pneumatic tires

Abstract

Pneumatic tires, including: at least four main circumferential grooves (21, 22) extending in one direction around the circumference of the tire; and at least five web sections (31, 32, 33) defined by the main circumferential grooves (21; 22); wherein the rib sections (31, 32, 33) comprise rib sections arranged at the outermost points on a left and a right side in a transverse direction of the tire, which are defined as shoulder rib sections (33), rib sections arranged as second rib sections (32) on a left and a right side in a transverse direction of the tire, which are defined as second rib sections (32), and a rib section arranged closer to an equatorial plane of the tire than the second rib sections (32), which is defined as a center rib section (31); wherein the central rib section (31) and the left and right second rib sections (32) each comprise a plurality of continuous tread grooves (411, 412, 421, 422) which are inclined at a predetermined angle of inclination with respect to the tire transverse direction and extend through the rib section in the tire transverse direction; wherein the majority of continuous lug grooves (411, 412) arranged in the central rib section (31) and the majority of continuous lug grooves (421, 422) arranged in the left and right second rib section (32) are inclined in opposite directions to each other in the transverse direction of the tire; wherein at least one groove wall of each of the plurality of continuous lug grooves (421, 422) arranged in the left and right second rib section (32) comprises a step-shaped curved section which, when viewed from a top view of a tread, is curved in the circumferential direction of the tire; wherein a pair of multiple continuous lug grooves (411, 412) of the central rib section (31) adjacent in the circumferential direction of the tire has different groove widths and a groove width Wg11 of a narrower continuous lug groove of the pair of multiple continuous lug grooves (411, 412) and a groove width Wg12 of a wider continuous lug groove have a relationship 1.10 ≤ Wg12 / Wg11 ≤ 3.00 and where the angle of inclination (θ11) of the narrower first continuous tunnel groove (411) is greater than the angle of inclination (θ12) of the wider second continuous tunnel groove (412).

Description

Technical field

[0001] The invention relates to a pneumatic tire and in particular to a pneumatic tire that can provide improved snow performance. State of the art

[0002] All-season tires for passenger cars and tires for light trucks use a block pattern with multiple rows of blocks to improve the tire's snow performance. An example of such a well-known pneumatic tire is the technology described in JP 3718021 B.

[0003] DE 11 2015 003 720 T5 discloses a tread profile with five rib sections defined by four main circumferential grooves. The rib sections comprise continuous lug grooves that are alternately inclined at an angle to the tire's transverse direction. Furthermore, the rib sections also include stepped curved sections.

[0004] EP 2 913 204 A1 discloses a tread pattern with four circumferential main grooves and rib sections defined by the main grooves. Grooves traverse the rib sections and connect the main grooves on the respective sides of the rib sections. The shoulder rib sections have grooves that terminate within the rib section. The lug grooves are angled with respect to a transverse direction of the tire. Summary of the invention: Technical problem

[0005] One object of the invention is to provide an air-filled tire that can provide improved snow performance. Solution to the problem

[0006] To solve the problem described above, a pneumatic tire according to one embodiment of the invention includes the following: at least four main circumferential grooves extending in one direction around the tire; and at least five bridge sections defined by the main circumferential grooves; wherein the rib sections in a transverse direction of the tire include rib sections arranged at the outermost point on a left and a right side, which are defined as shoulder rib sections, rib sections arranged as the second rib sections in a transverse direction of the tire on a left and a right side, which are defined as the second rib sections, and a rib section arranged closer to an equatorial plane of the tire than the second rib sections, which is defined as the center rib section; wherein the central rib section and the left and right second rib sections each enclose a plurality of continuous lug grooves which are inclined at a predetermined angle of inclination with respect to the tire transverse direction and extend through the rib section in the tire transverse direction; wherein the majority of continuous lug grooves arranged in the central rib section and the majority of continuous lug grooves arranged in the left and right second rib sections run in opposite directions to each other in the transverse direction of the tire; and wherein at least one groove wall of each of the plurality of continuous lug grooves arranged in the left and right second rib section includes a stepped curved section which, when viewed from a top view of the tread, is curved in the circumferential direction of the tire, wherein a pair of continuous lug grooves of the central rib section adjacent in the direction of the tire circumference has different groove widths and a groove width of a narrower continuous lug groove of the pair of the majority of continuous lug grooves and a groove width of a wider continuous lug groove have a relationship 1.10 ≤ Wg12 / Wg11 ≤ 3.00 and where the angle of inclination of the narrower first continuous tunnel groove is greater than the angle of inclination of the wider second continuous tunnel groove. Advantageous effects of the invention

[0007] In a pneumatic tire according to one embodiment of the invention (1), the continuous lug grooves of the central rib section and the continuous lug grooves of the left and right second rib sections are inclined in opposite directions. This improves the traction properties on snow-covered road surfaces when the vehicle turns. Furthermore (2), the continuous lug grooves arranged in the left and right second rib sections enclose a groove wall with a stepped, curved section. This enlarges the edge components of the continuous lug groove in the central tread section. This has the advantage of improving the tire's snow performance. Brief description of the drawings Fig. Figure 1 is a cross-sectional view in a tire meridian direction illustrating a pneumatic tire according to an embodiment of the invention. Fig. 2 is a top view showing a tread pattern of the Fig. 1 illustrates an air tire. Fig. 3 is an enlarged view showing a central area of ​​the Fig. 2 illustrated tread patterns. Fig. 4 is an enlarged view showing a central web section of the in Fig. 2 illustrated tread patterns. Fig. 5 is an enlarged view showing a second bridge section of the in Fig. 2 illustrated tread patterns. Fig. 6 is an explanatory diagram that shows a modified example of the one in Fig. 5 illustrates the second bridge section. Fig. 7 is an enlarged view showing a shoulder strap section of the Fig. 2 illustrated tread patterns. Fig. Figure 8 is an explanatory diagram illustrating an example of a three-dimensional lamella. Fig. Figure 9 is an explanatory diagram illustrating an example of a three-dimensional lamella. Fig. Figure 10 is a table which shows in examples 8 to 12 the results of performance tests of pneumatic tires according to embodiments of the invention. Description of embodiments

[0008] Embodiments of the invention are described in detail below with reference to the drawings. However, the invention is not limited to these embodiments. Furthermore, components of the embodiments include elements that are interchangeable while maintaining conformity with the invention, as well as obviously interchangeable elements. Moreover, the modified examples described in the embodiments can be combined as needed within the scope of protection that is obvious to a person skilled in the art. pneumatic tires

[0009] Fig. Figure 1 is a cross-sectional view in a tire meridional direction, illustrating a pneumatic tire according to one embodiment of the invention. The same drawing is a cross-sectional view of a half-section in the tire radial direction. Likewise, the same drawing illustrates a radial tire for a passenger car as an example of a pneumatic tire.

[0010] Referring to the same drawing, "cross-section in a tire meridian direction" refers to a cross-section of the tire along a plane that includes the tire's axis of rotation (not shown). Furthermore, the reference symbol CL denotes the equatorial plane of the tire and refers to a plane perpendicular to the tire's axis of rotation, passing through the tire's center point in the direction of the tire's axis of rotation. Additionally, "tire lateral direction" refers to the direction parallel to the tire's axis of rotation. "tire radial direction" refers to the direction perpendicular to the tire's axis of rotation.

[0011] The pneumatic tire 1 has a ring structure, the center of which is the tire rotation axis, and includes a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, a tread rubber 15, a pair of sidewall rubbers 16, 16 and a pair of rim pad rubbers 17, 17 (see Fig. 1).

[0012] The pair of bead cores 11, 11 are ring-shaped elements formed by a plurality of bundled tire bead wires. The pair of bead cores 11, 11 forms the cores of the left and right bead sections. The pair of bead fillers 12, 12 are arranged outside the pair of bead cores 11, 11 in the tire radial direction and form the bead sections.

[0013] The carcass layer 13 has a single-layer structure, consisting of a single carcass ply, or a multi-layer structure, consisting of multiple carcass plies, and extends between the left and right bead cores 11, 11 in a torus shape, thus forming the support structure for the tire. Furthermore, both end sections of the carcass layer 13 are bent back outwards in the transverse direction of the tire so that they are wrapped around the bead cores 11 and the bead fillers 12 and fixed in place. The carcass ply(s) of the carcass layer 13 are produced by a process of coating multiple carcass cord threads made of steel or an organic fiber material (e.g., aramid, nylon, polyester, rayon, or the like) with a coating rubber and subsequently by a rolling process.The carcass ply (ply) has a carcass angle (inclination angle of the fiber direction of the carcass cord threads relative to the tire circumference direction) with a value in the range of 80 degrees to 95 degrees.

[0014] The belt layer 14 is a multi-layered structure comprising a pair of cross belts 141, 142 and a belt cover 143, and is arranged around the outer circumference of the carcass layer 13. The pair of cross belts 141, 142 are produced by coating a plurality of belt cord threads made of steel or an organic fiber material with a coating rubber and by a subsequent rolling process. The cross belts 141, 142 have a belt angle ranging from 20 degrees to 55 degrees. Furthermore, the pair of cross belts 141, 142 have belt angles (inclination angles of the fiber direction of the belt cord threads relative to the tire circumference) with opposite signs, and the belts are layered such that the fiber directions of the belt cord threads intersect (cross-layer structure).The belt cover 143 is produced by a process of coating a plurality of cord threads made of steel or an organic fiber material with a coating rubber and by a subsequent rolling process. The belt cover 143 has a belt angle in the range of 0 to 10 degrees. Furthermore, the belt cover layer 143 is arranged in a layered manner outside the cross belts 141, 142 in the tire radial direction.

[0015] The tread rubber 15 is arranged outside the carcass layer 13 and the belt layer 14 in the tire radial direction and forms a tread section. The pair of sidewall rubbers 16, 16 are arranged outside the carcass layer 13 in the tire transverse direction and form a left and a right sidewall section. The pair of rim pad rubbers 17, 17 are arranged inside the left and right bead core 11, 11 and the folded-back sections of the carcass layer 13 in the tire radial direction. The pair of rim pad rubbers 17, 17 form the contact surfaces of the left and right bead sections with the rim flanges. Tread pattern

[0016] Fig. 2 is a top view showing a tread pattern of the Fig. Figure 1 illustrates a pneumatic tire. The same drawing illustrates a tread pattern for an all-season tire. Referring to the same drawing, "tire circumference direction" refers to the direction of rotation around the tire's axis of rotation. Furthermore, the reference symbol T denotes a contact patch of the tire. As shown in FIG. 2, the pneumatic tire 1 is in

[0017] The tread section is provided with a plurality of main circumferential grooves 21, 22 extending in the direction of the tire circumference, a plurality of rib sections 31 to 33 defined by the main circumferential grooves 21, 22, and a plurality of lug grooves 411, 412, 421, 422, 431, 432 arranged in the rib sections 31 to 33.

[0018] “Main circumferential groove” refers to a circumferential groove with a wear indicator that shows the final stage of wear, and typically with a groove width of 5.0 mm or more and a groove depth of 7.5 mm or more. Furthermore, “lug groove” refers to a transverse groove with a groove width of 2.0 mm or more and a groove depth of 3.0 mm or more. Additionally, “lamella,” as described below, refers to a cut formed in a web section, typically having a lamella width of less than 1.5 mm.

[0019] The groove width is the maximum distance between the left and right groove walls at the groove opening section and is measured when the tire is mounted on a specified rim, inflated to the specified internal pressure, and in an unloaded state. In configurations where the groove sections include recessed sections or chamfered sections on their edges, the groove width is measured with reference to the points where, viewed in a cross-section perpendicular to the groove's longitudinal direction, the tread contact surface and the extension lines of the groove walls intersect. Additionally, in configurations where the grooves extend in a zigzag or wave-like manner around the tire's circumference, the groove width is measured with reference to the center line of the groove wall amplitude.

[0020] Groove depth is the maximum distance from the tread contact surface to the groove base and is measured when the tire is mounted on a specified rim, inflated to the specified internal pressure, and in an unloaded state. Additionally, in configurations where the grooves include a serrated / grooved section or sipes on the groove base, the groove depth is measured excluding these sections.

[0021] "Specified rim" refers to an "applicable rim" as defined by the Japan Automobile Tyre 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 Tyre and Rim Technical Organisation (ETRTO). "Specified inflation 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 the TRA, and "inflation pressures" as defined by the ETRTO.Furthermore, "specified 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, and a "LOAD CAPACITY" as defined by ETRTO. However, in the case of JATMA, the specified internal pressure for a passenger car tire is 180 kPa, and the specified load is 88% of the maximum load capacity.

[0022] For example, in the configuration of Fig. 2 of the pneumatic tire 1 has a tread pattern with left-right point symmetry around a point on the equatorial plane of the tire CL. Furthermore, the four main circumferential grooves 21, 22 are arranged with left-right symmetry around the equatorial plane of the tire CL. Additionally, five rib sections 31 to 33 are defined by the four main circumferential grooves 21, 22. One rib section 31 is located on the equatorial plane of the tire CL.

[0023] However, the configuration is not limited to this, and five or more main circumferential grooves can be arranged (not shown). Furthermore, the main circumferential grooves 21, 22 can be arranged with left-right asymmetry around the equatorial plane of the tire CL (not shown). Additionally, a main circumferential groove can be located on an equatorial plane of the tire CL (not shown). Therefore, the rib section 31 can be located at a position outside the equatorial plane of the tire CL.

[0024] In the configuration of Fig. 2 The four main circumferential grooves 21, 22 have an overall straight shape, and the edge sections of the left and right rib sections 31 to 33 project into the main circumferential grooves 21, 22, whereby the groove walls of the main circumferential grooves 21, 22 are formed in a stepped shape in the tire circumferential direction.

[0025] However, no such restriction is intended, and the main circumferential grooves 21, 22 may have a perfectly straight shape, a zigzag shape, or a wave-like shape that bends or curves as it extends in the circumferential direction of the tire (not shown).

[0026] Here, the left and right main circumferential grooves 22, 22, which are located at the outermost points in the tire's transverse direction, are referred to as the outermost main circumferential grooves. Furthermore, a tread section center area and a tread section shoulder area are defined by the left and right outermost main circumferential grooves 22, 22.

[0027] Furthermore, of the majority of the rib sections 31 to 33 defined by the main circumferential grooves 21, 22, rib section 33 on the outermost side in the tire transverse direction is defined as a shoulder rib section. A shoulder rib section 33 is an outer rib section in the tire transverse direction, defined by the outermost main circumferential groove 22, and a ground contact edge of the tire T is located on the tread surface of the shoulder rib section 33. Additionally, the second rib section 32 from the outside in the tire transverse direction is defined as a second rib section. The second rib section 32 is an inner rib section in the tire transverse direction, defined by the outermost main circumferential groove 22, and is adjacent to the shoulder rib section 33, with the outermost main circumferential groove 22 positioned between them.Furthermore, the rib section 31, which is located closer to the equatorial plane of the tire CL than the second rib section 32, is defined as a central rib section. The central rib section 31 can be located on the equatorial plane of the tire CL ( ). Fig. 2) or may be located at a position outside the equatorial plane of the tire CL (not shown).

[0028] Furthermore, the configuration of Fig. 2. Each of the rib sections 31 to 33 comprises a plurality of respective lug grooves 411, 412; 421, 422; 431, 432, extending in the transverse direction of the tire. Furthermore, at least one of the lug grooves 411, 412; 421, 422, 431 is a continuous lug groove that extends transversely through the respective rib section 31; 32; 33 and is also arranged circumferentially at predetermined intervals. Accordingly, each of the rib sections 31 to 33 is subdivided circumferentially by the lug grooves 411, 412; 421, 422; 431 and is designed as a block row enclosing a plurality of blocks.

[0029] However, no such limitation is intended, and, for example, each of the lug grooves 431, 432 of the shoulder rib section 33 can be a non-continuous lug groove that terminates blindly at an end section within the shoulder rib section 33 (not shown). In such an embodiment, the shoulder rib section 33 is a rib that is continuous in the circumferential direction of the tire. Arrangement structure of the continuous tread grooves

[0030] All-season tires for passenger cars and light trucks use a block pattern with multiple rows of blocks to improve the tire's performance in snow. However, such a block pattern tends to result in increased tread noise and reduced noise performance.

[0031] Accordingly, the following configuration is used for the pneumatic tire 1 to provide good snow performance and noise performance in a compatible manner.

[0032] Fig. 3 is an enlarged view showing a central area of ​​the Fig. Figure 2 illustrates the running surface pattern. In the same drawing, the arrangement structure of the continuous stud grooves 411, 412 of the central web section 31 and the continuous stud grooves 421, 422 of the second web section 32 is shown in a simplified manner.

[0033] As in Fig. As shown in Figure 3, the central rib section 31 and the left and right second rib sections 32, 32 are provided with a majority of continuous lug grooves 411, 412; 421, 422, which extend transversely through the rib section 31; 32. The continuous lug grooves 411, 412; 421, 422 subdivide the central rib section 31 and the left and right second rib sections 32, 32 in the circumferential direction of the tire, forming rows of blocks. This increases the traction properties on snow-covered road surfaces (shear force in the snow) and the snow performance (especially the mileage) of the tire.

[0034] Furthermore, the continuous lug grooves 411, 412; 421, 422 of the central rib section 31 and the second rib sections 32, 32 are inclined at a predetermined angle of inclination (dimensional symbol omitted in the drawing) with respect to the tire's transverse direction. The continuous lug grooves 411, 412; 421, 422 also have an angle of inclination that is preferably in the range of 5 degrees to 70 degrees, more preferably in the range of 10 degrees to 60 degrees, and more preferably in the range of 20 degrees to 48 degrees. In addition, the angle of inclination of the continuous lug grooves 411, 412 of the central rib section 31 is preferably 15 degrees or more lower than the angle of inclination of the continuous lug grooves 421, 422 of the left and right second rib sections 32, 32.

[0035] The angle of inclination of the continuous lug grooves in the center rib section and in the second rib sections is measured as an angle formed by an imaginary line connecting the centers of the continuous lug grooves at the openings to the left and right main grooves, and the tire's axis of rotation. The angle of inclination of the continuous lug grooves in the shoulder rib section is also measured as an angle formed by an imaginary line connecting the centers of the continuous lug grooves at the openings on the outermost main circumferential groove and the tire's contact patch, and the tire's axis of rotation.

[0036] Here, the continuous lug grooves 411, 412, located in the central rib section 31, and the continuous lug grooves 421, 422, located in the left and right second rib sections 32, are inclined in opposite directions in the transverse direction of the tire. Furthermore, the continuous lug grooves 421, 422, located in the left and right second rib sections 32, 32, are inclined to each other in the same direction. This improves the traction properties on snow-covered road surfaces when the vehicle turns and enhances the tire's snow performance (especially its turning performance).

[0037] In the configuration of Fig. 2, as described above, the five rib sections 31 to 33 are each provided with a plurality of the respective continuous lug grooves 411, 412; 421, 422, 431, which are inclined at a predetermined angle with respect to the transverse direction of the tire. The continuous lug grooves 411, 412, 431 of the central rib section 31 and of the left and right shoulder rib sections 33, 33 and the continuous lug grooves 421, 422 of the left and right second rib section 32, 32 run in opposite directions to each other in the transverse direction of the tire. Furthermore, the continuous lug grooves 411, 412 of the central rib section 31 and the continuous lug grooves 431 of the shoulder rib sections 33 are inclined to each other in the same direction. Furthermore, the continuous tunnel grooves 411, 412 of the left and right second bridge section 32, 32 are inclined towards each other in the same direction.Furthermore, the continuous lug grooves of adjacent pairs of rib sections 31, 32; 32, 33 exhibit opposite orientations in each pair. Accordingly, the continuous lug grooves 411, 412; 421, 422, 431 in the tread pattern are arranged in a zigzag pattern in the transverse direction of the tire. This further enhances traction on snow-covered road surfaces when the vehicle is turning.

[0038] As in Fig. As shown in Figure 2, the positions of the opening sections of the continuous lug grooves 411, 412, 421, 422; 421, 422, 431 of adjacent pairs of the rib sections 31, 32; 32, 33 are offset from each other in the tire's circumferential direction relative to the main circumferential grooves 21, 22. Thus, the continuous lug grooves 411, 412, 421, 422; 421, 422, 431 of the adjacent pairs of the rib sections 31, 32; 32, 33 are arranged discontinuously and not on an extension line of a groove centerline relative to each other. This further increases the traction properties on snow-covered road surfaces.

[0039] Arrangement structure with different block types Fig. 4 is an enlarged view showing the central web section of the in Fig. 2 illustrated tread patterns. Fig. 5 is an enlarged view showing the second bridge section of the in Fig. 2 illustrated tread patterns. Fig. 6 is an explanatory diagram that shows a modified example of the one in Fig. 5 illustrates the second bridge section.

[0040] As in Fig. 2 and Fig. Figure 3 shows the central web section 31 and the left and right second web sections 32, 32 with a plurality of types of continuous tunnel grooves 411, 412; 421, 422 and a plurality of types of blocks 311, 312; 321, 322 (see Fig. 3), which are defined by the continuous lug grooves 411, 412; 421, 422. Furthermore, a plurality of types of continuous lug grooves 411, 412; 421, 422 are arranged periodically in the circumferential direction of the tire. In addition, the plurality of block types 311, 312; 321, 322 have different shapes. The plurality of block types 311, 312; 321, 322 form a set as a block unit, and a plurality of these block units are arranged repeatedly around the entire circumference of the tire. In such a configuration, the rib sections 31, 32 of the tread section center area are each provided with a row of blocks, which includes the plurality of block types 311, 312; 321, 322. This reduces tread noise dependent on the block shape when the tire is rolling. This improves the tire's noise performance (especially its interior noise performance).

[0041] The number of the above-described types of continuous tunnel grooves and blocks ranges from two to three.

[0042] Furthermore, the tread pattern of the pneumatic tire 1 can have a variable pitch spacing structure, wherein the pitch spacing arrangement varies in the tire's circumferential direction, and the circumferential length of the blocks of the rib sections 31 to 33 can vary periodically in the tire's circumferential direction. Accordingly, in the central rib section 31 and in the left and right second rib sections 32, 32, the circumferential length of a block unit described above, which includes a set of a plurality of block types 311, 312; 321, 322, varies periodically in the tire's circumferential direction due to the variable pitch spacing structure described above. This effectively reduces tread noise when the tire is rolling.

[0043] For example, in the configuration of Fig. 4 The central rib section 31 is provided with two types of continuous lug grooves 411, 412. These continuous lug grooves 411, 412 are arranged alternately in the circumferential direction of the tire (see Fig. 2) Furthermore, the continuous lug grooves 411, 412 adjacent in the circumferential direction of the tire have different angles of inclination θ11, θ12 (dimension symbol omitted in the drawing). In addition, the two types of blocks 311, 312, defined by the continuous lug grooves 411, 412, are arranged alternately in the circumferential direction of the tire. Furthermore, the blocks 311, 312 adjacent in the circumferential direction have different shapes. Additionally, the blocks 311, 312 have a profile shape with point symmetry with respect to each other.

[0044] Furthermore, an edge section of the first block 311 (right side of) is located closer to one of the main circumferential grooves 22. Fig. 4) longer in the direction of the tire circumference than an edge section (left side of) that is closer to the other main circumferential groove 21 Fig. 4) Alternatively, a marginal section of the second block 312 (right side of) located closer to one of the main circumferential grooves 22 is used. Fig. 4) shorter than a marginal section (left side of) that lies closer to the other main circumferential groove 21 Fig. 4) Thus, when considering only the edge section of the central rib section 31 on one side, the longer edge section and the shorter edge section are arranged alternately in the direction of the tire circumference.

[0045] Furthermore, the two types of continuous lug grooves 411, 412 are inclined in the same direction with respect to the tire's transverse direction. Additionally, the inclination angle θ11 of the narrower first continuous lug groove 411 is greater than the inclination angle θ12 of the wider second continuous lug groove 412 (θ12 < θ11). The difference between the inclination angles θ11, θ12 is preferably in the range of 3 degrees ≤ θ11 - θ12 ≤ 20 degrees, and more preferably in the range of 5 degrees ≤ θ11 - θ12 ≤ 10 degrees. This ensures a difference θ11 - θ12 between the inclination angles θ11, θ12 of the adjacent continuous lug grooves 411, 412 and guarantees a reduction in tread noise when the tire is rolling. Furthermore, the difference in stiffness or the difference in edge length between the adjacent blocks 311, 312; 321, 322 in the direction of the tire circumference is reduced, and the uneven wear of the block is suppressed.

[0046] Furthermore, the groove width Wg11 of the narrower first continuous adit groove 411 and the groove width Wg12 of the wider second continuous adit groove 412 preferably have the relationship 1.10 ≤ Wg12 / Wg11 ≤ 3.00 and more preferably have the relationship 1.30 ≤ Wg12 / Wg11 ≤ 2.00. In this way, the ratio Wg12 / Wg11 of the groove widths Wg11, Wg12 of the adjacent continuous adit grooves 411, 412 is suitably determined.

[0047] It should be noted that the groove width Wg12 of the wider second continuous lug groove 412 can be selected appropriately depending on the tire size. For a typical all-season tire for a passenger car or light truck, the groove width Wg12 of the wider second continuous lug groove 412 can be within the range of 3.8 mm ≤ Wg12 ≤ 5.3 mm.

[0048] As in Fig. As shown in Figure 4, the continuous lug grooves 411, 412 of the central rib section 31 enclose a stepped, curved section when viewed from a top view of the tread. Specifically, the left and right groove walls of the continuous lug grooves 411, 412 of the central rib section 31 both enclose a stepped, curved section that is bent in the tire's circumferential direction in a central region of the blocks 311, 312 in the transverse direction (a region in one-third of the block width). Furthermore, the curved sections of the continuous lug grooves 411, 412 have a Z-shape or a crank-like shape when viewed from a top view of the tread. The left and right groove walls of the continuous lug grooves 411, 412 are arranged parallel to each other, resulting in a substantially constant groove width for the continuous lug grooves 411, 412.In such a configuration, the continuous lug grooves 411, 412 enclose more edge components than in a configuration where the lug grooves have a straight shape. This improves the tire's snow performance.

[0049] The stepped, curved section is defined by a first groove wall section, a second groove wall section offset in the tire's circumferential direction relative to the first groove wall section, and a circumferential groove wall section extending in the tire's circumferential direction and connecting the first and second groove wall sections. Furthermore, an angle (dimension symbol omitted in the drawing) formed by the wall surface of the circumferential groove wall section and the tire's circumferential direction is preferably in the range of 80 to 100 degrees, and more preferably in the range of 85 to 95 degrees.

[0050] Furthermore, the configuration of Fig. 4. The continuous tunnel grooves 411, 412 include only a single curved section. However, no such limitation is intended, and the continuous tunnel grooves 411, 412 can include a plurality of curved sections (not shown). Furthermore, in Fig. 4. The groove walls of the continuous adit grooves 411, 412 have an overall linear shape, with the exception of the curved section. However, no such restriction is intended, and the groove walls of the continuous adit grooves 411, 412 may have an overall curved or bent shape, like the continuous adit grooves 421, 422 described above (see Figure 4). Fig. 5) of the second bridge section 32 possess.

[0051] Furthermore, the configuration of Fig. 4. The continuous tunnel grooves 411, 412 of the central web section 31 have respective groove widths Wg11, Wg12, which are constant over the entire area in the longitudinal direction of the groove. However, no such restriction is intended, and the continuous tunnel grooves 411, 412 can, for example, increase in width at the opening section to the main circumferential groove 21, causing the groove widths Wg11, Wg12 of the continuous tunnel grooves 411, 412 to vary in the longitudinal direction of the groove (not shown).

[0052] Similarly, in the configuration of Fig. 5 The left and right second rib sections 32, 32 are provided with two types of continuous lug grooves 421, 422. These continuous lug grooves 421, 422 are arranged alternately in the circumferential direction of the tire (see Fig. 2) Furthermore, the continuous lug grooves 421, 422 adjacent in the circumferential direction of the tire have different angles of inclination θ21, θ22 (dimension symbol omitted in the drawing). Moreover, the two types of blocks 321, 322, defined by the continuous lug grooves 421, 422, are arranged alternately in the circumferential direction of the tire. Thus, the blocks 321, 322 adjacent in the circumferential direction of the tire have different shapes.

[0053] The adjacent continuous lug grooves 421, 422 have different angles of inclination to each other. Therefore, the left and right edge sections of blocks 321, 322, which are closer to the main circumferential grooves 21, 22, have different circumferential lengths. Furthermore, the edge section of one of the adjacent blocks 321 that is closer to the equatorial plane of the tire CL is longer in the circumferential direction than the edge section that is closer to the ground contact edge of the tire T. Conversely, the edge section of the other block 322 that is closer to the equatorial plane of the tire CL is shorter in the circumferential direction than the edge section that is closer to the ground contact edge of the tire T. Thus, considering only the edge section of the second rib section 32 on one side, the longer and shorter edge sections alternate in the circumferential direction of the tire.Furthermore, the edge sections of the adjacent blocks 321, 322 are arranged offset in the tire transverse direction such that, in both the left and the right main circumferential groove, the shorter edge section protrudes further into the respective main circumferential groove 21, 22 than the longer edge section.

[0054] Furthermore, the two types of continuous lug grooves 421, 422 are inclined in the same direction with respect to the tire's transverse direction (in Fig. 5 upwards towards the equatorial plane of the tire). Furthermore, the inclination angle θ21 of the continuous lug groove 421 is greater than the inclination angle θ22 of the continuous lug groove 422 (θ22 < θ21). The difference between the inclination angles θ21, θ22 is preferably in the range of 5 degrees ≤ θ21 - θ22 ≤ 40 degrees and more preferably in the range of 10 degrees ≤ θ21 - θ22 ≤ 20 degrees. This ensures the difference θ21 - θ22 between the inclination angles θ21, θ22 of the adjacent continuous lug grooves 421, 422 and guarantees a reduction in tread noise when the tire is rolling. Furthermore, the difference in stiffness or the difference in edge length between the adjacent blocks 311, 312; 321, 322 in the direction of the tire circumference is reduced, and the uneven wear of the block is suppressed.

[0055] Furthermore, as in Fig. As shown in Figure 5, the blocks 321, 322 of the second rib section 32 each have a single narrow circumferential groove 323, 324. Furthermore, the narrow circumferential grooves 323, 324 have a curved shape with an amplitude in the transverse direction of the tire and extend circumferentially through the blocks 321, 322, opening towards the adjacent continuous lug grooves 421, 422. Accordingly, the blocks 321, 322 are divided transversely in the tire direction, and the ground contact pressure of the blocks 321, 322 is more uniform when the tire comes into contact with the ground. Moreover, the curved shape of the narrow circumferential grooves 323, 324 enlarges the edge components of the second rib section 32 and improves the tire's snow performance.

[0056] Furthermore, the configuration of Fig. 5. The narrow circumferential grooves 323, 324 are arranged in the transverse direction of the tire in a central region (a region in one-third of the block width) of the blocks 321, 322 and divide the road contact surface of the blocks 321, 322 into approximately two equal parts. Furthermore, the narrow circumferential grooves 323, 324 have a stepped curved section with an amplitude in the transverse direction of the tire. The curved section of the narrow circumferential grooves 323, 324 is arranged in the circumferential direction in a central section of the blocks 321, 322 (a central section if the blocks 321, 322 are divided into three equal parts in the circumferential direction). In this way, the stiffness of the blocks 321, 322 is homogenized in the circumferential direction of the tire.

[0057] Furthermore, the groove width Ws of the narrow circumferential grooves 323, 324 is specified such that the narrow circumferential grooves 323, 324 do not close at the contact surface between the tire and a flat plate when the tire is mounted on a specified rim, inflated to the specified internal pressure, placed vertically on the flat plate in a static state, and loaded with a load corresponding to the specified load. In particular, the groove width Ws of the narrow circumferential grooves 323, 324 is specified in the range of 1.5 mm ≤ Ws ≤ 6.0 mm. Accordingly, the narrow circumferential grooves 323, 324 are suitably open when the tire comes into contact with the ground, the blocks 321, 322 are divided, and the ground contact pressure of the blocks 321, 322 is suitably evened out. Furthermore, the edge components of blocks 321, 322 are ensured by the narrow circumferential grooves 323, 324, and the traction properties of the tire are improved.

[0058] The groove width Ws of the narrow circumferential grooves 323, 324 is measured as the distance corresponding to the opening section of the groove wall surface when the tire is mounted on a specified rim and inflated to the specified internal pressure and is in an unloaded state.

[0059] Furthermore, the narrow circumferential grooves 323, 324 adjacent to each other in the tire's circumferential direction open at different positions towards the same continuous lug groove 421, 422. In other words, the opening sections of the narrow circumferential grooves 323, 324 opposite each other on each side of the continuous lug groove 421, 422 are arranged at positions that are offset in the transverse direction of the tire. Thus, the opening sections of the adjacent narrow circumferential grooves 323, 324 are arranged in a distributed manner in the transverse direction of the tire. Accordingly, the overall stiffness of the second rib section 32 is homogenized.

[0060] It should be noted that in the configuration of Fig. 5, as described above, the narrow circumferential grooves 323, 324 enclose a stepped curved section. However, no such restriction is intended, and the narrow circumferential grooves 323, 324 may have a straight shape, an arc shape, or a wave-like shape (not shown).

[0061] Furthermore, as in Fig. 5 shown, the continuous lug grooves 421, 422 have a shape that increases in groove width towards the ground contact edge of the tire T (see Fig. 2) Furthermore, the groove widths Wg21_cl, Wg22_cl of the continuous lug grooves 421, 422 are narrower at the opening sections closer to the equatorial plane of the tire CL than the groove widths Wg21_t, Wg22_t at the opening sections closer to the ground contact edge of the tire T. Accordingly, the stiffness of the blocks 321, 322 of the second rib section 32 is ensured in the area closer to the equatorial plane of the tire CL, and uneven wear of the blocks 321, 322 is suppressed. Furthermore, the groove widths Wg21_cl, Wg22_cl of the continuous lug grooves 421, 422 adjacent in the direction of the tire circumference are equal to each other at the opening sections located closer to the equatorial plane of the tire CL (Wg21_cl = Wg22_cl), and the groove widths Wg21_t, Wg22_t at the opening sections located closer to the ground contact edge of the tire T are equal to each other (Wg21_t = Wg22_t).Please note that the groove widths may differ (not shown).

[0062] Furthermore, the configuration of Fig. 5. One of the groove walls of the continuous tunnel grooves 421, 422 of the second web section 32, viewed from the running surface in a plan view, has a stepped, curved section, while the other groove wall has a linear or arc shape. Accordingly, the groove widths Wg21_cl, Wg21_t; Wg22_cl, Wg22_t of the left and right groove opening sections of the continuous tunnel grooves 421, 422 differ from each other. Furthermore, because the groove walls of the continuous tunnel grooves 421, 422 include a stepped, curved section, the edge components of the tunnel grooves 421, 422 are increased, and the traction properties are improved.

[0063] Furthermore, because one of the groove walls of the continuous lug grooves 411, 412 is bent in the central section of the second rib section 32, the left and right groove centerlines of the bent section in the central section of the second rib section 32 are offset in the tire's circumferential direction. Accordingly, the offset amounts G1, G2 of the groove centerlines of the continuous lug grooves 421, 422 in the tire's circumferential direction are preferably in the range of 2.0 mm to 12.0 mm.

[0064] Furthermore, the bending directions of the groove centerlines of the adjacent continuous lug grooves 421, 422 are opposite to each other with respect to the tire's circumferential direction. Thus, the edge section of block 322, which is arranged between the curved sections of the adjacent continuous lug grooves 421, 422, has a greater width on the side of the equatorial plane of the tire CL and a smaller width on the side of the ground contact edge of the tire T. Accordingly, the section of block 322 with the smaller width is given a suitable length in the tire's circumferential direction due to the difference in the inclination angles of the continuous lug grooves 421, 422 (the section of block 322, which is closer to the equatorial plane of the tire CL and is divided by the narrow circumferential groove 324).

[0065] It should be noted that in the configuration of Fig. 5, as described above, one of the groove walls of the continuous stud grooves 421, 422 of the second web section 32, when viewed from above, includes a stepped curved section, and the other groove wall has a linear or arc shape. However, no such restriction is intended, and as in the modified example of Fig. As shown in Figure 6, both the left and right groove walls of the continuous tunnel grooves 421, 422 of the second bridge section 32 can enclose a step-shaped curved section.

[0066] Recessed section and beveled section of the central web section In Fig. 3. The central web section 31 includes a recess section 313 only at the opening section of the narrower continuous tunnel groove 411 and does not include a recess section at the opening section of the wider continuous tunnel groove 412. Furthermore, as in Fig. As shown in Figure 4, the central rib section 31 incorporates a chamfered section 314 on an edge section of the recess section 313. This ensures the drainage and snow removal properties of the narrower continuous lug groove 411. Furthermore, the groove volume of the narrower continuous lug groove 411 is increased by the recess section 313 and the chamfered section 314, and the stiffness of the central rib section 31 in the circumferential direction of the tire is homogenized.

[0067] The “recess section 313” refers to the section with a predetermined depth formed in the edge section of the web section 31. The recess section 313 serves to increase the groove volume of the continuous tunnel groove 411 and has a depth D2 that is greater than that of the chamfered section 314 of the recess section 313 or of a chamfered section (not shown) formed in the edge section of the web section 31. The depth D2 of the recess section 313 is described below.

[0068] "Beveled section" refers to a flat surface (for example, a corner bevel) or a curved surface (for example, a rounded chamfer) that connects the edge section to an adjacent surface.

[0069] Furthermore, as shown in Fig. As shown in Figure 3, the adjacent continuous tunnel grooves 421, 422 of the second web section 32 exhibit different angles of inclination to each other, and the extension lines of the groove centerlines of the continuous tunnel grooves 421, 422 meet at the edge section of the central web section 31. Furthermore, the recess section 313 of the central web section 31 surrounds the extension lines of the groove centerlines of the adjacent continuous tunnel grooves 411, 412. In addition, the recess section 313 encloses a wall surface that is curved in an L-shape or a V-shape such that it surrounds the extension lines of the groove centerlines of a pair of the continuous tunnel grooves 421, 422. The chamfered section 314 is formed along the curved recess section 313.

[0070] Furthermore, the projecting side of the curved shape of the recess section 313 points inwards in the circumferential direction of the tire and inwards in the width direction of the central rib section 31. In addition, one of the V-shaped recess sections 313 extends over two of the blocks 311, 312 adjacent in the circumferential direction of the tire and intersects a single opening section of the continuous lug groove 411, 412. In other words, the continuous lug groove 411, 412 is connected to the recess section 313 and opens through the recess section 313 towards the main circumferential groove 21. Accordingly, a single recess section 313 increases the width of the opening section of the continuous lug groove 411, 412 to the left and right along the main circumferential groove 21.

[0071] Furthermore, a majority of the recess sections 313 are formed on the left and right edge sections of the central rib section 31. Additionally, the narrower continuous lug groove 411, which encloses the recess sections 313 on both the left and right opening sections, and the wider continuous lug groove 412, which does not enclose the recess sections 313 on any opening section, are arranged alternately in the tire's circumferential direction. The continuous lug groove 412, which does not enclose the recess section 313, is arranged separately from the recess section 313 in the tire's circumferential direction and opens towards the main circumferential groove 21 without being connected to the recess section 313.

[0072] Furthermore, there is a crossing angle Φ1 (see Fig. 3) between the groove centerline of one continuous adit groove 421 and the groove centerline of the main circumferential groove 21 in the range of 50 degrees to 75 degrees, and a crossing angle Φ2 between the groove centerline of the other continuous adit groove 422 and the main circumferential groove 21 lies in the range of 15 degrees to 40 degrees.

[0073] The bending angle of the recess section 313 (dimensional symbol omitted in the drawing) is preferably in the range of 10 degrees to 70 degrees and more preferably in the range of 15 degrees to 55 degrees. Thus, by having the recess section 313 have a curved shape projecting in the circumferential direction with an acute angle, as shown in Fig. 3 shown, the recess section 313 surrounds the intersection section of the extension lines along the extension lines of the groove center lines of the continuous tunnel grooves 421, 422 of the second bridge section 32.

[0074] The bending angle of the recess section 313 is measured when viewing the tread in a top view along the profile line of the wall surface of the recess section, when the tire is mounted on a specified rim, inflated to the specified internal pressure, and in an unloaded state. It should be noted that the bending angle of the recess section 313 is appropriately determined depending on the pitch spacing of the tread pattern with a variable pitch structure.

[0075] Furthermore, they indicate Fig. 4. The maximum width W1 of the central web section 31 and the maximum width W2 of the recess section 313 preferably have the relationship 0.05 ≤ W2 / W1 ≤ 0.25 and more preferably the relationship 0.10 ≤ W2 / W1 ≤ 0.15. This ensures the maximum width W2 of the recess section 313, improves the drainage and snow drainage properties of the narrower continuous groove 411, and prevents a decrease in the stiffness of the central web section 31 caused by an excessive size of the recess section 313.

[0076] The maximum width W1 of the rib section is the maximum value of the width of the road contact surface of the rib section in the tire axial direction and is measured when the tire is mounted on a specified rim and inflated to the specified internal pressure and is in an unloaded state (see Fig. 4).

[0077] The maximum width W2 of the recess section is the maximum value of the width of the recess section in the tire axial direction and is measured using the measuring point of the maximum width W1 of the rib section as a reference when the tire is mounted on a specified rim and inflated to the specified internal pressure and is in an unloaded state (see Fig. 4).

[0078] Furthermore, the maximum groove depth D1 (not shown) of the continuous groove 411 and the maximum groove depth D2 of the recess section 313 (not shown) preferably have the relationship 0.30 ≤ D2 / D1 ≤ 1.00 and more preferably have the relationship 0.50 ≤ D2 / D1 ≤ 0.80. This ensures the maximum depth D2 of the recess section 313, improves the drainage and snow runoff properties of the continuous groove 411, and prevents a decrease in the stiffness of the web section 31 caused by an excessive depth of the recess section 313.

[0079] The maximum groove depth D1 of the lug groove is the maximum value of the distance from the tread contact surface to the groove base and is measured when the tire is mounted on a specified rim, inflated to the specified internal pressure, and in an unloaded state. Additionally, in configurations where the lug grooves partially include a raised section or sipe on the groove base, the depth is measured excluding these sections.

[0080] The maximum depth D2 of the recess section is the maximum value of the distance from the tread contact surface to the base section and is measured when the tire is mounted on a specified rim, inflated to the specified internal pressure, and in an unloaded state. Additionally, in configurations where the recess sections include a raised base section or sipes on the groove bottom, the groove depth is measured excluding these sections.

[0081] Furthermore, the maximum groove depth D0 (not shown) of the main circumferential groove 21 and the maximum groove depth D1 (not shown) of the continuous tunnel groove 411 of the central web section 31 are preferably in the range of 0.6 ≤ D1 / D0 ≤ 0.8. Accordingly, the maximum groove depth D1 of the continuous tunnel groove 411 is made suitable and the drainage properties of the tunnel groove 411 (412) are ensured.

[0082] Furthermore, they indicate Fig. 4. The maximum width W2 of the recess section 313 and a width W3 of the chamfered section 314 preferably have the relationship 0.20 ≤ W3 / W2 ≤ 4.00 and more preferably have the relationship 0.30 ≤ W3 / W2 ≤ 2.00. The width W3 of the chamfered section 314 is preferably in the range of 1.5 mm ≤ W3 ≤ 6.0 mm. Accordingly, the width W3 of the chamfered section 314 is made suitable.

[0083] The width W3 of the chamfered section is the distance from the profile line of the recess section to the tread contact surface when viewing the tread from above and is measured when the tire is mounted on a specified rim, inflated to the specified internal pressure and in an unloaded state (see Fig. 4).

[0084] Furthermore, the depth D3 (not shown) of the chamfered section 314 and the maximum depth D2 of the recessed section 313 (not shown) preferably have the relationship 0.50 ≤ D3 / D2 ≤ 0.80. Additionally, the depth D3 of the chamfered section 314 is preferably in the range of 1.3 mm ≤ D3 ≤ 5.5 mm. Accordingly, the depth D3 of the chamfered section 314 is made suitable.

[0085] The depth D3 of the chamfered section is the distance from the tread contact surface to a maximum depth position of the chamfered section and is measured when the tire is mounted on a specified rim, inflated to the specified internal pressure, and in an unloaded state. The boundary between the recessed section and the chamfered section is defined by the intersection of the extension line of the wall surface of the recessed section 313, which is closer to the ground section, and the inclined surface of the chamfered section 314, which adjoins the road contact surface of the center rib section 31.

[0086] Non-continuous stud groove of the shoulder bridge section Fig. 7 is an enlarged view showing the shoulder strap section of the Fig. 2 illustrated tread patterns.

[0087] In the configuration of Fig. 2 closes, as in Fig. 7 shown, the shoulder bridge section 33 includes the above-described majority of continuous stud grooves 431 and the majority of non-continuous stud grooves 432.

[0088] The continuous lug grooves 431 open towards the main circumferential groove 22 and the ground contact edge of the tire T and extend transversely through the shoulder rib section 33. For example, in the configuration of Fig. 7. The continuous lug grooves 431 have a shape that increases in width from the main circumferential groove 22 to the ground contact edge of the tire T. In particular, one of the groove walls of the continuous lug groove 431, when viewed from above, includes a stepped, curved section, and the other groove wall has a linear or arc shape. However, no such restriction is intended, and the left and right groove walls of the continuous lug groove 431 can have a linear or arc shape. Furthermore, the groove depth of a narrow, wider section of the continuous lug groove 431 located closer to the main circumferential groove 22 is preferably in the range of 30% to 80% of the groove depth of the wider, wider section located closer to the ground contact edge of the tire T. Accordingly, the snow drainage properties and the noise reduction effect of the continuous lug grooves 431 are ensured.

[0089] As in Fig. As shown in Figure 7, the non-continuous lug groove 432 opens at one end section towards the main circumferential groove 22 and ends blindly at the other end section within the contact spot of the shoulder bridge section 33. lamella

[0090] As in Fig. 4, Fig. 5 and Fig. As shown in Figure 7, the central rib section 31, the second rib sections 32, and the shoulder rib sections 33 are each provided with a plurality of sipes 5. The sipes 5 are classified as two-dimensional sipes (i.e., sipes with a flat surface) and three-dimensional sipes (i.e., 3D sipes). The sipes 5 ensure the edge components of the rib sections 31 to 33 and improve the traction properties of the tire.

[0091] When viewed in a cross-section along a normal direction to the lamella's longitudinal direction (when viewed in a cross-section that includes both the lamella's width and depth directions), the two-dimensional lamella has a straight lamella wall surface. The two-dimensional lamella only needs to have a straight shape when viewed in a cross-section as described above; in its longitudinal direction, it can have a straight shape, a zigzag shape, a wave-like shape, an arc shape, or the like.

[0092] The three-dimensional lamella, when viewed in a cross-section along a normal direction to the lamella's longitudinal axis and also in a cross-section along a normal direction to the lamella's depth, encloses a lamella wall surface with a curved shape and an amplitude in the lamella width direction. Compared to two-dimensional lamellae, the three-dimensional lamellae exhibit a greater interlocking force between opposing lamella wall surfaces and thus act in such a way as to increase the stiffness of the web sections. The three-dimensional lamella only needs to have the structure described above on the lamella wall surface and can, for example, have a straight shape, a zigzag shape, a wave-like shape, an arc shape, or the like on the running surface contact surface. Examples of such three-dimensional lamellae are listed below (see Fig. 8 and Fig. 9).

[0093] Fig. 8 and Fig. Figure 9 are explanatory diagrams illustrating examples of three-dimensional lamellae. These drawings are perspective views of three-dimensional lamellae with a pyramidal lamella wall surface.

[0094] In the configuration of Fig. 8. The sipe wall surface has a structure in which triangular pyramids and inverted triangular pyramids are connected in the longitudinal direction of the sipes. In other words, the sipe wall surface has a zigzag shape closer to the tread surface and a zigzag shape closer to the base section, with the pitch being offset in the transverse direction of the tire, so that the two zigzag shapes together form opposing ridges and grooves.Furthermore, when viewed in the direction of tire rotation, the ridges and grooves of the sidewall surface are formed by comb lines between a protruding curvature point closer to the tread surface and a depression curvature point closer to the bottom section, a depression curvature point closer to the tread surface and a protruding curvature point closer to the bottom section, and a protruding curvature point closer to the tread surface and a protruding curvature point closer to the bottom section, which are adjacent to each other, with the flat surfaces between the comb lines being connected in sequence in the transverse direction of the tire.Furthermore, a first sipe wall surface has a combed surface with convex triangular pyramids and inverted triangular pyramids arranged alternately in the tire transverse direction; and a second sipe wall surface has a combed surface with concave triangular pyramids and inverted triangular pyramids arranged alternately in the tire transverse direction. Additionally, the combed surface of the sipe wall surface is oriented towards the outside of the blocks, at least at the outer ends of the sipe. It should be noted that examples of such a three-dimensional sipe include the known technology described in JP 3894743 B.

[0095] In the configuration of Fig. 9. The sipe wall surface has a structure in which a plurality of prism shapes, exhibiting a block shape, are connected in the sipe depth direction and the sipe longitudinal direction, while being inclined with respect to the sipe depth direction. In other words, the sipe wall surface has a zigzag shape on the tread surface. Furthermore, the sipe wall surface includes curved sections at at least two points in the tire radial direction within the blocks, which are curved in the tire circumferential direction and connected in the tire transverse direction. Moreover, these curved sections have a zigzag shape with an amplitude in the tire radial direction.While the amplitude in the circumferential direction of the sipe wall surface is constant, the angle of inclination in the circumferential direction with respect to a normal direction of the tread surface is smaller in a section on the sipe base side than in a section on the tread surface side; and the amplitude of the curved section in the tire radial direction is larger in a section on the sipe base side than in a section on the tread surface side. It should be noted that examples of such a three-dimensional sipe include the known technology described in JP 4316452 B.

[0096] For example, in the configuration of Fig. 4. Blocks 311, 312 of the central rib section 31 each contain a plurality of sipes 5, and these sipes 5 are three-dimensional. Furthermore, the sipes 5 terminate blindly at a first end section within blocks 311, 312 and are connected at a second end section to the opening of the main circumferential groove 21 at the edge section of blocks 311, 312. Additionally, the sipes 5 are inclined in the same direction with respect to the tire's circumferential direction as the continuous lug grooves 411 and extend in the tire's transverse direction, intersecting the centerline of the central rib section 31 (in Fig. 4 the equatorial plane of the tire CL). Furthermore, the sipes 5 and the continuous lug grooves 411, 412 are arranged parallel to each other and at equal intervals in the circumferential direction of the tire. This defines the blocks 311, 312 as rectangular areas of substantially the same width. Additionally, in the blocks 311, 312 adjacent in the circumferential direction of the tire, the sipes 5 are inclined in the same direction with respect to the circumferential direction of the tire and open on different sides from each other towards the edge sections.

[0097] Furthermore, the sipes 5 open towards the edge section of block 311 without being connected to the recess section 313. Accordingly, the opening sections of the sipes 5 and the recess sections 313 are offset from each other in the circumferential direction of the tire at the edge section of block 311. Consequently, there is a distance g1 (dimensional symbol omitted in the drawing) between the opening section of the sipe 5 and the recess section 313 at the edge section of block 311, preferably in the range of 2.0 mm ≤ g1. This appropriately ensures the distance g1 between the opening section of the sipe 5 and the recess section 313.

[0098] Furthermore, at least one of the lamellae 5 extends through the chamfered section 314 of the recessed section 313 and opens towards the edge section of the block 311. In particular, as shown in Fig. As shown in Figure 4, the recessed section 313 and the chamfered section 314 form a V-shape that projects in the circumferential direction of the tire and extend through the continuous lug groove 411 over the two blocks 311 and 312. Accordingly, in the block 311 that encloses the recessed section 313 and the chamfered section 314 with a V-shape, all sipes 5 are arranged separately from the recessed section 313 and the chamfered section 314. On the other hand, in another block 311, at least one of the sipes 5 extends through the chamfered section 314 and opens towards the edge section of the block 311.

[0099] Furthermore, as described above, a blind-ending end section of the sipe 5 is arranged separately from the recess section 313 and the chamfered section 314 within block 311. In such a configuration, the road contact surface of block 311 extends continuously in the tire's circumferential direction without being divided by the sipe 5, the recess section 313, or the chamfered section 314. This ensures the road contact surface of block 311. Here, a distance g2 (dimensional symbol omitted in the drawing) from the blind-ending end section of the sipe 5 to the chamfered section 314 is preferably in the range of 2.0 mm ≤ g2. This appropriately ensures the distance g2 from the blind-ending end section of the sipe 5 to the chamfered section 314.

[0100] It should be noted that in the configuration of Fig. 4, as described above, at least one of the lamellae 5 passes through the chamfered section 314 of the recess section 313. However, no such restriction is intended, and all lamellae 5 may be arranged separately from the recess section 313 and the chamfered section 314. In this way, the stiffness of the central web section 31 is ensured.

[0101] Furthermore, the configuration of Fig. Each of the blocks 321, 322 of the second rib section 32 contains a plurality of sipes 5, and these sipes 5 are three-dimensional. Furthermore, the sipes 5 terminate blindly at a first end section within the blocks 321, 322 and are connected at a second end section to the opening of the main circumferential grooves 21, 22 at the edge section of the blocks 321, 322. The sipes 5 are inclined in the same direction relative to the tire's circumferential direction as the continuous lug grooves 421, 422 and extend transversely around the tire. The sipes 5 and the continuous lug grooves 421, 422 are parallel to each other and equidistant from each other along the tire's circumferential direction. This defines the blocks 321, 322 into rectangular areas of substantially equal width.

[0102] Furthermore, the two types of continuous lug grooves 421, 422 of the second rib section 32 have different angles of inclination. Thus, the road contact surface of at least one of the blocks 322 is relatively narrower in the area closer to the equatorial plane of the tire CL, which is defined by the narrow circumferential groove 324. Consequently, the number of sipes in this area is lower than the number of sipes in other areas. In this way, the sipe density of the road contact surface of each of the blocks 321, 322 is homogenized. Effects

[0103] As described above, the pneumatic tire 1 includes at least four main circumferential grooves 21, 22 extending in the direction of the tire circumference and at least five rib sections 31 to 33 defined by the main circumferential grooves 21, 22 (see Fig. 2) Furthermore, the central rib section 31 and the left and right second rib sections 32, 32 are each provided with the plurality of continuous lug grooves 411, 412; 421, 422, which are inclined at a predetermined angle of inclination with respect to the tire transverse direction and extend through the rib sections 31, 32 in the tire transverse direction (see Fig. 3) The continuous lug grooves 411, 412, which are arranged in the central rib section 31, and the continuous lug grooves 421, 422, which are arranged in the left and right second rib sections 32, run in opposite directions in the transverse direction of the tire. Furthermore, at least one of the groove walls of the continuous lug grooves 421, 422, which are arranged in the left and right second rib sections 32, 32, includes a stepped curved section which, when viewed from above, is curved in the circumferential direction of the tire.

[0104] In such a configuration (1), the continuous lug grooves 411, 412 of the central rib section 31 and the continuous lug grooves 421, 422 of the left and right second rib sections 32, 32 are inclined in opposite directions. This improves the traction properties on snow-covered road surfaces when the vehicle turns. Furthermore (2), the continuous lug grooves 421, 422 arranged in the left and right second rib sections 32, 32 include a stepped curved section. This increases the edge components of the continuous lug groove in the tread section's central region (see Fig. 2) This has the advantage of improving the tire's performance in snow.

[0105] Furthermore, in the case of the pneumatic tire 1, the central rib section 31 and / or the left and right second rib sections 32, 32 (in Fig. 3 all bridge sections 31, 32) are provided with the majority of blocks 311, 312, 321, 322, which are defined by the majority of continuous tunnel grooves 411, 412, 421, 422 (see Fig. 3) Furthermore, the blocks 311, 312; 321, 322 adjacent in the direction of the tire's circumference have different shapes. In this configuration, the rib sections 31, 32 of the tread section's central area are each provided with a row of blocks, which includes the majority of block types 311, 312; 321, 322. This reduces tread noise dependent on the block shape when the tire is rolling. This has the advantage of improving the tire's noise performance (especially its interior noise performance).

[0106] Furthermore, in the pneumatic tire 1, the central rib section 31 and / or the left and right second rib sections 32, 32 (in Fig. 3 both the central rib section 31 and the left and right second rib sections 32, 32) are provided with the majority of sets of continuous lug grooves 411, 412; 421, 422, wherein the continuous lug grooves 411, 412; 421, 422 are adjacent in the sets in the circumferential direction of the tire and have different angles of inclination from each other (see Fig. 3) This has the advantage of reducing tread noise generated when the tire is rolling and improving the tire's noise performance (especially its interior noise performance).

[0107] Furthermore, in the pneumatic tire 1, the continuous lug grooves 411, 412 adjacent in the circumferential direction of the central rib section 31 have groove widths Wg11, Wg12, which differ from each other (see Fig. 4) Furthermore, the groove width Wg11 of the narrower continuous lug groove 411 and the groove width Wg12 of the wider continuous lug groove 412 exhibit the relationship 1.10 ≤ Wg12 / Wg11 ≤ 3.00. This has the advantage of appropriately defining the ratio Wg12 / Wg11 of the groove widths Wg11, Wg12 of the adjacent continuous lug grooves 411, 412. In other words, by ensuring 1.10 ≤ Wg12 / Wg11, the groove width ratio is guaranteed, and tread noise during tire rolling is reduced. Moreover, by ensuring Wg12 / Wg11 ≤ 3.00, the uneven block wear caused by an excessively large groove width ratio is suppressed.

[0108] Furthermore, in the case of the pneumatic tire 1, the left and right groove walls of the continuous lug grooves 411, 412 of the central rib section 31, when viewed from above, both enclose a stepped curved section (see Fig. 4) Furthermore, one of the groove walls of the continuous stud grooves 421, 422 of the left and right second web section 32, 32, when viewed from above, includes a step-shaped curved section, and the other groove wall has a linear or arc shape (see Fig. 5) This has the advantage that the edge components of the continuous lug grooves are enlarged and the snow performance of the tire is improved.

[0109] Furthermore, in the pneumatic tire 1, the left and right groove walls of the continuous lug grooves 411, 412, 421, 422 of the central rib section 31 and of the left and right second rib section 32, 32 enclose a step-shaped curved section when viewing the tread in a top view (see Fig. 4 and Fig. 6) This has the advantage that the edge components of the continuous lug grooves are enlarged and the snow performance of the tire is improved.

[0110] Furthermore, in the pneumatic tire 1, the opening sections to the main circumferential groove 21 of the continuous lug grooves 411, 412 of the central rib section 31 and the opening sections of the continuous lug grooves 421, 422 of the second rib section 32 are arranged offset from each other in the tire circumferential direction (see Fig. 3) This has the advantage that tread noise generated when the tire is rolling is reduced more than in a configuration where the opening sections of the tread grooves of the left and right rib sections are opposite to each other (not shown).

[0111] Furthermore, in the pneumatic tire 1, the continuous lug grooves 411, 412 adjacent in the circumferential direction of the central rib section 31 have groove widths Wg11, Wg12, which differ from each other (see Fig. 4) Furthermore, the central web section 31 only encloses the recess section 313 at the opening section of the narrower continuous tunnel groove 411 and does not enclose the recess section 313 at the opening section of the wider continuous tunnel groove 412. This has the advantage that the drainage properties and the snow drainage properties of the narrower continuous tunnel groove 411 are ensured.

[0112] Furthermore, in the pneumatic tire 1, the central rib section 31 encloses the chamfered section 314 on the edge section of the recess section 313 (see Fig. 4) This has the advantage of improving the drainage properties and the snow drainage properties of the narrower continuous groove 411.

[0113] Furthermore, in the pneumatic tire 1, the adjacent continuous lug grooves 421, 422 of the second rib section 32 have different angles of inclination from each other (see Fig. 3) Furthermore, the extension lines of the groove centerlines of the adjacent continuous lug grooves 421, 422 of the second rib section 32 meet at the edge section of the central rib section 31. Additionally, the recess section 313 of the central rib section 31 surrounds the extension lines of the groove centerlines of the adjacent continuous lug grooves 421, 422 of the second rib section 32. In this configuration, a drainage channel is formed from the recess section 313 of the central rib section 31 through the lug grooves 421, 422 of the second rib section 32 to the main circumferential groove 22, which is located closer to the ground contact edge T of the tire of the second rib section 32. This has the advantage of improving the drainage properties of the tread section's central area and enhancing the tire's wet performance.

[0114] Furthermore, in the case of the pneumatic tire 1, the second rib section 32 includes the plurality of blocks 321, 322, which are defined by the plurality of continuous lug grooves 421, 422 (see Fig. 5) Furthermore, the majority of blocks 321, 322 have a curved shape with an amplitude in the tire's transverse direction and include narrow circumferential grooves 323, 324 that extend through the blocks 321, 322 in the tire's circumferential direction. In such a configuration, the stiffness of the blocks 321, 322 in the tire's transverse direction is reduced by the narrow circumferential grooves 323, 324. This has the advantage of reducing the ground contact pressure of the blocks 321, 322 when the tire contacts the ground and suppressing uneven wear of the blocks 321, 322. Additionally, the narrow circumferential grooves 323, 324 increase the edge components of the blocks 321, 322, thus improving the tire's snow performance.

[0115] Furthermore, in the pneumatic tire 1, the left and right shoulder rib sections 33 are each provided with a plurality of continuous tread grooves 431, which are inclined at a predetermined angle of inclination with respect to the tire transverse direction and extend through the rib sections 33 in the tire transverse direction (see Fig. 2) Furthermore, the continuous lug grooves 431, located in the left and right shoulder rib sections 33, and the continuous lug grooves 421, 422, located in the left and right second rib sections 32, are inclined in opposite directions in the tire's transverse direction. In this configuration, the continuous lug grooves 431 of the left and right shoulder rib sections 33, 33 and the continuous lug grooves 421, 422 of the left and right second rib sections 32, 32 are inclined in opposite directions. This improves traction on snow-covered road surfaces when the vehicle is turning. This has the advantage of improving the tire's snow performance.

[0116] Furthermore, in the pneumatic tire 1, at least one of the groove walls (both in Fig. 7) the continuous lug groove 431 of the shoulder rib section 33 includes a stepped curved section which, when viewed from above, is curved in the circumferential direction of the tire (see Fig. 7) This has the advantage that the edge components of the continuous lug grooves 431 are enlarged and the snow performance of the tire is improved.

[0117] Furthermore, in the pneumatic tire 1, the opening sections to the main circumferential groove 22 of the continuous lug grooves 431 of the shoulder rib section 33 and the opening sections of the continuous lug grooves 421, 422 of the second rib section 32 are arranged offset from each other in the tire circumferential direction (see Fig. 2) This has the advantage that tread noise generated when the tire is rolling is reduced more than in a configuration where the opening sections of the lug grooves of the left and right rib sections are opposite to each other (not shown). In particular, the arrangement of the continuous lug grooves 421, 422, 431, which open towards the outermost main circumferential groove 22, has a significant effect on tread noise. Examples

[0118] Fig. Figure 10 is a table which shows in examples 8 to 12 the results of performance tests of pneumatic tires according to embodiments of the invention.

[0119] In the performance tests, a number of different test tires were evaluated with regard to (1) snow performance and (2) noise performance. Test tires with a size of 265 / 65R17 112H were mounted on rims with a rim size of 17 × 8J, inflated to a pressure of 230 kPa, and loaded with the maximum load defined by JATMA. The test tires were then fitted to all wheels of the test vehicle, which was a four-wheel-drive recreational vehicle (RV) with a 3.5-liter engine.

[0120] (1) In the snow performance assessment, the test vehicle was driven at a speed of 40 km / h on a predefined handling course, which was a snow-covered road, and a sensory evaluation of steering stability was carried out by a test driver. The results of the evaluation are expressed as index values ​​and assessed by defining the prior art as the reference value (100). Higher values ​​are preferred in this assessment.

[0121] (2) In assessing noise performance, the test vehicle was driven at a speed of 60 km / h on a test track with an uneven road surface, and the sound pressure level of the interior noise (profile noise) was measured by a microphone mounted on the window side of the driver's seat. The results are expressed as index values ​​and evaluated by determining the prior art as the reference value (100). In this evaluation, higher numbers indicate lower sound pressure levels and are more preferable.

[0122] The test tires of examples 1 to 12 essentially have the configuration of Fig. 1 and Fig. 2 and include four main circumferential grooves 21, 22 and five web sections 31 to 33. Furthermore, web sections 31 to 33 each include the majority of continuous drift grooves 411, 412, 421, 422, 431, which are bent in a Z-shape or a crank-like shape, as well as block rows defined by the continuous drift grooves. The groove depth of the main circumferential grooves is 10.0 mm and the maximum groove depth of the continuous drift grooves 411, 412, 421, 422, 431 is 7.0 mm. The groove width Ws of the narrow circumferential grooves 323, 324 of the second web section 32 is 2.0 mm, and the groove depth is 5.0 mm. The offset amounts G1, G2 (see Fig. 5) The center lines of the continuous grooves 421, 422 of the second web section 32 are G1 = G2 = 6.0 mm. Furthermore, in Example 11, the central web section 31 includes the recess section 313, and as in Fig. As shown in Figure 2, the extension lines of the continuous stud grooves 421, 422 of the second web section 32 meet at the recess section of the middle web section 31. Furthermore, in Example 12, the shoulder web sections 33 enclose the continuous stud groove 431 and the non-continuous stud groove 432. It should be noted that in Fig. 10 “MI” designates the middle bridge section 31, “2.” designates the left and right second bridge section 32, 32 and “SCH” designates the left and right shoulder bridge section 33, 33.

[0123] The test tire of the prior art example has the same configuration as the test tire of Example 1, except that the rib sections of the former all enclose a single type of continuous lug groove and the continuous lug grooves have a linear or arc shape.

[0124] As can be seen from the test results, the snow performance and noise performance of the test tires in examples 1 to 12 are improved. List of reference symbols 1 pneumatic tire 11 bead core 12 bead fillers 13 Carcass layer 14 Belt layer 141, 142 Cross belt 143 Belt cover 15 tread rubber 16 side wall rubber 17 Wheel rim pad rubber 21, 22 Main circumferential groove 31 Central bridge section Block 311, 312 313 Recess section 314 Beveled section 32 Second section of the jetty Block 321, 322 323, 324 Narrow circumferential groove 33 Shoulder strap section 411, 412, 421, 422, 431 Continuous cleat groove 432 Non-continuous lug groove 5 slats

Claims

[1] Pneumatic tires, including: at least four main circumferential grooves (21, 22) extending in one direction around the circumference of the tire; and at least five web sections (31, 32, 33) defined by the main circumferential grooves (21; 22); wherein the rib sections (31, 32, 33) comprise rib sections arranged at the outermost points on a left and a right side in a transverse direction of the tire, which are defined as shoulder rib sections (33), rib sections arranged as second rib sections (32) on a left and a right side in a transverse direction of the tire, which are defined as second rib sections (32), and a rib section arranged closer to an equatorial plane of the tire than the second rib sections (32), which is defined as a center rib section (31); wherein the central rib section (31) and the left and right second rib sections (32) each comprise a plurality of continuous tread grooves (411, 412, 421, 422) which are inclined at a predetermined angle of inclination with respect to the tire transverse direction and extend through the rib section in the tire transverse direction; wherein the majority of continuous lug grooves (411, 412) arranged in the central rib section (31) and the majority of continuous lug grooves (421, 422) arranged in the left and right second rib section (32) are inclined in opposite directions to each other in the transverse direction of the tire; wherein at least one groove wall of each of the plurality of continuous lug grooves (421, 422) arranged in the left and right second rib section (32) comprises a step-shaped curved section which, when viewed from a top view of a tread, is curved in the circumferential direction of the tire; wherein a pair of multiple continuous lug grooves (411, 412) of the central rib section (31) adjacent in the circumferential direction of the tire has different groove widths and a groove width Wg11 of a narrower continuous lug groove of the pair of multiple continuous lug grooves (411, 412) and a groove width Wg12 of a wider continuous lug groove have a relationship 1.10 ≤ Wg12 / Wg11 ≤ 3.00 and where the angle of inclination (θ11) of the narrower first continuous tunnel groove (411) is greater than the angle of inclination (θ12) of the wider second continuous tunnel groove (412). [2] Pneumatic tires according to claim 1, wherein the central bridge section (31) and / or the left and right second bridge sections (32) each comprise a plurality of blocks (311, 312, 321, 322) defined by the plurality of continuous tunnel grooves (411, 412, 421, 422); and a pair of blocks (311, 312, 321, 322) adjacent in the direction of the tire circumference has different shapes. [3] Pneumatic tires according to claim 1 or 2, wherein the central web section (31) and / or the left and right second web section (32) comprise the majority of continuous tunnel grooves (411, 412, 421, 422) in a majority of sets, wherein continuous tread grooves (411, 412, 421, 422) of each of the majority of sets are adjacent in the circumferential direction of the tire and have different angles of inclination. [4] Pneumatic tires according to any one of claims 1 to 3, wherein each of the left and right groove walls of each of the plurality of continuous tread grooves (411, 412) of the central web section (31) comprises a step-shaped curved section when viewed from a top view of the running surface; and one of the groove walls of each of the plurality of continuous tread grooves (421, 422) of the left and right second tread section (32) when viewed from above in a plan view comprises a step-shaped curved section and the other groove wall has a linear or arc shape. [5] Pneumatic tire according to one of claims 1 to 3, wherein each of the left and right groove walls of each of the plurality of continuous lug grooves (411, 412, 421, 422) of the central rib section (31) and of the left and right second rib section (32) when viewed in a top view of the tread, comprises a step-shaped curved section. [6] Pneumatic tire according to one of claims 1 to 5, wherein opening sections open to one of the main circumferential grooves (21, 22) of the plurality of continuous lug grooves (411, 412) of the central rib section (31) and opening sections of the plurality of continuous lug grooves (421, 422) of the second rib sections (32) are arranged offset from one another in the circumferential direction of the tire. [7] Pneumatic tires according to any one of claims 1 to 6, wherein a pair of continuous tread grooves (411, 412) adjacent in the circumferential direction of the majority of the continuous tread grooves of the central rib section (31) has different groove widths; and the central web section (31) includes a recess section (313) only at an opening section of the narrower continuous tunnel groove (411) and does not include the recess section at an opening section of the wider continuous tunnel groove (412). [8] Pneumatic tire according to claim 7, wherein the central web section (31) comprises a chamfered section (314) on an edge section of the recess section (313). [9] Pneumatic tires according to claim 7 or 8, wherein an adjacent pair of the majority of continuous tunnel grooves (421, 422) of the second bridge sections (32) has the different inclination angles (θ11, θ12); Extension lines of groove centerlines of the adjacent pair (421, 422) meet at an edge section of the central web section (31); and the recess section of the central web section (31) surrounds the extension lines of the groove centerlines of the adjacent pair (421, 422). [10] Pneumatic tires according to any one of claims 1 to 9, wherein the second bridge sections (32) comprise a plurality of blocks (321, 322) defined by the plurality of continuous tunnel grooves (421, 422); and the majority of blocks (321, 322) each have a curved shape with an amplitude in the tire transverse direction and include a narrow circumferential groove (323) that runs through the block. [11] Pneumatic tires according to any one of claims 1 to 10, wherein the left and right shoulder rib sections (33) each comprise a plurality of continuous tread grooves (431) inclined at a predetermined angle of inclination with respect to the tire transverse direction, wherein the majority of continuous lug grooves (431) extend transversely through the shoulder rib section (33); and the majority of continuous lug grooves (431) arranged in the left and right shoulder rib section (33) and the majority of continuous lug grooves (421, 422) arranged in the left and right second rib section (32) extend transversely in opposite directions to each other. [12] Pneumatic tire according to claim 11, wherein at least one of the groove walls of each of the plurality of continuous lug grooves (431) of the shoulder rib sections (33) comprises a step-shaped curved section which is curved in the circumferential direction of the tire when viewed from a top view of the tread. [13] Pneumatic tire according to one of claims 1 to 12, wherein opening sections which are open to one of the main circumferential grooves (22), the plurality of continuous lug grooves (431) of the shoulder rib sections (33) and opening sections of the plurality of continuous lug grooves (421, 422) of the second rib sections (32) are arranged offset from one another in the circumferential direction of the tire.

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