tire

Abstract

To improve performance on snow, wet conditions and cornering performance on snow without impairing performance on ice. [Solution] The orientation relative to the vehicle width direction when mounted on a vehicle is specified, and the tread portion 2 includes multiple circumferential grooves, multiple land portions, multiple lug grooves 41, 44, and multiple sipes 51, 52, 61, the sipes have two or more types of different widths, and include widest sipes 51, 52 that are arranged adjacent to at least one of the lug grooves 41, 44 between adjacent lug grooves 41, 44 in the tire circumferential direction, and the sum of the lengths of the wide sipes 51, 52 on the outer side in the vehicle width direction is greater than the sum of the lengths on the inner side in the vehicle width direction.

Description

[Technical Field]

[0001] The present invention relates to tires. [Background technology]

[0002] For example, the tire described in Patent Document 1 has, in the tread portion, a land portion defined between two circumferential grooves, a plurality of lug grooves crossing the land portion, and a plurality of sipes of different types. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7371429 Summary of the Invention [Problem to be solved by the invention]

[0004] Traditionally, studless tires have been focused on performance on ice, but there is also a demand for improved performance on snow. Generally, improving performance on ice requires improving adhesion friction, but this is achieved by reducing the hardness of the compound to improve road adhesion. However, this method reduces the rigidity of the land area and reduces the open groove area, which has the drawback of worsening performance on snow and wet surfaces, as well as worsening cornering performance on snow.

[0005] An object of the present invention is to provide a tire that can improve performance on snow, wet conditions, and cornering performance on snow without impairing performance on ice by optimizing the pattern configuration. [Means for solving the problem]

[0006] In order to achieve the above object, a tire according to one embodiment of the present invention has a specified orientation with respect to the vehicle width direction when mounted on a vehicle, and includes, in a tread portion, a plurality of circumferential grooves formed in a straight line along the tire circumferential direction and adjacent in the tire width direction, a plurality of land portions partitioned between each of the circumferential grooves, lug grooves in each of the land portions, at least one end of which extending along the tire width direction communicates with the circumferential groove, and a plurality of sipes extending along the tire width direction between each of the lug grooves adjacent in the tire circumferential direction in each of the land portions and a plurality of sipes arranged side by side in the tire circumferential direction, the sipes having two or more types of widths, and including a wide sipe that is the widest between each of the lug grooves adjacent in the tire circumferential direction and is arranged adjacent to at least one of the lug grooves, and the sum of the lengths of the wide sipes on the outer side in the vehicle width direction is greater than the sum of the lengths of the wide sipes on the inner side in the vehicle width direction. [Effects of the Invention]

[0007] According to the present invention, it is possible to improve performance on snow, wet conditions, and cornering performance on snow without impairing performance on ice. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a meridian cross-sectional view of a pneumatic tire according to an embodiment. [Figure 2] FIG. 2 is a plan view of a tread portion of a pneumatic tire according to the embodiment. [Figure 3] FIG. 3 is a partial cross-sectional view of a tread portion of a pneumatic tire according to the embodiment. [Figure 4] FIG. 4 is a partial cross-sectional view showing the operation of the pneumatic tire according to the second embodiment. [Figure 5] FIG. 5 is a partial cross-sectional view showing the operation of a typical pneumatic tire. [Figure 6] FIG. 6 is a cross-sectional view showing the shape of the bottom of a wide sipe. [Figure 7] FIG. 7 is a cross-sectional view showing another example of the bottom shape of the wide sipe. [Figure 8]FIG. 8 is a cross-sectional view showing another example of the bottom shape of the wide sipe. [Figure 9] FIG. 9 is a plan view of another example of the tread portion of the pneumatic tire according to the embodiment. [Figure 10] FIG. 10 is a plan view of another example of the tread portion of the pneumatic tire according to the embodiment. [Figure 11] FIG. 11 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. [Figure 12] FIG. 12 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. [Figure 13] FIG. 13 is a table showing the results of a performance test of the pneumatic tire according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these embodiments. Furthermore, the components of these embodiments include those that can be substituted and are obvious substitutes while maintaining the identity of the invention. Furthermore, the multiple modifications described in these embodiments can be arbitrarily combined within the scope obvious to those skilled in the art.

[0010] In the following description, the tire radial direction refers to the direction perpendicular to the tire rotational axis (not shown), which is the rotational axis of the pneumatic tire 1 of this embodiment. The tire radial inner side refers to the side toward the tire rotational axis in the tire radial direction, and the tire radial outer side refers to the side away from the tire rotational axis in the tire radial direction. The tire circumferential direction refers to the direction around the tire rotational axis as the central axis. The tire width direction refers to the direction parallel to the tire rotational axis. The tire width inner side refers to the side toward the tire equatorial plane (tire equator line) CL in the tire width direction, and the tire width outer side refers to the side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL is a plane that is perpendicular to the tire rotational axis and passes through the center of the tire width of the pneumatic tire 1. The tire equatorial plane CL coincides in position in the tire width direction with the tire width centerline, which is the center position of the pneumatic tire 1 in the tire width direction. The tire equator line refers to a line that is on the tire equatorial plane CL and runs along the tire circumferential direction of the pneumatic tire 1. Also, a cross section in the tire meridian direction (meridian cross section) refers to a cross section of the tire cut by a plane including the tire rotation axis.

[0011] As shown in FIG. 1, a pneumatic tire 1 of the embodiment has a tread portion 2, a sidewall portion 8, and a bead portion 10.

[0012] The tread portion 2 is disposed at the outermost portion in the tire radial direction when viewed in a tire meridian cross section. The tread portion 2 has tread rubber 2A made of a rubber composition. The surface of the tread portion 2, i.e., the portion that comes into contact with the road surface when a vehicle (not shown) equipped with the pneumatic tire 1 is running, is formed as a tread contact surface (also referred to as a tread surface) 2B. The tread contact surface 2B forms part of the contour of the pneumatic tire 1. The tread portion 2 has shoulder portions 2C formed at both outer ends in the tire width direction.

[0013] The sidewall portions 8 are disposed on both sides in the tire width direction of the tread portion 2 and on the inner side in the tire radial direction of the shoulder portions 2C. The sidewall portions 8 are disposed in two locations on both sides in the tire width direction of the pneumatic tire 1, and form the outermost exposed portions of the pneumatic tire 1 in the tire width direction.

[0014] The bead portions 10 are disposed on the radially inner side of each sidewall portion 8. Like the sidewall portions 8, the bead portions 10 are disposed at two locations on both sides in the tire width direction. Each bead portion 10 is provided with a bead core 11, and a bead filler 12 is provided on the radially outer side of the bead core 11 in the tire radial direction. The bead core 11 is an annular member formed by bundling bead wires, which are steel wires, into a circular shape. The bead filler 12 is a rubber member disposed on the radially outer side of the bead core 11 in the tire radial direction.

[0015] The pneumatic tire 1 has an internal structure including a belt layer 14 and a carcass layer 13 .

[0016] The belt layer 14 is disposed on the tread rubber 2A of the tread portion 2. The belt layer 14 has a multi-layer structure in which a plurality of belts 141, 142 and a belt cover 143 are laminated. In this embodiment, the belt layer 14 has two layers of belts 141, 142 laminated together.

[0017] The belts 141 and 142 are formed by covering a plurality of belt cords made of steel or organic fiber material such as polyester, rayon, or nylon with a coating rubber and rolling the covered belt cords. The belt angles of the belts 141 and 142, defined as the inclination angle of the belt cords relative to the tire circumferential direction, are within a predetermined range (for example, 20° to 55°). The belt angles of the belts 141 and 142 are different from each other. For this reason, the belts 141 and 142 are formed as a so-called cross-ply structure (cross belt) in which the inclination directions of the belt cords are layered crossing each other.

[0018] The belt cover 143 is formed by covering a plurality of belt cover cords made of steel or organic fiber material such as polyester, rayon, or nylon with coating rubber and rolling the covered cords. The belt cover 143 has a belt angle, defined as the inclination angle of the belt cover cords with respect to the tire circumferential direction, within a predetermined range (for example, 0° to 10°). The belt cover 143 is formed, for example, by spirally winding a strip material, made of one or more belt cover cords covered with coating rubber, around the tire radially outer side of the two-layer belts 141 and 142 in the tire circumferential direction.

[0019] The carcass layer 13 is disposed continuously on the radially inner side of the belt layer 14 in the tread portion 2, the sidewall portion 8, and the bead portion 10. Both ends of the carcass layer 13 in the tire width direction are wound back and secured to the outer side in the tire width direction so as to enclose the bead cores 11 and bead fillers 12 of both bead portions 10, and are wound around the tire circumferentially in a toroidal shape to form the tire framework. The carcass layer 13 has a single-layer structure consisting of one carcass ply or a multi-layer structure consisting of multiple carcass plies stacked together. The carcass ply of the carcass layer 13 is formed by coating multiple carcass cords made of steel or organic fiber material such as aramid, nylon, polyester, or rayon with coating rubber and rolling them. The carcass cords that make up the carcass ply are arranged side by side at an angle to the tire circumferential direction, with the angle aligned along the tire meridian direction.

[0020] A rim cushion rubber 17 is arranged on the radially inner side and the widthwise outer side of the turned-up portion of the carcass layer 13. The rim cushion rubber 17 forms the contact surface of the bead portion 10 with the rim flange. An inner liner 16 is formed along the carcass layer 13 on the inner side of the carcass layer 13. The inner liner 16 forms the tire inner surface 18, which is the inner surface of the pneumatic tire 1.

[0021] 1 and 2, a pneumatic tire 1 of the embodiment has a tread pattern on a tread contact surface 2B of a tread portion 2. Here, each dimension of the tread pattern is measured in an unloaded state with the tire mounted on a specified rim and inflated to a specified internal pressure.

[0022] Specified rim refers to the "standard rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. Specified internal pressure refers to the "maximum air pressure" specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" specified by TRA, or the "inflation pressures" specified by ETRTO. Specified load refers to the "maximum load capacity" specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" specified by TRA, or the "load capacity" specified by ETRTO.

[0023] The groove width (also called the open groove width) is measured as the maximum distance between the opposing groove walls at the groove opening at the tread contact surface 2B when the tire is mounted on a specified rim, inflated to a specified internal pressure, and in an unloaded state. In addition, when the groove opening has a notch or chamfer, the groove width is measured using the intersection of an extension of the tread contact surface 2B and an extension of the groove wall as the endpoint in a cross section parallel to the tire width direction and the tire radial direction.

[0024] The groove depth is measured as the maximum distance from the tread contact surface 2B to the groove bottom when the tire is mounted on a specified rim, inflated to a specified internal pressure, and under no load. If the tire has partial unevenness or sipes at the groove bottom, the groove depth is measured excluding these.

[0025] 1 and 2, the pneumatic tire 1 of the embodiment mainly includes, as a tread pattern, a center circumferential groove 31 and shoulder circumferential grooves 32. Each of the circumferential grooves 31, 32 may be defined as a groove obligated to display a wear indicator as defined by JATMA.

[0026] The center circumferential groove 31 extends along the tire circumferential direction and has an annular structure provided continuously around the entire tire circumference. Two center circumferential grooves 31 are provided parallel to each other in the tire width direction with the tire equatorial plane CL sandwiched between them. The center circumferential grooves 31 are formed linearly along the tire circumferential direction without any bends. The center circumferential groove 31 has a maximum groove width of 3.0 mm or more and 13.0 mm or less in a cross section perpendicular to the tire circumferential direction, and a groove depth of 7.0 mm or more and 10.0 mm or less.

[0027] The shoulder circumferential grooves 32 extend along the tire circumferential direction and have an annular structure that is continuously provided around the entire tire circumference. The shoulder circumferential grooves 32 are provided in parallel in the tire width direction on the outer side of the two center circumferential grooves 31 in the tire width direction, with the tire equatorial plane CL sandwiched between them. The shoulder circumferential grooves 32 are formed in straight lines without any bends along the tire circumferential direction. The shoulder circumferential grooves 32 have a maximum groove width of 3.0 mm or more and 13.0 mm or less in a cross section perpendicular to the tire circumferential direction, and a groove depth of 7.0 mm or more and 10.0 mm or less.

[0028] In the pneumatic tire 1 of the embodiment, a plurality of land portions 20 are defined in the tread portion 2 by two center circumferential grooves 31 and two shoulder circumferential grooves 32. The land portions 20 include a center land portion 21, a middle land portion 22, and a shoulder land portion 23. The center land portion 21 is formed between the two center circumferential grooves 31 in a single rib-like row along the tire circumferential direction, including the tire equatorial plane CL. The middle land portion 22 is defined between one center circumferential groove 31 and one shoulder circumferential groove 32, and is formed in a total of two rib-like rows along the tire circumferential direction on both outer sides of the center land portion 21 in the tire width direction. The shoulder land portions 23 are defined on the outer side of each shoulder circumferential groove 32 in the tire width direction, and are formed in a single rib-like row along the tire circumferential direction on the outer side of each middle land portion 22 in the tire width direction, for a total of two rows. The shoulder land portions 23 include the ground contact edges T.

[0029] Here, the ground contact edges T refer to the outermost ends in the tire width direction in the area where the tread contact surface 2B of the pneumatic tire 1 comes into contact with the road surface when the pneumatic tire 1 is mounted on a standard rim, inflated to a standard internal pressure, and subjected to 70% of a standard load, and are continuous in the tire circumferential direction.

[0030] Furthermore, the pneumatic tire 1 of the embodiment has a specified orientation relative to the vehicle width direction when mounted on a vehicle. The pneumatic tire 1 of the embodiment has a defined orientation relative to the vehicle width direction (tire width direction) when mounted on a vehicle, i.e., a defined inner side in the vehicle width direction and an outer side in the vehicle width direction. Specifically, the pneumatic tire 1 has a mounting direction indicator (not shown) that indicates the tire mounting direction relative to the vehicle. The mounting direction indicator is configured, for example, by a mark or a recess or protrusion on the sidewall of the tire. For example, ECER30 (Article 30 of the Economic Commission for Europe Regulation) requires that a vehicle mounting direction indicator be provided on the sidewall that is on the outer side in the vehicle width direction when mounted on a vehicle.

[0031] Therefore, in the pneumatic tire 1 of the embodiment, the center circumferential groove 31 is a center circumferential groove 31A on the outer side in the vehicle width direction (referred to as an outer center circumferential groove) and a center circumferential groove 31B on the inner side in the vehicle width direction. Also, in the pneumatic tire 1 of the embodiment, the shoulder circumferential grooves 32 are a shoulder circumferential groove 32A on the outer side in the vehicle width direction (referred to as an outer shoulder circumferential groove) and a shoulder circumferential groove 32B on the inner side in the vehicle width direction (referred to as an inner shoulder circumferential groove).

[0032] The outer center circumferential groove 31A extends in the tire circumferential direction and has a zigzag shape that alternately bends in the tire width direction. The inner center circumferential groove 31B extends in the tire circumferential direction and has a zigzag shape such that the groove wall on the inner side in the vehicle width direction meanders in a curved pattern in the tire width direction. The zigzag shape of the outer center circumferential groove 31A and the zigzag shape of the inner center circumferential groove 31B are arranged at the same pitch in the tire circumferential direction. The outer shoulder circumferential groove 32A and the inner shoulder circumferential groove 32B extend linearly in the tire circumferential direction.

[0033] In the pneumatic tire 1 of the embodiment, the middle land portion 22 is made up of a middle land portion 22A on the outer side in the vehicle width direction (referred to as an outer middle land portion) and a middle land portion 22B on the inner side in the vehicle width direction. In the pneumatic tire 1 of the embodiment, the shoulder land portion 23 is made up of a shoulder land portion 23A on the outer side in the vehicle width direction (referred to as an outer shoulder land portion) and a shoulder land portion 23B on the inner side in the vehicle width direction (referred to as an inner shoulder land portion).

[0034] As shown in FIG. 2, the pneumatic tire 1 of the embodiment has outer middle lug grooves 41, outer middle circumferential grooves 33, outer middle sipes 61a (sipes 61), and outer wide sipes (wide sipes) 51 provided in the outer middle land portion 22A.

[0035] The outer middle lug groove 41 extends along the tire width direction, with one end 41a communicating with the outer shoulder circumferential groove 32A and the other end 41b communicating with a portion of the outer center circumferential groove 31A that bends outward in the vehicle width direction. The outer middle lug groove 41 is formed at an angle with respect to the tire width direction. Multiple outer middle lug grooves 41 are arranged side by side at intervals in the tire circumferential direction. In this embodiment, the outer middle lug groove 41 is formed to extend linearly. As shown in FIG. 3 , the outer middle lug groove 41 has a maximum groove width W1 of 1.5 mm or more and 7.0 mm or less in a cross section perpendicular to the center line connecting the one end 41a and the other end 41b, and a groove depth of 5.0 mm or more and 10.0 mm or less.

[0036] Each outer middle circumferential groove 33 extends circumferentially along the tire between two adjacent outer middle lug grooves 41, with one end communicating with one outer middle lug groove 41 and the other end communicating with the other outer middle lug groove 41. The outer middle circumferential groove 33 is formed with bent portions at multiple locations (two locations in this embodiment). The outer middle circumferential grooves 33 are arranged offset in the tire width direction without facing each other with the outer middle lug groove 41 in between. The outer middle circumferential groove 33 has a maximum groove width of 1.5 mm to 7.0 mm in a cross section perpendicular to the centerline connecting one end and the other end, and a groove depth of 3.0 mm to 8.0 mm.

[0037] The outer middle land portion 22A is divided into multiple block-shaped land portions in the tire circumferential direction by multiple outer middle lug grooves 41, and these block-shaped land portions are divided into two block-shaped outer small land portions 22Ao on the outer side in the vehicle width direction and inner small land portions 22A1 on the inner side in the vehicle width direction by the outer middle circumferential grooves 33.

[0038] The outer middle sipes 61a extend along (in the embodiment, parallel to) the slope of the outer middle lug grooves 41, and a plurality of outer middle sipes 61a are arranged side by side in the tire circumferential direction. The ends of the outer middle sipes 61a may terminate inside the outer middle land portion 22A, or may communicate with the outer center circumferential groove 31A or the outer shoulder circumferential groove 32A.

[0039] The sipes 61, including the outer middle sipes 61a, may have a shape at the tread contact surface 2B that is linear, curved, wavy, or zigzag. The sipes 61 may have a shape inside the tread rubber 2A that is linear or uneven in the depth direction or extension direction. In this embodiment, the sipes 61 are formed in a zigzag shape at the tread contact surface 2B, and are formed in a linear or uneven shape inside the tread rubber 2A. The sipes 61 have a width of 1.0 mm or less and a depth of 2.0 mm or more and 10.0 mm or less.

[0040] The outer wide sipes 51 are formed with the widest width Ws of the sipes in the outer middle land portion 22A (the outer small land portion 22Ao and the inner small land portion 22A1). The outer wide sipes 51 have a width Ws of 0.4 mm or more and 1.5 mm or less, and a depth Ds of 2.0 mm or more and 10.0 mm or less, as shown in FIG. 3. The outer wide sipes 51 are disposed adjacent to at least one of the outer middle lug grooves 41 between the outer small land portion 22Ao and the inner small land portion 22A1 and between the outer middle lug grooves 41 adjacent to each other in the tire circumferential direction. Here, adjacent means immediately adjacent to the outer middle lug grooves 41, meaning that no other grooves or sipes exist between them. 2, one end 51a of the outer wide sipe 51 communicates with the outer shoulder circumferential groove 32A or the outer center circumferential groove 31A, and the other end 51b terminates at the outer small land portion 22Ao or the inner small land portion 22A1. Alternatively, the outer wide sipe 51 may have a configuration in which the one end 51a and the other end 51b terminate at the outer small land portion 22Ao or the inner small land portion 22A1, as shown in FIG.

[0041] The outer wide sipes 51 have shapes that include a straight shape, a curved shape, or a zigzag shape at the tread contact surface 2B. The outer wide sipes 51 have shapes that include a straight shape or an uneven shape in the depth direction or extension direction inside the tread rubber 2A. In this embodiment, the outer wide sipes 51 are formed to have straight shapes at the tread contact surface 2B and inside the tread rubber 2A.

[0042] Here, the "sipes" referred to in the embodiment are formed in the shape of narrow grooves in the tread contact surface 2B, and when the pneumatic tire 1 is mounted on a specified rim and under specified internal pressure conditions, the wall surfaces constituting the narrow grooves may not come into contact with each other when no load is applied, but when a load is applied vertically on a flat plate and the narrow groove is located in the contact surface formed on the flat plate, or when the land portion where the narrow groove is formed collapses, the wall surfaces constituting the narrow grooves, or at least a portion of the portion provided on the wall surface, come into contact with each other due to deformation of the land portion.

[0043] As shown in FIG. 2, the pneumatic tire 1 of the embodiment is provided with a center lug groove 42 and a center sipe 61b (sipe 61) in the center land portion 21.

[0044] The center lug grooves 42 extend along the tire width direction, with one end 42a communicating with a portion of the outer center circumferential groove 31A that bends inward in the vehicle width direction, and the other end 42b communicating with the inner center circumferential groove 31B. One end 42a of each center lug groove 42 communicates with every other portion of the outer center circumferential groove 31A that bends inward in the vehicle width direction in the tire circumferential direction. The other end 42b of each center lug groove 42 faces and communicates with a portion of the inner center circumferential groove 31B where the groove wall bends. The center lug grooves 42 are formed at an angle with respect to the tire width direction. A plurality of center lug grooves 42 are arranged side by side in the tire circumferential direction at intervals. In this embodiment, the center lug grooves 42 are formed to extend linearly. The center lug groove 42 has a maximum groove width of 1.5 mm to 7.0 mm in a cross section perpendicular to the center line connecting one end 42a and the other end 42b, and a groove depth of 5.0 mm to 10.0 mm.

[0045] The center land portion 21 is divided into a plurality of block-shaped land portions in the tire circumferential direction by a plurality of center lug grooves 42.

[0046] The center sipes 61b extend along (in the embodiment, parallel to) the inclination of the center lug grooves 42, and a plurality of center sipes 61b are provided side by side in the tire circumferential direction. The ends of the center sipes 61b may terminate inside the center land portion 21, or may communicate with the outer center circumferential groove 31A or the inner center circumferential groove 31B.

[0047] As shown in FIG. 2, the pneumatic tire 1 of the embodiment has an inner first middle lug groove 43, an inner second middle lug groove 44, an inner first middle sipe 61c (sipe 61), an inner second middle sipe 61f (sipe 61), and an inner wide sipe (wide sipe) 52 provided in the inner middle land portion 22B.

[0048] The inner first middle lug groove 43 extends along the tire width direction, and one end 43a and the other end 43b terminate inside the inner middle land portion 22B, so that the inner first middle lug groove 43 does not penetrate the inner middle land portion 22B. The inner first middle lug groove 43 is formed to be inclined with respect to the tire width direction. Multiple inner first middle lug grooves 43 are arranged side by side in the tire circumferential direction at intervals. One end 43a of the inner first middle lug groove 43 is arranged toward the portion where the groove wall of the inner center circumferential groove 31B bends. In this embodiment, the inner first middle lug groove 43 is formed to extend linearly. The inner first middle lug groove 43 has a maximum groove width of 1.5 mm or more and 7.0 mm or less in a cross section perpendicular to the center line connecting the one end 43a and the other end 43b, and a groove depth of 5.0 mm or more and 10.0 mm or less.

[0049] The inner second middle lug groove 44 extends along the tire width direction, with its base end 44a communicating with the inner shoulder circumferential groove 32B and its tip end 44b terminating inside the inner middle land portion 22B, thereby not penetrating the inner middle land portion 22B. The inner second middle lug groove 44 is formed at an angle with respect to the tire width direction. Multiple inner second middle lug grooves 44 are arranged side by side in the tire circumferential direction at intervals. The inner second middle lug grooves 44 and the inner first middle lug grooves 43 are alternately arranged in the tire circumferential direction. In this embodiment, the inner second middle lug groove 44 is formed to extend linearly. As shown in FIG. 3 , the inner second middle lug groove 44 has a maximum groove width W2 of 1.5 mm or more and 7.0 mm or less in a cross section perpendicular to the centerline connecting the base end 44a and the tip end 44b, and a groove depth of 5.0 mm or more and 10.0 mm or less.

[0050] The inner first middle sipes 61c extend along (in the embodiment, parallel to) the slope of the inner second middle lug grooves 44, and a plurality of inner first middle sipes 61c are arranged side by side in the tire circumferential direction. An end of each inner first middle sipe 61c may terminate inside the inner middle land portion 22B, or one end may be connected to the inner center circumferential groove 31B.

[0051] The inner second middle sipe 61f extends outward in the vehicle width direction from one end 43a of the inner first middle lug groove 43 and communicates with a portion where the groove wall of the inner center circumferential groove 31B is bent. In this embodiment, the inner second middle sipe 61f is formed to extend linearly.

[0052] The inner wide sipe 52 has the widest width Ws of all the sipes in the inner middle land portion 22B. The inner wide sipe 52 has a width Ws of 0.4 mm or more and 1.5 mm or less and a depth Ds of 2.0 mm or more and 10.0 mm or less, as shown in FIG. 3 . The inner wide sipe 52 is disposed adjacent to at least one of the inner second middle lug grooves 44 between adjacent inner second middle lug grooves 44 in the tire circumferential direction. As shown in FIG. 2 , one end 52a of the inner wide sipe 52 communicates with the inner shoulder circumferential groove 32B, and the other end 52b terminates at the inner middle land portion 22B. Alternatively, the inner wide sipe 52 may have both the one end 52a and the other end 52b terminate at the inner middle land portion 22B, as shown in FIG. 9 .

[0053] The inner wide sipes 52 have shapes including a straight shape, a curved shape, and a zigzag shape at the tread contact surface 2B. The inner wide sipes 52 have shapes including a straight shape or an uneven shape in the depth direction or extension direction inside the tread rubber 2A. In this embodiment, the inner wide sipes 52 are formed in straight shapes at the tread contact surface 2B and inside the tread rubber 2A.

[0054] As shown in FIG. 2, the pneumatic tire 1 of the embodiment has outer shoulder lug grooves 45, outer shoulder sipes 61d (sipes 61), and outer shoulder circumferential grooves 71 provided in the outer shoulder land portion 23A.

[0055] The outer shoulder lug grooves 45 extend along the tire width direction, with their base ends 45a communicating with the outer shoulder circumferential groove 32A and extending outward in the tire width direction, passing through the ground contact edge T. The outer shoulder lug grooves 45 are formed at an angle with respect to the tire width direction. Multiple outer shoulder lug grooves 45 are arranged side by side in the tire circumferential direction at intervals. The base ends 45a of the outer shoulder lug grooves 45 face one ends 41a of the outer middle lug grooves 41 in the tire width direction, with the outer shoulder circumferential groove 32A as the boundary. In other words, the same number of outer shoulder lug grooves 45 as the outer middle lug grooves 41 are arranged, and they are continuous with the outer middle lug grooves 41, with the outer shoulder circumferential groove 32A as the boundary. The outer shoulder lug groove 45 has a maximum groove width of 1.5 mm or more and 7.0 mm or less in a cross section perpendicular to the center line connecting the base end 45a and the ground contact end T side end, and a groove depth of 5.0 mm or more and 10.0 mm or less.

[0056] The outer shoulder sipes 61d extend along (in the embodiment, parallel to) the slope of the outer shoulder lug grooves 45, and a plurality of outer shoulder sipes 61d are provided side by side in the tire circumferential direction. The ends of the outer shoulder sipes 61d may terminate inside the outer shoulder land portion 23A, or may communicate with the outer shoulder circumferential groove 32A.

[0057] The outer shoulder circumferential grooves 71 are arranged linearly without any bends along the tire circumferential direction between the outer shoulder circumferential groove 32A and the ground contact edge T, and are arranged between the outer shoulder lug grooves 45 arranged in the tire circumferential direction. One end of each outer shoulder circumferential groove 71 communicates with one of the outer shoulder lug grooves 45, and the other end terminates inside the outer shoulder land portion 23A. The outer shoulder circumferential grooves 71 are arranged in a line in the tire circumferential direction. The outer shoulder circumferential grooves 71 do not communicate with the outer shoulder sipes 61d, but divide the outer shoulder sipes 61d in the tire width direction. The outer shoulder circumferential grooves 71 have a groove width of 0.5 mm or more and 2.5 mm or less, and a groove depth of 0.5 mm or more and 3.5 mm or less.

[0058] As shown in FIG. 2, the pneumatic tire 1 of the embodiment is provided with inner shoulder lug grooves 46, inner shoulder sipes 61e (sipes 61), and inner shoulder circumferential grooves 72 in the inner shoulder land portion 23B.

[0059] The inner shoulder lug groove 46 extends along the tire width direction, with its base end 46a communicating with the inner shoulder circumferential groove 32B and extending outward in the tire width direction, passing through the ground contact edge T. The inner shoulder lug groove 46 is formed at an angle with respect to the tire width direction. Multiple inner shoulder lug grooves 46 are arranged side by side in the tire circumferential direction at intervals. The base end 46a of each inner shoulder lug groove 46 faces the base end 44a of the inner second middle lug groove 44 in the tire width direction, with the inner shoulder circumferential groove 32B as the boundary. In other words, the number of inner shoulder lug grooves 46 is the same as the number of inner second middle lug grooves 44, and they are arranged contiguous to the inner second middle lug groove 44, with the inner shoulder circumferential groove 32B as the boundary. The inner shoulder lug groove 46 has a maximum groove width of 1.5 mm or more and 7.0 mm or less in a cross section perpendicular to the center line connecting the base end 46a and the ground contact end T side end, and a groove depth of 5.0 mm or more and 10.0 mm or less.

[0060] The inner shoulder sipes 61e extend along (in parallel with) the inner shoulder lug grooves 46, and a plurality of inner shoulder sipes 61e are arranged side by side in the tire circumferential direction. The ends of the inner shoulder sipes 61e may terminate inside the inner shoulder land portion 23B, or may communicate with the inner shoulder circumferential groove 32B.

[0061] The inner shoulder circumferential groove 72 is arranged linearly without a bend along the tire circumferential direction between the inner shoulder circumferential groove 32B and the ground contact edge T, and is arranged between the inner shoulder lug grooves 46 arranged in the tire circumferential direction, with one end communicating with one of the inner shoulder lug grooves 46 and the other end terminating inside the inner shoulder land portion 23B. The inner shoulder circumferential grooves 72 are arranged in a line in the tire circumferential direction. The inner shoulder circumferential groove 72 does not communicate with the inner shoulder sipe 61e and divides the inner shoulder sipe 61e in the tire width direction. The inner shoulder circumferential groove 72 has a groove width of 0.5 mm or more and 2.5 mm or less and a groove depth of 0.5 mm or more and 3.5 mm or less.

[0062] In the pneumatic tire 1 of the embodiment, the center lug grooves 42 and the inner first middle lug grooves 43 are inclined in the same direction relative to the tire width direction. Also, in the pneumatic tire 1, the outer shoulder lug grooves 45, the outer middle lug grooves 41, the inner second middle lug grooves 44, and the inner shoulder lug grooves 46 are inclined in the same direction relative to the tire width direction, while the center lug grooves 42 and the inner first middle lug grooves 43 are inclined in the opposite direction.

[0063] Furthermore, as shown in FIG. 10 , the pneumatic tire 1 may have narrow grooves 81 in the tread contact surface 2B. The narrow grooves 81 are formed to be narrower and shallower than the circumferential grooves, lug grooves, and sipes, for example, having a width of 0.4 mm or less and a depth of 0.3 mm or less. The narrow grooves 81 are arranged to extend in a direction intersecting the extension directions of the circumferential grooves, lug grooves, and sipes. The narrow grooves 81 may be connected to the circumferential grooves, lug grooves, and sipes, or may terminate at the tread contact surface 2B of the land portion 20 without communicating with the circumferential grooves, lug grooves, and sipes. While the narrow grooves 81 are shown in a zigzag shape bending partway in FIG. 10 , they may be formed to be straight or curved partway. The narrow groove 81 shown in Figure 10 is provided in a configuration in which one end of the wide sipes 51, 52 is connected to a circumferential groove, but it may also be provided in a configuration in which one and the other ends of the wide sipes 51, 52 terminate at the land portion 20, as shown in Figure 9.

[0064] When mounting the pneumatic tire 1 according to this embodiment on a vehicle, the pneumatic tire 1 is mounted on a rim wheel, filled with air, and mounted on the vehicle in an inflated state. When a vehicle mounted with the pneumatic tire 1 runs, the pneumatic tire 1 rotates while the lower tread contact surface 2B of the tread portion 2 comes into contact with the road surface. When a vehicle mounted with the pneumatic tire 1 runs on a dry road surface, the vehicle runs by transmitting driving force and braking force to the road surface and generating turning force mainly due to friction between the tread contact surface 2B and the road surface.

[0065] Furthermore, when traveling on a wet road surface, water between the tread surface 2B and the road surface enters each of the grooves 31, 32, 41, 42, 43, 44, 45, 46 and the sipes 51, 52, 61, and the water between the tread surface 2B and the road surface is drained while traveling. This makes it easier for the tread surface 2B to make contact with the road surface, and the friction between the tread surface 2B and the road surface provides wet performance, enabling the vehicle to travel.

[0066] Furthermore, when traveling on snowy roads, the pneumatic tire 1 compacts snow on the road surface with the tread contact surface 2B, and the snow on the road surface also enters each of the grooves 31, 32, 41, 42, 43, 44, 45, and 46, compacting the snow within the grooves. In this state, when driving or braking forces act on the pneumatic tire 1, or when a force acts in the tire width direction due to turning of the vehicle, a shear force acting on the snow in the grooves, known as snow column shear force, is generated between the pneumatic tire 1 and the snow. When traveling on snowy roads, this snow column shear force generates resistance between the pneumatic tire 1 and the road surface, allowing driving and braking forces to be transmitted to the road surface, ensuring snow traction and snow performance. This allows the vehicle to travel on snowy roads.

[0067] Furthermore, when traveling on snowy or icy road surfaces, the tire also utilizes the edge effect of the grooves 31, 32, 41, 42, 43, 44, 45, 46 and the sipes 51, 52, 61. That is, when traveling on snowy or icy road surfaces, the tire also utilizes the resistance created by the edges of the grooves 31, 32, 41, 42, 43, 44, 45, 46 and the sipes 51, 52, 61 catching on the snow or ice surface. Furthermore, when traveling on icy road surfaces, the sipes 61 absorb water on the surface of the icy road surface, removing the water film between the icy road surface and the tread contact surface 2B, thereby facilitating contact between the icy road surface and the tread contact surface 2B. As a result, the frictional force and the edge effect of the tread contact surface 2B increase the resistance between the icy road surface and the icy road surface, thereby improving ice performance. This allows the vehicle to travel on icy road surfaces.

[0068] The grooves 31, 32, 41, 42, 43, 44, 45, 46 and sipes 51, 52, 61 formed in the tread portion 2 contribute to ensuring driving performance when traveling on wet, snowy, or icy road surfaces, and therefore, in order to improve wet performance, i.e., driving performance on wet road surfaces, it is effective to increase the groove area of ​​the tread portion 2. In other words, if the groove area of ​​the grooves 31, 32, 41, 42, 43, 44, 45, 46, etc. is increased, water on the road surface can easily enter the grooves when traveling on a wet road surface, thereby improving the drainage of water between the tread contact surface 2B and the road surface and improving wet performance.

[0069] Increasing the groove area also effectively improves snow performance, which is driving performance on snowy roads. In other words, increasing the groove area increases the amount of snow that can enter each groove 31, 32, 41, 42, 43, 44, 45, and 46 when driving on snowy roads, thereby increasing the snow column shear force acting on the snow that has entered the grooves. This improves snow traction when driving on snowy roads, and improves snow performance.

[0070] The pneumatic tire 1 of the embodiment is characterized in that its orientation with respect to the vehicle width direction when mounted on a vehicle is specified, and the tread portion 2 has a plurality of circumferential grooves 30 formed linearly along the tire circumferential direction and adjacent to each other in the tire width direction, a plurality of land portions 20 partitioned between each of the circumferential grooves 30, lug grooves 41, 44 arranged side by side in the tire circumferential direction in each of the land portions 20, at least one end of which extends along the tire width direction in each of the land portions 20 and communicates with the circumferential groove 30, and a plurality of lug grooves 41, 44 arranged side by side in the tire circumferential direction in each of the land portions 20 in the tire circumferential direction. and sipes 51, 52, 61 extending along the tire width direction between adjacent lug grooves and arranged in a row in the tire circumferential direction, the sipes having two or more types of different widths, including wide sipes 51, 52 which are the widest and arranged adjacent to at least one of the lug grooves 41, 44 between adjacent lug grooves 41, 44 in the tire circumferential direction, and the sum of the lengths of the wide sipes 51, 52 on the outer side in the vehicle width direction is greater than the sum of the lengths on the inner side in the vehicle width direction.

[0071] In studless tires, the tread rubber 2A is a rubber with a relatively low hardness, so the lug grooves 41, 44 are easily crushed during braking and driving, which can reduce the original functions of the lug grooves 41, 44, i.e., shear force in snow and drainage performance, resulting in a decrease in snow performance and wet performance. As shown in Figure 5, if a relatively narrow sipe 61 is placed adjacent to the lug grooves 41, 44, the sipe 61 will be crushed first, which can cause the above phenomenon.

[0072] In this regard, according to the pneumatic tire 1, by arranging the wide sipes 51, 52 adjacent to the lug grooves 41, 44, as shown in Fig. 4, the wide sipes 51, 52 intentionally become locations that are easily crushed during braking / driving and function to prevent the lug grooves 41, 44 from collapsing, thereby improving the shear force in snow and drainage performance of the lug grooves 41, 44, and improving performance on snow and wet conditions. In other words, the wide sipes 51, 52 are wider than the other sipes 61, and therefore have a large range until they close and collapse during braking / driving, and by suppressing deformation around them, they function to prevent the lug grooves 41, 44 from collapsing.

[0073] Furthermore, in the pneumatic tire 1 of the embodiment, if all the sipes in the land portion 20 were wide sipes 51, 52, the ground contact area would be reduced, which would decrease the adhesive friction force and reduce performance on ice, and the rigidity of the land portion 20 would also be reduced, reducing wear resistance. For this reason, the pneumatic tire 1 of the embodiment has two or more types of sipes with different widths, thereby ensuring performance on ice.

[0074] In particular, in the pneumatic tire 1 of the embodiment, the sum of all lengths of the wide sipes 51, 52 on the outer side in the vehicle width direction is greater than the sum of all lengths of the wide sipes on the inner side in the vehicle width direction, and therefore, by improving drainage and snow removal on the outer side in the vehicle width direction where ground pressure is high during cornering, cornering performance on snow is improved. Note that the sum of all lengths of the wide sipes 51 on the outer side in the vehicle width direction is preferably 10 mm or more greater than the sum of all lengths of the wide sipes 52 on the inner side in the vehicle width direction.

[0075] As a result, the pneumatic tire 1 can improve performance on snow, wet roads, and cornering performance on snow without compromising performance on ice.

[0076] In the embodiment of the pneumatic tire 1, the wide sipes 51, 52 are arranged adjacent to only one side of the lug grooves 41, 44 in the tire circumferential direction, but the wide sipes 51, 52 may also be arranged adjacent to the other side of the lug grooves 41, 44 in the tire circumferential direction, and the same effect can be obtained.

[0077] In the pneumatic tire 1 of the embodiment, the groove depth Dr of the lug grooves 41, 44 and the depth Ds of the wide sipes 51, 52 adjacent to each other satisfy the relationship 0.2≦Ds / Dr≦1.0.

[0078] In this pneumatic tire 1, if Ds / Dr is less than 0.2, the rigidity of the land portion 20 increases, which tends to reduce the ability to crush the wide sipes 51, 52, making it difficult to achieve the effects of improving snow performance, wet performance, and snow cornering performance. Also, in this pneumatic tire 1, if Ds / Dr exceeds 1.0, the rigidity of the land portion 20 decreases, which tends to reduce the effect of suppressing the crushing of the lug grooves 41, 44. Therefore, by setting Ds / Dr in the above range, this pneumatic tire 1 can significantly improve snow performance, wet performance, and snow cornering performance without impairing ice performance.

[0079] In the pneumatic tire 1 of the embodiment, the length Ls of each of the wide sipes 51, 52 and the tire width direction dimension L of the land portion 20 (22Ao, 22A1, 22B) in which the wide sipes 51, 52 are provided satisfy the relationship 0.3≦Ls / L≦0.9.

[0080] In this pneumatic tire 1, if Ls / L is less than 0.3, the rigidity of the land portion 20 increases, which tends to reduce the ability to crush the wide sipes 51, 52, making it difficult to achieve the effect of improving snow performance, wet performance, and snow cornering performance. Also, in this pneumatic tire 1, if Ls / L exceeds 0.9, the rigidity of the land portion 20 decreases, which tends to reduce the effect of suppressing the crushing of the lug grooves 41, 44. Therefore, by setting Ls / L in the above range, this pneumatic tire 1 can significantly achieve the effect of improving snow performance, wet performance, and snow cornering performance without impairing ice performance.

[0081] In the pneumatic tire 1 of the embodiment, the width of the openings 51c, 52c of the wide sipes 51, 52 is in the range of 0.5 mm to 1.5 mm.

[0082] In this pneumatic tire 1, when the widths of the openings 51c and 52c are less than 0.5 [mm], the wide sipes 51 and 52 tend to close, resulting in a reduction in the effect of suppressing the collapse of the lug grooves 41 and 44, making it difficult to obtain the effects of improving snow performance, wet performance, and snow cornering performance. Further, in this pneumatic tire 1, when the widths of the openings 51c and 52c exceed 1.5 [mm], the rigidity of the land portion 20 decreases, and the effect of suppressing the collapse of the lug grooves 41 and 44 also tends to decrease. Therefore, by setting the widths of the openings 51c and 52c within the above range, this pneumatic tire 1 can significantly obtain the effect of improving snow performance, wet performance, and snow cornering performance without sacrificing ice performance.

[0083] Further, in the pneumatic tire 1 of the embodiment, on the tread contact surface 2B, the groove area ratio Go on the outer side in the vehicle width direction with respect to the tire equatorial plane CL and the groove area ratio Gi on the inner side in the vehicle width direction satisfy Gi < Go.

[0084] Here, the groove area ratio is defined as the percentage of groove area / (groove area + contact area). The groove area is the sum of the opening areas of the grooves on the tire contact surface. The contact area is measured between the grounding ends based on the plane where the pneumatic tire 1 contacts the flat plate when the pneumatic tire 1 is mounted on a standard rim, filled with the standard internal pressure, placed perpendicular to the flat plate in a stationary state, and a load corresponding to the standard load is applied. The groove area does not include the sipes.

[0085] According to the pneumatic tire 1 of the embodiment, by setting the groove area ratio to Gi < Go, the snow performance can be improved on the outer side in the vehicle width direction, and the ice performance can be improved on the inner side in the vehicle width direction by increasing the contact area, making it possible to further improve the snow performance, wet performance, and snow cornering performance. In the pneumatic tire 1 of the embodiment, it is preferable to satisfy the relationship of 1.1 ≦ Go / Gi ≦ 1.3. According to this pneumatic tire 1, when Go / Gi is less than 1.1, although the ice performance improves, the snow performance tends to deteriorate, and when it exceeds 1.3, although the snow performance improves, the ice performance tends to deteriorate. Therefore, the above range is set.

[0086] In the pneumatic tire 1 of the embodiment, the number of wide sipes 51, 52 on the outer side in the vehicle width direction is greater than the number on the inner side in the vehicle width direction.

[0087] According to the pneumatic tire 1 of the embodiment, by making the number of wide sipes 51 on the outer side in the vehicle width direction greater than the number of wide sipes 52 on the inner side in the vehicle width direction, water drainage and snow removal on the outer side in the vehicle width direction are improved, and cornering performance on snow is improved. It is desirable that the number of wide sipes 51 on the outer side in the vehicle width direction is three or more greater than the number of wide sipes 52 on the inner side in the vehicle width direction. Also, the number of wide sipes 52 on the inner side in the vehicle width direction may be zero.

[0088] In addition, the pneumatic tire 1 of the embodiment has sipes 51, 52, 61 arranged on the land portion 20, so that it can be used as a studless tire that ensures driving performance on icy and snowy roads, or an all-season tire that ensures driving performance in winter.

[0089] Furthermore, the pneumatic tire 1 of the embodiment has a snow traction index of 100 or more in the 0° direction.

[0090] The snow traction index in the 0° direction is an empirical formula proposed by Uniroyal at the SAE (Society of Automotive Engineers) and is defined by the following formula (1): In this formula, ρg is the groove density [1 / mm], and is the ratio [mm] of the groove length of all grooves (all grooves excluding sipes) projected in the circumferential direction of the tire on the tread contact surface to the tread contact area (the product of the tire contact width and tire circumference) [mm 2 ]. ρs is the sipe density [1 / mm], and is calculated as the ratio of the sipe length [mm] of all sipes projected in the circumferential direction of the tire on the tread contact surface to the tread contact area [mm 2 Dg is the average value of the groove depth [mm] of all grooves projected in the circumferential direction of the tire on the tread contact surface.

[0091] STI=-6.8+2202×ρg+672×ρs+7.6×Dg...(1)

[0092] According to this pneumatic tire 1, by making the snow traction index in the 0° direction 100 or more, improved performance on snow can be ensured, and the tire is applicable to studless tires or all-season tires.

[0093] In the pneumatic tire 1 of the embodiment, the wide sipes 51, 52 are arranged to extend along the direction in which the lug grooves 41, 44 adjacent to each other extend.

[0094] The lug grooves 41, 44 and the wide sipes 51, 52 adjacent to each other are inclined in the same direction relative to the tire width direction, and the difference in inclination angle between the two extending in the same direction is within an absolute value of 10°. The lug grooves 41, 44 and the wide sipes 51, 52 adjacent to each other are preferably parallel to each other. This pneumatic tire 1 improves the crushing effect of the wide sipes 51, 52, making it easier to obtain the effect of improving snow performance and wet performance. Note that it is preferable that all of the lug grooves 41, 44 and the wide sipes 51, 52 arranged in one land portion 20 be inclined in the same direction relative to the tire width direction.

[0095] In the pneumatic tire 1 of the embodiment, the tread portion 2 has a tread rubber (cap rubber) 2A with a hardness in the range of 40 or more and 70 or less.

[0096] The hardness is rubber hardness indicated by JIS-A hardness in accordance with JIS-K6253 under the condition of 20°C.

[0097] According to this pneumatic tire 1, by setting the hardness of the tread rubber 2A in the range of 40 or more and 70 or less, the rigidity of the land portion 20 can be ensured and performance on snow can be further improved. Note that, in the pneumatic tire 1 of the embodiment, when the hardness of the tread rubber 2A is in the range of 40 or more and 55 or less, it is suitable for a studless tire, and when the hardness of the tread rubber 2A is in the range of 55 or more and 70 or less, it is suitable for an all-season tire.

[0098] In the pneumatic tire 1 of the embodiment, the tread portion 2 has a groove area ratio of the tread pattern in the range of 20% to 40%.

[0099] According to this pneumatic tire 1, by setting the groove area ratio of the tread pattern in the range of 20% to 40%, it is possible to obtain a significant effect of improving the performance on snow and wet conditions.

[0100] In the pneumatic tire 1 of the embodiment, the wide sipes 51, 52 have a depth Ds that is constant or gradually changes in the length direction, or have bottom portions 51e, 52e on the bottom portions 51d, 52d.

[0101] "Constant depth Ds in the longitudinal direction" means that the depth Ds from the openings 51c, 52c to the bottoms 51d, 52d does not change in the longitudinal direction (between one end 51a, 52a and the other end 51b, 52b), as shown in FIG. 6. "Gradually varying depth Ds in the longitudinal direction" means that the bottoms 51d, 52d are inclined in the longitudinal direction, and the depth Ds of the wide sipes 51, 52 gradually changes, as shown in FIG. 7. "Having upper bottom portions 51e, 52e at the bottoms 51d, 52d of the wide sipes 51, 52" means that the bottoms 51d, 52d protrude radially outward midway in the longitudinal direction, and the depth Ds suddenly becomes shallower, as shown in FIG. 8. The upper bottom portions 51e, 52e may have a constant depth Ds in the longitudinal direction or a gradually varying depth Ds.

[0102] According to the pneumatic tire 1, the above-mentioned effects are not hindered even if the bottom shapes of the wide sipes 51, 52 vary. However, in order to significantly achieve the above-mentioned effects, it is preferable that the depth Ds of the pneumatic tire 1 be constant in the length direction, since this has a significant effect on the lug grooves 41, 44.

[0103] Incidentally, in the pneumatic tire 1 of the embodiment, the width Ws of the wide sipes 51, 52 and the width Wsa of the other sipes 61 satisfy the relationship 1.1≦Ws / Wsa≦4.0.

[0104] In this pneumatic tire 1, if Ws / Wsa is less than 1.1, it becomes difficult to obtain the effect of preventing the lug grooves 41, 44 from collapsing. Also, in this pneumatic tire 1, if Ws / Wsa exceeds 4.0, the rigidity of the land portions 20 decreases, making it difficult to obtain performance on ice. Therefore, by setting Ws / Wsa in the above range, this pneumatic tire 1 can significantly obtain the effect of improving snow performance, wet performance, and snow cornering performance without compromising ice performance.

[0105] In addition, in the pneumatic tire 1 of the embodiment, the distance Bs between adjacent lug grooves 41, 44 and wide sipes 51, 52 and the circumferential length B of the land portion 20 between adjacent lug grooves 41, 44 in the circumferential direction of the tire satisfy the relationship 0.1≦Bs / B≦0.4.

[0106] The distance Bs between the lug grooves 41, 44 and the wide sipes 51, 52 is the distance between the center lines of the lug grooves 41, 44 and the wide sipes 51, 52. The center lines are straight lines connecting the centers of the ends of the lug grooves 41, 44 and the wide sipes 51, 52.

[0107] In this pneumatic tire 1, if Bs / B is less than 0.1, the rigidity of the land portions 20 decreases, tending to degrade ice performance. Also, in this pneumatic tire 1, if Bs / B exceeds 0.4, the rigidity of the land portions 20 increases, tending to reduce the ability to crush the wide sipes 51, 52, making it difficult to achieve the effects of improving snow performance, wet performance, and snow cornering performance. Therefore, by setting Bs / B in the above range, this pneumatic tire 1 can achieve a significant effect of improving snow performance, wet performance, and snow cornering performance without compromising ice performance.

[0108] To achieve the above-described effects, it is preferable that the distance Bs between the lug grooves 41, 44 and the wide sipes 51, 52 be in the range of 3.0 mm to 10.0 mm. In the pneumatic tire 1 of the embodiment, if the distance Bs is less than 3.0 mm, the tread rubber 2A between the lug grooves 41, 44 becomes thin and tends to chip easily. In addition, if the distance Bs exceeds 10.0 mm, the tread rubber 2A between the lug grooves 41, 44 becomes thick, which tends to reduce the function of the wide sipes 51, 52 in preventing the lug grooves 41, 44 from being crushed, making it difficult to achieve the effects of improving snow performance, wet performance, and snow cornering performance. Therefore, by setting the distance Bs between the lug grooves 41, 44 and the wide sipes 51, 52 in the above-described range, the pneumatic tire 1 significantly achieves the effects of improving snow performance, wet performance, and snow cornering performance, and also prevents chipping of the land portion 20.

[0109] In addition, in the pneumatic tire 1 of the embodiment, the distance Bs between the adjacent lug grooves 41, 44 and wide sipes 51, 52 and the groove widths W1, W2 of the lug grooves 41, 44 satisfy the relationship 1.0≦Bs / W1≦3.0 (1.0≦Bs / W2≦3.0).

[0110] In this pneumatic tire 1, if Bs / W1 (Bs / W2) is less than 1.0, the rigidity of the land portion 20 decreases, tending to degrade ice performance. Also, in this pneumatic tire 1, if Bs / W1 (Bs / W2) is more than 3.0, the rigidity of the land portion 20 increases, tending to reduce the ability to crush the wide sipes 51, 52, making it difficult to achieve the effects of improving snow performance, wet performance, and snow cornering performance. Therefore, by setting Bs / W1 (Bs / W2) in the above range, this pneumatic tire 1 can significantly improve snow performance, wet performance, and snow cornering performance without compromising ice performance.

[0111] In the present embodiment, as described above, a pneumatic tire 1 has been described as an example of a tire. The pneumatic tire 1 can be filled with air, an inert gas such as nitrogen, or other gases. However, the tread pattern configuration of the pneumatic tire 1 described in the present embodiment can be applied to other tires as desired within the scope of what is obvious to those skilled in the art. Examples of other tires include airless tires and solid tires. [Example]

[0112] 11 to 13 are tables showing the results of performance tests of pneumatic tires according to the embodiment. Performance evaluation tests conducted on a conventional pneumatic tire and an example pneumatic tire according to the embodiment will be described below. The performance evaluation tests included tests on ice performance, snow performance, dry running performance, uneven wear resistance, wet performance, and snow cornering performance.

[0113] The performance evaluation test was carried out by mounting a pneumatic tire 1 having a tire nominal size of 195 / 65R15 91Q as specified by JATMA on a JATMA standard rim wheel having a rim size of 15 x 6.5J, mounting the test tire on a front-wheel drive evaluation vehicle with an engine displacement of 1800cc, adjusting the air pressure to 240 kPa for the front wheels and 240 kPa for the rear wheels, and running the evaluation vehicle.

[0114] To evaluate ice performance, a test vehicle fitted with the test tires is subjected to a braking test on an icy test course, and the braking distance is measured. Based on the results of these tests, the reciprocal of the tire's braking distance is used to evaluate the tire's performance, with the conventional tire being used as the benchmark (100). The higher the evaluation value, the better.

[0115] The evaluation test for snow performance involves braking tests on a test vehicle fitted with test tires on a snowy test course, measuring the braking distance. Based on the results of these tests, the reciprocal of the tire's braking distance is used to evaluate the tire's performance, with the conventional tire being used as the standard (100). The higher the evaluation value, the better.

[0116] The wet performance evaluation test involves a braking test on a test vehicle fitted with a test tire on a wet road test course with 1mm of water depth, and the braking distance is measured. Based on the measurement results, the reciprocal of the tire is used to evaluate the tire's performance on an index basis, with the conventional tire being used as the standard (100). The higher the evaluation value, the better.

[0117] To evaluate cornering performance on snow, an evaluation vehicle fitted with test tires was driven on a test course on a snowy road surface, and a professional test driver evaluated the feeling of cornering by making turns with a turning radius of 20 m. This evaluation was based on an index rating, with the conventional example being set as the standard (100), and the higher the number, the better.

[0118] The conventional pneumatic tire does not have wide sipes in the tread pattern shown in Fig. 2. The pneumatic tire of the example has wide sipes in the tread pattern shown in Fig. 2, and the sum of the lengths on the outer side in the vehicle width direction is greater than the sum of the lengths on the inner side in the vehicle width direction. Note that the "same direction" in Example 12 means that the difference in inclination angle between the lug grooves and the wide sipes is 10°.

[0119] As shown in the test results, the pneumatic tire of this embodiment has improved ice performance, snow performance, wet performance, and snow cornering performance compared to the conventional tire.

[0120] The present disclosure includes the following inventions. [Invention 1] The direction relative to the vehicle width when installed is specified. In the tread area, a plurality of circumferential grooves formed linearly along the tire circumferential direction and adjacent to each other in the tire width direction; a plurality of land portions defined between the circumferential grooves; lug grooves, each of which has at least one end extending along the tire width direction in each land portion and communicating with the circumferential groove, arranged in a row in the tire circumferential direction; a plurality of sipes extending along the tire width direction between the lug grooves adjacent to each other in the tire circumferential direction in each land portion and arranged side by side in the tire circumferential direction; Including, The sipes have two or more types of widths different from each other, and include a wide sipe having the widest width and arranged adjacent to at least one of the lug grooves between the lug grooves adjacent to each other in the tire circumferential direction, The wide sipes have a total length on the outer side in the vehicle width direction that is greater than a total length on the inner side in the vehicle width direction. tire. [Invention 2] A groove depth Dr of the lug groove between which the wide sipe is disposed and a depth Ds of the wide sipe adjacent to the lug groove satisfy a relationship of 0.2≦Ds / Dr≦1.0. A tire according to claim 1. [Invention 3] The length Ls of the wide sipe and the dimension L in the tire width direction of the land portion where the wide sipe is provided satisfy the relationship of 0.3≦Ls / L≦0.9. The tire according to claim 1 or 2. [Invention 4] The width of the opening of the wide sipe is in the range of 0.5 [mm] to 1.5 [mm]. A tire according to any one of inventions 1 to 3. [Invention 5] In the tread contact surface, the groove area ratio on the outer side in the vehicle width direction is higher than the groove area ratio on the inner side in the vehicle width direction. A tire according to any one of inventions 1 to 4. [Invention 6] The number of the wide sipes on the outer side in the vehicle width direction is greater than the number of the wide sipes on the inner side in the vehicle width direction. A tire according to any one of inventions 1 to 5. [Invention 7] The wide sipes are arranged to extend along the extension direction of the lug grooves adjacent to each other. A tire according to any one of inventions 1 to 6. [Invention 8] The snow traction index in the 0° direction is 100 or higher. A tire according to any one of inventions 1 to 7. [Invention 9] The tread portion has a tread rubber hardness in the range of 40 or more and 70 or less. A tire according to any one of inventions 1 to 8. [Invention 10] The tread portion has a groove area ratio of a tread pattern in the range of 20% to 40%. A tire according to any one of claims 1 to 9. [Invention 11] The wide sipe has a constant or gradually varying depth in the length direction, or has a bottom portion at the bottom. A tire according to any one of inventions 1 to 10. [Explanation of symbols]

[0121] 1. Pneumatic tires (tires) 2 Tread section 2A Tread rubber 2B tread contact surface 20 Land 22A Outer Middle Land Section (Land Section) 22B Inner Middle Land Section (Land Section) 30 Circumferential groove 41 Outer middle lug groove (lug groove) 44 Inner second middle lug groove (lug groove) 51 Wide outer sipes (wide sipes) 52 Wide inner sipe (wide sipe) 61 Sipe

Claims

1. The direction relative to the vehicle width when installed is specified. In the tread area, a plurality of circumferential grooves formed linearly along the tire circumferential direction and adjacent to each other in the tire width direction; a plurality of land portions defined between the circumferential grooves; lug grooves arranged side by side in the tire circumferential direction, with at least one end extending along the tire width direction in each land portion communicating with the circumferential groove; a plurality of sipes extending along the tire width direction between the lug grooves adjacent to each other in the tire circumferential direction in each land portion and arranged side by side in the tire circumferential direction; Including, The sipes have two or more types of widths different from each other, and include a wide sipe having the widest width and arranged adjacent to at least one of the lug grooves between the lug grooves adjacent to each other in the tire circumferential direction, The wide sipes have a total length on the outer side in the vehicle width direction that is greater than a total length on the inner side in the vehicle width direction. tire.

2. A groove depth Dr of the lug groove between which the wide sipe is disposed and a depth Ds of the wide sipe adjacent to the lug groove satisfy a relationship of 0.2≦Ds / Dr≦1.

0.

2. The tire of claim 1.

3. The length Ls of the wide sipe and the dimension L in the tire width direction of the land portion where the wide sipe is provided satisfy the relationship of 0.3≦Ls / L≦0.

9.

2. The tire of claim 1.

4. The width of the opening of the wide sipe is in the range of 0.5 mm to 1.5 mm.

2. The tire of claim 1.

5. In the tread contact surface, the groove area ratio on the outer side in the vehicle width direction is higher than the groove area ratio on the inner side in the vehicle width direction; 2. The tire of claim 1.

6. The number of the wide sipes on the outer side in the vehicle width direction is greater than the number of the wide sipes on the inner side in the vehicle width direction.

2. The tire of claim 1.

7. The wide sipes are arranged to extend along the extension direction of the lug grooves adjacent to each other.

2. The tire of claim 1.

8. The snow traction index in the 0° direction is 100 or more.

2. The tire of claim 1.

9. The tread portion has a tread rubber hardness in the range of 40 or more and 70 or less.

2. The tire of claim 1.

10. The tread portion has a groove area ratio of a tread pattern in the range of 20% to 40%.

2. The tire of claim 1.

11. The wide sipe has a constant or gradually varying depth in the length direction, or has a bottom portion at the bottom.

2. The tire of claim 1.

Images