pneumatic tires

Abstract

A pneumatic tire (10) comprising a tread portion (10T) provided with a tread pattern, the tread pattern comprising: a pair of circumferential main grooves (50, 52) comprising an inner circumferential main groove (50) provided in a first half-tread area on one side with respect to a tire equator line (CL) in the tire transverse direction and an outer circumferential main groove (52) provided outside the inner circumferential main groove (50) in the tire transverse direction; a land portion (60) defined by the pair of circumferential main grooves (50, 52) in the tire transverse direction; and a plurality of sipes (60a, 60b) provided at an interval in the tire circumferential direction, the plurality of sipes (60a, 60b) being provided in a region of the land portion (60) and connecting the pair of circumferential main grooves (50, 52) to each other, each of the plurality of slats (60a, 60b) comprising: a pair of inclined sipe portions (60a1, 60a2, 60b1, 60b2) which approach each other as they advance from the connecting ends of the pair of circumferential main grooves (50, 52) to a first side in the tire circumferential direction; and a slat turning portion (60a3, 60b3) connecting ends of the pair of inclined slat portions (60a1, 60a2, 60b1, 60b2) and bent to project toward the first side, and a profile line (PL1) formed by the tread surface of the land portion (60), which is a swell profile line (PL1) projecting outside the standard profile line (PL0) in the tire radial direction, when an arc passing through two land portion edge points at which the tread surface of the land portion (60) is connected to groove wall surfaces of the pair of circumferential main grooves (50, 52) is set on a standard profile line (PL0) in a profile cross section of the tread portion (10T) along the tire transverse direction, wherein a protrusion end of the sipe turning portion (60a3, 60b3) projecting furthest to the first side is present within a range of 70% of a width of the land portion (60) in the tire transverse direction with a maximum swell position of the swell profile line (PL1) as the center; wherein the tread pattern comprises a plurality of lug grooves (61) provided at an interval in the tire circumferential direction, the plurality of lug grooves (61) connecting the pair of main circumferential grooves (50, 52) to each other, each of the plurality of lug grooves (61) comprises: a pair of inclined groove portions (61a1) which approach each other as they advance from connecting ends of the pair of circumferential main grooves (50, 52) to the first side in the tire circumferential direction; and a groove turning portion (61a2) which connects ends of the pair of inclined groove portions (61a1) to each other and is bent to project toward the first side in the tire circumferential direction, the land portion (60) is formed of a plurality of block land portions divided by the plurality of lug grooves (61) in the tire circumferential direction, and in a region of each of the plurality of block web sections, two of the plurality of sipes (60a, 60b) are provided as a first sipe (60a) and a second sipe (60b); where a protrusion end of the groove turning portion (61a2) protruding furthest toward the first side is present within a maximum swell position of the swell profile line (PL1) in the tire transverse direction.

Description

Technical field

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

[0002] In the prior art, a tread pattern of a pneumatic tire provides a plurality of circumferential main grooves extending in the tire circumferential direction, and lug grooves and sipes intersecting land portions defined in the tire transverse direction by two circumferential main grooves. An all-season pneumatic tire, widely used in North America and Europe (hereinafter referred to as an all-season tire), is positioned as a tire between a regular summer tire used in the snow-free season and a snow tire, referred to as a winter tire. Excellent control performance, braking performance, and driving performance on snow-covered road surfaces (snow performance) are required for the all-season tire. Thus, in order to increase the edge components, a series of sipes and lug grooves are provided in addition to the circumferential main grooves.

[0003] For example, a pneumatic tire that improves the resistance to uneven wear of a center portion in the tread transverse direction while ensuring performance on snow is known (JP 2013-244907 A). The pneumatic tire includes: a center circumferential main groove formed in a center portion of a tread in the tire transverse direction and extending in the tire circumferential direction; outer circumferential main grooves formed outside the center circumferential main groove in the tread and adjacent to the center circumferential main groove and extending in the tire circumferential direction;lateral main grooves formed in the tread, extending in a direction crossing the tire circumferential direction, communicating with the central circumferential main groove and the outer circumferential main grooves, and having a groove depth, with respect to a tread surface as a reference, that is deeper than a groove depth of the central circumferential main groove and shallower than a groove depth of the outer circumferential main grooves; and center blocks defined by the central circumferential main groove, the outer circumferential main grooves, and the lateral main grooves. Further, a sipe is provided in a groove bottom of the central circumferential main groove.

[0004] Furthermore, document JP 2013-244907 A relates to a pneumatic tire provided with a tread pattern. A first position in a tire transverse direction of a protruding apex of the sipe turn portion of a first sipe is located in a region of a raised bottom portion in the tire transverse direction in which the raised groove bottom portion is provided. Document DE 11 2018 006 716 T5 relates to a pneumatic tire having a tread portion including an intermediate land portion in the tire transverse direction positioned on one side across a tire centerline as a boundary; and a side land portion positioned outside the outer circumferential main groove in the tire transverse direction and including a ground contact edge of the pneumatic tire in a region thereof. Further prior art is provided by DE 11 2019 000 697 T5. Brief description of the inventionTechnical problem

[0005] With the edges of the center blocks formed by the lateral main grooves, the pneumatic tire described above can ensure snow performance. Furthermore, the lateral main grooves communicate with the center circumferential main groove and the outer circumferential main grooves. The groove depth of the lateral main grooves is set shallower than that of the outer circumferential main grooves, and the groove depth of the center circumferential main groove is set shallower than that of the lateral main grooves. Thus, the rigidity of the center blocks is ensured and excessive deformation of the center blocks during loaded tire rolling is suppressed. This can suppress sawtooth wear of the center blocks. As a result, the resistance to uneven wear of the center portion in the tread transverse direction can be improved while ensuring snow performance.

[0006] The pneumatic tire exhibits excellent resistance to uneven wear. However, when applied to an all-season passenger car tire, such a tread pattern does not always achieve steering stability on dry road surfaces suitable for a passenger car.

[0007] In view of the above, the present invention has an object to provide a pneumatic tire capable of improving steering stability performance on dry road surfaces and performance on snow with a new tread pattern different from the tread pattern described above. Solution to the problem

[0008] One aspect of the present invention is a pneumatic tire provided with a tread pattern.

[0009] The tread pattern includes a pair of circumferential main grooves including an inner circumferential main groove provided in a first-half tread region on one side with respect to a tire equator line in the tire transverse direction and an outer circumferential main groove provided outside the inner circumferential main groove in the tire transverse direction; a land portion defined by the pair of circumferential main grooves in the tire transverse direction; and a plurality of sipes provided at an interval in the tire circumferential direction, the plurality of sipes being provided in a region of the land portion and connecting the pair of circumferential main grooves to each other.

[0010] Each of the plurality of sipes includes a pair of inclined sipe portions that approach each other while advancing from the connecting ends of the pair of circumferential main grooves to a first side in the tire circumferential direction; and a sipe turn portion that connects ends of the pair of inclined sipe portions to each other and is bent to project toward the first side. A pattern line formed by the tread surface of the land portion is a swell pattern line projecting outside the standard pattern line in the tire radial direction. When an arc passing through two land portion edge points where the tread surface of the land portion is connected to groove wall surfaces of the pair of circumferential main grooves is set on the standard pattern line, in a pattern cross-section of the tread portion along the tire transverse direction.

[0011] According to the invention, a protrusion end of the sipe turning portion protruding most toward the first side is present within a range of 70% of a width of the land portion in the tire transverse direction with a maximum swell position of the swell profile line as a center.

[0012] According to the invention, the tread pattern includes a plurality of lug grooves provided at an interval in the tire circumferential direction, the plurality of lug grooves connecting the pair of circumferential main grooves with each other, each of the plurality of lug grooves including: a pair of inclined groove portions that approach each other while advancing from connecting ends of the pair of circumferential main grooves to the first side in the tire circumferential direction;and a groove turn portion connecting ends of the pair of inclined groove portions to each other and bent to project toward the first side in the tire circumferential direction, wherein the land portion is formed of a plurality of block land portions divided by the plurality of lug grooves in the tire circumferential direction, and in a region of each of the plurality of block land portions, two of the plurality of sipes are provided as a first sipe and a second sipe.;

[0013] According to the invention, a protrusion end of the groove turning portion protruding furthest to the first side is located inward of a maximum swell position of the swell profile line in the tire transverse direction.

[0014] Preferably, a protrusion end of the sipe turning portion protruding furthest toward the first side is located inward of a maximum swell position of the swell profile line in the tire transverse direction.

[0015] Preferably, a protrusion end of the groove turn portion protruding most toward the first side is present within a range of 70% of a width of the land portion in the tire transverse direction with a maximum swell position of the swell profile line as a center.

[0016] Preferably, the groove turning portion is provided with a raised groove bottom portion having a groove depth shallower than a groove depth of the pair of inclined groove portions, wherein the first sipe is provided on the first side with respect to the second sipe, and a first position of a protrusion end of the sipe turning portion of the first sipe in the tire transverse direction, which protrudes most toward the first side, is in a raised bottom portion region in the tire transverse direction in which the raised groove turning portion is provided, and is inward in the tire transverse direction with respect to a second position of a protrusion end of the sipe turning portion of the second sipe in the tire transverse direction, which protrudes most toward the first side.

[0017] Preferably, in the region of each of the plurality of block land portions, a region between the first sipe and the second sipe in the tire circumferential direction is provided with a third sipe having a terminal end in the raised land portion region in the tire transverse direction, the third sipe extending, with an inclination with respect to the tire transverse direction, from the inner circumferential main groove outward in the tire transverse direction along at least one of the pair of inclined sipe portions of the first sipe and the second sipe extending from the inner circumferential main groove.

[0018] Preferably, a maximum projection amount of the threshold profile line with respect to the standard profile line falls within a range of 0.1 mm to 1.0 mm.

[0019] When the land portion is a first intermediate land portion, the tread pattern preferably further includes a first side land portion outside the outer circumferential main groove in the tire transverse direction, the first side land portion having a ground contact edge of the pneumatic tire in a region, a region of the first side land portion being provided with a sixth sipe connected to the outer circumferential main groove, each of the first sipe, the second sipe, and the sixth sipe being a composite sipe including: a straight sipe having a shape extending linearly from the tread surface in the sipe depth direction;and a wave-like sipe bent or curved so as to project in a direction orthogonal to the sipe depth direction and an extension direction in which each of the first sipe, the second sipe, and the sixth sipe extends along the tread surface as it advances from the tread surface in the sipe depth direction, the straight sipe being provided on one side in the sipe extension direction from the tread surface, and the wave-like sipe being provided on another side in the sipe extension direction, the straight sipe and the wave-like sipe being connected in the composite sipe, and each of the parts of the first sipe, the second sipe, and the sixth sipe connected to the outer circumferential main groove being the wave-like sipe.

[0020] Preferably, when the inner circumferential main groove is a first inner circumferential main groove and the outer circumferential main groove is a first outer circumferential main groove, a second half tread region on a side opposite to the first half tread region in the tire transverse direction includes: a second inner circumferential main groove; a second outer circumferential main groove provided outside the second inner circumferential main groove in the tire transverse direction; a continuous land portion defined by the second inner circumferential main groove and the second outer circumferential main groove and present around a circumference in the tire circumferential direction;and a fourth sipe and a fifth sipe connecting the second inner circumferential main groove and the second outer circumferential main groove, the fourth sipe and the fifth sipe extending to be inclined with respect to the tire transverse direction in a region of the continuous land portion, each of the fourth sipe and the fifth sipe including: an inner inclined portion provided in a region of the continuous land portion;and wherein both laterally inclined portions are provided on both sides of the inner inclined portion in the tire transverse direction and are connected to the second inner circumferential main groove and the second outer circumferential main groove, wherein the inner inclined portion of the fourth sipe and the inner inclined portion of the fifth sipe are parallel to each other, and an inclination angle of the inner inclined portion with respect to the tire transverse direction is larger than an inclination angle of the two laterally inclined portions with respect to the tire transverse direction.;

[0021] When the continuous land portion is a second intermediate land portion, the tread pattern preferably further includes a second side land portion provided outside the second outer circumferential main groove in the tire circumferential direction, the second side land portion having a ground contact edge of the pneumatic tire in a region thereof, a region of the second side land portion being provided with a seventh sipe connected to the second outer circumferential main groove, each of the fourth sipe, the fifth sipe, and the seventh sipe being a composite sipe including: a straight sipe having a shape extending linearly from the tread surface in the sipe depth direction;and a wave-like sipe bent or curved so as to project in a direction orthogonal to the sipe depth direction and an extension direction in which each of the fourth sipe, the fifth sipe, and the seventh sipe extends along the tread surface as they advance from the tread surface in the sipe depth direction, the straight sipe being provided on one side and the wave-like sipe being provided on another side, the straight sipe and the wave-like sipe being connected in the composite sipe, and each of the parts of the fourth sipe, the fifth sipe, and the seventh sipe connected to the second outer circumferential main groove being the wave-like sipe;

[0022] When the inner circumferential main groove is a first inner circumferential main groove and the outer circumferential main groove is a first outer circumferential main groove, a second half-tread region in the tread pattern on a side opposite to the first half-tread region in the tire transverse direction preferably includes: a second inner circumferential main groove; a second outer circumferential main groove provided outside the second inner circumferential main groove in the tire transverse direction; the first inner circumferential main groove between the first inner circumferential main groove and the second inner circumferential main groove; a central continuous land portion defined by the first inner circumferential main groove and the second inner circumferential main groove and present around a circumference in the tire circumferential direction;a plurality of first center lug grooves provided at an interval in the tire circumferential direction, the plurality of first center lug grooves extending inwardly in the tire transverse direction from the first inner main circumferential groove and terminating in a region of the center continuous land portion;and a plurality of second center lug grooves provided at an interval in the tire circumferential direction, the plurality of second center lug grooves extending inward in the tire transverse direction from the second inner circumferential main groove and terminating in a region of the center continuous land portion, any one of the plurality of second center lug grooves being provided in a region in the tire circumferential direction between two first center lug grooves adjacent to each other in the tire circumferential direction among the plurality of first center lug grooves, and any one of the plurality of first center lug grooves being provided in a region in the tire circumferential direction between two second center lug grooves adjacent to each other in the tire circumferential direction among the plurality of second center lug grooves;

[0023] Preferably, a maximum groove depth of the plurality of second central lug grooves is shallower than a maximum groove depth of the plurality of first central lug grooves.

[0024] Preferably, the pneumatic tire is provided to have one side of both sides in the tire transverse direction, the one side being a vehicle outer side when the pneumatic tire is mounted on a vehicle, and a side in the tire transverse direction provided with the first half tread portion being provided as the vehicle outer side.

[0025] Preferably, a shoulder lug groove is provided outside the outer circumferential main groove in the first half tread region in the tire transverse direction; the tread pattern includes, in a second half tread region on a side opposite to the first half tread region in the tire transverse direction, a second inner circumferential main groove; a second outer circumferential main groove provided outside the second inner circumferential main groove in the tire transverse direction; and a shoulder lug groove provided outside the second outer circumferential main groove in the tire transverse direction, and a groove area ratio in a region outside the first outer circumferential main groove in the tire transverse direction is smaller than a groove area ratio in a region outside the second outer circumferential main groove in the tire transverse direction. Advantageous effects of the invention

[0026] According to the pneumatic tire described above, steering stability performance on dry road surfaces and performance on snow can be improved. Brief description of the drawings Fig. 1 is a tire cross-sectional view of a tire according to one embodiment. Fig. 2 is an explanatory view of a tread pattern of an embodiment. Fig. 3 is an explanatory view of profile lines formed by land portions of the tire according to an embodiment. Fig. 4 is a detailed explanatory view of an intermediate land portion and a lug groove of an embodiment in an enlarged form. Fig. 5A to 5E are explanatory views of embodiments of a composite sipe provided in the tread pattern of an embodiment. Fig. 6A and Fig.6B are explanatory views of embodiments of sipes of an embodiment extending along a depth direction. Fig. 7 is a view partially illustrating a tread pattern used in Comparative Examples 1 and 3. Description of embodiments

[0027] Now, a pneumatic tire according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0028] The pneumatic tire according to an embodiment described below is applied to an all-season tire for a passenger car and can also be applied to an all-season tire for a light truck or an all-season tire for a bus and a truck.

[0029] Herein, "tire transverse direction" is the direction parallel to the rotational axis of the pneumatic tire. "Tire transverse outward" is the tire transverse direction direction away from a tire equator line CL, which represents the equatorial plane of the tire, with respect to a reference position. "tire transverse inward" is the tire transverse direction direction toward the tire equator line CL with respect to a reference position. "tire circumferential direction" is the direction in which the pneumatic tire rotates around the rotational axis of the pneumatic tire. "tire circumferential direction" includes a first side and a second side in different directions from each other. "tire radial direction" is the direction perpendicular to the rotational axis of the pneumatic tire. "tire radial outward" is the direction away from the rotational axis along the tire radial direction with respect to a reference position.“Inward in tire radial direction” is the direction toward the axis of rotation along the tire radial direction with respect to a reference position.

[0030] In the following description, the ground contact edges of the pneumatic tire refer to edges farthest from the tire equator line CL in an area where a tread surface of a tread portion of the pneumatic tire contacts a dry, horizontal surface when the pneumatic tire is mounted on a regular rim, inflated to a regular internal pressure, and loaded with 70% of a regular load. Here, "regular rim" refers to a "standard rim" as defined by the Japan Automobile Tire Manufacturers Association Inc. (JATMA), a "design rim" as defined by the Tire and Rim Association, Inc. (TRA), or a "measuring rim" as defined by the European Tire and Rim Technical Organization (ETRTO).Additionally, "Regular Air Pressure" refers to a "maximum air pressure" as defined by JATMA, the maximum value in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" as defined by TRA, or "INFLATION PRESSURES" as defined by ETRTO. "Regular Load" refers to a "maximum load capacity" as defined by JATMA, the maximum value in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" as defined by TRA, or "LOAD CAPACITY" as defined by ETRTO. Tire structure

[0031] Fig.1 is a tire cross-sectional view of a tire 10 according to an embodiment. 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 both sides of the tread portion 10T, connecting the pair of bead portions 10B and the tread portion 10T.

[0032] The tire 10 mainly includes: a carcass ply layer 12, a belt layer 14 and a bead core 16 as frame members or layers of frame members and 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.

[0033] The carcass ply layer 12 consists of a carcass ply member made of rubber-coated organic fibers, which is wound between a pair of annular bead cores 16 and formed into a ring shape. The carcass ply member is wound around the bead cores 16 and extends outward in the tire radial direction. The belt layer 14 is provided outside the carcass ply layer 12 in the tire radial direction and consists of two belt links 14a, 14b. The belt layer 14 is a link made of rubber-coated steel cords. The steel cords are inclined at a predetermined angle, for example, of 20 to 30 degrees with respect to the tire circumferential direction. A width in the tire transverse direction of the belt link 14a located in the lower layer is larger than that of the belt link 14b located in the upper layer.The inclination direction of the steel cords of the two belt links 14a and 14b is opposite to each other with respect to the tire equator line CL. As such, the belt links 14a, 14b are intersecting layers that suppress expansion of the carcass ply layer 12 due to the pressure of the air in the tire.

[0034] The tread rubber member 18 is disposed outside the belt layer 14 in the tire radial direction. Both end portions of the tread rubber member 18 are bonded to the side rubber members 20 to form the side portions 10S. The rim cushion rubber members 24 are provided at the inner ends of the side rubber members 20 in the tire radial direction and come into contact with a rim on which the tire 10 is mounted. The bead filler rubber members 22 are provided outside the bead cores 16 in the tire radial direction so as to be interposed between a portion of the carcass ply layer 12 before being wound around the bead cores 16 and a portion of the carcass ply layer 12 after being wound around the bead cores 16. The inner liner rubber member 26 is provided on the inner surface of the tire 10 facing a tire cavity portion filled with air and surrounded by the tire 10 and the rim.

[0035] In addition, the tire 10 includes two belt cover layers 30 formed of rubber-coated organic fibers or steel cords, the belt cover layers 30 covering the belt layer 14 from an outer side in the tire radial direction of the belt layer 14. Furthermore, the tire 10 may include a bead reinforcing member between the carcass layer 12 wrapped around the bead core 16 and the bead filler rubber member 22.

[0036] The tire structure of the present embodiment is as described above. However, the tire structure is not particularly limited, and a known tire structure is applicable. Tread pattern

[0037] Fig. 2 is an explanatory view of an example of the tread pattern of an embodiment. Fig.The tread pattern illustrated in Figure 2, which will be described below, is an asymmetric pattern with respect to the tire equator line CL and may not necessarily be a symmetric pattern. For example, a point-symmetric pattern can be obtained by forming a tread pattern on a right side of an inner circumferential main groove 54 in Fig. 2 combined with a tread pattern in which a part of the tread pattern outside an inner main circumferential groove 50 in the tire transverse direction is rotated 180 degrees (upside down) on the paper sheet in Fig. 2 is turned over and then arranged in a part on a left side of the inner main circumferential groove 54 on the left side of the tire equator line CL.

[0038] As in Fig.2, the tread pattern of the tread portion 10T mainly includes: the inner circumferential main grooves 50 and 54, the outer circumferential main grooves 52 and 56, a central continuous land portion 58, the intermediate land portions 60 and 62, the side land portions 64 and 66, and the lug grooves 59a, 59b, 61, 63, 65, and 67.

[0039] It should be noted that, among the two types of circumferential main grooves respectively defining the intermediate land portions 60 and 62 provided on both sides in the tire transverse direction across the tire equator line CL as a boundary, the inner circumferential main grooves 50 and 54 do not necessarily have to be provided on one side in the tire transverse direction. Specifically, in one embodiment, the inner circumferential main grooves 50 and 54 may be provided as one groove on the tire equator line CL, and one of the two types of circumferential main grooves defining the intermediate land portions 60 and 62 may be shared as one inner circumferential main groove, that is, three circumferential main grooves may be provided.

[0040] On both sides in the tire transverse direction across the tire equator line (tire center line) CL as a boundary, the tread portion 10T includes: the intermediate land portion 60 defined by the inner circumferential main groove 50 and the outer circumferential main groove 52 in the tire transverse direction; and the intermediate land portion 62 defined by the inner circumferential main groove 54 and the outer circumferential main groove 56 in the tire transverse direction. Further, the tread portion 10T includes the side land portions 64 and 66 that are in contact with the outer circumferential main grooves 52 and 56, formed outside the outer circumferential main grooves 52 and 56 in the tire transverse direction, and enclose the ground contact edges of the pneumatic tire 10 within their regions.

[0041] The inner circumferential main grooves 50 and 54 are positioned inside the outer circumferential main grooves 52 and 56 in the tire transverse direction (on the side near the tire equator line CL) and are arranged to be in contact with the central land portion 58 to define the central land portion 58.

[0042] The outer circumferential main grooves 52 and 56 are positioned outside the inner circumferential main grooves 50 and 54 in the tire transverse direction and are arranged to be in contact with the intermediate land portion 60 and the intermediate land portion 62 to define the intermediate land portion 60 and the intermediate land portion 62 together with the inner circumferential main grooves 50 and 54. The intermediate land portion 60 is defined by the lug groove 61 in the tire circumferential direction and forms a plurality of block land portions. The intermediate land portion 60 and the side land portions 64 and 66 are block land portions obtained by arranging a plurality of block land portions defined by the lug grooves in the tire circumferential direction at an interval in the tire circumferential direction.Each of the central land portion 58 and the intermediate land portion 62 is a substantially continuous land portion extending continuously around the tire circumference in the tire circumferential direction. The substantially continuous land portion refers to a land portion that is not divided by a lug groove in the tire circumferential direction. In the substantially continuous land portion, a sipe may be connected to the circumferential main grooves on both sides in the tire transverse direction. Hereinafter, the substantially continuous land portion is referred to as a continuous land portion.

[0043] Specifically, the center land portion 58, the lug groove 59a (first center lug grooves), and the lug groove 59b (second center lug grooves) are provided between the inner circumferential main groove 50 (first inner circumferential main groove) and the inner circumferential main groove 54 (second inner circumferential main groove). Hereinafter, the lug grooves 59a and 59b are also referred to as the center lug grooves 59a and 59b. The center land portion 58 is a continuous land portion defined by the inner circumferential main groove 50 and the inner circumferential main groove 54 and is present around the circumference in the tire circumferential direction. The center lug groove 59a extends inwardly from the inner main circumferential groove 50 in the tire transverse direction and terminates in a region of the center land portion 58. The center lug groove 59b extends inwardly from the inner main circumferential groove 54 in the tire transverse direction and terminates in the region of the center land portion 58.A plurality of center lug grooves 59a and a plurality of center lug grooves 59b are provided at an interval in the tire circumferential direction. One center lug groove 59b is provided in a region in the tire circumferential direction between two center lug grooves 59a adjacent to each other in the tire circumferential direction, and one center lug groove 59a is provided in a region in the tire circumferential direction between two center lug grooves 59b adjacent to each other in the tire circumferential direction. Specifically, the lug grooves 59a extending from the inner circumferential main groove 50 and the lug groove 59b extending from the inner circumferential main groove 54 are provided alternately in the tire circumferential direction.

[0044] The sipes 58a are provided in the region of the central land portion 58. The sipe 58a communicates with a terminal end of the central lug groove 59a and the inner circumferential main groove 54 or communicates with a terminal end of the central lug groove 59b and the inner circumferential main groove 50.

[0045] The intermediate land portion 60 and the lug groove 61 are provided between the inner circumferential main groove 50 (the first inner circumferential main groove) and the outer circumferential main groove 52 (the first outer circumferential main groove) formed in a half-tread area on the right side of the tire equator line CL in Fig. 2 are provided.

[0046] A plurality of lug grooves 61 are provided at an interval in the tire circumferential direction.

[0047] The intermediate land portion 60 is formed of a plurality of block land portions defined by the inner circumferential main groove 50 and the outer circumferential main groove 52 in the tire transverse direction, defined by the lug grooves 61 in the tire circumferential direction, and aligned in the tire circumferential direction.

[0048] The lug grooves 61 communicate with the inner circumferential main groove 50 and the outer circumferential main groove 52. The plurality of lug grooves 61 are provided at an interval in the tire circumferential direction and define the intermediate land portion 60 in the tire circumferential direction. As shown in Fig.As illustrated in Figure 2, the lug groove 61 has a peak-like shape when viewed from the outside of the tread surface in the tire radial direction, having substantially the same groove width and projecting to one side in the tire circumferential direction. According to the invention, the lug groove 61 includes: a pair of inclined groove portions 61a1 that approach each other while advancing from a connecting end of the inner circumferential main groove 50 and a connecting end of the outer circumferential main groove 52 toward the first side in the tire circumferential direction (see Fig. 4); and a groove turning portion 61a2 which connects ends of the pair of inclined groove portions 61a1 to each other and which turns to project in a tip-like shape toward the first side in the tire circumferential direction (see Fig. 4). As in Fig.As illustrated in FIG. 2, a protrusion end of the tip-like shape is offset inward in the tire transverse direction with respect to a center line of the intermediate land portion 60 in the tire transverse direction. In a region of the intermediate land portion 60, the sipes 60a, 60b, and 60c are provided. The sipes 60a and 60b connect the inner circumferential main groove 50 and the outer circumferential main groove 52 to each other. Similar to the lug groove 61, when the tread surface is viewed from the outside in the tire radial direction, the sipes 60a and 60b extend to have a tip-like shape projecting to one side in the tire circumferential direction and being parallel to the lug groove 61. According to the invention, a plurality of the sipes 60a and a plurality of sipes 60b are provided at an interval in the tire circumferential direction. The slat 60a and the slat 60b include: a pair of inclined slat portions 60a1 and 60a2 (see Fig.4) or a pair of inclined slat sections 60b1 and 60b2 (see Fig. 4) and slat turning sections 60a3 and 60b3 (see Fig. 4). The pair of inclined sipe portions 60a1 and 60a2 and the pair of inclined sipe portions 60b1 and 60b2 approach each other as they extend in the tire circumferential direction from a connecting end of the inner circumferential main groove 50 and a connecting end of the outer circumferential main groove 52 to the first side (in Fig. 2 upwards). The slat turning sections 60a3 and 60b3 connect the pair of inclined slat sections 60a1 and 60a2 (see Fig. 4) or the pair of inclined slat sections 60b1 and 60b2 (see Fig.4) and rotate to project to the first side. Meanwhile, the sipe 60c is provided between the sipe 60a and the sipe 60b in the tire circumferential direction, extends outward from the inner circumferential main groove 50 parallel to the sipe 60a and the sipe 60b in the tire transverse direction in an inclined manner with respect to the tire transverse direction, and terminates in the region of the intermediate land portion 60.

[0049] The lug groove 63 extends from the outer circumferential main groove 56 toward the inner circumferential main groove 54 and terminates in a region of the intermediate land portion 62 without communicating with the inner circumferential main groove 54. A plurality of lug grooves 63 are provided at an interval in the tire circumferential direction. In the region of the intermediate land portion 62, a sipe 62c communicating with a terminal end of the lug groove 63 and the inner circumferential main groove 54 is provided from the terminal end of the lug groove 63. Further, in the region of the intermediate land portion 62, between the adjacent lug grooves 63 in the tire circumferential direction, sipes 62a and 62b are provided, connecting the outer circumferential main groove 56 and the inner circumferential main groove 54. The lug groove 63 and the sipes 62a, 62b and 62c are each inclined with respect to the tire transverse direction.This inclination direction is inclined from the tire transverse direction to another side in the tire circumferential direction with respect to the inclination direction of the center lug grooves 59a and 59b and the sipe 58a. The sipes 62a and 62b (the fourth and fifth sipes) include steeply inclined parts 62a1 and 62b1 that are parallel to each other and steeply inclined so that the inclination directions of the sipes 62a and 62b are close to the tire circumferential direction; and gently inclined parts 62a2 and 62b2 that are provided on both sides of the steeply inclined parts and are slightly inclined with respect to the tire transverse direction. The gently inclined parts 62a2 and 62b2 are open to the inner circumferential main groove 54 and the outer circumferential main groove 56.

[0050] Specifically, the sipes 62a and 62b each include: an inner inclined portion provided within the range of the intermediate land portion 62; and lateral inclined portions provided on both sides of the inner inclined portion in the tire transverse direction, which are respectively connected to the inner circumferential main groove 54 and the outer circumferential main groove 56. An inclination angle of the inner inclined portion of each of the sipes 62a and 62b with respect to the tire transverse direction is larger than an inclination angle of the two laterally inclined portions with respect to the tire transverse direction.

[0051] The lug groove 65 extends from the outer circumferential main groove 52 outward in the tire transverse direction to a pattern end E1. A plurality of lug grooves 65 are provided at intervals in the tire circumferential direction. The sipes 64a and 64b extending outward in the tire transverse direction from the outer circumferential main groove 52 are provided in a region of the side land portion 64 between the lug grooves 65 adjacent to each other in the tire circumferential direction.

[0052] The lug groove 67 extends from the outer circumferential main groove 56 outward in the tire transverse direction to a pattern end E2. A plurality of lug grooves 67 are provided at an interval in the tire circumferential direction. The sipes 66a and 66b extending outward in the tire transverse direction from the outer circumferential main groove 56 are provided in a region of the side land portion 66 between the lug grooves 67 adjacent to each other in the tire circumferential direction.

[0053] The groove depths of the inner circumferential main grooves 50 and 54 and the outer circumferential main grooves 52 and 56, and the groove depths of the lug grooves 59a, 59b, 61, 63, 65, and 67 fall within a range of, for example, 1.5 mm to 11.0 mm. The groove widths of the inner circumferential main grooves 50 and 54 and the outer circumferential main grooves 52 and 56, and the groove widths of the lug grooves 59a, 59b, 61, 63, 65, and 67 fall within a range of, for example, 1.5 mm to 17.5 mm.

[0054] The sipes 58a, 60a, 60b, 60c, 62a, 62b, 62c, 64a, 64b, 66a, and 66b have a sipe depth that falls within a range of, for example, 3.0 mm to 8.0 mm; and a distance between the sipe wall surfaces that falls within a range of, for example, 0.4 mm to 1.5 mm. The dimensional ranges of the groove depth and the distance between the sipe wall surfaces are distinguished from those of the groove depth and groove width. This allows the sipes to be distinguished from the grooves.

[0055] Fig. 3 is an explanatory view of profile lines of the tread surface obtained by each of the Fig. 2 illustrated web sections of the tread pattern are formed.

[0056] As in Fig.3, the intermediate land portions 60 and 62 and the side land portions 64 and 66 include sill profile lines PL1 and PL2. The center land portion 58 includes a standard profile line PL0. Here, in the profile cross section of the tread portion along the tire transverse direction, the standard profile line PL0 refers to an arc line. The arc line passes through at least two land portion edge points where the intermediate land portion 60 is connected to the two circumferential main grooves (the inner circumferential main groove 50 and the outer circumferential main groove 52), and the arc line has a center point located on the tire equator line CL. In this case, the standard profile line PL0 may pass through a side land portion edge point where the side land portion 64 is connected to the outer circumferential main groove 52.Furthermore, in the profile cross section of the tread portion along the tire transverse direction, the standard profile line PL0 refers to an arc line. The arc line passes through at least two land portion edge points where the intermediate land portion 62 connects to the two circumferential main grooves (the inner circumferential main groove 54 and the outer circumferential main groove 56), and the arc line has a center point located on the tire equator line CL. In this case, the standard profile line PL0 preferably passes through the two side land portion edge points where the side land portions 64 and 66 connect to the outer circumferential main grooves 52 and 56. In many cases, the profile lines of the tread portion have a line-symmetrical shape with respect to the tire equator line CL.In such a case, the standard profile line PL0 passes through the two land portion edge points and the one side land portion edge point located on both sides in the tire transverse direction. Also in this case, the standard profile line PL0 preferably passes through the two side land portion edge points where the side land portions 64 and 66 are connected to the outer circumferential main grooves 52 and 56.

[0057] Note that the expression that the standard profile line PL0 passes through the two web section edge points and the one side web section edge point indicates a case where the standard profile line PL0 passes through locations slightly deviating from these points, in addition to a case where the standard profile line PL0 passes exactly through these points. In this case, it is preferable to specify an arc line with a minimum total distance from each of the points to the arc line as the standard profile line PL0.For example, in the case of the profile line having a line-symmetric shape with respect to the tire equator line CL, an arc line having a center point on the tire equator line CL and having a radius with a minimum of total distances to the two land portion edge points and the one side land portion edge point located on both sides in the tire transverse direction is preferably set as the standard profile line PL0.

[0058] Meanwhile, the sill profile lines PL1 and PL2 are profile lines that project outward from the standard profile line in the tire radial direction. Specifically, the profile lines of the intermediate land portions 60 and 62 project outward in the tire radial direction with respect to the standard profile line PL0 passing through the land portion edge points of each of the land portions, and the profile lines of the side land portions 64 and 66 project outward in the radial direction with respect to the standard profile line PL0 passing through the side land portion edge points of each of the land portions. Therefore, the sill profile line PL1 projects outward from the two land portion edge points of each of the intermediate land portions 60 and 62 with respect to the standard profile line PL0 in the tire radial direction.The swell pattern line PL2 protrudes outward from the one lateral land portion edge point of each of the side land portions 64 and 66 with respect to the standard pattern line PL0 in the tire radial direction. A maximum protrusion amount of the swell pattern lines PL1 and PL2 with respect to the standard pattern line PL0 preferably falls within a range of, for example, 0.1 mm to 1.0 mm. The maximum swell amount is set to fall within a range of 0.1 mm to 1.0 mm, and thus a ground contact pressure of the central regions of the intermediate land portions 60 and 62 and the side land portions 64 and 66 can be effectively increased. Thus, the ground contact length can be increased.

[0059] The intermediate land portion 60 has a profile line formed from the swell profile line PL1. As described above, in the region of the intermediate land portion 60, the sipe 60a and the sipe 60b are formed in a tip-like shape, projecting to one side in the tire circumferential direction.

[0060] In this way, the sipe 60a and the sipe 60b are provided, which are long enough to have a length exerting a high edge effect due to such a tip-like shape. However, the block rigidity of the intermediate land portion 60 is deteriorated, which is disadvantageous in terms of steering stability. However, the profile line of the intermediate land portion 60 is set to the swell profile line PL1, and therefore, a ground contact pressure of the intermediate land portion 60 is increased at the central part of the intermediate land portion 60 in the tire transverse direction. Thus, even if a slip angle is formed for the tire 10 during cornering and a pressure of an end of the intermediate land portion 60 on a cornering inner side in the tire transverse direction is lowered, the pressure at the central portion of the intermediate land portion 60 is still high. In this way, the ground contact of the intermediate land portion 60 can be ensured.In this regard, the steering stability, which is likely to be deteriorated by the deterioration of the block rigidity due to the sipe 60a and the sipe 60b, can be improved by increasing the ground contact pressure of the central part due to the swell profile line PL1.

[0061] According to the embodiment, the protrusion ends of the tip-like shapes of the sipe turning portions 60a3 and 60b3 of the sipe 60a and the sipe 60b, which protrude furthest toward the first side, are located within 70% of the width of the intermediate land portion 60 in the tire transverse direction, with the maximum swell position of the swell profile line PL1 in the tire transverse direction as the center. At this time, the sipe turning portions of the sipe 60a and the sipe 60b are arranged at the central portions where the ground contact length of the intermediate land portion 60 is the largest. Thus, an edge length of the sipe in contact with a road surface is increased. As a result, snow performance can be improved by increasing the edge effect of the sipe 60a and the sipe 60b.

[0062] In this case, the protrusion ends of the sipe turning portions 60a3 and 60b3 of the sipe 60a and the sipe 60b are preferably provided inward in the tire transverse direction with respect to the maximum swell position of the sill pattern line PL1 in the tire transverse direction. Thus, the sipe portions 60a1 and 60b1 continuously inclined in one direction are provided outside the maximum swell position of the sill pattern line PL1 in the tire transverse direction. Thus, when the tire 10 is steered with the intermediate land portion 60 located on the cornering outer side with respect to the tire equator line CL, thus forming a slip angle, a marginal effect of the inclined sipe portions 60a1 and 60b1 is effectively exerted, and handling (steerability) on snow-covered road surfaces is improved.

[0063] As described above, the intermediate land portion 60 is a block land portion defined by the lug grooves 61 in the tire circumferential direction. Two sipes 60a and 60b are provided in the area of ​​each of the intermediate land portions 60. Thus, with the edges of the lug grooves 61 and the edges of the sipes 60a and 60b aligned, snow performance, particularly braking and driving performance on snow-covered road surfaces, is improved.

[0064] According to the embodiment, the protrusion end of the groove turning portion 61a2 of the lug groove 61, which protrudes in a tip-like shape toward the first side, is preferably located in a range of 70% of the width of the intermediate land portion 60 in the tire transverse direction, with the maximum swell position of the swell profile line PL1 in the tire transverse direction as the center. Thus, similar to the sipe 60a and the sipe 60b, the groove turning portion 61a2 of the lug groove 61 is located in the central portion where the ground contact length of the intermediate land portion 60 is the largest. Thus, an edge length of the lug groove 61 in contact with a road surface is increased. As a result, snow performance can be improved by increasing an edge effect of the lug groove 61.

[0065] In this case, the protrusion end of the groove turning portion 61a2 of the lug groove 60 is located inward in the tire transverse direction with respect to the maximum swell position of the swell pattern line PL1 in the tire transverse direction. Thus, the inclined groove portion continuously inclined in one direction is provided outside the maximum swell position of the swell pattern line PL1 in the tire transverse direction. Thus, when steering the tire 10 is performed so that the intermediate land portion 60 is located on the cornering outer side with respect to the tire equator line CL and thus a slip angle is formed, a marginal effect of the inclined groove portion is effectively exerted, and handling (steerability) on snow-covered road surfaces is improved.

[0066] According to the embodiment as shown in Fig.4, the groove turning portion 61a2 of the lug groove 61 is preferably provided with a raised groove bottom portion 61a3 (the hatched portion in Fig. 4) which has a groove depth that is shallower than the groove depth of the inclined groove section. Fig. 4 is a detailed explanatory view of the intermediate land portion 60 and the lug groove 61 of the embodiment in an enlarged form. As in Fig. 4, the slat 60a (the first slat) on the first side (in Fig.4 above) of the sipe 60b (the second sipe). In this case, a first position of the protrusion end of the sipe turn portion 60a3 of the sipe 60a in the tire width direction, which projects most toward the first side, is preferably located in a raised land portion area W in the tire width direction in which the raised groove bottom portion 61a3 is provided, and is preferably located inward in the tire width direction with respect to a second position of the protrusion end of the sipe turn portion 60b3 of the sipe 60b in the tire width direction, which projects most toward the first side. The intermediate land portion 60 can improve snow performance with an edge effect of the sipes 60a and 60b. On the other hand, the block rigidity of the intermediate land portion 60 is deteriorated when the sipes 60a and 60b are provided.

[0067] Specifically, the groove turning portion 61a2 of the lug groove 61 defining the intermediate land portion 60 in the tire circumferential direction is a part where strain is likely to concentrate when the intermediate land portion 60 receives a lateral force or a longitudinal force from a road surface and is deformed, and is a part that affects a magnitude of deformation of the intermediate land portion 60. Thus, the groove turning portion 61a2 is provided with the raised groove bottom portion 61a3, and thus the block rigidity of the intermediate land portion 60 can be increased. Specifically, the sipe turning portion 60a3 of the sipe 60a is provided near the raised groove bottom portion 61a3 of the lug groove 61. Specifically, the protrusion end of the sipe turning portion 60a3 is provided in the raised bottom portion region where the raised groove bottom portion 61a3 of the lug groove 61 is provided in the tire transverse direction.Furthermore, the protruding end of the sipe turning portion 60a3 is provided inward in the tire transverse direction with respect to the position of the protruding end of the sipe turning portion 60b3 of the sipe 60b in the tire transverse direction. Thus, when the sipe 60a exerts an edge action, the deterioration of the block rigidity of the intermediate land portion 60 can be suppressed. This can improve steering stability and snow performance.

[0068] According to the embodiment, in a region between the sipe 60a and the sipe 60b in the tire circumferential direction in the region of each of the intermediate land portions 60, which are block land portions, the sipe 60c (the third sipe) extending outward from the inner circumferential main groove 50 in the tire transverse direction is inclined with respect to the tire transverse direction and has a terminal end in the raised land portion region in the tire transverse direction, is preferably provided parallel to the inclined sipe portions 60a2 and 60b2 of the sipe 60a and the sipe 60b extending from the inner circumferential main groove 50. The position of the protruding end of the sipe turning portion 60a3 of the sipe 60a and the position of the protruding end of the sipe turning portion 60b3 of the sipe 60b are different from each other in the tire transverse direction.Thus, a space for providing the sipe 60c can be easily provided in a part of the inter-block land portion 60 located on a side near the inner circumferential main groove 50. The sipe 60c can be provided, and an edge effect can be enhanced, which improves snow performance.

[0069] As in Fig.2, the sipes 64a and 64b (the sixth sipes) connected to the outer circumferential main groove 52 are provided in the region of the side land portion 64 provided outside the outer circumferential main groove 52 in the tire transverse direction. The region includes the ground contact edge of the tire 10. According to the embodiment, all of the sipes 60a, 60b, 64a, and 64b connected to the region of the intermediate land portion 60 and the region of the side land portion 64 are preferably formed of composite sipes.The composite sipe includes: a straight sipe having a shape that extends linearly from the tread surface in the sipe depth direction; and a wave-like sipe that is bent or curved in a wave-like shape and projects in a direction perpendicular to the sipe depth direction and an extension direction that extends along the tread surface of the sipe as it advances from the tread surface in the sipe depth direction. The composite sipe has a structure in which the straight sipe and the wave-like shape are connected, while the straight sipe is provided on one side in the extension direction and the wave-like sipe is provided on the other side as viewed from the tread surface of the sipes 60a, 60b, 64a, and 64b.In this case, according to the embodiment, all parts of the sipes 60a, 60b, 64a, and 64b connected to the outer circumferential main groove 52 are preferably wave-like sipes. Further, in another embodiment, all parts of the sipes 60a, 60b, 64a, and 64b connected to the outer circumferential main groove 52 are the wave-like sipes in the composite sipes. In addition, the sipes 62a and 62b and the sipes 66a and 66b (the seventh sipes) are preferably formed of composite sipes, and all parts of the sipes 62a, 62b, 66a, and 66b connected to the outer circumferential main groove 56 are preferably wave-like sipes.

[0070] Fig. 5A to 5E are explanatory views of embodiments of the composite sipe provided in the tread pattern of an embodiment. Fig. 6A and Fig.6B are explanatory views of embodiments of the sipes 60a, 60b, 60c, 62a, 62b, 64a, 64b, 66a and 66b extending along the depth direction.

[0071] Each of the slats 60a, 60b, 60c, 62a, 62b, 64a, 64b, 66a and 66b is a composite slat in which a slat S1 and a slat S2 are connected to each other.

[0072] Here is how in Fig. 6A illustrates that the sipe S1 is a straight sipe having a shape extending linearly from the tread surface in the sipe depth direction. As shown in Fig. 6B, the sipe S2 is a wave-like sipe that is bent or curved in a wave-like shape and projects in the direction perpendicular to the sipe depth direction and the extension direction from the tread surface as it advances from the tread surface in the sipe depth direction.

[0073] The sipe 58a provided in the region of the central land portion 58 is a sipe having a shape extending linearly from the tread surface in the depth direction, that is, the sipe S1.

[0074] As from Fig. 2 and Fig. 5A and Fig. 5B, in the sipes 60a and 60b, the sipe S2 is provided on the side near the outer circumferential main groove 52, and the sipe S1 is provided on the side near the inner circumferential main groove 50. In each of the sipes 60a and 60b, a connecting position of the sipe S1 and the sipe S2 is provided such that an upper portion of the tip-like shape of each of the sipes 60a and 60b, which protrudes to one side in the tire circumferential direction, is the sipe S1.

[0075] As from Fig. 2 and Fig.5C, in each of the sipes 64a and 64b, the sipe S2 is provided on the side near the outer main circumferential groove 52 and the sipe S1 is provided on the side near the pattern end E1.

[0076] As from Fig. 2 and Fig. 5D, in each of the sipes 62a and 62b, the sipe S2 is provided on the side near the outer circumferential main groove 56, and the sipe S1 is provided on the side near the inner circumferential main groove 54. In each of the sipes 62a and 62b, a connecting position of the sipe S1 and the sipe S2 is provided such that the steeply inclined part steeply inclined with respect to the tire transverse direction is the sipe S1.

[0077] Furthermore, as can be seen from Fig. 2 and Fig.5E, in each of the sipes 66a and 66b (the seventh sipe), the sipe S2 is provided on the side near the outer main circumferential groove 56, and the sipe S1 is provided on the side near the pattern end E2.

[0078] The intermediate land portion 60 and the side land portion 64, which are arranged on both sides of the outer circumferential main groove 52 in the tire transverse direction, and the intermediate land portion 62 and the side land portion 66, which are arranged on both sides of the outer circumferential main groove 56 in the tire transverse direction, are located outside the central land portion 58 in the tire transverse direction and are parts that contribute to the generation of lateral force during cornering. Thus, the tread rigidity of the parts is preferably high. Thus, in the parts on both sides of the outer circumferential main grooves 52 and 56 in the tire transverse direction, the tread rigidity or block rigidity, which is likely to be deteriorated by the sipes 60a, 60b, 64a, and 64b and the sipes 62a, 62b, 66a, and 66b, is preferably improved.All the portions of the sipes 60a, 60b, 64a, and 64b that are connected to the outer circumferential main groove 52, and the portions of the sipes 62a, 62b, 66a, and 66b that are connected to the outer circumferential main groove 56, are the wave-like sipes. Thus, the wave-like sipes are engaged with each other, and the tread rigidity or block rigidity can be improved.

[0079] Therefore, by disposing the wave-like sipes in the parts of the sipes 60a, 60b, 64a and 64b connected to the outer circumferential main groove 52 and the parts of the sipes 62a, 62b, 66a and 66b connected to the outer circumferential main groove 56, the steering stability can be improved.

[0080] As described above, the discontinuous lug groove 63, which does not communicate with the inner circumferential main groove 54, is provided in the region of the intermediate land portion 62, and the continuous land portion is formed. Thus, the tread rigidity can be improved and the wear resistance can be enhanced. On the other hand, if the sipes 62a and 62b including the steeply inclined portions are provided inside, the deterioration of the tread rigidity can be suppressed and the on-snow performance can be improved.

[0081] Furthermore, the non-continuous lug grooves 59a, which do not communicate with the inner circumferential main groove 54, and the non-continuous lug grooves 59b, which do not communicate with the inner circumferential main groove 50, are provided in the region of the central land portion 58, and the lug grooves 59a and 59b are alternately provided in the tire circumferential direction. Thus, the continuous land portion with high tread rigidity is formed, which is advantageous in terms of wear resistance. Furthermore, in the continuous land portion, a peripheral effect of the lug grooves 59a and 59b can be effectively exerted, improving snow performance.

[0082] It should be noted that the maximum groove depth of the central lug groove 59b is preferably shallower than the maximum groove depth of the central lug groove 59a. As in Fig.As illustrated in Figure 2, in the tread pattern, in the half-tread area on the right side of the tire equator line CL, the use of sipes and lug grooves enhances edge performance, thereby improving snow performance. The maximum groove depth of the center lug groove 59a is deeper than the maximum groove depth of the center lug groove 59b. Thus, the center lug groove 59a can capture a large amount of snow, and edge performance can be enhanced. Thus, snow performance can be improved.

[0083] According to the embodiment, the tire 10 is provided such that one side of both sides in the tire transverse direction corresponds to a vehicle outer side when the tire is mounted on a vehicle. This designation is displayed in information indicating a vehicle outer side or a vehicle inner side as a side pattern with alphanumeric characters, symbols, reference characters, or the like in the side portion 10S. In a case of the tire in Fig. 2, one side of the half-tread area is on the right side of the Fig. 2 illustrated tire equator line CL is preferably provided as a vehicle outer side. In the Fig. In the half-tread area on the right side of the tire equator line CL illustrated in Figure 2, an edge effect is enhanced by the use of the sipes and the lug grooves to improve performance on snow. Fig.2, the intermediate land portion 62 is provided as a continuous land portion to improve wear resistance. A vehicle on which the tire is mounted is often set to have a negative camber. Thus, taking the negative camber into account, for the purpose of improving wear resistance, the tire 10 is preferably mounted on a vehicle such that the half-tread portion on the left side is in Fig. 2 on one side of the vehicle and that the half-tread area on the right side is in Fig. 2, in which a ground contact surface is likely to be increased during cornering, braking and driving, on an outer side of the vehicle.

[0084] In this case, a groove area ratio in the shoulder region including the side land portion 64 (the first side land portion) provided outside the outer circumferential main groove 52 in the tire transverse direction and located on the vehicle outer side is preferably smaller than a groove area ratio in the shoulder region including the side land portion 66 (the second side land portion) provided outside the outer circumferential main groove 56 in the tire transverse direction. Fig.In the embodiment illustrated in FIG. 2, the lug groove 65 has a groove width in the vicinity connected to the outer circumferential main groove 52 that is narrower than the groove width of the lug groove 67, and a groove width that is even narrower. This creates a difference in the groove area ratios. The side land portions 64 with a small groove area ratio are arranged on the vehicle outer side, and thus the block rigidity of the side land portion 64 is higher than that of the side land portion 66. This can improve steering stability. Examples and comparative examples

[0085] In order to confirm the effects of the tire according to the embodiment, the tread pattern was changed differently and the steering stability and snow performance (snow braking performance and snow handling performance) were evaluated.

[0086] Structures of the manufactured tires (tire size: 265 / 50R20 111W) were tested on the Fig. The structure illustrated in Figure 1 was established. The manufactured tires were mounted on a rim (rim size: 20×8.5J) (air pressure of 250 kPa). Furthermore, the manufactured tires were mounted on a test vehicle (a 3.6-liter SUV).

[0087] For the evaluation of steering stability, the test vehicle was driven on a predetermined route on a dry road surface, and a sensory evaluation of the test vehicle's responsiveness to the driver's steering was provided. For the sensory evaluation, the evaluation values ​​of other comparative examples and examples were indexed, with the index of Comparative Example 1 being 100. A higher index indicates better steering stability.

[0088] To evaluate snow braking performance, the test vehicle was driven on a predetermined route on snow-covered road surfaces, and the braking distance was measured when performing an emergency stop from a speed of 30 km / h. The measurement results were indexed as the reciprocals of the braking distances of other comparative examples and examples using the reciprocal of the braking distance of Comparative Example 1 as a reference. In this way, snow braking performance was evaluated. The index of Comparative Example 1 was 100. Thus, a higher index indicates better snow braking performance.

[0089] Furthermore, with regard to snow handling performance, the test vehicle was driven on a predetermined route with snow-covered road surfaces, and a sensory evaluation of the test vehicle's responsiveness to driver steering was provided. For the sensory evaluation, the evaluation values ​​of other comparative examples and examples were also indexed, with the index of Comparative Example 1 being 100. A higher index indicates better snow handling performance.

[0090] Tables 1 and 2 below show various modified specifications of the tread pattern and their evaluation results, where the Fig. 2 serves as a reference. The tire 10 was mounted on a vehicle so that the right side of the tread pattern shown in Fig.2 illustrated tire equator line CL of the vehicle outer side. The “presence of spike-like sipes and spike-like lug grooves” in Tables 1 and 2 indicates whether the Fig. 2 and the tip-like lug grooves 61 were provided. In Comparative Examples 1 and 3, in which the presence of tip-like sipes and tip-like lug grooves was indicated as "No", the Fig. 7 illustrated intermediate web sections 160 instead of the Fig. 2 was used, and unidirectionally inclined sipes and lug grooves were provided between an outer main circumferential groove and an inner main circumferential groove. Fig. 7 is a view partially illustrating a tread pattern used in Comparative Examples 1 and 3.

[0091] Furthermore, the "position from the maximum swell position to the sipe protrusion end (%)" and the "position from the maximum swell position to the lug groove protrusion end (%)" in Tables 1 and 2 indicate ratios (%) obtained by dividing the distances in the tire transverse direction from the maximum swell position of the swell profile line PL1 to the positions of the protrusion ends of the sipes 60a and 60b and the lug groove 61 by the width of the intermediate land portion 60 in the tire transverse direction. "Inside" indicates that the positions of the protrusion ends of the sipes 60a and 60b and the lug groove 61 were within the maximum swell position in the tire transverse direction, and "outside" indicates that the positions of the protrusion ends of the sipes 60a and 60b and the lug groove 61 were outside the maximum swell position in the tire transverse direction.

[0092] It should be noted that the maximum threshold amount of the threshold profile lines PL1 and PL2 with respect to the standard profile line PL0 was set to 0.2 mm.

[0093] The groove area ratio in the area of ​​the side web section 66 was set at 24%.

[0094] In Example 8 in Table 2, the groove width of the lug groove 65 was set equal to the groove width of the lug groove 67, and thus the groove area ratio in the region of the side land portion 64 was set equal to the groove area ratio in the region of the side land portion 66.

[0059] [Table 1] Comparison example 1 Comparison example 2 Comparison example 3 Example 1 Example 2 Example 3 Presence of spike-like lamellae and spike-like lug grooves No Yes No Yes Yes Yes Presence of threshold profile lines PL1 and PL2 No No Yes Yes Yes Yes Position from maximum threshold position to slat projection end (%) Inwards by 20% Inwards by 35% Inwards by 35% Position from maximum swell position to lug groove protrusion end (%) Inwards by 10% Inwards by 25% Inwards by 35% Whether the groove area ratio in the shoulder region on the side near the side land portion 64 is smaller than the groove area ratio in the shoulder region on the side near the side land portion 66. Small Small Small Small Small Small Handling performance on snow 100 101 100 105 104 103 Braking performance on snow 100 101 100 105 104 103 Steering stability on dry road surfaces 100 100 102 103 103 102

[0060] [Table 2] Example 4 Example 5 Example 6 Example 7 Example 8 Presence of spike-like lamellae and spike-like lug grooves Yes Yes Yes Yes Yes Presence of threshold profile lines PL1 and PL2 Yes Yes Yes Yes Yes Position from maximum threshold position to slat projection end (%) Inwards by 40% Away by 20% Away by 35% Away by 40% Inwards by 20% Position from maximum swell position to lug groove protrusion end (%) Inwards by 40% Away by 20% Away by 35% Away by 40% Inwards by 10% Whether the groove area ratio in the shoulder region on the side near the side land portion 64 is smaller than the groove area ratio in the shoulder region on the side near the side land portion 66. Small Small Small Small No (equivalent groove area ratio) Handling performance on snow 102 104 103 102 105 Braking performance on snow 102 103 102 101 105 Steering stability on dry road surfaces 102 102 102 102 102

[0095] From Comparative Examples 1 to 3 and Examples 1 to 8, it is understood that the handling performance on snow, the braking performance on snow, and the steering stability on dry road surfaces are improved by providing the tip-like sipes and lug grooves in the intermediate land portion 60 and setting the pattern line of the intermediate land portion 60 to the sill pattern line.

[0096] From Examples 1 to 7, it is understood that the snow handling performance and the snow braking performance are improved by providing the protrusion end of the tip-like sipe within the range of 70% of the width of the intermediate land portion 60 in the tire transverse direction, with the maximum swell position of the swell pattern line PL1 as the center. Furthermore, it is understood that at least one of the snow handling performance and the snow braking performance is improved by providing the protrusion end of the sipe within the maximum swell position of the swell pattern line PL1 in the tire transverse direction.

[0097] From Examples 1 and 8, it is understood that the steering stability on dry road surfaces is improved by setting the groove area ratio in the shoulder region on the side of the side land portion 64 disposed on the vehicle outer side smaller than the groove area ratio in the shoulder region including the side land portion 66 disposed on the vehicle inner side.

[0098] Although the pneumatic tire according to the present invention is described in detail above, the present invention is not limited to the above embodiment and examples, and can of course be improved or modified in various ways within a range without departing from the gist of the present invention. List of reference symbols 10 pneumatic tires 10T tread section 10S side section 10B Bead section 12 carcass ply layers 14 Belt layer 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 30 Belt cover layer 50, 54 Inner main circumferential groove 52, 56 Outer main circumferential groove 58 Middle bridge section 60, 62 intermediate bridge section 60a1, 60a2, 60b1, 60b2 Inclined slat section 60a3, 60b3 slat turning section 61a1 Inclined groove section 61a2 Groove turning section 61a3 Raised groove bottom section 62a1, 62b1 Steeply inclined section 62a2, 62b2 Slightly inclined part 64, 66 sidewalk section 59a, 59b, 61, 63, 65, 67 lug groove 58a, 60a, 60b, 60c, 62a, 62b, 62c, 64a, 64b, 66a, 66b lamella

Claims

[1] A pneumatic tire (10) comprising a tread portion (10T) provided with a tread pattern, the tread pattern comprising: a pair of circumferential main grooves (50, 52) comprising an inner circumferential main groove (50) provided in a first half-tread area on one side with respect to a tire equator line (CL) in the tire transverse direction and an outer circumferential main groove (52) provided outside the inner circumferential main groove (50) in the tire transverse direction; a land portion (60) defined by the pair of circumferential main grooves (50, 52) in the tire transverse direction; and a plurality of sipes (60a, 60b) provided at an interval in the tire circumferential direction, the plurality of sipes (60a, 60b) being provided in a region of the land portion (60) and connecting the pair of circumferential main grooves (50, 52) to each other, each of the plurality of slats (60a, 60b) comprising: a pair of inclined sipe portions (60a1, 60a2, 60b1, 60b2) which approach each other as they advance from the connecting ends of the pair of circumferential main grooves (50, 52) to a first side in the tire circumferential direction; and a slat turning portion (60a3, 60b3) connecting ends of the pair of inclined slat portions (60a1, 60a2, 60b1, 60b2) and bent to project toward the first side, and a profile line (PL1) formed by the tread surface of the land portion (60), which is a swell profile line (PL1) projecting outside the standard profile line (PL0) in the tire radial direction, when an arc passing through two land portion edge points at which the tread surface of the land portion (60) is connected to groove wall surfaces of the pair of circumferential main grooves (50, 52) is set on a standard profile line (PL0) in a profile cross section of the tread portion (10T) along the tire transverse direction, wherein a protrusion end of the sipe turning portion (60a3, 60b3) projecting furthest to the first side is present within a range of 70% of a width of the land portion (60) in the tire transverse direction with a maximum swell position of the swell profile line (PL1) as the center; wherein the tread pattern comprises a plurality of lug grooves (61) provided at an interval in the tire circumferential direction, the plurality of lug grooves (61) connecting the pair of main circumferential grooves (50, 52) to each other, each of the plurality of lug grooves (61) comprises: a pair of inclined groove portions (61a1) which approach each other as they advance from connecting ends of the pair of circumferential main grooves (50, 52) to the first side in the tire circumferential direction; and a groove turning portion (61a2) which connects ends of the pair of inclined groove portions (61a1) to each other and is bent to project toward the first side in the tire circumferential direction, the land portion (60) is formed of a plurality of block land portions divided by the plurality of lug grooves (61) in the tire circumferential direction, and in a region of each of the plurality of block web sections, two of the plurality of sipes (60a, 60b) are provided as a first sipe (60a) and a second sipe (60b); where a protrusion end of the groove turning portion (61a2) protruding furthest toward the first side is present within a maximum swell position of the swell profile line (PL1) in the tire transverse direction. [2] The pneumatic tire (10) according to claim 1, wherein a protrusion end of the sipe turning portion (60a3, 60b3) protruding most toward the first side is located within a maximum swell position of the swell profile line (PL1) in the tire transverse direction. [3] The pneumatic tire (10) according to claim 1, wherein a protrusion end of the groove turn portion (61a2) protruding most toward the first side is present within a range of 70% of a width of the land portion (60) in the tire transverse direction with a maximum swell position of the swell profile line (PL1) as a center. [4] The pneumatic tire (10) according to any one of claims 1 to 3, wherein the groove turning portion (61a2) is provided with a raised groove bottom portion (61a3) having a groove depth shallower than the groove depth of the pair of inclined groove portions (61a1), the first sipe (60a) is provided on the first side with respect to the second sipe (60b), and a first position of a protruding end of the sipe turning portion (60a3) of the first sipe (60a) in the tire transverse direction, which projects most toward the first side, is located in a raised bottom portion region (W) in the tire transverse direction in which the raised groove bottom portion (61a3) is provided, and is located in the tire transverse direction, with respect to a second position of a protruding end of the sipe turning portion (60b3) of the second sipe (60b) in the tire transverse direction, which projects most toward the first side protrudes. [5] The pneumatic tire (10) according to claim 4, wherein, in the region of each of the plurality of block land portions, a region between the first sipe (60a) and the second sipe (60b) in the tire circumferential direction is provided with a third sipe (60c) having a terminal end in the raised land portion region in the tire transverse direction, the third sipe (60c) extending outward in the tire transverse direction from the inner circumferential main groove (50) with an inclination with respect to the tire transverse direction along at least one of the pair of inclined sipe portions (60a1, 60a2, 60b1, 60b2) of the first sipe (60a) and the second sipe (60b) extending from the inner circumferential main groove (50). [6] A pneumatic tire (10) according to any one of claims 1 to 5, wherein the maximum protrusion amount of the threshold profile line (PL1) with respect to the standard profile line (PL0) falls within a range of 0.1 mm to 1.0 mm. [7] Pneumatic tire (10) according to one of claims 1 to 6, wherein, when the land portion (60) is a first intermediate land portion (60), the tread pattern further comprises a first side land portion (64) outside the outer main circumferential groove (52) in the tire transverse direction, the first side land portion (64) comprising a ground contact edge (E1) of the pneumatic tire (10) in one area; a region of the first side web section (64) is provided with a sixth lamella (64a, 64b) which is connected to the outer Main circumferential groove (52), each of the first slat (60a), the second slat (60b) and the sixth slat (64a, 64b) is a composite slat comprising: a straight sipe (S1) having a shape extending linearly from the tread in the sipe depth direction; and a wave-like sipe (S2) bent or curved so as to project in the sipe depth direction and in a direction orthogonal to an extension direction in which each of the first sipe (60a), the second sipe (60b) and the sixth sipe (64a, 64b) extends along the tread surface as they advance from the tread surface in the sipe depth direction, the straight sipe (S1) is provided on one side in the sipe extension direction viewed from the tread surface and the wave-like sipe (S2) is provided on another side in the sipe extension direction, the straight slat (S1) and the wave-like slat (S2) are connected in the composite slat and each of the parts of the first sipe (60a), the second sipe (60b) and the sixth sipe (64a, 64b) connected to the outer main circumferential groove (52) is the wave-like sipe (S2). [8] Pneumatic tire (10) according to one of claims 1 to 7, wherein, when the inner main circumferential groove (50) is a first inner main circumferential groove (50) and the outer main circumferential groove (52) is a first outer main circumferential groove (52), a second half-tread region on a side opposite the first half-tread region in the tire transverse direction comprises: a second inner main circumferential groove (54); a second outer circumferential main groove (56) provided outside the second inner circumferential main groove (54) in the tire transverse direction; a continuous land portion (62) defined by the second inner main circumferential groove (54) and the second outer main circumferential groove (56) and extending around a circumference in the tire circumferential direction; and a fourth and a fifth sipe (62a, 62b) connecting the second inner main circumferential groove (54) and the second outer main circumferential groove (56), the fourth sipe (62a) and the fifth sipe (62b) extending so as to be inclined in a region of the continuous land portion (62) with respect to the tire transverse direction, each of the fourth slat (62a) and the fifth slat (62b) comprises: an inner inclined portion (62a1, 62b1) provided in a region of the continuous web portion (62); and wherein both laterally inclined portions (62a2, 62b2) are provided on both sides of the inner inclined portion (62a1, 62b1) in the tire transverse direction and are connected to the second inner circumferential main groove (54) and the second outer main circumferential groove (56), and an inclination angle of the inner inclined portion (62a1, 62b1) with respect to the tire transverse direction is greater than an inclination angle of the two laterally inclined portions (62a2, 62b2) with respect to the tire transverse direction. [9] Pneumatic tire (10) according to claim 8, wherein, when the continuous land portion (62) is a second intermediate land portion (62), the tread pattern further comprises a second side land portion (66) provided outside the second outer circumferential main groove (56) in the tire transverse direction, the second side land portion (66) comprising a ground contact edge (E2) of the pneumatic tire (10) in a region thereof, a region of the second side web portion (66) is provided with a seventh sipe (66a, 66b) connected to the second outer main circumferential groove (56), each of the fourth lamella (62a), the fifth lamella (62b) and the seventh lamella (66a, 66b) is a composite lamella comprising: a straight sipe (S1) having a shape extending linearly from the tread in the sipe depth direction; and a wave-like sipe (S2) bent or curved so as to project in a direction orthogonal to the sipe depth direction and an extension direction in which each of the fourth sipe (62a), the fifth sipe (62b) and the seventh sipe (66a, 66b) extends along the tread surface as they advance from the tread surface in the sipe depth direction, the straight slat (S1) is provided on one side in the extending direction and the wave-like slat (S2) is provided on another side in the extending direction, the straight slat (S1) and the wave-like slat (S2) are connected in the composite slat and each of the parts of the fourth sipe (62a), the fifth sipe (62b) and the seventh sipe (66a, 66b) connected to the second outer main circumferential groove (56) is the wave-like sipe (S2). [10] Pneumatic tire (10) according to one of claims 1 to 9, wherein, when the inner main circumferential groove (50) is a first inner main circumferential groove (50) and the outer main circumferential groove (52) is a first outer main circumferential groove (52), in the tread pattern, a second half-tread region on a side opposite the first half-tread region in the tire transverse direction comprises: a second inner main circumferential groove (54); a second outer circumferential main groove (56) provided outside the second inner circumferential main groove (54) in the tire transverse direction; a central continuous land portion (58) defined by the first inner circumferential main groove (50) and the second inner circumferential main groove (54) and present around a circumference in the tire circumferential direction; a plurality of first center lug grooves (59a, 59b) provided at an interval in the tire circumferential direction, the plurality of first center lug grooves (59a) extending inwardly in the tire transverse direction from the first inner main circumferential groove (50) and terminating in a region of the center continuous land portion (58);and a plurality of second center lug grooves (59b) provided at an interval in the tire circumferential direction, the plurality of second center lug grooves (59b) extending inward in the tire transverse direction from the second inner main circumferential groove (54) and terminating in a region of the center continuous land portion (58), any one of the plurality of second center lug grooves (59b) being provided in a region in the tire circumferential direction between two adjacent first center lug grooves (59a) in the tire circumferential direction among the plurality of first center lug grooves (59a), and ; any one of the plurality of first center lug grooves (59a) is provided in a region in the tire circumferential direction between two adjacent second center lug grooves (59b) in the tire circumferential direction among the plurality of second center lug grooves (59b). [11] The pneumatic tire (10) according to claim 10, wherein a maximum groove depth of the plurality of second center lug grooves (59b) is shallower than a maximum groove depth of the plurality of first center lug grooves (59a). [12] The pneumatic tire (10) according to any one of claims 1 to 11, wherein the pneumatic tire (10) is provided to have one side of both sides in the tire transverse direction, the one side being a vehicle outer side when the pneumatic tire (10) is mounted on a vehicle, and a side in the tire transverse direction provided with the first half tread portion being provided as a vehicle outer side. [13] Pneumatic tire (10) according to claim 12, wherein a shoulder lug groove (65) is provided outside the outer main circumferential groove (52) in the first half-tread area in the tire transverse direction, the tread pattern in a second half-tread area on a side opposite the first half-tread area in the tyre transverse direction comprises: a second inner main circumferential groove (54); a second outer circumferential main groove (56) provided outside the second inner circumferential main groove (54) in the tire transverse direction; and a shoulder lug groove (67) provided outside the second outer main circumferential groove (56) in the tire transverse direction, and a groove area ratio in a region outside the first outer circumferential main groove (52) in the first half-tread region in the tire transverse direction is smaller than a groove area ratio in a region outside the second outer circumferential main groove (52) in the tire transverse direction.

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