opening to the beveled surface.

[0014] Preferably, the chamfered surface has a substantially triangular shape which decreases in length in the tire width direction from one side in the tire circumferential direction to another side in the tire circumferential direction.

[0015] Preferably, the slat includes a raised lower portion at an opening end portion of the slat opening toward the beveled surface, the raised lower portion having a depth greater than a maximum depth of the slat.

[0016] Preferably, the tread pattern further includes, in the region of the land portion, a surface of the land portion adjacent to the tapered surface, wherein the wall surface of the land portion extends continuously from a wall surface of the sipe from an opening end portion of the sipe opening to the tapered surface to a wall surface of the circumferential main groove to which the tapered surface is inclined, and wherein the wall surface extends without being inclined with respect to a tire radial direction.

[0017] Preferably, the tread pattern further includes, in the region of the land portion, a surface of the land portion adjacent to the tapered surface, wherein the wall surface of the land portion extends continuously from a wall surface of the sipe from an opening end portion of the sipe opening to the tapered surface to a wall surface of the circumferential main groove to which the tapered surface is inclined, and wherein the wall surface extends without being inclined with respect to a tire radial direction.

[0018] Preferably, the first sipe and the second sipe are inclined to the same side in the tire circumferential direction with respect to the tire width direction.

[0019] Preferably, a maximum depth of the third beveled surface is smaller than a depth of the first slat.

[0020] Preferably, the tread pattern does not include lug grooves extending in the tire width direction within the region of the land portion. Advantageous effects of the invention

[0021] The tire of the above-described aspect can suppress the degradation of wet performance while improving the noise performance. Brief description of the drawings Fig. 1 is a diagram illustrating an example of a tread cross section of a pneumatic tire according to an embodiment of the present invention. Fig. 2 is a diagram showing an example of a tread pattern of the tire of Fig. 1 illustrates. Fig. 3 is a diagram illustrating a cross section of a region between a first outer main groove and a narrow groove. Fig.4 is a perspective view illustrating an embodiment of a chamfered portion. Fig. Figure 5 is a diagram explaining an extension line. Description of embodimentsOverall description of the tire

[0022] A tire of the present embodiment will be described below. The tire of the present invention is preferably a pneumatic tire, and the tire of the present embodiment is a pneumatic tire. A pneumatic tire is a tire including a cavity portion surrounded by a tire and a rim, the cavity portion being filled with air. Note that in the tire of the present embodiment, the cavity portion surrounded by a tire and a rim may be filled with an inert gas such as nitrogen or another gas instead of air. The present embodiment includes various embodiments described below.

[0023] Fig. 1 is a tire cross-sectional view illustrating an example of a tread cross section of a pneumatic tire (hereinafter referred to simply as “tire”) 10.

[0024] For example, tire 10 is a passenger car tire. A "passenger car tire" refers to a tire specified in Chapter A of the 2012 JATMA YEARBOOK (Standards of the Japan Automobile Tire Manufacturers Association, Inc.). Tire 10 can also be applied to a light truck tire specified in Chapter B and a truck and bus tire specified in Chapter C.

[0025] The tire width direction is a direction parallel to a tire's rotational axis. "Tire width direction outboard side" is a side away from a tire center line CL (tire equatorial line), which represents the tire's equatorial plane in the tire width direction. Furthermore, "tire width direction inboard side" is a side close to the tire center line CL in the tire width direction. The tire circumferential direction is a direction of rotation around a tire's rotational axis. "Tire radial direction" is a direction perpendicular to the tire's rotational axis. "Tire radial direction outboard side" refers to a side farther from the rotational axis. Similarly, "tire radial direction inboard side" refers to a side closer to the rotational axis. Tire structure

[0026] The tire 10 includes a tread portion 10T including a tread pattern, a pair of bead portions 10B, and a pair of side portions 10S provided on two sides of the tread portion 10T and connecting the pair of bead portions 10B and the tread portion 10T.

[0027] The tire 10 includes a carcass ply 12, a belt 14 and a bead core 16 as frame members, and mainly includes a tread rubber member 18, side rubber members 20, bead filler rubber members 22, rim cushion rubber members 24 and an inner liner rubber member 26 around the frame members.

[0028] The carcass ply 12 is formed of a carcass ply member made of rubber-covered organic fibers wound between a pair of bead cores 16, each having a ring shape, and is formed in a torus shape. The carcass ply 12 is wound around the bead cores 16 and extends to an outer side in the tire radial direction. The belt 14 is provided on an outer side of the carcass ply 12 in the tire radial direction and includes two belt links 14a, 14b. The belt 14 includes a link made of a steel cord covered with rubber and inclined at a predetermined angle, for example, from 20 to 30 degrees with respect to the tire circumferential direction. The inner layer belt link 14a has a width in the tire width direction that is larger than a width in the tire width direction of the outer layer belt link 14b.The steel cords of the two belt links 14a, 14b extend obliquely in opposite directions. Thus, the belt links 14a, 14b are intersecting layers that serve to suppress expansion of the carcass ply 12 due to the pressure of the air in the tire.

[0029] The tread rubber member 18 is provided on an outer side of the belt 14 in the tire radial direction. The side rubber members 20 are connected to two end portions of the tread rubber member 18 and form the side portions 10S. The rim cushion rubber members 24 are provided at ends on an inner side of the side rubber member 20 in the tire radial direction and come into contact with a rim on which the tire 10 is mountable. Each of the bead filler rubber members 22 is provided on an outer side of each of the bead cores 16 in the tire radial direction and is arranged between a portion of the carcass ply 12 before being wound around the bead core 16 and a portion of the carcass ply 12 wound around the bead core 16. The inner liner rubber member 26 is provided on an inner surface of the tire 10 facing a tire cavity portion filled with air and surrounded by the tire 10 and the rim.

[0030] In addition, two belt covers 30 made of organic fiber and covered with rubber are provided between the belt member 14b and the tread rubber member 18. The two belt covers 30 cover the belt 14 from the outer side of the belt 14 in the tire radial direction. Tread pattern

[0031] Fig. Fig. 2 is a diagram showing a section developed into a plan view of an example of the tread pattern of the tire 10 of Fig. 1 illustrates.

[0032] The tread pattern according to the Fig. 2 includes a first outer main groove 21 (first circumferential main groove), a first inner main groove 23 (second circumferential main groove), a second inner main groove 25 and a second outer main groove 27 as circumferential main grooves extending in the tire circumferential direction.

[0033] The first outer main groove 21 and the first inner main groove 23 are formed in a first half-tread area on one side (left side in Fig. 2) the tire center line CL in the tire width direction and are arranged at intervals from each other in the tire width direction.

[0034] The second inner main groove 25 and the second outer main groove 27 are formed in a second half-tread area on the other side (right side in Fig. 2) provided in the tire width direction and arranged at intervals from each other in the tire width direction.

[0035] Herein, main groove means a groove having a groove depth of, for example, 6.5 to 9.0 mm and a groove width of, for example, 5.0 to 15.0 mm. The number of main grooves provided in the tread pattern is Fig.2, but may be, for example, three or five. In a configuration including three main grooves, the first inner main groove 23 and the second inner main groove 25 are in the Fig. 2 is replaced by a main circumferential groove running across the tire center line CL.

[0036] The tread pattern according to the Fig. The example illustrated in FIG. 2 further includes narrow grooves 31, 33 as two circumferential narrow grooves extending in the tire circumferential direction. The narrow grooves 31, 33 each have a smaller groove width than the main grooves 21, 23, 25, 27. The narrow grooves 31, 33 each have a smaller groove depth than the main grooves 21, 23, 25, 27. The groove depths of the narrow grooves 31, 33 are, for example, 1.0 to 5.0 mm, and the groove widths of the narrow grooves 31, 33 are, for example, 0.8 to 3.0 mm.

[0037] The narrow groove 31 is provided in a shoulder portion 77 of the tread pattern on an outer side of the first outer main groove 21 in the tire width direction.

[0038] The narrow groove 33 is provided in a first central region (first land portion region) 71 between the first outer circumferential main groove 21 and the first inner main groove 23. The narrow groove 33 is located within the first central region 71 on a first inner main groove 23 on the tire width direction center side of the first central region 71.

[0039] According to one embodiment, the narrow circumferential groove is preferably not provided in a second central region 75 and a central region 73, which are described below. In the tread pattern according to the Fig.2, the narrow circumferential groove is not provided in a shoulder region 79, which is described below.

[0040] The tread pattern according to the Fig. The example illustrated in FIG. 2 further includes first center sipes 51 (first sipes), center sipes 53 (second sipes), and second center sipes 55, 57. The first center sipes 51, the center sipes 53, and the second center sipes 55, 57 ensure edge components extending in the tire width direction, thereby improving edge performance against a force in a front-rear direction (direction parallel to the tire circumferential direction on a ground contact surface). Herein, sipe refers to a sipe having a sipe depth of, for example, from 2.0 to 7.5 mm and a sipe width of, for example, from 0.3 to 1.0 mm.

[0041] A plurality of first center sipes 51 are provided at intervals in the tire circumferential direction in the first center region 71, communicate with the first outer main groove 21, extend in the tire width direction, and close within the first center region 71.

[0042] A plurality of center sipes 53 are provided at intervals in the tire circumferential direction in the center region (second land portion region) 73 between the first inner main groove 23 and the second inner main groove 25, communicate with the first inner main groove 23, extend in the tire width direction, and close within the center region 73.

[0043] A plurality of second center sipes 55 are provided at intervals in the tire circumferential direction in the second center region 75 between the second inner main groove 25 and the second outer main groove 27, communicate with the second inner main groove 25, extend in the tire width direction, and close within the second center region 75.

[0044] A plurality of second center sipes 57 are provided at intervals in the tire circumferential direction in the second center region 75, communicate with the second outer main groove 27, extend in the tire width direction in the second center region 75, and close within the second center region 75 without reaching the second inner main groove 25.

[0045] According to one embodiment, the second central region 75 may include only one of the second central slats 55 and the second central slats 57.

[0046] The tread pattern according to the Fig. 2 further includes shoulder lug grooves 58, 59.

[0047] A plurality of lug grooves 58 are arranged at intervals in the tire circumferential direction in the shoulder region 77 on an outer side in the tire width direction of the first outer circumferential main groove 21, extend in the tire width direction from the outer side in the tire width direction to the first outer circumferential main groove 21 within an outer region 77A, in the shoulder region 77 located on an outer side in the tire width direction of the narrow groove 31, intersect the narrow groove 31 and close within an inner region 77B between the narrow groove 31 and the main groove 21 without reaching the first outer main groove 21.

[0048] A plurality of lug grooves 59 are arranged at intervals in the tire circumferential direction in a shoulder region 79 on an outer side in the tire width direction of the second outer circumferential main groove 27, extend in the tire width direction from the outer side in the tire width direction to the main groove 27 within the shoulder region 79, and close within the region 79 without reaching the main groove 27.

[0049] Note that the areas 77A, 79 include ground contact edges E in the tire width direction. "Ground contact edges" refers to two ends of a ground contact surface in the tire width direction in a case where the tire 10 mounted on a regular rim, inflated to regular internal pressure, and loaded with 88% of a regular load, is brought into contact with a horizontal surface. "Conventional rim" means a "measurement rim" as defined by the Japan Automobile Tire Manufacturers Association (JATMA), a "design rim" as defined by the Tire and Rim Association (TRA), or a "measuring rim" as defined by the European Tire and Rim Technical Organization (ETRTO)."Normal air pressure" refers to a "maximum air pressure" as defined by JATMA, a maximum value in "tire load limits at various cold inflation pressures" as defined by TRA, or "inflation pressures" as defined by ETRTO. "Normal load" refers to a "maximum load capacity" as defined by JATMA, a maximum value in "tire load limits at various cold inflation pressures" as defined by TRA, or "load capacity" as defined by ETRTO.

[0050] The shoulder lug grooves 58 and 59 include closed ends 58a and 59a of the shoulder lug grooves 58 and 59, and main groove side portions 58b and 59b, which are located on one side of the outer circumferential main groove 21 and one side of the outer circumferential main groove 27 of the ground contact edges E, respectively, extend inclined with respect to the tire width direction.

[0051] The tread pattern of the Fig. 2 further includes a first central beveled surface 81 (first beveled surface), a central beveled surface 83 (second beveled surface), and second central beveled surfaces 85, 87.

[0052] An end portion in the tire width direction of the sipe 51, which communicates with the first outer main groove 21, is located adjacent to portions of a land portion in the tire circumferential direction. The first center tapered surface 81 is a surface including a tread surface of one of the portions of the land portion inclined toward the first outer main groove 21. The first center tapered surface 81 is provided at a plurality of intervals in the tire circumferential direction, and the first center sipes 51 open toward it without reaching the groove wall of the first outer main groove 21.

[0053] An end portion in the tire width direction of the sipe 53, which communicates with the first inner main groove 23, is located adjacent to portions of a land portion in the tire circumferential direction. The center tapered surface 83 is a surface including a tread surface of one of the portions of the land portion inclined toward the first inner main groove 23. The center tapered surface 83 is provided at a plurality of intervals in the tire circumferential direction, and the center sipes 53 open toward it without reaching the groove wall of the first inner main groove 23.

[0054] An end portion in the tire width direction of the sipe 53, which communicates with the second inner main groove 25, is located adjacent to portions of a land portion in the tire circumferential direction. The second center tapered surface 85 is a surface including a tread surface of one of the portions of the land portion inclined toward the second inner main groove 25. The second center tapered surface 85 is provided at a plurality of intervals in the tire circumferential direction, and the second center sipes 55 open toward it without reaching the groove wall of the second inner main groove 25.

[0055] An end portion in the tire width direction of the sipe 57, which communicates with the second outer main groove 27, is located adjacent to portions of a land portion in the tire circumferential direction. The second center tapered surface 87 is a surface including a tread surface of one of the portions of the land portion inclined toward the second outer main groove 27. The second center tapered surface 87 is provided at a plurality of intervals in the tire circumferential direction, and the second center sipes 57 open toward it without reaching the groove wall of the second outer main groove 27.

[0056] According to the present embodiment, the tapered surfaces 81, 83 are longer in the tire circumferential direction than in the tire width direction. The present embodiment includes the sipes 51, 53 in the first center region 71 and the center region 73, respectively, and thus has a smaller groove volume and better noise performance than a configuration including lug grooves instead of the sipes 51, 53. On the other hand, the embodiment includes the tapered surfaces 81, 83 in the first center region 71 and the center region 73, respectively, and thus has more edge components in contact with the surface and a greater edge effect than a configuration not including the tapered surfaces 81, 83.This results in an effect of suppressing a decrease in steering stability performance (wet performance) due to a decrease in drainage performance, which in turn is due to the provision of the sipes 51, 53 instead of lug grooves.Furthermore, as described above, the present embodiment includes the sipes 51, 53 and thus ensures edge components having an effect on a force in a front-rear direction (tire circumferential direction), and thus the length in the tire circumferential direction of each of the tapered surfaces 81, 83 is longer than the length in the tire width direction thereof, edge components having an effect on a force in a front-rear direction can be ensured, edge components having an effect on a lateral force can also be ensured, and an effect of improving wet performance with respect to forces in various directions received from the road surface can be obtained. This increases the effect of suppressing a decrease in wet performance.That is, compared with a configuration in which lug grooves are included instead of the sipes 51, 53, in the present embodiment, degradation of wet performance is suppressed while improving noise performance. Note that the present embodiment including the tapered surfaces 81, 83 in the first center region 71 and the center region 73, respectively, has a larger groove volume than an embodiment without the tapered surfaces 81, 83, but the amount of increase is smaller than, for example, an embodiment including notches (grooves in a lateral direction, the grooves each having a relatively short length in their extension direction), and the effect thereof on noise performance is small.According to one embodiment, in addition to the chamfered surfaces 81, 83, preferably at least one of the chamfered surfaces 85, 87 is longer in the tire circumferential direction than in the tire width direction.

[0057] According to one embodiment, the sipes 51, 53 each open to the tapered surfaces 81, 83, and the length of each of the tapered surfaces 81, 83 in the tire circumferential direction is preferably 5 to 50% of the length of the distance between a corresponding pair of sipes 51, 53, each of the pairs being adjacent in the tire circumferential direction. Tapered surfaces 81, 83 longer than this percentage in the tire circumferential direction may have poorer noise performance due to an increase in groove volume and may adversely affect wet performance due to a decrease in the rigidity of the land portions. Furthermore, tapered surfaces 81, 83 smaller than this percentage in the tire circumferential direction reduce the effect of improving wet performance.The length in the tire circumferential direction of at least one of the tapered surfaces 85, 87, in addition to the tapered surfaces 81, 83, is preferably the length of the above percentage.

[0058] According to one embodiment, the ratio of the length of each of the tapered surfaces 81, 83 in the tire width direction to the length thereof in the tire circumferential direction is preferably greater than 1 and 10 or less, and more preferably 1.5 or more and 8 or less. The above-described ratio of at least one of the tapered surfaces 85, 87, in addition to the tapered surfaces 81, 83, is preferably within the above-described ranges.

[0059] According to one embodiment, the lengths of the first central tapered surface 81 and the central tapered surface 83 in the tire circumferential direction are preferably different from each other. This embodiment can achieve the effect of improving wet performance by the longer one of the tapered surfaces 81, 83 in the tire circumferential direction and the effect of improving noise performance by the shorter one of the tapered surfaces 81, 83 in the tire circumferential direction, wherein the longer component has edge components that affect a lateral force, and the shorter component reduces the groove volume. Further, according to one embodiment, the lengths of the second central tapered surfaces 85, 87 in the tire circumferential direction are preferably different from each other.In these embodiments, the length of the chamfered surface having the longest length in the tire circumferential direction, among the chamfered surfaces having different lengths in the tire circumferential direction, is preferably 1.2 to 3 times, and more preferably 1.5 to 2 times, the length in the tire circumferential direction of the chamfered surface having the shortest length in the tire circumferential direction.

[0060] According to one embodiment, the length in the tire circumferential direction of the first central tapered surface 81, which is farther from the center line CL than the central tapered surface 83, is preferably greater than the length in the tire circumferential direction of the tapered surface 83 closer to the tire center line CL. This embodiment results in the effect of improving noise performance in a region at or near the tire center line CL and the effect of improving wet performance in a region away from the tire center line CL, and can thus effectively achieve the effect of suppressing a decrease in wet performance while improving noise performance as described above.Further, according to one embodiment, the length in the tire circumferential direction of the central tapered surface 87, which is farther from the tire center line CL than the central tapered surface 85, is preferably greater than the length in the tire circumferential direction of the tapered surface 85, which is closer to the tire center line CL.

[0061] According to one embodiment, the positions of the first central tapered surface 81 and the central tapered surface 83 in the tire circumferential direction preferably do not overlap with each other. Thus, the tapered surfaces 81, 83 are distributed in the tire circumferential direction, and the effects of the tapered surfaces on noise performance can be distributed. According to another embodiment, the positions of the second central tapered surfaces 85, 87 in the tire circumferential direction preferably do not overlap with each other. According to another embodiment, the positions of the tapered surfaces 81, 83, 85, 87 in the tire circumferential direction preferably do not overlap with each other.

[0062] According to one embodiment, the maximum depths of the tapered surfaces 81, 83, 85, 87 are preferably greater than the depths (maximum depths) of the sipes 51, 53, 55, 57, which open to the tapered surfaces 81, 83, 85, 87, respectively. The tapered surfaces 81, 83, 85, 87 are inclined toward the main grooves 21, 23 and 25, 27, respectively, and are deepest at the groove walls of the main grooves 21, 23 and 25, 27, respectively. Fig. 3 illustrates a maximum depth D81 of the beveled surface 81. Fig. 3 is a diagram illustrating a cross-section of an area between the first outer main groove 21 and the narrow groove 33. The maximum depths of the beveled surfaces 81, 83, 85, 87 are thus greater than the depths of the sipe depths 51, 53, 55, 57, and the sipes 51, 53, 55, 57 reach, as shown in Fig.4, not the groove walls of the main grooves 21, 23, 25, 27, which respectively open toward the tapered surfaces 81, 83, 85, 87 and close within the tapered surfaces 81, 83, 85, 87. That is, the sipes 51, 53, 55, 57, although not connected (directly open) to the respective main grooves 21, 23, 25, 27, are open to the tapered surfaces 81, 83, 85, 87, as described above, and thus communicate with the respective main grooves 21, 23, 25, 27. Fig.4 illustrates an embodiment of the tapered surfaces 81, 83 as depicting the tapered surfaces 81, 83, 85, 87. In an embodiment in which the sipes 51, 53, 55, 57 are not connected to the respective main grooves 21, 23, 25, 27, in contrast to an embodiment in which the sipes 51, 53, 55, 57 are connected to the respective main grooves 21, 23, 25, 27, excessive deformation of the land portion due to a decrease in rigidity is suppressed, and appropriate rigidity of the land portions is maintained. Such an embodiment contributes to improving wet performance.

[0063] According to one embodiment, the maximum depths of the beveled surfaces 81, 83 are preferably equal to one another. The maximum depths of the beveled surfaces 85, 87 are also preferably equal to one another. Furthermore, the maximum depths of the beveled surfaces 81, 83, 85, 87 are preferably equal to one another.

[0064] According to one embodiment, a side in the tire circumferential direction on which the first beveled surface 81 is located with respect to the first central sipe 51 (second side in Fig. 2), preferably the same side as a side in the tire circumferential direction on which the central beveled surface 83 is located with respect to the central sipe 53 (second side in Fig. 2). Furthermore, according to an embodiment, there is a side in the tire circumferential direction at which the second beveled surface 85 is inclined relative to the second central sipe 55 (second side in Fig. 2), preferably opposite a side in the tire circumferential direction on which the second central beveled surface 87 is arranged with respect to the second central sipe 57 (first side in Fig. 2) is arranged.

[0065] According to one embodiment, as in Fig.As illustrated in Figure 4, the tapered surfaces 81, 83 preferably each have a substantially triangular shape that decreases in length from one side to the other side in the tire width direction in the tire circumferential direction. This can minimize an effect of the tapered surfaces 81, 83 on noise performance. At least one of the tapered surfaces 85, 87, in addition to the tapered surfaces 81, 83, is preferably a surface having the substantially triangular shape. The vertices of the triangle of the substantially triangular shape are located in the groove wall of the main groove on the ground contact surface of the land portion in contact with the groove wall, and at the boundary between the ground contact surface and the groove wall.

[0066] According to one embodiment, each of the sipes 51, 53 preferably opens to a portion of a corresponding one of the tapered surfaces 81, 83, the portion being located where the tapered surface is longest in the tire width direction (a portion having a vertex of a substantially triangular shape in Fig. 4). Each of the sipes 55, 57 preferably opens to a portion of a corresponding one of the beveled surfaces 85, 87, the portion being located where the beveled surface is longest in the tire width direction.

[0067] According to one embodiment, each of the sipes 51, 53 preferably has a raised bottom portion (a main groove side connecting portion, which will be described later) at an opening end portion thereof opening to a corresponding one of the tapered surfaces 81, 83, the raised bottom portion having a depth greater than the maximum depth of a corresponding one of the sipes 51, 53. An embodiment in which the sipes 51, 53 are not connected to the main grooves 21, 23 increases the effect of maintaining appropriate rigidity of the land portions.According to one embodiment, each of the sipes 55, 57 preferably has a raised bottom portion (a main groove side connecting portion, which will be described later) at an opening end portion thereof opening to a corresponding one of the tapered surfaces 85, 87, the raised bottom portion having a depth greater than the maximum depth of a corresponding one of the sipes 55, 57.

[0068] According to one embodiment, as in Fig.4, the tread pattern further includes, in the first central region 71 and the central region 73, wall surfaces 82 and 84 of the land portions, respectively, which adjoin the tapered surfaces 81 and 83, respectively. The wall surfaces 82, 84 each extend continuously from the wall surface of a corresponding one of the sipes 51, 53, from an opening end portion of a corresponding one of the sipes 51, 53 to the groove wall of a corresponding one of the main grooves 21, 23, the sipes 51, 53 each opening toward the tapered surfaces 81, 83, and the tapered surfaces 81, 83 each being inclined toward the main grooves 21, 23. The wall surfaces 82, 84 preferably extend without inclination with respect to the tire radial direction. This reduces the groove volume and contributes to improving noise performance compared to an embodiment in which the wall surfaces 82, 84 are inclined with respect to the tire radial direction.This also improves the water film cutting effect and contributes to improving wet performance compared to an embodiment in which the wall surfaces 82, 84 are inclined with respect to the tire radial direction. For the same reasons, the tread pattern in the second central region 75 preferably further includes wall surfaces of the land portions adjacent to the tapered surfaces 85, 87. The wall surfaces of the land portions extend continuously from the wall surfaces of the sipes 55, 57, each from an opening end portion of a corresponding sipe 55, 57 to the wall surface of a corresponding main groove 25, 27, the sipes 55, 57 each opening toward the tapered surfaces 85, 87, and the tapered surfaces 85, 87 each being inclined toward the main grooves 25, 27.

[0069] According to one embodiment, each of the wall surfaces 82, 84 preferably extends along the extension direction of a corresponding one of the sipes 51, 53, which open to the tapered surfaces 81, 83, respectively. Furthermore, each of the wall surfaces 86, 88 connected to the tapered surfaces 85, 87 preferably extends along the extension direction of a corresponding one of the sipes 55, 57, which open to the tapered surfaces 85, 87. In an embodiment in which the wall surfaces extend away from the tapered surfaces 81, 83, 85, 87 with respect to the extension directions of the sipes 51, 53, 55, 57 (so that the inclination angles with respect to the tire width direction increase), the edge components that affect a lateral force can decrease, and the effect of suppressing a decrease in wet performance can decrease.

[0070] According to one embodiment, the inclination angles of the sipes 51, 53 with respect to the tire width direction are preferably 45 degrees or less. Edge components that have an effect on a lateral force are ensured by the chamfered surfaces 81, 83, and an edge effect with respect to a force in a front-rear direction can be enhanced by reducing the inclination angles of the sipes 51, 53. The inclination angles are preferably 10 to 35 degrees. The inclination angles of the sipes 55, 57 with respect to the tire width direction are also preferably 45 degrees or less.

[0071] According to the invention, the tread pattern further includes a tapered surface 89 (third tapered surface) having a surface inclined toward the narrow groove 33 in an end portion in the tire width direction on the narrow groove 33 side of the region 71A including the first center groove 51, the region 71A being one of two regions divided in the tire width direction by the narrow groove 33 in the first center region 71. The tapered surfaces 89 are provided in a plurality in the tire circumferential direction and are each adjacent in the tire circumferential direction to a connecting portion of the first center groove 51 and the narrow groove 33. According to one embodiment, the maximum depth of the tapered surface 89 is preferably smaller than the depth of the first center sipe 51.That is, the first middle slat 51 is preferably connected to the narrow groove 33 (directly opened).

[0072] According to the invention, the length of the chamfered surface 89 in the tire circumferential direction is smaller than the lengths of the chamfered surfaces 81, 83 in the tire circumferential direction, and smaller than the lengths of the chamfered surfaces 85, 87 in the tire circumferential direction.

[0073] According to one embodiment, the beveled surface 81 and the beveled surface 89 are preferably located on opposite sides of the first central sipe 51 in the tire circumferential direction (second side and first side in Fig. 2).

[0074] According to one embodiment, the tread pattern preferably has a vehicle mounting orientation provided such that the second half-tread area is on a vehicle outer side (referred to as “outer” side in Fig.2) of the first half tread region. As described above, the effect of improving noise performance can be achieved in the first center region 71 and the center region 73, which are adjacent to each other, and the first tread half including the tapered surfaces 81, 83 can be arranged on a vehicle inner side to effectively improve noise performance. Furthermore, the second tread half has a smaller groove area ratio than the first tread half and thus improves noise performance because it is arranged on the vehicle outer side. Number of spacings of the middle slats

[0075] According to one embodiment, the number of pitches G2 of the second center sipes 55, 57 adjacent in the tire circumferential direction (hereinafter referred to as the pitches G2 of the second center sipes 55, 57) is preferably greater than the number of pitches G1 of the first center sipes 51 adjacent in the tire circumferential direction (hereinafter referred to as the pitches G1 of the first center sipes 51). "The pitches of the adjacent sipes in the tire circumferential direction" refers to pitches of positions at which lines extending along the shapes of the sipes on the tread surface intersect the groove wall of the main groove in connection with the sipes (hereinafter the connection positions), and the positions are adjacent in the tire circumferential direction. Two adjacent connection positions may be located in the same main groove or in different main grooves.Thus, the intervals between second middle sipes having the connecting positions at the same positions in the tire circumferential direction in the region are not included in the “intervals of the sipes adjacent in the tire circumferential direction”.

[0076] In the present embodiment, the first central region 71 and the second central region 75 include the lug grooves 51, 55, 57, thereby reducing the groove volume and improving noise performance compared with a configuration in which they include lug grooves instead of the sipes 51, 55, 57. On the other hand, the first central region 71 including the narrow groove 33 compensates for the degradation of drainage properties caused by including the sipes 51 instead of the lug grooves and suppresses the degradation of wet performance. Furthermore, in the second central region 75, as described above, the number of pitches G2 of the second central sipes 55, 57 is larger than the number of pitches G1 of the first central sipes 51, which reduces the rigidity of the land portion of the second central region 75 and makes it easily deformable and more likely to follow the road surface.Thus, in the second center region 75, the adhesion friction with the road surface is large, and the effect of suppressing degradation of wet performance increases. That is, in the present embodiment, deterioration of wet performance is suppressed while simultaneously improving noise performance, compared with a configuration including lug grooves instead of the sipes 51, 55, 57. In the present embodiment, the two center regions 71, 75 differ in shape and have different functions related to wet performance, thereby suppressing degradation of wet performance. Thus, the tread pattern of the present embodiment is asymmetrical with respect to the tire center line CL.

[0077] Here, in the configuration where the number of pitches G2 of the second center sipes 55, 57 is equal to or smaller than the number of pitches G1 of the first center sipes 51, the rigidity of the second center region 75 is too high, the land portion is difficult to deform, and the tracking accuracy with the road surface is not excellent. Thus, the force required to adhere to the road surface by varying the force received from the road surface is insufficient.

[0078] According to one embodiment, the tread pattern preferably does not include lug grooves in the first central region 71 that communicate or are connected to at least one of the first outer main groove 21 or the first inner main groove 23 and extend in the tire width direction, and lug grooves in the second central region 75 that communicate or are connected to at least one of the second outer main groove 27 or the second inner main groove 25 and extend in the tire width direction. This reduces the groove volume and improves noise performance. According to another embodiment, the tread pattern preferably does not include lug grooves in the central region 73 that communicate or are connected to at least one of the first inner main groove 23 and the second inner main groove 25 and extend in the tire width direction.The lug groove is a groove having a component extending in the tire width direction and having a groove width of 1.5 mm or more.

[0079] According to one embodiment, the second middle slats preferably close, as in the Fig.2, the second center sipes 55 communicate with the second inner main groove 25 and the second center sipes 57 have connection positions with the second outer main groove 27 at positions in the tire circumferential direction different from the connection positions between the second center sipes 55 and the second inner main groove 25. Thus, in a configuration in which the second center region 75 includes both the sipes communicating with the second inner main groove 25 and the sipes communicating with the second outer main groove 27, the balance of the rigidity of the land portion in the second center region 75 in the tire width direction improves, and the land portion can easily follow various changes in the force received from the road surface.The percentage of the number of the second middle slats 55 and the second middle slats 57 to the total number of the second middle slats is preferably between 20 to 80%, more preferably between 30 to 70%.

[0080] In this embodiment, according to another embodiment, the second center sipes 57 are individually arranged between the second center sipes 55 adjacent in the tire circumferential direction. Accordingly, the rigidity balance in the tire width direction of the land portion of the second center region 75 is particularly improved. The above-described percentages are preferably 50% each.

[0081] In an embodiment in which a length L1 is a length along the tire circumferential direction between two connecting positions at which two second center sipes 55 adjacent in the tire circumferential direction communicate with the second circumferential main groove 25, the connecting positions of the second center sipes 57 with the second outer main groove 27 are as shown in Fig. 2, preferably in the range of 50 to 97% of the length L1 from one of the two connection positions (first side in Fig.2), and more preferably in the range of 70 to 95% thereof. This increases the effect of reducing tire noise. Note that "one of the two connection positions" refers to a connection position of the second center sipe 55 with the second inner main groove 25, the second center sipe 55 including a closed end within the range in the tire circumferential direction between the two connection positions.

[0082] In these embodiments, according to another embodiment, the direction connecting two ends of the second center sipe 55 in the extending direction thereof and the direction connecting two ends of the second center sipe 57 in the extending direction thereof are preferably inclined, as a direction from one end to the other in the tire width direction, to the same side in the tire circumferential direction with respect to the tire width direction. This can suppress a concentration of low-rigidity spots of the land portion in the second center region 75. Fig. 2, the two directions in the tire circumferential direction with respect to the tire width direction are directed to a first side (upper side in Fig.2) inclined. According to another embodiment, the first center sipe 51 and the second center sipe 55, 57 preferably have the above-described relationship of being inclined to the same side in the tire circumferential direction, and more preferably, the first center sipe 51, the center sipe 53, and the second center sipe 55, 57 have the above-described relationship of being inclined to the same side in the tire circumferential direction.

[0083] According to one embodiment, the length of the intervals G2 of the second central sipes 55, 57 preferably differs between the intervals adjacent in the tire circumferential direction. Fig. Figure 2 illustrates a plurality of gaps G2 having different lengths. This results in the effect of dispersing the frequency of the pattern noise, which contributes to improving noise performance.

[0084] According to one embodiment, the first central slats 51 are preferably connected to the narrow groove 33. This increases the drainage properties in the first central region 71.

[0085] In this embodiment, according to a further embodiment, as in Fig.3, a groove depth D51c of a narrow groove side connecting portion 51 of the first middle sipe 51, the narrow groove side connecting portion being connected to the narrow groove 33, is smaller than a groove depth D33 of the narrow groove 33, and a sipe depth D51b of an intermediate portion 51b of the first middle sipe 51, the intermediate portion being located between the first outer main groove 21 communicating with the first middle sipe 51 and the narrow groove side connecting portion 51c, is larger than the groove depth D33 of the narrow groove 33. The narrow groove side connecting portion 51c having such a raised bottom portion can suppress a decrease in rigidity at the connecting position of the first middle sipe 51 to the narrow groove 33.Furthermore, the intermediate portion 51b of the first middle sipe 51 is deeper than the narrow groove 33, and this improves the water absorption capacity of the first middle sipe 51 and contributes to improving the wet performance. Fig. 3 is a diagram illustrating a cross-sectional view of a portion of a tire width direction section of the first center region 71 extending along the extending direction of the first center sipe 51. In Fig. 3 lacks a third bevelled surface, which is described below.

[0086] In these two embodiments, according to another embodiment, a groove depth D51a of a main groove side connecting portion 51a of the first middle sipe 51, the main groove side connecting portion communicating with the first outer main groove 21, is preferably smaller than the groove depth D33 of the narrow groove 33. The main groove side connecting portion 51a having such a raised bottom portion can suppress a decrease in rigidity in a connecting position of the first middle sipe 51 with the first outer main groove 21.

[0087] The sipe depth D51c of the narrow groove side connecting portion 51c and the sipe depth D51a of the main groove side connecting portion 51a are preferably 20 to 50% of the sipe depth D51b of the intermediate portion 51b, and more preferably 30 to 40% thereof.

[0088] A groove depth D21 of the first outer main groove 21, the sipe depth D51b of the intermediate portion 51b, the groove depth D33 of the narrow groove 33, and the sipe depths D51c, D51a of the narrow groove side connecting portion 51c and the main groove side connecting portion 51a are preferably smaller in this order. That is, D21 > D51b > D33 > D51c, D51a is preferred. D51c and D51a may be different from each other, but are preferably the same.

[0089] According to one embodiment, the first center sipe 51 preferably extends in a curved shape to bulge to one side in the tire circumferential direction in the tread surface. This suppresses, in the first center region 71, the movement of portions on two sides of the first center sipe 51 in the tire circumferential direction that are displaced from each other in the tire width direction when a lateral force is applied, and this contributes to improving wet performance. In the Fig. In the example illustrated in Figure 2, the first center sipe 51 extends to form an arcuate shape that curves toward a first side in the tire circumferential direction on the tread surface. The radius of curvature of the arcuate shape of the first center sipe 51 is preferably 50 to 150 mm.

[0090] On the other hand, the second middle sipes 55, 57 and the middle sipes 53 preferably extend in a straight line on the tread surface.

[0091] In this case, according to another embodiment, the length of the first central sipe 51 in the extending direction thereof is preferably greater than the lengths of the second central sipes 55, 57 in the extending directions thereof. The number of first central sipes 51 is smaller than the total number of second central sipes 55, 57, and such an embodiment contributes to improving the balance of the rigidity of the first central region 71 and the second central region 75. This also facilitates adjusting the rigidity of the first central region 71 to a level between the rigidity of the second central region 75 and that of the central region 73.It should be noted that the length of the first middle slat 51 in the extending direction thereof is preferably greater than the length of the middle slat 53 in the extending direction thereof (for example, 115 to 125% of the length of the middle slat 53 in the extending direction thereof).

[0092] According to one embodiment, the second center sipes 55, 57 each extend in a straight line, and the inclination angle, with respect to the tire width direction, of the direction connecting two ends of the extending direction of the second center sipe 55 and the inclination angle, with respect to the tire width direction, of the direction connecting two ends of the extending direction of the second center sipe 57 are preferably different between the second center sipes 55, 57 adjacent in the tire circumferential direction.

[0093] According to one embodiment, the number of pitches G2 of the second center sipes 55, 57 is preferably larger than the number of pitches G3 of the adjacent center sipes 53 in the tire circumferential direction (hereinafter referred to as the pitches G3 of the center sipes 53). That is, the number of pitches G3 of the center sipes 53 is preferably smaller than the number of pitches G2 of the second center sipes 55, 57. The center region 73 has the longest ground contact length in the tire circumferential direction in the tread portion, and thus, a ground contact area with the road surface according to the above-described embodiment is preferably ensured.

[0094] In this case, according to another embodiment, the length of the second center sipe 55 and the length of the second center sipe 57 in the tire width direction are preferably 20 to 50% of the length of the second center region 75 in the tire width direction, and more preferably 30 to 40% thereof, and the length of the center sipe 53 in the tire width direction is 40 to 70% of the length of the center region 73 in the tire width direction, and more preferably 50 to 60% thereof. This can suppress an excessive decrease in the rigidity of the second center region 75 and the center region 73. Extension line

[0095] According to one embodiment, as described in Fig.5, the second center sipes 55 preferably overlap each of a plurality of extension lines S. The second center sipe 57 extends between two extension lines S of the plurality of extension lines S adjacent in the tire circumferential direction in a direction along the extension lines S. Fig. Figure 5 is a diagram explaining the extension lines S and illustrating two of the extension lines S in dashed lines.

[0096] The extension lines S are imaginary lines extending from a plurality of shoulder lug grooves 59 from the closed ends 59a of the plurality of shoulder lug grooves 59 smoothly along an inclination direction of the main groove side portions 59b to the closed ends 53a of a plurality of center sipes 53. The main groove side portion 59b is a portion of the shoulder lug groove 59 on one side of the main groove 27, the portion including the closed end 59a. The extension line S is a straight line. "Smoothly extending" means that, among the angles formed at the closed end 59a, 53a of the shoulder lug groove 59 between an inclination direction of the shoulder lug groove 59 with respect to the tire width direction and an extension direction of the extension line S, a smaller angle is 10 degrees or less, and preferably 5 degrees or less.Of the angles formed at the closed end 53a of the central slat 53 between a tilt direction of the central slat 53 and a tilt direction of the extension line S, the smaller one is preferably 10 degrees or less, and more preferably 5 degrees or less. Even more preferably, the two directions are the same.

[0097] That the “second center sipes 55 overlap the extension lines S” includes not only an embodiment in which the second center sipes 55 each contact or intersect the extension line S, but also an embodiment in which the second center sipes 55 each contact or intersect a region that is twice as far away from the extension line S in a direction orthogonal to the extension line S as the groove width of the main groove side portion 59b of the shoulder lug groove 59. Further, that “the second center sipe 57 extends in a direction along the extension lines S” means that an inclination angle of the extension direction of the second center sipe 57 with respect to the extension lines S is 10 degrees or less, preferably 5 degrees or less, and more preferably 0 degrees.

[0098] Thus, the shoulder lug groove 59, the second center sipe 55, and the center sipe 53 overlap the extension line S inclined with respect to the tire width direction, and the shoulder lug groove 59, the second center chamfered surface 87, and the second center chamfered surface 85 are slightly distributed in the tire circumferential direction and contribute to improving the noise performance.

[0099] On the other hand, the second central tapered surface 87 is arranged closer to the shoulder lug groove 59 than the second central tapered surface 85. Accordingly, the second central tapered surface 87 is arranged between two tire circumferentially adjacent extension lines S extending along the extension lines S, and thus does not overlap the extension lines S. Since the shoulder lug groove 59 has a large groove volume and generates a loud popping sound, the second central tapered surface 87 and the shoulder lug groove 59 are preferably separated from each other in the tire circumferential direction.

[0100] According to one embodiment, preferably, each of the shoulder lug grooves 59 and the center sipes 53 forms one end in the extending direction of one of the plurality of extension lines S, and each of the second center grooves 55 overlaps one of the extension lines S, and each of the second center sipes 57 extends between one of the pairs of extension lines S adjacent in the tire circumferential direction. Accordingly, an effect of distributing the second center tapered surface 85, the second center tapered surface 87, and the shoulder lug groove 59 at mutually different positions in the tire circumferential direction over the entire circumference in the tire circumferential direction can be obtained, and the effect of improving noise performance is increased.

[0101] Furthermore, according to another embodiment, the area of ​​the second central tapered surface 85 along the tire circumferential direction preferably does not overlap with the area of ​​the shoulder lug groove 59 in the tire circumferential direction. The second central tapered surface 85 and the shoulder lug groove 59, which are arranged at different positions in the tire circumferential direction, contribute to improving noise performance.

[0102] According to one embodiment, the regions in the tire circumferential direction of the adjacent extension lines S preferably do not overlap. An embodiment in which regions of two extension lines S overlap along the tire circumferential direction is less likely to result in the second central tapered surface 85, the second central tapered surface 87, and the shoulder lug groove 59 being distributed in the tire circumferential direction. Thus, the size of the inclination angle of the extension line S with respect to the tire width direction is preferably 10 to 30 degrees.

[0103] Furthermore, according to another embodiment, the center sipe 53, the second center sipe 55, and the second center sipe 57 preferably have substantially equal inclination angles with respect to the tire width direction. "Substantially equal" refers to a difference in inclination angle between the lug grooves of up to 10 degrees and preferably up to 5 degrees.

[0104] According to one embodiment, the first center sipe 51 preferably overlaps an unillustrated imaginary straight line (second extension line) extending from a connecting position of the center sipe 53 with the first inner main groove 23 to the outside in the tire width direction (vehicle mounting inside in Fig.2) extends along the inclination direction of the center sipe 53 with respect to the tire width direction. The expression "the first center sipe 51 overlaps the second extension line" includes not only an embodiment in which the first center sipe 51 contacts or intersects the second extension line, but also an embodiment in which the first center sipe 51 contacts or intersects a region that is twice as far from the extension line S in a direction orthogonal to the extension line S as the groove width of the main groove side portion 58b of the shoulder lug groove 58.

[0105] In the tread pattern according to the Fig.In the example illustrated in Figure 2, in the region 71B between the narrow groove 33 and the first inner main groove 23, no lug grooves and sipes communicating or connected with the narrow groove 33 or the first inner main groove 23 are provided, and a rib extending continuously in the tire circumferential direction is formed therein. In addition, the region 77B of the shoulder region 77 does not include lug grooves or sipes communicating or connected with the narrow groove 31 or the main groove 21, but includes a rib extending continuously in the tire circumferential direction. Thus, two narrow grooves 31, 33 in a region located on the inner side of the vehicle, the tread pattern, form many edge components extending in the tire circumferential direction, and the rigidity of the two ribs is ensured.This increases steering stability through an inner ring when turning. Preferably, the length (width) of the portion 77B in the tire width direction is greater than the width of the portion 71B. The narrow groove 31 preferably has a wider groove width than the narrow groove 33.

[0106] The tread pattern of the present embodiment is not limited to the tread pattern according to the Fig. 2 illustrated example. Comparison examples and examples

[0107] To investigate the effects of a pneumatic tire of the present embodiment, a tread pattern of the tire was varied, and wet performance and noise performance were examined. The prototype tires each had a size of 235 / 60R18 and were based on the tire described in Table 1 and below, except for the specifications illustrated in Table 1 and below. Fig. 2 illustrated tread pattern and the one in Fig. 1 and Fig.3 illustrated cross-sectional profile, and the beveled surfaces and wall surfaces on the Fig. 4 illustrated embodiment.

[0108] Table 1 shows an embodiment with respect to the tread pattern of each of the tires and evaluation results thereof.

[0109] In the comparative example and the examples including beveled surfaces, the beveled surfaces each have a substantially triangular shape as shown in Fig. 4. The wall surface adjacent to the beveled surface is a surface extending without inclination in the tire radial direction and along the extension direction of the sipe.

[0110] In the comparative example and the examples including tapered surfaces, the tapered surfaces 81, 83, 85, 87 are inclined to the main grooves 21, 23, 25, and 27, respectively, and the maximum depths of the tapered surfaces 81, 83, 85, 87 are 70% of the depths of the main grooves 21, 23, 25, and 27, respectively, and are greater than the maximum depths of the sipes 51, 53, 55, and 57 opening to the tapered surfaces 81, 83, 85, and 87, respectively. On the other hand, the maximum depth of the tapered surface 89 is 50% of the sipe depth of the raised bottom portion (narrow groove connecting portion) of the first middle sipe.

[0111] In Table 1, the "longitudinal / lateral length ratio of the chamfered surface" refers to the ratio of the tire circumferential direction length of the chamfered surface to its tire width direction length. In Comparative Example 3 and Examples, the chamfered surfaces 81, 83, 85, 87 have the same length in the tire width direction. Furthermore, in Comparative Example 3, the ratio of the chamfered surfaces 81, 83, 85, 87 was set to 1:3.

[0112] “Percentage of the length of the chamfered surface” refers to the percentage of the length of each of the chamfered surfaces 81, 83, 85, 87 in the tire circumferential direction with respect to the pitch of the sipes opening to the chamfered surface, the sipes being adjacent in the tire circumferential direction.

[0113] "Difference in length between chamfered surfaces" refers to whether there is a difference in the tire circumferential length between the chamfered surfaces 81, 83, 85, and 87. In the "Yes" example, the length of the chamfered surfaces 83, 85 in the tire circumferential direction was 2 / 3 times the length of the chamfered surfaces 81, 87 in the tire circumferential direction. Note that for the "Yes" example, the "Percentage of Longitudinal / Side Length of the Chamfered Surface" and the "Percentage of Longitudinal Length of the Chamfered Surface" in the table are represented by the values ​​of the chamfered surfaces 81, 87.

[0114] “Overlap of the chamfered surfaces in the circumferential direction” refers to the overlap in the tire circumferential direction of position ranges of the chamfered surfaces 81, 83, 85, 87. The “Yes” examples and the comparative example have the same configuration as Example 4, except that the center region 73 was shifted in the tire circumferential direction with respect to the first center region 71, so that the region, in the tire circumferential direction, of the location of the chamfered surface 83 overlaps with the regions, in the tire circumferential direction, of the positions of the chamfered surfaces 81, 85.

[0115] “Number of louver pitches of regions 71, 75” refers to the size ratio between the number of pitches G1 of the first middle louvers 51 in the first middle region 71 and the number of pitches G2 of the second middle louvers 55, 57 in the second middle region 75. “71 = 75” means that the number of pitches G1 and the number of pitches G2 are the same, whereas “71 < 75” means that the number of pitches G2 is greater than the number of pitches G1. The “71 = 75” examples and the comparative examples have the same configuration as the “71 < 75” examples, except that the pitch length of the second middle louvers 55, 57 was set to twice the pitch length in the “71 < 75” examples, and the number of second middle louvers and the number of first middle louvers 51 were the same.

[0116] Comparative Example 1 has the same configuration as Comparative Example 2, except that the sipes 51, 53, 55, 57 were replaced by lug grooves.

[0117] These test tires were evaluated for noise and wet performance as described below. The evaluation results are presented in Tables 1 and 2. During the evaluation, each of the test tires was mounted on a wheel with a rim size of 18x7.5J, mounted on a front-wheel drive vehicle with a displacement of 2400 cc, and inflated to an air pressure of 230 kPa. Noise output

[0118] For each test tire, the pass-by noise outside a vehicle was measured according to the requirements of the European noise regulation (ECE R117). The evaluation results were expressed as index values ​​using the reciprocals of measured values, with Comparative Example 1 assigned 100 as the reference. Higher index values ​​indicate excellent noise performance. Wet performance

[0119] Driving at speeds ranging from 40 to 100 km / h was conducted on a test track with an asphalt road surface sprayed with less than 1 mm of water. A test driver performed sensory evaluations of the steering characteristics during lane changes and cornering, and straight-line stability. Wet performance is expressed as index values, with Comparative Example 1 used as the prior art tire and assigned 100 as the reference. Larger index values ​​indicate excellent wet performance.

[0120] The allowable range of the noise performance index value for each tire of size 235 / 60R18 was evaluated as 103 or more, and that of the wet performance index value was evaluated as 98 and more, and a case satisfying these conditions was evaluated as successful in suppressing a decrease in wet performance while improving noise performance. [Table 1-I] Comparison example 1 Comparison example 2 Comparison example 3 Example 1 Example 2 Lug groove or sipe lug groove slat slat slat slat Presence of the beveled surface No No Yes Yes Yes Longitudinal / side length ratio of the beveled surface - - 1:3 12:1 3:1 Longitudinal direction Percentage of beveled surface (%) - - 1,7 20 5 Longitudinal difference between beveled surfaces - - No No No Circumferential overlap of beveled surfaces - - Yes Yes Yes Number of slat spacings of areas 71, 75 - 71 = 75 71 = 75 71 = 75 71 = 75 Side including the second tread half Inside Inside Inside Inside Inside Noise output 100 110 109 106 108 Wet performance 100 95 97 99 98 [Table 1-II] Example 3 Example 4 Example 5 Example 6 Lug groove or sipe slat slat slat slat Presence of the beveled surface Yes Yes Yes Yes Longitudinal / side length ratio of the beveled surface 3:1 3:1 3:1 3:1 Longitudinal direction Percentage of beveled surface (%) 5 5 5 5 Longitudinal difference between beveled surfaces Yes Yes Yes Yes Overlap in the circumferential direction of Yes No No No bevelled surfaces Number of slat spacings of areas 71, 75 71 = 75 71 = 75 71 < 75 71 < 75 Side including the second tread half Inside Inside Inside Outside Noise output 109 111 110 112 Wet performance 98 98 101 102

[0121] A comparison between Comparative Example 1 and Example 1 shows that a decrease in wet performance can be suppressed while improving noise performance in a configuration where the first and second sipes are provided and the chamfered surfaces opening to the sipes are longer in the tire circumferential direction than in the tire width direction. A comparison between Comparative Example 3 and Example 1 shows that the chamfered surfaces that are longer in the tire circumferential direction than in the tire width direction can improve wet performance.

[0122] A comparison between Example 1 and Example 2 shows that the noise performance improves in a configuration in which the ratios of the tire width direction lengths of the chamfered surfaces to the tire circumferential direction lengths are greater than 1 and 10 or less.

[0123] A comparison between Example 2 and Example 3 shows that the wet performance improves in a configuration in which the chamfered surfaces 81, 83, 85, 87 have different lengths in the tire circumferential direction.

[0124] A comparison between Example 3 and Example 4 shows that the wet performance improves in a configuration in which the areas in the tire circumferential direction of the positions of the beveled surfaces 81, 83, 85, 87 do not overlap.

[0125] A comparison between Example 4 and Example 5 shows that a configuration that includes more pitches of the second center sipes than the first center sipes improves wet performance. A comparison between Example 5 and Example 6 shows that noise performance and wet performance improve when a tire is mounted on a vehicle with the second tread half positioned on the vehicle's outer side of the first tread half.

[0126] Although the tire according to an embodiment of the present invention has been described in detail above, the tire according to an embodiment of the present invention is not limited to the above-described embodiments or examples and can of course be improved or modified in various ways without departing from the scope of the present invention. List of reference symbols 10 tires 10T tread section 10S page section 10B Bead section 12 carcass ply 14 belts 16 Bead core 18 Tread rubber link 20 side rubber link 22 Bead filler rubber link 24 Wheel rim cushion rubber link 26 inner liner rubber link 21 First outer main circumferential groove (first main circumferential groove) 23 First inner main groove (second main circumferential groove) 25 Second inner main groove 27 Second outer main groove 31, 33 Narrow groove 51 First slat (first middle slat) 51a Connecting section of the main groove side 51b Intermediate section 51c Connecting section of the narrow groove side 53 Second slat (middle slat) 55, 57 Second middle lamella 58, 59 shoulder lug groove 58a, 59a Closed end 58b, 59b Main groove side section 51a Closed end 71 First central area (area of ​​the first bridge section) 71A, 71B area in the first middle area 73 Middle area (area of ​​the second bridge section) 75 Second middle area 77, 79 shoulder area 77A Outer Area 77B Inner Area 81 surface)First beveled surface (first middle beveled 83 Second beveled surface (middle beveled surface) 85 Beveled surface (second middle beveled surface) 87 Beveled surface (second middle beveled surface) 89 Third beveled surface 82, 84 wall area

Claims

[1] A tire (10) comprising a tread pattern in a tread portion (10T), the tread pattern comprising: a first main circumferential groove (21) and a second main circumferential groove (22), which extend in the tire circumferential direction and are arranged at a distance in the tire width direction; a plurality of first sipes (51) extending in the tire width direction in a region of a first land portion (71) between the first circumferential main groove (21) and the second circumferential main groove (22) and arranged at intervals in the tire circumferential direction; a first tapered surface (81) having a tread surface of the first land portion (71) which is inclined toward the first circumferential main groove (21) in an end portion in the tire width direction on a first circumferential main groove side of the first land portion (71), the first tapered surface (89) being provided in a plurality in the tire circumferential direction, and the first sipes (51) opening to the plurality of first tapered surfaces (89) without reaching a groove wall of the first circumferential main groove (21); a plurality of second sipes (53) extending in the tire width direction within a region of a second land portion (73) located on an opposite side of the region of the first land portion (71) with respect to the second circumferential main groove (22) and arranged at intervals in the tire circumferential direction; and a second tapered surface (83) having a tread surface of the second land portion (73) which is inclined toward the second circumferential main groove (22) in an end portion in the tire width direction on a second circumferential main groove side (22) of the second land portion (73), the second tapered surface (83) being in a PS:CZ:al plurality in the tire circumferential direction, and the second sipes (53) open to the plurality of second tapered surfaces (83) without reaching a groove wall of the second circumferential main groove (22); a length in the tire circumferential direction of the first tapered surface (81) and a length in the tire circumferential direction of the second tapered surface (83) are greater than a length in the tire width direction of the first tapered surface (81) and a length in the tire width direction of the second tapered surface (83), wherein the tread pattern comprises a narrow circumferential groove (31, 33) extending in the tire circumferential direction in the region of the first land portion (71) and having a groove width that is smaller than the groove width of the first main circumferential groove (21) and the second main circumferential groove (22), and the first sipe (51) is arranged in a region between the first main circumferential groove (21) and the narrow circumferential groove (31, 33) and is connected to the narrow circumferential groove (31, 33), wherein the tread pattern has a third chamfered surface (89) with a surface inclined toward the narrow circumferential groove (31, 33) in an end portion in the tire circumferential direction on a side of the narrow circumferential groove (31, 33) of a region including the first sipes (51), the region being one of two regions of the first land portion (71) divided in the tire circumferential direction by the narrow circumferential groove (31, 33), the third chamfered surface (89) being provided in a plurality in the tire circumferential direction, and the third tapered surface (89) is provided in a plurality adjacent in the tire circumferential direction to connecting end portions of the first sipes (51) having the narrow circumferential groove (31, 33), wherein a length of the third tapered surface (89) in the tire circumferential direction is smaller than the lengths of the first tapered surface (81) and the second tapered surface (83) in the tire circumferential direction. [2] The tire (10) according to claim 1, wherein the length of the tapered surface (81, 83) in the tire circumferential direction is 5 to 50% of a length of a pitch of the sipes (51, 53) adjacent in the tire circumferential direction, the sipes (51, 53) opening toward the tapered surface (81, 83). [3] The tire (10) according to claim 1, wherein a ratio of the length of the chamfered surface (81, 83, 85, 87) in the tire circumferential direction to the length of the chamfered surface (81, 83, 85, 87) in the tire width direction is greater than 1 and 10 or less. [4] A tire (10) according to any one of claims 1 to 3, wherein the tire circumferential lengths of the first tapered surface (81) and the second tapered surface (83) are different from each other. [5] Tire (10) according to claim 4, wherein the first beveled surface (81) and the second beveled surface (83) are arranged on one side of a tire center line in the tire width direction, and of the first tapered surface (81) and the second tapered surface (83), the tire circumferential length of the one tapered surface farther from the tire center line is greater than the tire circumferential length of the one tapered surface closer to the tire center line. [6] The tire (10) according to claim 4 or 5, wherein the positional ranges of the first tapered surface (81) and the second tapered surface (83) do not overlap in the tire circumferential direction. [7] Tire (10) according to one of claims 1 to 6, wherein the maximum depth of the beveled surface (81, 83, 85, 87) is greater than the depth of the sipe opening (51, 53, 55, 57) to the beveled surface (81, 83, 85, 87). [8] A tire (10) according to any one of claims 1 to 7, wherein the chamfered surface (81, 83, 85, 87) has a substantially triangular shape decreasing in length in the tire width direction from one side in the tire circumferential direction to another side in the tire circumferential direction. [9] A tire (10) according to any one of claims 1 to 8, wherein the sipe (51, 53) includes a raised lower portion at an opening end portion of the sipe (51, 53) opening toward the tapered surface (81, 83), the raised lower portion having a depth greater than a maximum depth of the sipe. [10] A tire (10) according to any one of claims 1 to 9, wherein the tread pattern further comprises, in the region of the land portion (71, 73), a wall surface of the land portion (71, 73) adjacent to the tapered surface (81, 83), the wall surface of the land portion continuously extending from a wall surface of the sipe (51, 53, 55, 57) from an opening end portion of the sipe opening to the tapered surface (81, 83, 85, 87) to a wall surface of the circumferential main groove (21, 23, 25, 27) to which the tapered surface (81, 83, 85, 87) is inclined, and the wall surfaces (82, 84) extend without inclination with respect to the tire radial direction. [11] A tire (10) according to any one of claims 1 to 10, wherein the tread pattern further comprises, in the region of the land portion (71, 73), a wall surface of the land portion (71, 73) adjacent to the tapered surface (81, 83, 85, 87), the wall surface of the land portion continuously extending from a wall surface of the sipe (51, 53, 55, 57) from an opening end portion of the sipe opening to the tapered surface (81, 83, 85, 87) to a wall surface of the circumferential main groove (21, 23, 25, 27) to which the tapered surface (81, 83, 85, 87) is inclined, and the wall surface extends along an extending direction of the sipe (51, 53, 55, 57) to the tapered surface (81, 83, 85, 87). [12] A tire (10) according to any one of claims 1 to 11, wherein the first sipe (51) and the second sipe (53) are inclined to the same side in the tire circumferential direction with respect to the tire width direction. [13] The tire (10) of claim 1, wherein a maximum depth of the third beveled surface (89) is smaller than a depth of the first sipe (51). [14] A tire (10) according to any one of claims 1 to 13, wherein the tread pattern does not include lug grooves extending in the tire width direction within the area of ​​the land portion (71, 73, 75).

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