R E I F E N

Abstract

Tires (1), comprising: a pair of humeral grooves (21) and one or more medial grooves (22), which run in a circumferential direction of the tire; and four or more rows of bridge sections (31, 32, 33) defined by the pair of shoulder main grooves (21) and the one or more mid-main grooves (22), wherein each pair of shoulder main grooves (21) comprises a groove opening section (211) having a straight shape or a zigzag shape or a wave-like shape with an amplitude in a tire width direction, wherein each pair of shoulder main grooves (21) comprises a groove bottom section (212) having a zigzag shape or a wave-like shape with an amplitude in a tire width direction, and wherein the groove opening section (211) in each pair of shoulder main grooves (21) has an amplitude A1_sh which has a ratio A1_sh < A2_sh with respect to an amplitude A2_sh of the groove bottom section (212); wherein the groove opening section (211) in each pair of shoulder main grooves (21) has a wave-like shape formed by connecting a plurality of arcs, which protrude to one side of an equatorial plane of the tire (1).

Description

Technical field

[0001] The invention relates to a tire, and in particular to a tire that can provide acceleration performance on snow, resistance to uneven abrasion, and tear resistance performance in a compatible manner. State of the art

[0002] High-performance tires in the prior art use main grooves with zigzag shapes to improve the acceleration performance of tires on snow. An example of a prior art tire using this configuration is a technology described in JP 2017 154 708 A. Brief description of the invention: Technical problem

[0003] On the other hand, the high-performance tire mounted on a vehicle's steering axle has a problem in that uneven wear (especially track wear in an edge section of a rib section) and tearing of the rib section, caused by the zigzag shapes of the main grooves described above, are likely to occur.

[0004] EP 2 039 534 A1 discloses a tire comprising a pair of shoulder main grooves and one or more central main grooves extending in the circumferential direction of the tire; and four or more rows of rib sections defined by the pair of shoulder main grooves and the one or more central main grooves, wherein each pair of shoulder main grooves comprises a groove opening section having a straight shape, wherein each pair of shoulder main grooves comprises a groove bottom section having a zigzag shape or a wavy shape with an amplitude in a tire width direction, and wherein the groove opening section in each pair of shoulder main grooves has an amplitude A1_sh with a ratio A1_sh < A2_sh with respect to an amplitude A2_sh of the groove bottom section.

[0005] Other tires are known from EP 2 949 482 A1, WO 2020 066 404 A1, EP 3 335 908 A1 and JP H11 123 909 A.

[0006] In light of the foregoing, an object of the invention is to provide a tire that can provide acceleration performance on snow, resistance to uneven abrasion and tear resistance performance in a compatible manner. Solution to the problem

[0007] To accomplish the task described above, a tire includes a pair of shoulder main grooves, one or more center main grooves, and four or more rows of rib sections. The pair of shoulder main grooves and the one or more center main grooves run circumferentially. The four or more rows of rib sections are defined by the pair of shoulder main grooves and the one or more center main grooves. Each groove of the pair of shoulder main grooves includes a groove opening section with a straight, zigzag, or wave-like shape and an amplitude in the tire width direction. Each pair of shoulder main grooves includes a groove bottom section with a zigzag or wave-like shape and an amplitude in the tire width direction.The groove opening section in each pair of shoulder main grooves has an amplitude A1_sh with a ratio A1_sh < A2_sh with respect to an amplitude A2_sh of the groove bottom section. The groove opening section in each pair of shoulder main grooves has a wave-like shape formed by connecting a multitude of arcs projecting to one side of an equatorial plane of the tire. Advantageous effects of the invention

[0008] Since, according to one embodiment of the invention (1), the amplitude A1_sh of the groove opening section in the main shoulder groove is set to be small, wear on the edge section of the rib section, which is likely to occur at a position with maximum amplitude towards the main shoulder groove side, is suppressed. Additionally, (2) since the amplitude A2_sh of the groove bottom section of the main shoulder groove is set to be large, the stiffness of the rib section is ensured, and the tear resistance performance of the tire is ensured. Furthermore, (3) since the groove opening section of the main shoulder groove has a zigzag or wave-like shape with an amplitude in the tire width direction, the edge component of the rib sections is increased, and the acceleration performance of the tire on snow is improved.This is advantageous in that acceleration performance on snow, unequal abrasion resistance performance and tear resistance performance of the tire are provided in a compatible manner. Brief description of the drawings Fig. Figure 1 is a cross-sectional view in a tire meridian direction, illustrating a tire according to an embodiment of the invention. Fig. 2 is a top view showing a running surface of the in Fig. 1 illustrated tire illustrated. Fig. 3 is an enlarged top view showing a grooved wall structure of the in Fig. 2 illustrated shoulder grooves. Fig. 4 is an enlarged top view showing the groove wall structure of the in Fig. 2 illustrated shoulder grooves. Fig. 5 is a cross-sectional view in one groove depth direction of the in Fig. 2 illustrated shoulder groove. Fig. Figure 6 is an explanatory diagram showing the groove wall structures of the main shoulder groove and a [unclear] Fig. 2 illustrated midline groove illustrated. Fig. 7 is an enlarged view showing a shoulder strap section of the Fig. 2 illustrated tires. Fig. Figure 8 is an enlarged view showing a narrow, shallow groove of the in Fig. 7 illustrated shoulder strap section. Fig. 9 is a cross-sectional view of the in Fig. 7 illustrated shoulder bridge section. Fig. 10 is an explanatory diagram that shows a modified example of the one in Fig. 8 illustrated narrow flat groove. Fig. 11 is an explanatory diagram that shows a modified example of the one in Fig. 8 illustrated narrow flat groove. Fig. 12 is an explanatory diagram that shows a modified example of the one in Fig. 8 illustrated narrow flat groove. Fig. 13 is an explanatory diagram that shows a modified example of the one in Fig. 8 illustrated narrow flat groove. Fig. 14 is an explanatory diagram that shows a modified example of the one in Fig. 8 illustrated narrow flat groove. Fig. 15 is an explanatory diagram that shows a modified example of the one in Fig. 8 illustrated narrow flat groove. Fig. 16 is an explanatory diagram that presents a modified example of the one in Fig. 8 illustrated narrow flat groove. Fig. 17 is an explanatory diagram that shows a modified example of the one in Fig. 8 illustrated narrow flat groove. Fig. 18 is an explanatory diagram that presents a modified example of the one in Fig. 8 illustrated narrow flat groove. Fig. 19 is an explanatory diagram that shows a modified example of the one in Fig. 8 illustrated narrow flat groove. Fig. Figure 20 is a table showing the results of performance tests of tires according to the embodiments of the invention and comparative examples. Fig. Figure 21 is a table showing the results of performance tests of tires according to the embodiments of the invention. Fig. 22 is an explanatory diagram showing a shoulder bridge section of the test tire of the in Fig. 21 illustrated comparative examples. Description of embodiments

[0009] 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. Tires

[0010] Fig. Figure 1 is a cross-sectional view in a tire meridional direction, illustrating the tire according to one embodiment of the invention. The same drawing illustrates a cross-sectional view of a half-section in the tire radial direction. In the embodiments, a high-performance radial pneumatic tire mounted on a steering axle of a truck and a tractor is described as an example of the tire.

[0011] 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 illustrated). 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. "Tire width 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.

[0012] A pneumatic tire 1 has a ring structure, the center of which is the tire's axis of rotation, 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).

[0013] The pair of bead cores 11, 11 is formed by winding a multitude of steel tire bead wires in a ring shape and in several layers, and embedding them in a bead section to form a core for the left and right bead sections. The pair of bead fillers 12, 12 is arranged outwards in the tire radial direction from the pair of bead cores 11, 11 and reinforces the bead sections.

[0014] 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 to form the support structure of the tire. Furthermore, both end sections of the carcass layer 13 are folded back on an outer side in the tire width direction so that they are wrapped and fixed around the bead cores 11 and the bead fillers 12. The carcass layer 13 is formed by rolling carcass cord threads made of steel or an organic fiber material (for example, aramid, nylon, polyester, or rayon) coated with a rubber coating and has a carcass angle (defined as an angle of inclination in a longitudinal direction of the carcass cord threads with respect to the tire circumference) in the range of 80 degrees to 100 degrees as an absolute value.

[0015] The belt layer 14 is formed by laying four layers of belt plies 141 to 144 and is arranged by wrapping them around the outer circumference of the carcass layer 13. The pair of belt plies 141 to 144 is manufactured by a rolling process on a multitude of belt cord threads, made of steel or an organic fiber material, coated with a coating rubber. The belt cover 144 has a belt angle in the range of 15 degrees to 55 degrees as an absolute value. Furthermore, the belt plies 141 to 144 have belt angles (defined as an angle of inclination in a longitudinal direction of the belt cord threads with respect to the tire circumference) with opposite signs and are layered such that the longitudinal directions of the belt cord threads intersect (so-called belt ply structure).

[0016] The tread rubber 15 is arranged radially outward from the carcass layer 13 and the belt layer 14 and forms a tread section of the tire 1. The pair of sidewall rubbers 16, 16 are arranged radially outward from the carcass layer 13 and form a left and a right sidewall section. The pair of rim pad rubbers 17, 17 extend radially inward from the folded-back sections of the carcass layer 13 and the left and right tire bead core 11, 11 to form a rim mating surface of the tire bead section outward in the tire width direction. Tread pattern

[0017] Fig. 2 is a top view showing a running surface of the in Fig. Figure 1 illustrates the tread surface of an all-season tire with the mud / snow marking "M+S". Referring to the same drawing, "tire circumference direction" refers to the direction of rotation around the tire's axis of rotation. The reference symbol T denotes a ground contact edge, and the size symbol TW denotes a tire ground contact width.

[0018] As in Fig. As illustrated in Figure 2, the tire 1 includes a plurality of main circumferential grooves 21, 22 extending in the direction of the tire circumference and a plurality of rib sections 31, 32, 33 defined by the main circumferential grooves 21, 22 in the tread surface.

[0019] “Main groove” refers to a groove on which an abrasion indicator must be provided, as specified by JATMA, and which has a maximum groove width of not less than 7.0 mm and a maximum groove depth of not less than 12 mm.

[0020] The groove width is measured as the distance between a left and a right groove wall at a groove opening section when the tire is mounted on a specified rim, inflated to the specified internal pressure, and in an unloaded state. In a configuration where the rib sections include recessed sections or chamfered sections on their edge segments, the groove width is measured with reference to the intersection points between the tread contact surface and the extension lines of the groove walls as measuring points, in a cross-sectional view where the groove length direction is perpendicular.

[0021] Groove depth is measured as the distance from the tread contact surface to the groove bottom when the tire is mounted on a specified rim, inflated to the specified internal pressure, and unloaded. Additionally, in configurations where the grooves include an uneven section or sipes on the groove bottom, the groove depth is measured excluding these sections.

[0022] Here, "specified rim" refers to a "standard rim" as defined by JATMA, a "design rim" as defined by TRA, or a "measuring rim" as defined by ETRTO. Furthermore, "specified internal pressure" refers to a "maximum air pressure" as defined by JATMA, the maximum value in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" as defined by TRA, or "INFLATION PRESSURES" as defined by ETRTO. 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, or “LOAD CAPACITY” as defined by ETRTO.However, in the case of JATMA, the specified internal pressure for a passenger car tire is an air pressure of 180 kPa, and the specified load is 88% of the maximum load capacity.

[0023] For example, the configuration of Fig. 2. The tire 1 has a substantially point-symmetric tread pattern with a center point on an equatorial plane CL of the tire. However, no such restriction is intended, and, for example, the tire 1 may have a left-right axially symmetric tread pattern or a left-right asymmetric tread pattern with the tire's equatorial plane CL as its center point, or may have a tread pattern with directional dependence in the direction of tire rotation (not illustrated).

[0024] Furthermore, the configuration of Fig. 2. The left and right areas, which are delimited by the equatorial plane CL of the tire, each have two main circumferential grooves 21, 22. These main circumferential grooves 21, 22 are arranged such that they are left-right symmetrical with respect to the equatorial plane CL of the tire. Five rows of rib sections 31 to 33 are defined by these main circumferential grooves 21, 22. Additionally, a rib section 33 is arranged on the equatorial plane CL of the tire.

[0025] However, no such restriction is intended, and three, five, or more major circumferential grooves can be arranged, or the major circumferential grooves can be arranged asymmetrically with respect to the equatorial plane CL of the tire (not illustrated). Furthermore, the rib section can be located outside the equatorial plane CL of the tire, with one major circumferential groove located within the equatorial plane CL of the tire (not illustrated).

[0026] Additionally, among the main circumferential grooves 21, 22, which are arranged in an area delimited by the equatorial plane CL of the tire, the main circumferential groove 21 on the outermost side in the tire width direction is defined as the shoulder main groove, and the main circumferential groove 22 is defined near the equatorial plane CL of the tire as the central main groove.

[0027] The rib section 31, located on the outer side in the tire width direction and defined by the main shoulder groove 21, is defined as a shoulder rib section. Shoulder rib section 31 is a rib section on the outermost side in the tire width direction and at the ground contact edge T of the tire. Rib section 32, located on the inner side in the tire width direction and defined by the main shoulder groove 21, is defined as a middle rib section. The middle rib section 32 is adjacent to shoulder rib section 31, with the main shoulder groove 21 located between them. Furthermore, rib section 33, located closer to the equatorial plane CL of the tire than the middle rib section 32, is defined as a middle rib section. The middle rib section 33 may be located on the equatorial plane CL of the tire (see Fig. 2) or may be placed at a position outside the equatorial plane of tire CL (not illustrated).

[0028] The ground contact width TW of the tire is measured as the maximum linear distance in the tire axial direction of a contact surface between the tire and a flat plate when the tire is mounted on a predetermined rim, inflated to a predetermined internal pressure, placed vertically on the flat plate in a static state, and loaded with a load corresponding to the predetermined load.

[0029] The ground contact edge T of the tire is defined as the position of maximum width in the tire axial direction of the contact surface between the tire and a flat plate when the tire is mounted on a predetermined rim, inflated to the predetermined internal pressure, placed vertically on the flat plate in a static state, and loaded with a load corresponding to the predetermined load.

[0030] It should be noted that in the configuration, the four main circumferential grooves 21, 22 as in Fig. 2 includes a pair of shoulder bar sections 31, 31, a pair of middle bar sections 32, 32, and the single middle bar section 33. Additionally, for example, in a configuration that includes five or more main perimeter grooves, two or more rows of middle bar sections are defined (not illustrated). Furthermore, in a configuration that includes three main perimeter grooves, the middle bar section also serves as the middle bar section (not illustrated).

[0031] Additionally, the configuration of Fig. 2. The maximum ground contact width Wb1 of the shoulder rib section 31 has a ratio of 0.15 ≤ Wb1 / TW ≤ 0.25 with respect to the ground contact width TW of the tire. Additionally, the maximum ground contact width Wb3 of the center rib section 33, which is closest to the equatorial plane CL of the tire, preferably has a ratio of 0.15 ≤ Wb3 / TW ≤ 0.25 with respect to the ground contact width TW of the tire, and more preferably has a ratio of 0.18 ≤ Wb3 / TW ≤ 0.23. Furthermore, in the configuration which includes the four main circumferential grooves 21, 22 and five rows of rib sections 31 to 33 as shown in Fig. 2 includes a maximum ground contact width Wb2 of the middle web section 32, preferably slightly narrower than the maximum ground contact width Wb1 of the shoulder web section 31, and is in particular in the range of 0.85≤Wb2 / Wb1≤0.95.

[0032] In the configuration of Fig. 2 The shoulder main groove 21 and the center main groove 22 exhibit zigzag or wave-like shapes with amplitudes in the tire width direction. However, no such restriction is intended, and as described below, the center main groove 22 may exhibit straight shapes in the groove opening section (not illustrated).

[0033] The shoulder rib section 31 is a rib with a continuous road contact surface in the circumferential direction of the tire and does not include any lug grooves. Additionally, the middle rib section 32 and the middle rib section 33 enclose a plurality of continuous lug grooves 321 and 331, respectively. The continuous lug grooves 321 and 331 have an open structure in which they penetrate the rib sections 32 and 33 and are arranged at predetermined intervals in the circumferential direction of the tire. Consequently, the middle rib section 32 and the middle rib section 33 are divided in the circumferential direction of the tire by the continuous lug grooves 321 and 331, forming rows of blocks. Groove width structure of the shoulder joint

[0034] Fig. 3, Fig. 4 to Fig. 5 are enlarged top views ( Fig. 3 and Fig. 4) and a cross-sectional view in the groove depth direction ( Fig. 5), which defines the groove wall structure of the in Fig. The shoulder groove 21 is illustrated in two drawings. Fig. 3 in particular the groove wall structure on the outside in the tire width direction of the main shoulder groove 21, and Fig. Figure 4 illustrates in particular the groove wall structure on the inside in the direction of tire width. Fig. Figure 5 illustrates a cross-sectional view at positions with maximum amplitude of the shoulder main groove 21 on the outside in the tire width direction.

[0035] In the configuration of Fig. 2, as in Fig. As illustrated in Figure 3, both the groove opening section 211 and the groove bottom section 212 in the shoulder main groove 21 have a zigzag shape or a wave-like shape with the amplitude in the tire width direction.

[0036] In the corresponding groove opening section and groove bottom section of the main groove, the outer and inner edge sections are defined in the direction of tire width. Additionally, positions of the outer maximum amplitude, projecting towards the outside in the direction of tire width, and positions of the inner maximum amplitude, projecting towards the inside in the direction of tire width, are defined in the corresponding outer and inner edge sections.

[0037] The boundary section of the groove opening section is defined by an imaginary line which represents the intersection points (see, for example, Fig. 5) connects the groove walls and a tread profile in a cross-sectional view in the groove depth direction over the entire area in the tire circumference direction. In a configuration where the edge section includes a chamfered section, an imaginary line of the edge section of the groove opening section is drawn by connecting intersection points (not illustrated) of the extension lines of the groove walls and the tread profile.

[0038] The edge section of the groove base is defined by an imaginary line connecting the endpoints of the positions with maximum groove depth in the cross-sectional view, in the groove depth direction, across the entire area in the tire's circumferential direction. If the groove base of the main groove is a flat, straight line at the position with maximum groove depth (see, for example, Fig. 5) The outer edge section and the inner edge section of the groove bottom section are defined at the corresponding endpoints of the flat straight line. If, meanwhile, the groove bottom section of the main groove has an arc shape or a funnel shape (not illustrated), the position of maximum groove depth is a point, and the edge section of the groove bottom section is defined by a point. Accordingly, the outer edge section and the inner edge section of the groove bottom section described above are located at the same position. The position of maximum groove depth of the main groove is defined by excluding any raised bottom section that is partially formed within the groove bottom section of the main groove.

[0039] In the configuration of Fig. 3 and Fig. 4. The groove opening section 211 of the main shoulder groove 21 has a wave-like shape with an amplitude in the tire width direction at the corresponding outer edge section 211o on the shoulder rib section 31 and the inner edge section 211i on the side of the middle rib section 32. Furthermore, the groove bottom section 212 of the main shoulder groove 21 has a zigzag shape with an amplitude in the tire width direction at the corresponding outer edge section 212o on the side of the shoulder rib section 31 and the inner edge section 212i on the side of the middle rib section 32.

[0040] As in Fig. As illustrated in Figure 3, the outer maximum amplitude P100 of the outer edge section 2110 of the groove opening section 211 in the shoulder main groove 21 is located at a position in the tire circumference direction that is identical to the position of the outer maximum amplitude P200 of the outer edge section 2120 of the groove bottom section 212. In particular, in Fig. 3 has an offset amount φoo_sh between the positions of the outer maximum amplitude P1oo, P2oo in the outer edge sections 211o, 212o of the groove opening section 211 and the groove bottom section 212 in the central main groove 21 the ratio 0 ≤ φoo_sh / λ1o_sh ≤ 0.10 with respect to a wavelength λ1o_sh of the outer edge section 211o of the groove opening section 211, and more preferably has the ratio 0 ≤ φoo_sh / λ1o_sh ≤ 0.05.

[0041] The offset between the positions of maximum amplitude is a distance between the positions of maximum amplitude in the tread plan view and is measured when the tire is mounted on a specified rim, inflated to the specified internal pressure and in an unloaded state.

[0042] Similarly, as in Fig. Figure 4 illustrates the position of the outer maximum amplitude P1io of the inner rim section 211i of the groove opening section 211 in the shoulder main groove 21 at the same position in the tire circumferential direction with respect to the position of the outer maximum amplitude P2io of the inner rim section 212i of the groove bottom section 212. In particular, Fig. 4 has an offset amount φio_sh between the positions of the outer maximum amplitude P1io, P2io in the inner edge sections 211i, 212i of the groove opening section 211 and the groove bottom section 212 in the central main groove 21 the ratio 0 ≤ φio_sh / λ1i_sh ≤ 0.10 with respect to a wavelength λ1i_sh of the inner edge section 211i of the groove opening section 211, and more preferably has the ratio 0 ≤ φio_sh / λ1i_sh ≤ 0.05.

[0043] As in Fig. As illustrated in Figure 3, the position of the outer maximum amplitude P1oo of the outer edge section 211o and the position of the outer maximum amplitude P1io of the inner edge section 211i of the groove opening section 211 in the shoulder main groove 21 are at the same position in the tire circumferential direction. In particular, an offset amount δ_sh between the position of the outer maximum amplitude P1oo in the outer edge section 211o and the position of the outer maximum amplitude P1io in the inner edge section 211i of the groove opening section 211 in the shoulder main groove 21 has the ratio 0 ≤ δ_sh / λ1o_sh ≤ 0.10 with respect to the wavelength λ1o_sh of the outer edge section 211o of the groove opening section 211, and more preferably has the relationship 0 ≤ δ_sh / λ1o_sh ≤ 0.05.

[0044] Furthermore, in Fig. 3. The wavelength λ1o_sh of the outer edge section 211o of the groove opening section 211 of the shoulder main groove 21 is determined such that it is essentially equal to the wavelength λ2o_sh of the outer edge section 212o of the groove bottom section 212. In particular, the wavelengths λ1o_sh, λ2o_sh of the groove opening section 211 and of the groove bottom section 212 are in the range of 0.90 ≤ λ2o_sh / λ1o_sh ≤ 1.10.

[0045] Similarly, in Fig. 4. The wavelength λ1i_sh of the inner edge section 211i of the groove opening section 211 in the shoulder main groove 21 is determined such that it is essentially equal to the wavelength λ2i_sh of the inner edge section 212i of the groove bottom section 212. In particular, the wavelengths λ1i_sh, λ2i_sh of the groove opening section 211 and of the groove bottom section 212 lie in the range of 0.90 ≤ λ2i_sh / λ1i_sh ≤ 1.10.

[0046] Additionally, the wavelength λ2_sh (λ2o_sh, λ2i_sh) of the groove bottom section 212 of the shoulder main groove 21 has a ratio of 0.10 ≤ λ2_sh / TW ≤ 0.35 with respect to the ground contact width TW of the tire.

[0047] In Fig. 3 also has a maximum distance L1o_sh in the tire circumferential direction between the position of the outer maximum amplitude P1oo and a position of the inner maximum amplitude P1oi in the outer edge section 211o of the groove opening section 211 in the shoulder main groove 21, the ratio 0.50 ≤ L1o_sh / λ1o_sh ≤ 0.60 with respect to the wavelength λ1o_sh of the outer edge section 211o, and preferably the ratio 0.50 ≤ L1o_sh / λ1o_sh ≤ 0.55. This makes the stiffness of the tread contact surface of a new tire uniform in the tire circumferential direction.

[0048] The maximum distance in the tire circumference direction between the position of the outer maximum amplitude and the position of the inner maximum amplitude is measured as a greater distance among distances in the tire circumference direction between the adjacent positions of the outer maximum amplitude and the position of the inner maximum amplitude, which is located between the positions of the outer maximum amplitude.

[0049] The wavelength λ1o_sh of the outer edge section 211o of the groove opening section 211 in the shoulder main groove 21 is only defined if the shoulder main groove 21 has the zigzag shape or the wave-like shape, and is not defined if it has the straight shape.

[0050] Similarly, in Fig. 4 a maximum distance L1i_sh in the tire circumferential direction between the position of the outer maximum amplitude P1io and a position of the inner maximum amplitude P1ii in the inner edge section 211i of the groove opening section 211 in the shoulder main groove 21 the ratio 0.50 ≤ L1i_sh / λ1i_sh ≤ 0.60 with respect to the wavelength λ1i_sh of the inner edge section 211i, and preferably the ratio 0.50 ≤ L1i_sh / λ1i_sh ≤ 0.55.

[0051] In Fig. 3 also has a maximum distance L2o_sh in the tire circumferential direction between the position of the outer maximum amplitude P2oo and a position of the inner maximum amplitude P2oi in the outer edge section 212o of the groove bottom section 212 in the shoulder main groove 21, the ratio 0.50 ≤ L2o_sh / λ2o_sh ≤ 0.60 with respect to the wavelength λ2o_sh of the outer edge section 212o, and preferably the ratio 0.50 ≤ L2o_sh / λ2o_sh ≤ 0.55. Accordingly, the position of the outer maximum amplitude P2oo and the position of the inner maximum amplitude P2oi of the groove bottom section 212 in the shoulder main groove 21 are arranged at substantially equal intervals in the tire circumferential direction.

[0052] Similarly, in Fig. 4 a maximum distance L2i_sh in the tire circumferential direction between the position of the outer maximum amplitude P2io and a position of the inner maximum amplitude P2ii in the inner edge section 212i of the groove bottom section 212 in the shoulder main groove 21 has the ratio 0.50 ≤ L2i_sh / λ2i_sh ≤ 0.60 with respect to the wavelength λ2i_sh of the inner edge section 212i, and preferably has the ratio 0.50 ≤ L2i_sh / λ2i_sh ≤ 0.55.

[0053] Additionally, it points out that Fig. 3. The amplitude A1o_sh of the outer edge section 211o of the groove opening section 211 in the shoulder main groove 21 has a ratio of 1.20 ≤ A2o_sh / A1o_sh ≤ 2.00 with respect to an amplitude A2o_sh of the outer edge section 212o of the groove bottom section 212, and more preferably has a ratio of 1.30 ≤ A2o_sh / A1o_sh ≤ 1.80. Accordingly, the amplitude A2o_sh of the zigzag shape of the groove bottom section 212 is set larger than the amplitude A1o_sh of the wave-like shape of the groove opening section 211.

[0054] Similarly, in Fig. 4 an amplitude A1i_sh of the inner edge section 211i of the groove opening section 211 in the shoulder main groove 21 has the ratio 1.20 ≤ A2i_sh / A1i_sh ≤ 2.00 with respect to an amplitude A2i_sh of the inner edge section 212i of the groove bottom section 212, and more preferably has the ratio 1.30 ≤ A2i_sh / A1i_sh ≤ 1.80.

[0055] In the configuration described above, (1) because the amplitude A1o_sh, A1i_sh of the groove opening section 211 in the main shoulder groove 21 is set to small, the uneven wear of the edge section of the rib sections 31, 32, which is likely to occur at the position of maximum amplitude P1io, P1oi on the side of the main shoulder groove 21, is suppressed. Additionally, (2) because the amplitude A2o_sh, A2i_sh of the groove bottom section 212 in the main shoulder groove 21 is set to large, the stiffness of the rib sections 31, 32 is ensured, and the tear resistance of the tire is guaranteed. As a result, the resistance to uneven wear and the tear resistance performance of the tire are provided in a compatible manner.Furthermore, (3) since the groove opening section 211 of the shoulder main groove 21 has the zigzag shape or the wave-like shape with the amplitude in the tire width direction, the edge components of the rib sections 31, 32 are thus increased and the acceleration performance of the tire on snow is improved.

[0056] Additionally, in Fig. 3 and Fig. 4. The amplitude A1o_sh of the outer edge section 211o of the groove opening section 211 in the shoulder main groove 21 is determined such that it is essentially identical to the amplitude A1i_sh of the inner edge section 211i. In particular, the amplitude A1o_sh of the outer edge section 211o has the ratio 0.90 ≤ A1o_sh / A1i_sh ≤ 1.10 with respect to the amplitude A1i_sh of the inner edge section 211i, and more preferably has the ratio 0.95 ≤ A1o_sh / A1i_sh ≤ 1.05.

[0057] Additionally, the amplitudes A1o_sh, A1i_sh of the groove opening section 211 in the shoulder main groove 21 lie in a range of not less than 0 mm to not more than 15.0 mm and preferably in a range of not less than 2.0 mm to not more than 10.0 mm. If the amplitudes A1o_sh, A1i_sh are 0 mm, the groove opening section 211 in the shoulder main groove 21 has a straight shape.

[0058] Furthermore, the amplitudes A2o_sh, A2i_sh of the groove bottom section 212 in the shoulder main groove 21 are in a range of not less than 2.5 mm to not more than 15.0 mm and preferably in a range of not less than 4.0 mm to not more than 12.0 mm.

[0059] As in Fig. As illustrated in Figure 5, a groove wall angle α100 at the position of the outer maximum amplitude P100 of the outer margin section 2110 of the groove opening section 211 in the shoulder main groove 21 has the ratio α100 < α10i with respect to a groove wall angle α10i at the position of the inner maximum amplitude P10i of the outer margin section 2110. Similarly, a groove wall angle α100 at the position of the outer maximum amplitude P100 of the inner margin section 211i of the groove opening section 211 in the shoulder main groove 21 has the ratio α1ii < α100 with respect to a groove wall angle α1ii at the position of the inner maximum amplitude P1ii of the inner margin section 211i.Therefore, the groove wall angles α1oi, α1io of the main shoulder groove 21 are set large at the position where the marginal section of the groove opening section of the main shoulder groove 21 projects towards the side of the main shoulder groove 21 (the position of the inner maximum amplitude P1oi of the outer marginal section 211o and the position of the outer maximum amplitude P1io of the inner marginal section 211i in . Fig. 3) As a result, the stiffness of the web sections 31, 32 is ensured at the positions of maximum amplitude P1oi, P1io.

[0060] Furthermore, as in Fig. Figure 3 illustrates that the groove bottom section 212 in the main shoulder groove 21 is arranged such that it is largely pre-stressed towards the inside in the tire width direction with respect to the entire groove opening section 211. Thus, the mean value of the groove wall angle of the inner edge section 211i of the main shoulder groove 21 is set such that it is greater than the mean value of the groove wall angles of the outer edge section 211o. This ensures the stiffness of the narrow central rib section 32 (see Figure 3). Fig. 2).

[0061] Additionally, it points out that Fig. 5. The maximum width Wg2_sh of the groove bottom section 212 in the main shoulder groove 21 has the ratio 0 ≤ Wg2_sh / Wg1_sh ≤ 0.60 with respect to the maximum width Wg1_sh of the groove opening section 211 (i.e., the maximum groove width of the main shoulder groove 21), and more preferably has the ratio 0.35 ≤ Wg2_sh / Wg1_sh ≤ 0.45. If the groove bottom section of the main groove has an arc shape or a funnel shape (not illustrated), the maximum width Wg2_sh of the groove bottom section 212 will be approximately 0.

[0062] Additionally, the configuration of Fig. 3 both the outer edge section 211o and the inner edge section 211i of the groove opening section 211 in the shoulder main groove 21 form a wave-like shape by connecting a multitude of arcs projecting inwards in the tire width direction (i.e. towards the equatorial plane CL of the tire, see Fig. 2). Additionally, the circumferential length of the arc (dimension symbol omitted in drawings) is not less than 80% with respect to the wavelength λ1o_sh of the outer edge section 211o, and more preferably not less than 85%. Furthermore, the adjacent arcs are connected by short straight lines or arcs. In such a configuration, compared to a configuration in which the edge section has a zigzag shape or a sinusoidal waveform, uneven wear at the maximum protrusion position of the edge section is suppressed.

[0063] Additionally, the configuration of Fig. 3 Both the outer edge section 212o and the inner edge section 212i of the groove base section 212 of the shoulder main groove 21 exhibit the zigzag shape, which is formed by connecting linear sections of essentially the same length in the tire's circumferential direction. Additionally, the circumferential length (essentially equal to the maximum distance L2o_sh in the tire's circumferential direction between the positions of maximum amplitude P2oo, P2oi in the outer edge section 212o) lies in Fig. 3, the dimension symbol omitted in the drawings) of the linear section of the groove bottom section 212 preferably in a range of not less than 40% to not more than 60% with respect to the wavelength λ2o_sh of the outer edge section 212o.

[0064] However, no such restriction is intended, and the groove floor section 212 of the shoulder main groove 21 may have the wave-like shape as described above (not illustrated). Groove wall structure of the medial groove

[0065] Fig. Figure 6 is an explanatory diagram showing the groove wall structures of the main shoulder groove 21 and the in Fig. 2 illustrated medial groove 22 illustrated.

[0066] As in Fig. 2 and Fig. 6. The groove wall structure of the major scapular groove 21 differs slightly from the groove wall structure of the medial scapular groove 22. However, the configuration is not limited to this, and the medial scapular groove 22 may have a groove wall structure identical to that of the major scapular groove 21. Here, the groove wall structure of the medial scapular groove 22 is primarily described by its differences from that of the major scapular groove 21, and a description of common features is omitted.

[0067] In the configuration of Fig. 2, as in Fig. As illustrated in Figure 6, a groove opening section 221 in the central main groove 22 has a wave-like shape with an amplitude in the tire width direction at the corresponding outer edge section 221o on the side of the central rib section 32 and the inner edge section 221i on the side of the central rib section 33. Furthermore, the groove bottom section 222 in the shoulder main groove 22 has a zigzag shape with an amplitude in the tire width direction at the corresponding outer edge section 222o on the side of the central rib section 32 and the inner edge section 222i on the side of the central rib section 33.

[0068] As in Fig. As illustrated in Figure 6, the position of the outer maximum amplitude P100 of the outer edge section 2210 of the groove opening section 221 in the central main groove 22 is at the same position in the tire circumferential direction with respect to the position of the outer maximum amplitude P200 of the outer edge section 2220 of the groove bottom section 222. In particular, Fig. 6 has an offset amount φoo_ce between the positions of the outer maximum amplitude P1oo, P2oo in the outer edge sections 221o, 222o of the groove opening section 221 and the groove bottom section 222 in the central main groove 22 the ratio 0 ≤ φoo_ce / λ1o_ce ≤ 0.10 with respect to a wavelength λ1o_ce of the outer edge section 221o of the groove opening section 221, and more preferably has the ratio 0 ≤ φoo_ce / λ1o_ce ≤ 0.05.

[0069] In Fig. 6 The wavelength λ1o_ce of the outer edge section 221o of the groove opening section 221 of the shoulder main groove 22 is defined such that it is essentially identical to the wavelength λ2o_ce (not illustrated) of the outer edge section 222o of the groove bottom section 222. In particular, the wavelengths λ1o_ce, λ2o_ce of the groove opening section 221 and the groove bottom section 222 lie in the range 0.90 ≤ λ2o_ce / λ1o_ce ≤ 1.10.

[0070] Furthermore, a wavelength λ2_ce (the wavelength λ2o_ce of the outer edge section 222o and the wavelength λ2i_ce of the inner edge section 222i, not illustrated) of the groove bottom section 222 in the central main groove 22 has the ratio 0.10 ≤ λ2_ce / TW ≤ 0.35 with respect to the ground contact width TW of the tire.

[0071] Additionally, in Fig. 6 the wavelength λ1_ce (the wavelength λ1o_ce of the outer edge section 221o and a wavelength λ1i_ce (not shown) of the inner edge section 221i of the groove opening section 221 in the central main groove 22) is defined such that it is substantially similar to the wavelength λ1_sh (the wavelength λ1o_sh of the outer edge section 211o and the wavelength λ1i_sh (see Fig. 4) of the inner edge section 211i) of the groove opening section 211 in the shoulder main groove 21 are identical, and in particular have the ratio 0.90 ≤ λ1_ce / λ1_sh ≤ 1.10.

[0072] Additionally, it points out that Fig. 6. The amplitude A1o_ce of the outer edge section 221o of the groove opening section 221 in the central main groove 22 has a ratio of 1.05 ≤ A2o_ce / A1o_ce ≤ 1.50 with respect to an amplitude A2o_ce of the outer edge section 222o of the groove bottom section 222, and more preferably has a ratio of 1.10 ≤ A2o_ce / A1o_ce ≤ 1.20. Accordingly, the amplitude A2o_ce of the wave-like shape of the groove bottom section 222 is set larger than the amplitude A1o_ce of the wave-like shape of the groove opening section 221.

[0073] Additionally, the amplitudes A1o_ce, A1i_ce (not illustrated) of the groove opening section 221 in the central main groove 22 lie in a range of not less than 0 mm to not more than 10.0 mm and preferably in a range of not less than 2.0 mm to not more than 6.0 mm. If the amplitudes A1o_ce, A1i_ce are 0 mm, the groove opening section 221 in the central main groove 22 has a straight shape.

[0074] Additionally, the amplitudes A2o_ce, A2i_ce of the groove bottom section 222 in the central main groove 22 are in a range of not less than 1.5 mm to not more than 13.5 mm and preferably in a range of not less than 2.2 mm to not more than 9.0 mm.

[0075] Additionally, in Fig. 6. The amplitudes A1_ce (A1o_ce, A1i_ce) of the left and right marginal sections 221o, 221i of the groove opening section 221 in the central main groove 22 are set such that they are smaller than the amplitudes A1_sh (A1o_sh, A1i_sh) of the left and right marginal sections 211o, 211i of the groove opening section 211 in the shoulder main groove 21. In particular, the amplitudes A1_ce of the left and right marginal sections 221o, 221i of the groove opening section 221 in the central main groove 22 have the ratio A1_ce / A1_sh ≤ 0.95 with respect to the amplitudes A1_sh of the left and right marginal sections 211o, 211i of the groove opening section 211 in the The shoulder joint 21 is located and more preferably exhibits the ratio A1_ce / A1_sh ≤ 0.90. The lower limit of the ratio A1_sh / A1_ce is not subject to any specific restrictions, but is subject to restrictions by other conditions.

[0076] Additionally, in Fig. 6. The amplitudes A2_ce (A2o_ce, A2i_ce) of the left and right marginal sections 222o, 222i of the groove base section 222 in the central main groove 22 are set such that they are smaller than the amplitudes A2_sh (A2o_sh, A2i_sh) of the left and right marginal sections 212o, 212i of the groove base section 212 in the shoulder main groove 21. In particular, the amplitudes A2_ce of the left and right marginal sections 222o, 222i of the groove base section 222 in the central main groove 22 have the ratio A2_ce / A2_sh ≤ 0.95 with respect to the amplitudes A2_sh of the left and right marginal sections 212o, 212i of the groove base section 212 in the shoulder main groove 21. and more preferably exhibit the ratio A2_ce / A2_sh ≤ 0.75. The lower bound of the ratio A2_ce / A2_sh is not subject to any specific restrictions, but is subject to restrictions by other conditions.

[0077] A maximum width Wg2_ce (dimension symbol omitted in the drawings) of the groove bottom section 222 in the central main groove 22 also has the ratio 0 < Wg2_ce / Wg1_ce ≤ 0.80 with respect to a maximum width Wg1_ce of the groove opening section 221 (that is, the maximum groove width of the central main groove 22, dimension symbol omitted in the drawings), and more preferably has the ratio 0.40 ≤ Wg2_ce / Wg1_ce ≤ 0.60. If the groove bottom section of the main groove has an arc shape or a funnel shape (not illustrated), the maximum width Wg2_ce of the groove bottom section 222 becomes approximately 0.

[0078] Additionally, the configuration of Fig. 6 both the outer edge section 221o and the inner edge section 221i of the groove opening section 221 in the central main groove 22 form a wave-like shape by connecting a multitude of arcs projecting inwards in the tire width direction (i.e. towards the equatorial plane CL of the tire, see Fig. 2). Additionally, the circumferential length of the arc (dimension symbol omitted in drawings) is not less than 80% with respect to the wavelength λ1o_ce of the outer edge section 221o, and more preferably not less than 85%. Furthermore, the adjacent arcs are connected by short straight lines or arcs. Middle web section and middle web section

[0079] In the configuration of Fig. 2 The middle bridge section 32 and the middle bridge section 33 each include a plurality of continuous tunnel grooves 321; 331 and a plurality of blocks 322; 332.

[0080] The edge sections of the central rib section 32 and the central rib section 33 have a wave-like shape formed by connecting the plurality of arcs as described above. The left and right edge sections of the central rib section 32 have a wave-like shape formed by connecting the plurality of arcs projecting towards the equatorial plane CL of the tire. The central rib section 33, on the other hand, is located on the tire's equatorial plane CL, and its left and right edge sections have a wave-like shape formed by connecting the plurality of arcs projecting towards the side of the tire's equatorial plane CL, that is, towards the inside in the lateral direction of the central rib section 33.As a result, the edge sections of the rib sections 31 to 33 of the entire tread have the wave-like shape formed by connecting the multitude of arcs that protrude towards the side of the equatorial plane of the tire CL.

[0081] As in Fig. 2 and Fig. As illustrated in Figure 6, the continuous lug grooves 321, 331 in the central rib section 32 and the central rib section 33 open towards the positions with maximum amplitude of the edge sections of the rib sections 32, 33. The pitch of the continuous lug grooves 321, 331 is set to be twice the pitch of the wave-like shapes of the edge sections in the rib sections 32, 33. Additionally, the pitch of the continuous lug grooves 321, 331 is within a range of not less than 110 and not more than 200 across the entire circumference of the tire. Furthermore, the wave-like shapes of the left and right edge sections in the central rib section 32 and the central rib section 33 are arranged with phases shifted in the circumferential direction of the tire. Accordingly, the second tread grooves 321, 331 extend in such a way that they run diagonally in relation to the tire width direction.

[0082] As in Fig. As illustrated in Figure 6, the continuous lug grooves 321, 331 have short linear sections parallel to the tire width direction at the opening end sections to the main grooves 21, 22. The length L21 of these linear sections preferably lies in a range of not less than 5% to not more than 25% of the ground contact widths Wb2, Wb3 (see Figure 6). Fig. 2) the bridge sections 31, 32.

[0083] The continuous grooves 321 (331) in the middle web section 32 (and in the middle web section 33) are narrow, shallow grooves and have a maximum groove width W21 (see Fig. 3) of not less than 1.5 mm and not more than 4.0 mm (see Fig. 3) and a maximum groove depth H21 (see Fig. 5) of not less than 1.0 mm and not more than 6.0 mm. Additionally, in Fig. 5 the maximum groove depth H21 of the continuous lug groove 321 (331) has the ratio 0.05 ≤ H21 / Hg1 ≤ 0.65 with respect to a maximum groove depth Hg1 of the shoulder main groove 21, and more preferably has the ratio 0.10 ≤ H21 / Hg1 ≤ 0.30.

[0084] The blocks 322; 332 are defined by the plurality of continuous lug grooves 321; 331. The blocks 322; 332 have a shape that is long in the tire width direction. In particular, the pitch spacing lengths of the blocks 322; 332 (The pitch spacing length of the blocks 322 in the middle rib section 32 is equal to the maximum distance L1i_sh in the tire circumferential direction between the position of the outer maximum amplitude P1io and the position of the inner maximum amplitude P1ii in the inner edge section 211i of the groove opening section 211 in the shoulder main groove 21) Fig. 4. The dimension symbol is omitted in drawings with regard to the division spacing length of the blocks 332 in the central web section 33.) in a range of not less than 40% to not more than 70% of the maximum ground contact widths Wb2; Wb3 of the web sections 32; 33 and preferably in a range of not less than 50% to not more than 60%.

[0085] A snow traction index (STI, so-called 0-degree snow traction index) in relation to the tire's circumferential direction over the entire circumference of the tire is in the range of 130 ≤ STI.

[0086] The Snow Traction Index (STI) is an empirical formula developed by Uniroyal Inc., proposed by the Society of Automotive Engineers (SAE), and defined by the following mathematical formula (1). In the formula, Pg is a groove density (1 / mm) and is calculated as the ratio between the groove length (mm) of all grooves (all grooves except sipes) projecting in the tire's circumferential direction onto the tire's ground contact surface and the tire's ground contact area (product of the tire's ground contact width and the tire's circumferential length (mm²)). Additionally, ρs is a sipe density (1 / mm) and is calculated as the ratio between the sipe length (mm) of all sipes projecting in the tire's circumferential direction onto the tire's ground contact surface and the tire's ground contact area (mm²).Furthermore, Dg is an average value of the groove depth (mm) of all grooves that protrude onto the ground contact surface of the tire in the circumferential direction. STI=−6.8+2202×Pg+672×ρs+7.6×Dg Shoulder strap section

[0087] Fig. 7 is an enlarged view showing the shoulder bridge section 31 of the in Fig. 2 illustrated tires 1 illustrated. Fig. Figure 8 is an enlarged view showing the narrow, shallow groove 311 of the in Fig. The shoulder bridge section 31 is illustrated in Figure 7. The same drawing illustrates the extracted single narrow shallow groove 311. Fig. 9 is a cross-sectional view of the in Fig. 7 illustrated shoulder bridge section 31. The same drawing illustrates the cross-sectional view of the shoulder bridge section 31 along the narrow flat groove 311.

[0088] In the configuration of Fig. As described above, the shoulder rib section 31 is the rib with the continuous road contact surface in the tire's circumferential direction and is not divided in the tire's circumferential direction by lug grooves or sipes. Furthermore, the edge section on the side of the main shoulder groove 21 of the shoulder rib section 31 has the wave-like shape formed by connecting the multitude of arcs that project towards the equatorial plane CL of the tire.

[0089] As in Fig. As illustrated in Figure 2, the shoulder bridge section 31 includes the multitude of narrow, shallow grooves 311.

[0090] The narrow, shallow groove 311 has a U-shape (or a V-shape or a C-shape) with an opening section facing the side of the tire's ground contact edge T. In other words, the narrow, shallow grooves 311 have closed sections on the side of the tire's equatorial plane CL and a one-sided opening shape with a continuous opening on the side of the tire's ground contact edge T. Additionally, the narrow, shallow grooves 311 have a closed structure that terminates within the ground contact surface of the shoulder rib section 31. Thus, the narrow, shallow grooves 311 are not connected to the tire's ground contact edge T and the main shoulder grooves 21 and are arranged to be separated from the edge section of the road contact surface of the shoulder rib section 31.In addition, the numerous narrow, flat grooves 311 are arranged at predetermined intervals in the circumferential direction of the tire. The adjacent narrow, flat grooves 311 are arranged so that they are separated from one another.

[0091] A maximum groove width Wn (see Fig. 8) The narrow, flat groove 311 preferably lies in the range of 0.1 mm ≤ Wn ≤ 5.0 mm and in the range of 0.3 mm ≤ Wn ≤ 2.0 mm. Additionally, it has a maximum groove depth Hn (see Fig. 9) The narrow, shallow groove 311 has a ratio of 0.01 ≤ Hn / Hg ≤ 0.30 with respect to the maximum groove depth Hg of the main shoulder groove 21, and preferably has a ratio of 0.03 ≤ Hn / Hg ≤ 0.25. By virtue of the maximum groove width Wn and the maximum groove depth Hn being described above, the narrow, shallow grooves 311 function as grooves that open and do not close when the tire comes into contact with the ground.

[0092] In the configuration described above, (1) the narrow flat grooves 311 have a U-shape. This improves the tire's acceleration performance on snow during vehicle travel through circumferential components of the narrow flat grooves 311 compared to a configuration (not shown) that has a multitude of narrow grooves in the width direction with an I-shape arranged in the tire's circumferential direction. Additionally, (2) because the narrow flat grooves 311 have a U-shape, with the opening section facing the tire's ground contact edge T, the circumferential components of the narrow flat grooves can be omitted in a region on the side of the tire's ground contact edge T compared to, for example, a configuration (not illustrated) that includes narrow flat grooves with an annular structure (not illustrated).This improves the noise performance of the tire during vehicle operation and suppresses the uneven wear originating from the narrow flat groove 311. Additionally, (3) because the narrow flat grooves 311 have a closed structure in which the narrow flat grooves 311 terminate within the ground contact surface of the rib section 31, the noise performance of the tire is improved compared to a configuration (not illustrated) that includes narrow flat grooves extending into the ground contact surface of the rib section in the tire width direction or the tire circumference direction (not illustrated).

[0093] In Fig. 7 has a width direction length W11 of the narrow flat groove 311 the ratio 0.40 ≤ W11 / Wb1 ≤ 0.90 with respect to the maximum ground contact width Wb1 of the shoulder rib section 31 and preferably has the ratio 0.50 ≤ W11 / Wb1 ≤ 0.80.

[0094] The width direction length W11 of the narrow flat grooves 311 is measured as the maximum extending length of the narrow flat grooves 311 in the tire width direction when the tire is mounted on a specified rim, inflated to the specified internal pressure and in an unloaded state.

[0095] Additionally, it points out that Fig. 7 a circumferential length L11 of the narrow flat groove 311 has the ratio 0.50 ≤ L11 / P11 ≤ 0.90 with respect to a pitch spacing length P11 of the narrow flat grooves 311 and preferably has the ratio 0.60 ≤ L11 / P11 ≤ 0.80.

[0096] The circumferential length L11 of the narrow flat groove 311 is measured as the maximum extending length in the tire circumferential direction of the narrow flat groove 311 when the tire is mounted on a specified rim, inflated to the specified internal pressure and in an unloaded state.

[0097] The pitch spacing Pn of the narrow flat grooves 311 is identical to the pitch spacing of the wave-like shapes of the edge sections of the shoulder rib section 31 and lies in a range of not less than 50 to not more than 100. Additionally, a distance (not illustrated) between the adjacent narrow flat grooves 311, 311 is preferably ensured in a range of not less than 10 mm.

[0098] In Fig. 7 has a distance D1 between the blind-ending points A1, A2 of the narrow flat groove 311 in the tire circumferential direction the ratio 0.30 ≤ D1 / P11 ≤ 0.70 with respect to the pitch distance length P11 of the narrow flat grooves 311, and preferably has the ratio 0.40 ≤ D1 / P11 ≤ 0.60.

[0099] In Fig. 7 has a distance D2 (see Fig. 8) between the blind-ending endpoints A1, A2 of the narrow flat groove 311 in the tire width direction the ratio 0 ≤ D2 / Wb1 ≤ 0.70 with respect to the maximum ground contact width Wb1 of the shoulder rib section 31, and preferably has the ratio 0 ≤ D2 / Wb1 ≤ 0.50.

[0100] In Fig. 7. A distance D3 between the narrow, flat groove 311 and the ground contact edge T of the tire has a ratio of 0.05 ≤ D3 / Wb1 with respect to the maximum ground contact width Wb1 of the shoulder rib section 31, and preferably has a ratio of 0.10 ≤ D3 / Wb1. Similarly, a distance D4 between the narrow, flat groove 311 and the edge section of the shoulder rib section 31 has a ratio of 0.10 ≤ D4 / Wb1 with respect to the maximum ground contact width Wb1 of the shoulder rib section 31, and preferably has a ratio of 0.15 ≤ D4 / Wb1. This ensures the stiffness of the edge section of the shoulder rib section 31. It should be noted that the upper limits of the distances D3, D4 are not particularly restricted, but are limited by the relationship with the ratio W11 / Wb1 of the lateral direction length W11 of the narrow, shallow grooves 311 described above. In the configuration of Fig. 7 is the measuring point of the distance D3, the blind-ending point A1, however, the other blind-ending point A2 can be the measuring point of the distance D3, depending on the shape of the narrow flat groove 311.

[0101] In Fig. 7 the width direction length W11 and the circumferential length L11 of the narrow flat groove 311 have the ratio 0.60 ≤ W11 / L11 ≤ 1.40, and preferably have the ratio of 0.80 ≤ W11 / L11 ≤ 1.20.

[0102] In Fig. 7, as described above, in the configuration in which the shoulder rib section 31 has an edge section with the zigzag shape or the wave-like shape with the amplitude in the tire width direction, the distance D5 in the tire circumferential direction between the innermost point B in the tire width direction of the narrow flat groove 311 and the position with maximum amplitude P100 to the outside in the tire width direction of the edge section of the shoulder rib section 31 is in a range of 0.30 ≤ D5 / λ1o_sh ≤ 0.70, and preferably in a range of 0.45 ≤ D5 / λ1o_sh ≤ 0.65, with respect to the wavelength λ1o_sh of the edge section. Accordingly, the innermost point B of the narrow, flat groove 311 is positioned such that it is separated from the position of maximum amplitude P100 to the outer edge in the tire width direction of the edge section of the shoulder rib section 31. This ensures the stiffness of the edge section of the shoulder rib section 31.

[0103] As in Fig. As illustrated in Figure 8, a pair of blind-ending points A1, A2 and the innermost point B in the tire width direction of the narrow, shallow groove 311 are defined. An imaginary line L1 is defined passing through a midpoint M of the closing endpoints A1, A2 and the innermost point B. At this point, an angle θ11 is formed between the imaginary line L1 and the tire circumference direction in a range of 45 degrees ≤ θ11 ≤ 135 degrees, and preferably in a range of 50 degrees ≤ θ11 ≤ 70 degrees. Consequently, the opening directions of the U-shapes of the narrow, shallow grooves 311 are suitably designed.

[0104] In the configuration of Fig. Figure 8 features the U-shape of the narrow, shallow groove 311 with continuous lateral direction sections Ra1, Ra2 having inclination angles of not less than 75 degrees and not more than 105 degrees with respect to the tire's circumferential direction. A total ΣLa of lateral direction lengths La1 to La4 (dimension symbols omitted in the drawings) of the lateral direction sections Ra1, Ra2 has a ratio of 1.00 ≤ ΣLa / W11 with respect to the lateral direction length W11 of the narrow, shallow groove 311, and preferably has a ratio of 1.30 ≤ ΣLa / W11. The lateral direction lengths La1 to La4 of the lateral direction sections Ra1, Ra2 preferably lie within a range of not less than 25% with respect to the lateral direction length W11 of the narrow, shallow groove 311.As a result, the latitude-direction lengths La1 to La4 of the latitude-direction progression sections Ra1, Ra2 are ensured; the upper limit of the ratio is not particularly restricted, but is subject to other conditions.

[0105] The inclination angle of the U-shape of the narrow flat groove 311 is measured as an angle through a tangent of the groove centerline of the narrow flat groove and the tire circumferential direction.

[0106] In the configuration of Fig. Figure 8: The U-shape of the narrow, shallow groove 311 encloses a continuous circumferential section Rb with an inclination angle of not less than 0 degrees and not more than 15 degrees with respect to the tire's circumferential direction. A circumferential length Lb1 (dimension symbol omitted in the drawings) of the circumferential section Rb has a ratio of 0.50 ≤ Lb / L11 with respect to the circumferential length L11 of the narrow, shallow groove 311, and preferably a ratio of 0.70 ≤ Lb / L11. Consequently, the circumferential length Lb1 of the circumferential section Rb is ensured. The upper limit of the ratio is not particularly restricted, but is subject to other conditions.

[0107] As in Fig. As illustrated in Figure 8, the U-shape of the narrow, shallow groove 311 preferably includes a curved section (reference numeral omitted in the drawings) arranged in at least one of the regions between points A1, B and between points A2, B to connect the adjacent width-direction sections Ra1, Ra1; Ra2, Ra2. The curved section has a crank-like or S-shape. A distance D6 from the ground contact edge T of the tire to a midpoint C of the curved section preferably has a ratio of 0.30 ≤ D6 / Wb1 ≤ 0.70 with respect to the maximum ground contact width Wb1 of the shoulder rib section 31, and more preferably has a ratio of 0.40 ≤ D6 / Wb1 ≤ 0.60. Thus, the curved section of the narrow, shallow groove 311 is arranged at the central section in the width direction of the shoulder rib section 31.

[0108] For example, in the configuration of Fig. 8. The pair of blind-ending endpoints A1, A2 of the narrow shallow groove 311 are arranged at substantially the same position in the tire width direction. The narrow shallow groove 311 has the single innermost point B. The narrow shallow groove 311 encloses the pair of width-direction sections Ra1, Ra1; Ra2, Ra2, which extend substantially parallel to the tire width direction between points A1, B and between points A2, B', respectively. The two sets of width-direction sections Ra1, Ra1; Ra2, Ra2 are each connected to each other via the curved section with the S-shape. As a result, a groove section is formed that runs in a stepped shape in the tire width direction. Additionally, the curved sections are inclined or bent in the same direction with respect to the tire circumference.The narrow, shallow groove 311 encloses the single circumferential section Rb, which extends substantially parallel to the tire's circumferential direction from the innermost point B. The circumferential section Rb has a linear or slightly arc-shaped form projecting towards the equatorial plane CL of the tire and is substantially L-shaped, connected to the lateral-direction sections Ra1, Ra2 at the innermost point B and at the other endpoint B'. The pair of blind-ending points A1, A2 and both endpoints B, B' of the circumferential section Rb are arranged such that they are offset from each other in the tire's circumferential direction.

[0109] In the configuration of Fig. 8 The U-shape of the narrow flat grooves 311 consists of a single line that has no branching section. However, no such restriction is intended, and the U-shape of the narrow flat grooves 311 may have a branching section that diverges from its center (not illustrated).

[0110] It should be noted that the edge section on the side of the main shoulder groove 21 of the shoulder bridge section 31 may have a multitude of fine, multi-layered lamellae (reference symbols omitted in drawings). These multi-layered lamellae have a width of less than 1.0 mm and extend over a length of less than 5.0 mm. These multi-layered lamellae suppress uneven wear of the edge section in the shoulder bridge section 31. Modified examples

[0111] Fig. 10, Fig. 11, Fig. 12, Fig. 13, Fig. 14, Fig. 15, Fig. 16, Fig. 17, Fig. 18 to Fig. 19 are explanatory diagrams that show modified examples of the in Fig. The narrow, flat groove 311 is illustrated in Figure 8. These drawings show components that correspond to those in Fig. The 8 illustrated components are identical, are provided with the same reference symbols, and their explanations are omitted.

[0112] In the configuration of Fig. 8. The circumferential section Rb has a straight line or a slight arc shape, inclined with respect to the tire's circumferential direction such that the narrow, shallow groove 311 has the single innermost point B'. Furthermore, the innermost point B' is located at the connecting section between the lateral direction section Ra1 and the circumferential section Rb of the narrow, shallow groove 311.

[0113] In contrast, in the Fig. In the illustrated configuration 10, the circumferential profile section Rb is formed by a straight line parallel to the tire's circumference direction. In this case, a midpoint of a region (the entire circumferential profile section Rb in Fig. 10) on the innermost side in the tire width direction under the groove sections of the narrow flat groove 311, defined as the innermost point B' of the narrow flat groove 311. In the configuration of Fig. The left and right lateral direction sections Ra1 and Ra2 are connected by groove sections that have an arc shape projecting towards the side of the tire's equatorial plane CL. The raised section with the arc shape has the innermost points B' of the narrow, shallow groove 311 and the circumferential direction section Rb.

[0114] Furthermore, the configuration of Fig. 8 the narrow flat groove 311 a pair of width direction progression sections Ra1, Ra1; Ra2, Ra2 which extend substantially parallel to the tire width direction between points A1, B and between points A2, B' respectively.

[0115] In contrast, the configuration of Fig. 12 The narrow, shallow groove 311 includes a pair of latitude-direction sections Ra1, Ra1 between points A1, B, with the single latitude-direction section Ra2 extending between points A2, B. Additionally, the latitude-direction section Ra2 on the side of point A2 and the innermost point B are connected by an extended arc that includes a short, S-shaped curved section and the circumferential section Rb.

[0116] In the configuration of Fig. 8 are the pair of blind-ending points A1, A2 of the narrow, flat groove 311 arranged at substantially the same position in the tire width direction. Thus, the distance D2 between the blind-ending points A1, A2 in the tire width direction is essentially zero.

[0117] In contrast, the configuration of Fig. 13 The pair of blind-ending points A1, A2 of the narrow flat groove 311 are arranged such that they are offset from each other in the tire width direction. Even in such a configuration, it is assumed that the opening section of the narrow flat groove 311 faces the side of the ground contact edge T of the tire, as long as the angle θ11 of the narrow flat groove 311 lies within the range described above.

[0118] In the configuration of Fig. 8 the opening section of the U-shape of the narrow flat groove 311 is configured such that the width direction sections Ra1, Ra2 have a straight line or a slight arc shape, and these width direction sections Ra1, Ra2 have the blind ending points A1, A2 of the narrow flat groove 311.

[0119] In contrast, in the configuration of Fig. 14 The opening section of the U-shape of the narrow, flat groove 311 is curved in a direction that narrows the opening width towards the endpoints A1 and A2. Additionally, in the configuration of Fig. 15 The S-shaped curved sections, which connect the adjacent width-direction-progression sections Ra1, Ra1; Ra2, Ra2, are curved in a direction that narrows the opening width of the U-shape. Thus, the U-shape of the narrow, shallow groove 311 can have a shape with a narrow opening width.

[0120] Furthermore, the configuration of Fig. 8 the narrow flat groove 311 a pair of width direction progression sections Ra1, Ra1; Ra2, Ra2 which extend substantially parallel to the tire width direction between points A1, B and between points A2, B respectively, and the two sets of the respective width direction progression sections Ra1, Ra1; Ra2, Ra2 are connected to each other via the S-shaped curved sections.

[0121] In contrast, the configuration of Fig. 16 The narrow, flat groove 311 encloses the single latitude-direction profile section Ra1 between points A1, B and encloses the pair of latitude-direction profile sections Ra2, Ra2 between points A2, B. In addition, points A1, B are connected to the long and linear latitude-direction profile section Ra1. Furthermore, in the configuration of Fig. 17. The pair of latitude-direction profile sections Ra1, Ra1 is provided between points A1, B, and one latitude-direction profile section is not provided between points A2, B. Points A2, B are connected by a long and arc-shaped groove section.

[0122] In the configuration of Fig. 18 and Fig. 19 The narrow, flat groove 311 has the individual sections Ra1, Ra2 running in the longitudinal direction between points A1, B and between points A2, B, respectively. In particular, in the configuration of Fig. 19 the points A1, B and the points A2, B are connected to the sections Ra1, Ra2 running in the latitude direction. Impact 1

[0123] As described above, this tire 1 includes the pair of shoulder main grooves 21 and one or more center main grooves 22 running in the tire circumferential direction, and four or more rows of rib sections 31 to 33 defined by the shoulder main grooves 21 and the center main grooves 22 (see Fig. 2) The groove opening section 211 in the shoulder main groove 21 has a straight shape, a zigzag shape, or a wave-like shape with the amplitude in the tire width direction (see Fig. 3) The groove bottom section 212 in the shoulder main groove 21 has a zigzag or wave-like shape with the amplitude in the tire width direction. The amplitude A1_sh (A1o_sh, A1i_sh) of the groove opening section 211 in the shoulder main groove 21 has the ratio A1_sh < A2_sh with respect to the amplitude A2_sh (A2o_sh, A2i_sh) of the groove bottom section 212.

[0124] In the configuration described above, (1) because the amplitude A1_sh of the groove opening section 211 in the main shoulder groove 21 is set to a small value, the uneven wear of the edge section of the rib sections 31, 32, which is likely to occur at the positions with maximum amplitude P10, P10i on the side of the main shoulder groove 21, is suppressed. Additionally, (2) because the amplitude A2_sh of the groove bottom section 212 in the main shoulder groove 21 is set to a large value, the stiffness of the rib sections 31, 32 is ensured, and the tear resistance of the tire is guaranteed. Furthermore, (3) since the groove opening section 211 of the shoulder main groove 21 has the zigzag shape or the wave-like shape with the amplitude in the tire width direction, the edge components of the rib sections 31, 32 are thus increased and the acceleration performance of the tire on snow is improved.This is advantageous in that the acceleration performance on snow, the resistance to uneven abrasion, and the tear resistance performance of the tire are provided in a compatible manner.

[0125] In tire 1, the amplitude A1_sh (A1o_sh, A1i_sh) of the groove opening section 211 in the shoulder main groove 21 has the ratio 1.20 ≤ A2_sh / A1_sh with respect to the amplitude A2_sh (A2o_sh, A2i_sh) of the groove bottom section 212 (see Fig. 3) As a result, an advantage is that the stiffness of the web sections 31, 32 is effectively suppressed.

[0126] In tire 1, the wavelength λ2_sh (λ2o_sh, λ2i_sh, see Fig. 3) of the groove bottom section 212 in the shoulder main groove 21 the ratio 0.10 ≤ λ2_sh / TW ≤ 0.35 with respect to the ground contact width TW of the tire on (see Fig. 2) This has the advantage that the amplitude A2_sh of the groove floor section 212 is suitably designed.

[0127] In tire 1, the positions of the outer maximum amplitude P100, P10 of the groove opening section 211 in the shoulder main groove 21 are located at the same position in the tire circumferential direction as the positions of the outer maximum amplitude P200, P20 of the groove bottom section 212 (see Fig. 3) This has the advantage of improving the reinforcing effect of the rib and the rib tear resistance performance of the tire.

[0128] In tire 1, the groove opening section 221 in the central main groove 22 has a straight shape, a zigzag shape, or a wave-like shape with the amplitude in the tire width direction, and the groove bottom section 222 in the central main groove 22 has a zigzag shape or a wave-like shape with the amplitude in the tire width direction. This has the advantage of improving the tire's acceleration performance on snow.

[0129] In tire 1, the amplitude A1_ce (A1o_ce, A1i_ce) of the groove opening section 221 in the central main groove 22 has the ratio 1.05 ≤ A2_ce / A1_ce with respect to the amplitude A2_ce (A2o_ce, A2i_ce) of the groove bottom section 222 (see Fig. 6) This has the advantage of improving the tire's resistance to uneven abrasion and its tear resistance.

[0130] In tire 1, the amplitude A1_ce (A1o_ce, A1i_ce) of the groove opening section 221 in the central main groove 22 has the ratio A1_ce / A1_sh ≤ 0.95 with respect to the amplitude A1_sh (A1o_sh, A1i_sh) of the groove opening section 211 in the shoulder main groove 21 (see Fig. 6) This configuration has the advantage of reinforcing the shoulder rib section 31 and improving the tear resistance performance of the tire.

[0131] In tire 1, the amplitude A2_ce (A2o_ce, A2i_ce) of the groove bottom section 222 in the central main groove 22 has the ratio A2_ce / A2_sh ≤ 0.75 with respect to the amplitude A2_sh (A2o_sh, A2i_sh) of the groove bottom section 212 in the shoulder main groove 21 (see Fig. 6) In such a configuration, (1) since the amplitude A2_sh of the groove bottom section 212 in the shoulder main groove 21, where a tear is likely to occur, is set large, there is an advantage in that the effect of improving tear resistance performance, which is achieved by increasing the amplitude A2_sh of the groove bottom section 212, is effectively realized. (2) Since the amplitude A2_ce of the groove bottom section 222 in the central main groove 22 is set small, there is an advantage in that a groove volume is ensured and the wet performance of the tire is improved.

[0132] In tire 1, the wavelength λ1_ce (λ1o_ce, λ1i_ce) of the groove opening section 221 in the central main groove 22 has a ratio of 0.90 ≤ λ1_ce / λ1_sh ≤ 1.10 with respect to the wavelength λ1_sh (λ1o_sh, λ1i_sh) of the groove opening section 211 in the shoulder main groove 21. This has the advantage of reducing the ground contact pressure at the edge section in the shoulder rib section 31 and improving resistance to uneven abrasion.

[0133] In tire 1, the groove opening section 211 in the main shoulder groove 21 has the wave-like shape formed by connecting the multitude of arcs that project to the side of the equatorial plane of the tire (see Fig. 3) With such a configuration, an advantage is that the uneven abrasion at the position with maximum amplitude is suppressed compared to the edge section with the zigzag shape.

[0134] In tire 1, the circumferential length (dimension symbol omitted in the drawings) of the arc is not less than 80% with respect to the wavelength λ1_sh (λ1o_sh, λ1i_sh) of the wave-like shape of the groove opening section 211. This has the advantage that the effect of suppressing uneven wear at the position of maximum amplitude is effectively improved. Impact 2

[0135] The tire 1 includes a plurality of main grooves 21, 22 extending in the circumferential direction of the tire and a plurality of rib sections 31 to 33 defined by the main grooves 21, 22 (see Fig. 2). In addition, at least one row of the bridge section (the left and right shoulder bridge sections 31, 31 in Fig. 2) the plurality of narrow, flat grooves 311. The narrow, flat groove 311 has a U-shape, with the opening section facing the side of the tire's ground contact edge T. The narrow, flat groove 311 terminates within the ground contact surface of the rib section 31 (see Fig. 7). (1) Since the narrow flat groove 311 has a U-shape, an advantage of this configuration is that the acceleration performance of the tire on snow during vehicle travel is improved by circumferential components of the narrow flat grooves 311, compared to a configuration (not illustrated) that has a plurality of narrow grooves in the width direction with an I-shape arranged in the tire's circumferential direction. Additionally, (2) since the narrow flat grooves 311 have a U-shape, with the opening section facing the ground contact edge T of the tire, the circumferential components of the narrow flat grooves can be omitted in a region on the side of the ground contact edge T of the tire, compared to, for example, a configuration (not illustrated) that includes narrow flat grooves with an annular structure (not illustrated).As a result, one advantage is that the noise performance of the tire is improved during vehicle operation, and the uneven wear resulting from the narrow flat grooves 311 is suppressed. Additionally, (3) because the narrow flat grooves 311 have a closed structure in which the narrow flat grooves 311 terminate within the ground contact surface of the rib section 31, the noise performance of the tire is improved compared to a configuration (not illustrated) that includes narrow flat grooves penetrating into the ground contact surface of the rib section in the tire width direction or in the tire circumference direction.

[0136] In the tire 1, the rib section 31, which encloses the narrow flat grooves 311, is the rib with a road contact surface that runs continuously in the circumferential direction of the tire (see Fig. 7) As a result, one advantage is that the stiffness of the rib section 31 is ensured and the acceleration performance of the tire on snow is improved, and there is an advantage in that the noise performance of the tire is improved compared to a configuration (not shown) which has narrow, shallow grooves that penetrate into the ground contact surface of the rib section in the tire width direction.

[0137] The maximum groove width Wn is located in tire 1 (see Fig. 8) the narrow, shallow groove 311 in the range of 0.1 mm ≤ Wn ≤ 5.0 mm, and the maximum groove depth Hn (see Fig. 9) The narrow, shallow groove 311 has a ratio of 0.01 ≤ Hn / Hg1 ≤ 0.30 with respect to the maximum groove depth Hg1 of the main shoulder groove 21. Consequently, an advantage is that the maximum groove width Wn and the maximum groove depth Hg1 of the narrow, shallow groove 311 are suitably designed.

[0138] In tire 1, the lateral direction length W11 of the narrow flat groove 311 has the ratio 0.40 ≤ W11 / Wb1 ≤ 0.90 with respect to the maximum ground contact width Wb1 of the rib section 31 (see Fig. 7) The lower limit has the advantage that the edge component of the narrow, flat grooves 311 is ensured in the tire's circumferential direction, thus guaranteeing the improved acceleration performance of the tire on snow. The upper limit has the advantage that the distances D3, D4 (see Fig. 7) between the narrow flat groove 311 and the edge sections of the web section 31 are ensured and the stiffness of the web section 31 is ensured.

[0139] Furthermore, in tire 1, the circumferential length L11 of the narrow flat groove 311 has a ratio of 0.50 ≤ L11 / P11 ≤ 0.90 with respect to the pitch distance length P11 of the narrow flat grooves 311 (see Fig. 7) The lower limit has the advantage of ensuring the circumferential components of the U-shapes of the narrow, flat grooves 311 are present, thus guaranteeing the tire's acceleration performance on snow while driving. The upper limit has the advantage of suppressing any deterioration in the tire's noise performance due to excessive circumferential components of the narrow, flat grooves 311.

[0140] In tire 1, the distance D1 between the pair of blind-ending points A1, A2 of the narrow flat groove 311 in the tire circumferential direction has the ratio 0.30 ≤ D1 / P11 ≤ 0.90 with respect to the pitch distance length P11 of the narrow flat grooves 311 (see Fig. 7) The lower limit has the advantage of ensuring the opening width of the U-shape of the narrow, shallow groove 311 and suppressing the deterioration of the tire's noise performance. The upper limit has the advantage of ensuring the distance between the blind-ending points A1, A2 of the adjacent narrow, shallow grooves 311, 311.

[0141] In tire 1, the distance D2 (see Fig. 8) between the pair of blind-ending points A1, A2 of the narrow flat groove 311 in the tire width direction the ratio 0 ≤ D2 / Wb1 ≤ 0.70 with respect to the maximum ground contact width Wb1 of the rib section 31 on (see Fig. 7) In such a configuration, the pair of blind-ending points A1, A2 of the narrow flat groove 311 are located in the same position in the tire width direction, and this has the advantage that the stiffness of the shoulder rib section 31 is made uniform and the resistance to uneven abrasion of the shoulder rib section 31 is suppressed.

[0142] In tire 1, if the pair of blind-ending points A1, A2 and the innermost point B are defined in the tire width direction of the narrow flat groove 311 and the imaginary line L1 is defined through the midpoint M of the blind-ending points A1, A2 and the innermost point B, the angle θ11 formed by the imaginary line L1 and the tire circumference direction lies in the range of 45 degrees ≤ θ11 ≤ 135 degrees (see Fig. 8) This has the advantage that the opening direction of the U-shape of the narrow flat groove 311 is suitably designed and the noise performance of the tire is improved while driving the vehicle.

[0143] In the tire 1, the U-shape of the narrow flat groove 311 encloses at least one of the width-direction sections Ra1, Ra2 with an inclination angle of not less than 75 degrees and not more than 105 degrees with respect to the tire circumference direction (see Fig. 8) The sum ΣLa of the lateral direction lengths La1 to La4 of the lateral direction sections Ra1, Ra2 has the ratio 1.00 ≤ ΣLa / W11 with respect to the lateral direction length W11 of the narrow, shallow groove 311. In such a configuration, the sum ΣLa of the lateral direction sections Ra1, Ra2, which run substantially perpendicular to the tire circumference, is ensured. Consequently, an advantage is that the effect of the improved acceleration performance on snow is effectively ensured when the vehicle travels straight through the narrow, shallow grooves 311.

[0144] In the tire 1, the U-shape of the narrow flat groove 311 encloses the pair of width-direction sections Ra1, Ra1; Ra2, Ra2, which are adjacent to each other, wherein the curved sections (reference numeral omitted in the drawings) have the crank-shaped or the S-shape that enclose the pair of width-direction sections Ra1, Ra1; Ra2, Ra2 (see Fig. 8) connect. This has the advantage that the circumference components of the narrow, flat grooves 311 are increased and the noise performance of the tire is improved while driving the vehicle.

[0145] In tire 1, the U-shape of the narrow, flat groove 311 encloses the continuous circumferential section Rb with an inclination angle of not less than 0 degrees and not more than 15 degrees with respect to the tire's circumferential direction (see Fig. 8) The circumferential length Lb of the circumferential section Rb has a ratio of 0.50 ≤ Lb / L11 with respect to the circumferential length L11 of the narrow, shallow groove 311. In such a configuration, the length Lb of the circumferential section Rb, which extends substantially parallel to the tire's circumferential direction, is ensured. Consequently, an advantage is that the effect of the improved acceleration performance on snow while driving is efficiently ensured by the narrow, shallow grooves 311. Application object

[0146] The tire 1 is a high-performance tire mounted on a vehicle's steering axle. Using such a tire as the intended application offers the advantage of effectively achieving improved resistance to uneven wear and tear performance, while also meeting the acceleration performance requirements for all-season tires on snow.

[0147] In the embodiments, a pneumatic tire was described as an example of the tire as described above. However, no such limitation is intended. The configurations described in the embodiments can optionally be applied to other tires within the scope obvious to those skilled in the art. Examples of other tires include airless tires and solid tires. Comparative example 1

[0148] Fig. Figure 20 is a table showing the results of performance tests of tires according to the embodiments of the invention and comparative examples.

[0149] The performance tests evaluated (1) acceleration performance on snow, (2) resistance to uneven wear, and (3) tear resistance for a variety of test tires. The test tires, size 315 / 70R22.5, were mounted on rims with a rim size of 22.5×9.00 inches, and an internal pressure of 900 kPa and a specified JATMA load were applied. The test tires were mounted on the steering axles of the 4×2 tractor. (1) Acceleration performance on snow is assessed by measuring the distance required for acceleration from a predetermined initial velocity to a final velocity under test conditions in accordance with the Economic Commission for Europe (ECE) Directive No. 117, Revision 2 (R117-2). Higher values ​​are to be preferred in this assessment. (2) When assessing resistance performance to uneven wear, after the test vehicle has been driven 40,000 km on a paved road, the degree of wear of a main groove is observed and evaluated, using the prior art example as a reference (100). Higher values ​​are to be preferred in this evaluation. (3) In assessing tensile strength performance, the test vehicle performs a cornering maneuver, and after traversing a 200 mm high curb 20 times, the appearance of a crack in a shoulder web section is observed. The observation results are expressed and evaluated as index values, with the prior art example (100) being assigned as a reference. Higher values ​​are preferred.

[0150] The test tires of comparison examples 1 to 11 and examples 12 to 13 exhibit the configurations of the Fig. 1 and Fig. 2. The shoulder main grooves 21 and the center main grooves 22 have groove depths of 14.6 mm and groove widths of 15.3 mm. The continuous lug grooves 321, 331 have maximum groove widths W21 of 2.1 mm and maximum groove depths H21 of 2.5 mm. The ground contact widths TW of the tire are 268 mm, the maximum ground contact widths Wb1 of the shoulder rib sections 31 are 49.5 mm, the maximum ground contact widths Wb2 of the center rib sections 32 are 36.0 mm, and the maximum ground contact widths Wb3 of the center rib sections 33 are 36.0 mm.

[0151] The test tire of prior art example 1 in the test tire of comparative example 1 encloses the edge sections of the groove opening sections 211, 221 and the groove bottom sections 212, 222 in the main grooves 21, 22 with a straight shape. The test tire of prior art example 2 in the test tire of comparative example 1 exhibits constant amplitude ratios A2o_sh / A1o_sh and A2i_sh / A1i_sh of the groove opening sections 211, 221 and the groove bottom sections 212, 222 in the main grooves 21, 22.

[0152] As can be seen from the test results, the acceleration performance on snow, the resistance to uneven abrasion and the tear resistance are provided in the test tires of comparison examples 1 to 11 and examples 12 to 13. Second embodiment

[0153] Fig. Figure 21 is a table showing the results of performance tests of tires according to the embodiments of the invention. Fig. 22 is an explanatory diagram showing a shoulder bridge section of the test tire of the in Fig. 21 illustrated comparative examples.

[0154] The performance tests evaluate (1) acceleration performance on snow and (2) pass-by noise performance for a variety of test tire types. The test tires, size 315 / 70R22.5, are mounted on rims with a rim size of 22.5×9.00 inches, and an internal pressure of 900 kPa and a specified JATMA load are applied. The test tires are mounted on the steering axles of the 4×2 tractor. (1) Acceleration performance on snow is assessed by measuring the distance required for acceleration from a predetermined initial velocity to a final velocity under test conditions in accordance with the Economic Commission for Europe (ECE) Directive No. 117, Revision 2 (R117-2). Higher values ​​are preferred in this assessment. If the value is 96 or higher, the performance is deemed to be adequately ensured. (2) The pass-by noise performance assessment measures the vehicle's pass-by noise under test conditions in accordance with ECE R117-2. Based on the measurement results, a decibel difference is calculated, with the comparison example being assigned as the reference value (0). Lower values ​​are preferred.

[0155] The test tires of examples 14 to 24 exhibit the configuration of Fig. 1, Fig. 2 and Fig. 7. The shoulder main grooves 21 and the center main grooves 22 have groove depths of 14.6 mm and groove widths of 15.3 mm. The continuous lug grooves 321, 331 have maximum groove widths W21 of 2.1 mm and maximum groove depths H21 of 2.5 mm. The ground contact widths TW of the tire are 268 mm, the maximum ground contact widths Wb1 of the shoulder rib sections 31 are 49.5 mm, the maximum ground contact widths Wb2 of the center rib sections 32 are 36.0 mm, and the maximum ground contact widths Wb3 of the center rib sections 33 are 36.0 mm. The division spacing numbers of the zigzag shapes of the groove opening sections 211, 221 of the main grooves 21, 22 are not less than 50 and not more than 100.

[0156] The test tire of the comparison example in the test tire of example 14 includes narrow, flat grooves with a straight shape and penetrates a shoulder rib section (see Fig. 22).

[0157] As can be seen from the test results, the test tires of examples 14 to 24 can improve the pass-by noise performance while driving the vehicle, while maintaining the tire's acceleration performance on snow. List of reference symbols 1 tire; 11. Bead core; 12 bead fillers; 13 Carcass layer; 14 Belt layer; 141 to 144 Belt position; 15 tread rubber; 16 side wall rubber; 17 Wheel rim pad rubber; 21 Shoulder groove; 211 Groove opening section; 211o, 211i marginal section; 212 Grooved floor section; 212o, 212i marginal section; 22. Midline groove; 221 Groove opening section; 221o, 221i marginal section; 222 Grooved floor section; 222o, 222i marginal section; 31 Shoulder bridge section; 311 Closed lamella; 32 Middle section of the bridge; 321 Continuous stollen groove; 322 Block; 33 Central web section; 331 Continuous tunnel groove; 332 Block

Claims

[1] Tires (1), comprising: a pair of humeral grooves (21) and one or more medial grooves (22), which run in a circumferential direction of the tire; and four or more rows of bridge sections (31, 32, 33) defined by the pair of shoulder main grooves (21) and the one or more mid-main grooves (22), wherein each pair of shoulder main grooves (21) comprises a groove opening section (211) having a straight shape or a zigzag shape or a wave-like shape with an amplitude in a tire width direction, wherein each pair of shoulder main grooves (21) comprises a groove bottom section (212) having a zigzag shape or a wave-like shape with an amplitude in a tire width direction, and wherein the groove opening section (211) in each pair of shoulder main grooves (21) has an amplitude A1_sh which has a ratio A1_sh < A2_sh with respect to an amplitude A2_sh of the groove bottom section (212); wherein the groove opening section (211) in each pair of shoulder main grooves (21) has a wave-like shape formed by connecting a plurality of arcs, which protrude to one side of an equatorial plane of the tire (1). [2] Tire according to claim 1, wherein the amplitude A1_sh of the groove opening section (211) in each pair of shoulder main grooves (21) has a ratio 1.20 ≤ A2_sh / A1_sh < 2.0 with respect to the amplitude A2_sh of the groove bottom section (212). [3] Tire (1) according to claim 1 or 2, wherein the groove bottom section (212) in each pair of shoulder main grooves (21) has a wavelength λ2_sh with a ratio 0.10 ≤ λ2_sh / TW ≤ 0.35 with respect to a ground contact width TW of the tire. [4] Tire (1) according to any one of claims 1 to 3, wherein a position of the outer maximum amplitude of the groove opening section (211) in each pair of shoulder main grooves (21) is located at a position in the tire circumferential direction which is identical to a position of the outer maximum amplitude of the groove bottom section (212). [5] Tires (1) according to any one of claims 1 to 4, wherein Each of the one or more central main grooves (22) comprises a groove opening section (211) having a straight shape, a zigzag shape, or a wave-like shape with an amplitude in the tire width direction, and wherein each of the one or more central main grooves (22) comprises a groove bottom section (212) having a zigzag shape or a wave-like shape with an amplitude in the tire width direction. [6] Tire (1) according to claim 5, wherein the groove opening section (211) in each of the one or more central main grooves (22) has an amplitude A1_ce which has a ratio 1.05 ≤ A2_ce / A1_ce with respect to an amplitude A2_ce of the groove bottom section (212). [7] Tire (1) according to claim 5 or 6, wherein the groove opening section (211) in each of the one or more central main grooves (22) has an amplitude A1_ce with a ratio A1_ce / A1_sh ≤ 0.95 with respect to the amplitude A1_sh of the groove opening section (211) in each pair of shoulder main grooves (21). [8] Tire (1) according to any one of claims 5 to 7, wherein the groove bottom section (212) in each of the one or more central main grooves (22) has an amplitude A2_ce with a ratio A2_ce / A2_sh ≤ 0.90 with respect to an amplitude A2_sh of the groove bottom section (212) in each pair of shoulder main grooves (21). [9] Tire (1) according to any one of claims 5 to 8, wherein the groove opening section (211) in each of the one or more central main grooves (22) has a wavelength λ1_ce with a ratio 0.90 ≤ λ1_ce / λ1_sh ≤ 1.10 with respect to a wavelength λ1_sh of the groove opening section (211) in each pair of shoulder main grooves (21). [10] Tire (1) according to claim 9, wherein each of the arcs has a circumferential length of not less than 80% with respect to a wavelength of the wave-like shape of the groove opening section (211). [11] Tire (1) according to any one of claims to 10, which is a heavy-duty tire mounted on a steering axle of a vehicle.

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