Tire

Abstract

At least one main groove (2) is a meandering main groove (21) having a first groove wall (2a) and a second groove wall (2b), each of which has an upper groove wall portion and a lower groove wall portion, the upper groove wall portion being connected to a groove bottom (2c) via the lower groove wall portion. An upper edge (2ale) of the lower groove wall of the first groove wall (2a) extends in a wavy manner along the tire circumferential direction such that a minimum groove wall angle portion and a maximum groove wall angle portion appear alternately along the tire circumferential direction at a predetermined repeating period, and an upper edge (2ble) of the lower groove wall of the second groove wall (2b) extends in a wavy manner along the tire circumferential direction. In the first groove wall (2a), the minimum groove wall angle portion and the wide groove section and the maximum groove wall angle portion and the narrow groove section are respectively located at the same position in the tire circumferential direction. An upper edge (2aue) of the upper groove wall of the first groove wall (2a) extends in a straight line, a wavy manner, or a zigzag manner, the amplitude of which is smaller than the amplitude of the upper edge (2ale) of the lower groove wall of the first groove wall (2a).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a tire. BACKGROUND

[0002] Many proposals have been made to control the hydroplaning phenomenon and improve the drainage performance of a tire. For example, Patent Literature 1 proposes a tire in which two groove walls of a main groove are made to meander along the tire circumferential direction when viewed from the tread surface. According to the tire described in Patent Literature 1, the drainage performance of the tire can be improved.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2010-179892 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, a tire such as that described in Patent Literature 1 above has the following problem compared to a tire in which the groove walls of a main groove extend in a straight line along the tire circumferential direction: the compression rigidity of the land portion that forms the main groove greatly varies along the tire circumferential direction, and thus the noise performance easily deteriorates.

[0008] Therefore, an object of the present disclosure is to provide a tire that can control the deterioration of the noise performance while improving the drainage performance.

[0009] SOLUTION TO PROBLEM

[0010] Means for achieving the above object are as follows.

[0011] (1) The tire of the present disclosure is:

[0012] A tire having one or more main grooves that extend along the tire circumferential direction on a tread surface, in which,

[0013] at least one of the one or more main grooves is a meandering main groove in which at least a portion of a groove surface extends in a wavy line along the tire circumferential direction in a tread surface view,

[0014] a first groove wall that is a groove wall on one side in the tire width direction of the meandering main groove and a second groove wall that is a groove wall on the other side in the tire width direction of the meandering main groove each have an upper groove wall portion that extends in a straight line or in a circular arc shape having a constant curvature with a center of curvature on the groove side from the tread surface, and a lower groove wall portion that extends in a circular arc shape having a constant curvature with a center of curvature on the groove side that is greater than the curvature of the upper groove wall portion and is connected to the upper groove wall portion, and the upper groove wall portion is connected to a groove bottom via the lower groove wall portion,

[0015] When: in a cross-section along the tire width direction, the groove wall angle of the upper groove wall portion on the tread surface relative to the normal on the tread surface is called the upper groove wall angle; the edge formed by connecting the upper ends of each portion located in the upper groove wall portion along the tire circumference in the cross-section along the tire width direction, and the edge formed by connecting the boundaries between the upper and lower groove walls along the tire circumference in the cross-section along the tire width direction, are respectively called the upper edge of the upper groove wall and the upper edge of the lower groove wall; and the distance in the tire width direction between the upper edges of the lower groove walls of the two groove walls of the meandering main groove is called the groove wall spacing.

[0016] In the tread surface view, the first groove wall of the meandering main groove has an upper edge of the lower groove wall extending in a wavy line along the tire circumference, such that a minimum groove wall angle portion where the upper groove wall angle is the smallest and a maximum groove wall angle portion where the upper groove wall angle is the largest alternate along the tire circumference at a predetermined repeating cycle.

[0017] In the tread surface view, the second groove wall of the meandering main groove has an upper edge of the lower groove wall extending in a wavy line along the tire circumference.

[0018] The minimum wall angle portion of the first groove wall of the meandering main groove and the wide groove section where the wall spacing of the meandering main groove is greatest are located at the same position in the tire circumferential direction, and the maximum wall angle portion of the first groove wall of the meandering main groove and the narrow groove section where the wall spacing of the meandering main groove is smallest are located at the same position in the tire circumferential direction, and

[0019] In a tread surface view, the upper edge of the upper groove wall of the first groove wall of the meandering main groove extends along the tire circumference in a straight line, a wavy line, or a serrated line, and its amplitude in the tire width direction is smaller than that of the upper edge of the lower groove wall in the tire width direction.

[0020] According to the tire disclosed herein, noise performance degradation can be controlled while drainage performance is improved.

[0021] (2) In the tires described in (1) above,

[0022] Preferably, in a tread surface view, the upper edge of the upper groove wall of the first groove wall of the meandering main groove extends in a straight line along the tire circumference.

[0023] (3) In the tires described in (1) above,

[0024] Preferably, the upper wall angle of the first wall of the meandering main channel is 25° or less.

[0025] It is also preferred that the tire described in (2) above has the above-described structure (3).

[0026] (4) Of any of the tires described in (1) to (3) above,

[0027] Preferably, the upper edge of the upper groove wall of the second groove wall of the meandering main groove extends in a wavy line along the tire circumference.

[0028] It is also preferred that the tire described in (3) above has the above structure (4) having the above structure (2).

[0029] (5) Of any of the tires described in (1) to (3) above,

[0030] Preferably, the amplitude of the upper edge of the lower wall of the first groove wall of the meandering main groove in the tire width direction is smaller than the amplitude of the upper edge of the lower wall of the second groove wall of the meandering main groove in the tire width direction.

[0031] It is also preferred that the tire having the above-described structure (3) has the above-described structure (2) and the tire having the above-described structure (4) has the above-described structure (5).

[0032] (6) In the tires described in (1) above,

[0033] Preferably, it has multiple main slots, and

[0034] Of the plurality of main grooves, the meandering main groove is the outermost main groove in the tire width direction on the inner side of the vehicle mounting.

[0035] It is also preferred that the tire having at least one of the above-described structures (1) to (5) has the above-described structure (6).

[0036] The effects of the invention

[0037] According to this disclosure, a tire that can control the deterioration of noise performance while improving drainage performance can be provided. Attached Figure Description

[0038] Figure 1 This is a front view of a tire according to a first embodiment of the present disclosure.

[0039] Figure 2 yes Figure 1 The unfolded diagram of part A's tread surface on a plane.

[0040] Figure 3 yes Figure 2 A magnified view of part B in the image.

[0041] Figure 4 (a) is along Figure 3 A cross-sectional view of line X1-X1 in the diagram.

[0042] Figure 4 (b) is along Figure 3 A cross-sectional view of line X2-X2 in the diagram.

[0043] Figure 5 It is along Figure 3 The cross-sectional view of line Y1-Y1 in the diagram.

[0044] Figure 6 It is similar to Figure 3 The enlarged view shows a portion of the tread surface of a tire according to a second embodiment of the present disclosure.

[0045] Figure 7 (a) is along Figure 6 The cross-sectional view of line X3-X3 in the diagram.

[0046] Figure 7 (b) is along Figure 6 The cross-sectional view of line X4-X4 in the diagram. Detailed Implementation

[0047] The tires disclosed herein can be suitably used for any type of pneumatic tire, such as passenger car pneumatic tires, truck and bus pneumatic tires, etc.

[0048] In the following description, embodiments of the tire according to the present disclosure will be described by way of example with reference to the accompanying drawings.

[0049] In each drawing, the same parts and components are indicated by the same reference numerals. In some drawings, the tire width direction is indicated by the symbol "WD", the tire circumferential direction by the symbol "CD", the inner side of the vehicle mounting (the side of the tire mounted on the vehicle that is inside the vehicle in the tire width direction) by "IN", and the outer side of the vehicle mounting (the side of the tire mounted on the vehicle that is outside the vehicle in the tire width direction) by "OUT".

[0050] Although detailed descriptions are omitted, the tire described in the following embodiments can employ a general tire structure, which includes: sidewalls, each sidewall extending radially outward from each of a pair of bead portions; a tread portion spanning between the two sidewalls; a carcass having carcass ply layers comprising, for example, organic fiber cords or steel cords extending from one bead portion through the tread portion to the other bead portion; and a belt layer comprising, for example, steel cords, disposed between the tread rubber of the carcass and the tread portion.

[0051] In the following text, unless otherwise stated, the positional relationships and dimensions of each element shall be measured under the reference condition of the tire mounted on an applicable rim, inflated to the specified internal pressure, and unloaded. As used herein, the term "tread surface" refers to the entire circumference of the tire in contact with the road surface when the tire is mounted on an applicable rim, inflated to the specified internal pressure, and under maximum load. The width of the tread surface in the tire width direction is referred to herein as the "tread width (TW)," and the individual edges of the tread surface in the tire width direction are referred to herein as "tread ends (TE)." Here, the dimensions of each element (such as grooves) on the tread surface shall be measured in a tread surface view. As used herein, the term "tread surface view" refers to a plan view of the tread surface unfolded in a plane.

[0052] As used herein, the term "applicable rim" refers to a standard rim of applicable size (measured rim in the ETRTO Standards Manual and designed rim in the TRA Yearbook) that is recorded or may be recorded in the future in an industry standard in effect in the region where the tire is manufactured and used. Such industry standards include, for example, the JATMA Yearbook of Japan's JATMA (Japan Automobile Tire Manufacturers Association), the standards manual of Europe's ETRTO (European Tire and Rim Technology Organization), and the yearbook of the US's TRA (Tire and Rim Association). For sizes not listed in these industry standards, "applicable rim" refers to a rim whose width corresponds to the bead width of the pneumatic tire. "Applicable rim" includes current sizes as well as sizes that will be specified in the aforementioned industry standards in the future. An example of "sizes to be specified in the future" could be sizes listed as "FUTURE DEVELOPMENTS" in the 2013 edition of ETRTO.

[0053] As used herein, “specified internal pressure” refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel for the applicable size and ply rating, as described in the aforementioned JATMA Yearbook and other industry standards. For sizes not listed in the aforementioned industry standards, “specified internal pressure” refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle with the tire mounted. Furthermore, as used herein, the term “maximum load” refers to the load corresponding to the maximum load capacity in a tire of the applicable size described in the aforementioned industry standards, or, for sizes not listed in the aforementioned industry standards, the load corresponding to the maximum load capacity specified for each vehicle with the tire mounted.

[0054] (First Implementation)

[0055] Figures 1 to 5 This is a diagram used to explain the tire 10 according to the first embodiment of this disclosure. Figure 1 This is a front view of a tire according to a first embodiment of the present disclosure.Figure 2 yes Figure 1 The unfolded diagram of part A's tread surface on a plane. Figure 3 yes Figure 2 A magnified view of part B in the image. Figure 4 (a) is along Figure 3 A cross-sectional view of line X1-X1 in the diagram. Figure 4 (b) is along Figure 3 The cross-sectional view of line X2-X2 in the diagram, and Figure 5 It is along Figure 3 A cross-sectional view of line Y1-Y1 in the diagram. Here, in Figure 2 and Figure 3 For ease of understanding, the meandering main groove 21, as described below, is depicted in detail not only at the groove opening but also inside the groove (the portion inside the groove along its depth direction from the opening). Figure 3 In the diagram, for ease of understanding, the outline of the winding main groove 21 extending to the two opening edges of the tread surface 1 and the ridge 5 rising from the groove bottom 2c are drawn with slightly thicker lines. Figure 3 China (and thus) Figure 2 The thin lines between them are edges (lines) formed by connecting points along the tire circumference, where the curvature (and thus the radius of curvature) varies in the tire width section.

[0056] It should be noted that the tire 10 in this embodiment can be constructed as any type of tire.

[0057] However, the tire 10 of this embodiment is constructed as a tire whose mounting direction on the vehicle is specified by printing on the tire or by the instruction manual or the like.

[0058] like Figure 1 and Figure 2 As shown, the tire 10 of this embodiment has one or more (four in this example) main grooves 2 (21, 22, 23 and 24) extending in the tire circumferential direction on the tread surface 1.

[0059] Each main groove 2 extends continuously along the entire tire circumference. Unless otherwise stated, each main groove 2, more specifically, each main groove 2 extending to the two opening edges of the tread surface 1, may extend along the tire circumference in a straight line, a wavy line, or a serrated line, etc., as shown below. Figure 2 As shown. Here, the description "extending with a wavy line" in this text refers to extending while repeatedly bending with circular curves; the description "extending with a smooth wavy line" refers to extending while repeatedly bending with circular curves without any straight sections; and the description "extending with a zigzag line" means extending while repeatedly bending with angled curves. In this text, the description "extending with a wavy line" is also referred to as "meandering," and the description "extending with a smooth wavy line" is also referred to as "smoothly meandering."

[0060] In this embodiment, the tire 10 has four main grooves 2 on the tread surface 1. However, at least one main groove 2 should be formed on the tread surface 1; for example, there may be one to three, or five or more main grooves. However, from the perspective of ensuring sufficient drainage performance, it is preferable to have multiple (two or more) main grooves 2, and from the perspective of achieving a good balance between drainage performance and handling stability, it is more preferable to have three to five main grooves.

[0061] In this embodiment, at least one of the main grooves 2 (one in the illustrated example) is a meandering main groove such that, in the tread surface view, at least a portion of the groove surface extends in a wavy line along the tire circumference. More specifically, in this embodiment, as... Figure 1 and Figure 2 As shown, among the multiple (four in the example shown) main slots 2, the outermost main slot in the tire width direction on the inner side of the vehicle mounting (the first main slot counted from the innermost side of the vehicle mounting; hereinafter also referred to as the "first main slot") is the meandering main slot. Note that the first main slot 21, which is the meandering main slot, is also simply referred to as the meandering main slot 21 in the following text.

[0062] The meandering main channel 21 will be described in detail later.

[0063] In this embodiment, more specifically, such as Figure 1 and Figure 2As shown, in the main groove 2, the outermost main groove (first main groove) 21 in the tire width direction on the inner side of the vehicle mounting is a meandering main groove as described above; the second main groove located from the outermost side in the tire width direction on the inner side of the vehicle mounting (the second main groove counted from the innermost side of the vehicle mounting, hereinafter referred to as the "second main groove") 22, the second main groove located from the outermost side in the tire width direction on the outer side of the vehicle mounting (the third main groove counted from the innermost side of the vehicle mounting, hereinafter referred to as the "third main groove") 23, and the outermost main groove in the tire width direction on the outer side of the vehicle mounting (the fourth main groove counted from the innermost side of the vehicle mounting, hereinafter referred to as the "fourth main groove") 24 are non-meandering main grooves. They are not meandering main grooves, that is, they are main grooves whose groove surface does not extend in a wavy line along the tire circumference in the tread surface view. However, in this embodiment, at least one of the main channels 2 can be a meandering main channel, for example, alternative to or additional to the first main channel 21, and at least one of the second main channel 22, the third main channel 23, and the fourth main channel 24 can be a meandering main channel. However, from the perspective of improving drainage performance, it is preferable that at least the first main channel 21 is a meandering main channel, and from the perspective of balancing improved drainage performance and control of noise performance degradation, it is more preferable that only the first main channel 21 is a meandering main channel, as in this embodiment.

[0064] like Figure 1 and Figure 2 As shown, the second main groove 22, the third main groove 23 and the fourth main groove 24, which are non-winding main grooves, are all straight main grooves, wherein the two opening edges to the tread surface 1 extend in a straight line along the tire circumference.

[0065] The width of the opening from each main groove 2 to the tread surface 1 in the tire width direction (hereinafter referred to as "groove opening width") Wo (if the groove opening width Wo varies in the tire circumferential direction, the maximum value is taken) is not particularly limited, but can be, for example, from 4 mm to 15 mm.

[0066] Similarly, the groove depth (also referred to as "groove depth" below) D of each main groove 2, measured perpendicular to the tread surface 1, is not particularly limited (if the groove depth D varies, the maximum value is taken), but can be, for example, from 6 mm to 20 mm.

[0067] like Figure 1 and Figure 2 As shown, the tire 10 of this embodiment has at least two (five in the example shown) land portions 3 (31, 32, 33, 34 and 35) on the tread surface 1, and each of the main grooves 2 is formed between adjacent land portions 3 in the tire width direction.

[0068] In this embodiment, in land section 3, the outermost land section in the tire width direction on the inner side of the vehicle mounting (the first land section counted from the innermost side of the vehicle mounting, hereinafter referred to as "first land section") 31, the second land section located on the outermost side of the tire width direction on the inner side of the vehicle mounting (the second land section counted from the innermost side of the vehicle mounting, hereinafter referred to as "second land section") 32, and the outermost land section in the tire width direction on the outer side of the vehicle mounting (the first land section counted from the outermost side of the vehicle mounting, hereinafter referred to as "fifth land section") 35 are rib-shaped land sections, which are continuous in the tire circumferential direction. The land portion 33, including the tire equatorial plane CL (the third land portion counting from the innermost side of the vehicle mounting, hereinafter referred to as the "third land portion") 33, and the second land portion in the tire width direction from the outermost side of the vehicle mounting (the fourth land portion counting from the innermost side of the vehicle mounting, hereinafter referred to as the "fourth land portion") 34, are block land portions, wherein the land portions are divided in the tire circumferential direction by lateral grooves 4 (more specifically lateral grooves 43 or 44) as described below. However, each land portion 3 may be either a ribbed land portion or a block land portion.

[0069] like Figure 1 and Figure 2 As shown in the example, each land section 3 may have multiple lateral grooves 4 extending in a direction intersecting the tire circumferential direction.

[0070] More specifically, in this embodiment, such as Figure 1 and Figure 2As shown, the first land portion 31 has a plurality of lateral grooves 41 extending from one end (the inner end of the vehicle mounting) of the first land portion 31 in the tire width direction and terminating in the first land portion 31. The second land portion 32 has a plurality of lateral grooves 42 extending from the other end (the outer end of the vehicle mounting) of the second land portion 32 in the tire width direction and terminating in the second land portion 32. The third land portion 33 has a plurality of lateral grooves 43 extending from one end of the third land portion 33 in the tire width direction across the third land portion 33 to the other end of the third land portion 33 in the tire width direction. The fourth land portion 34 has a plurality of lateral grooves 44 and a plurality of lateral grooves 45 alternating in the tire circumferential direction. The lateral grooves 44 extend from one end of the fourth land portion 34 in the tire width direction across the fourth land portion 34 to the other end of the fourth land portion 34 in the tire width direction, and the lateral grooves 45 extend from the other end (the outer end of the vehicle mounting) of the fourth land portion 34 in the tire width direction and terminating in the fourth land portion 34. The fifth land section 35 has a plurality of alternating lateral grooves 46 and 47 in the tire circumferential direction. The lateral grooves 46 extend from one end of the fifth land section 35 in the tire width direction (the inner end of the vehicle mounting) and terminate in the fifth land section 35, and the lateral grooves 47 extend from the other end of the fifth land section 35 in the tire width direction (the outer end of the vehicle mounting) and terminate in the fifth land section 35. The construction of these lateral grooves 4 (41 to 47) allows for a uniform distribution of tire circumferential rigidity across the entire tread surface, which in turn helps to improve noise performance, etc.

[0071] Specifically, such as Figure 1 and Figure 2 As shown, in this embodiment, the lateral groove 42 in the second land portion 32, that is, the lateral groove 42 connected to the main groove 22 adjacent to the meandering main groove 21 (more specifically, in the illustrated example, the main groove 22 is adjacent to the meandering main groove 21 on its inner side in the tire width direction), extends within the second land portion 32 toward the vicinity of the narrow groove segment Pwn in the meandering main groove 21 (more specifically, in the illustrated example, it extends outward in the tire width in the second land portion position 32), the narrow groove segment Pwn being described below. In particular, this allows for a more uniform distribution of rigidity in the tire circumferential direction, which in turn helps improve noise performance, etc.

[0072] In addition, such as Figure 1 and Figure 2 As shown above, the lateral groove 42 in the second land portion 32 terminates within the second land portion 32. This allows for a more uniform distribution of rigidity in the tire circumferential direction, which in turn contributes to improved noise performance, etc.

[0073] However, the construction of the transverse groove 4 is optional, and at least some or all of the land sections 3 may not have the transverse groove 4.

[0074] Next, also refer toFigure 1 The first main channel 21 (winding main channel 21) is described in detail in this embodiment as a winding main channel.

[0075] At least a portion of the groove surface of the meandering main groove 21 extends in a wavy line along the tire circumference in a tread surface view. More specifically, as Figure 2 As shown, in this embodiment, at least a portion of the groove surface of the meandering main groove 21, namely the first groove wall 2a, the second groove wall 2b, and the groove bottom 2c, except for the upper edge 2aue of the upper groove wall of the first groove wall 2a (in the illustrated example, for example, the lower edge 2ale of the first groove wall 2a, the boundary edge between the first groove wall 2a and the groove bottom 2c, the boundary edge between the second groove wall 2b and the groove bottom 2c, the lower edge 2ble of the second groove wall 2b, and the upper edge 2bue of the second groove wall 2b, etc., as described below), extends in a wavy line along the tire circumference, that is, meanders along the tire circumference.

[0076] In this embodiment, such as Figure 1 , Figure 2 (a) and Figure 3 to 5 As shown in (b), the meandering main groove 21 is asymmetrical between the first groove wall 2a side and the second groove wall 2b side. That is, the meandering main groove 21 does not have an axis of symmetry extending in the tire circumferential direction.

[0077] In this embodiment, such as Figure 3 , Figure 3 (a) and Figure 4 As shown in (b), the first groove wall 2a (which serves as the groove wall on one side of the meandering main groove 21 in the tire width direction (in the example shown, the outer side in the tire width direction)) and the second groove wall 2b (which serves as the groove wall on the other side of the meandering main groove 21 in the tire width direction (in the example shown, the inner side in the tire width direction)) each have an arc shape in the tire width direction section, extending from the tread surface 1 with a straight line or a constant curvature (the reciprocal of the radius of curvature). The center of curvature is on the groove side (more specifically, on the side of the main groove 2(21)). The upper tank wall portions 2au and 2bu extend from the non-land section 3 (31 or 32) side, and the lower tank wall portions 2a1 and 2b1 extend from the tank side (more specifically, from the main tank 2 (21) side, not from the land section 3 (31 or 32) side) with a constant curvature (greater than the constant curvature of the upper tank wall portions 2au and 2bu) in an arc shape (with the center of curvature at the tank side (more specifically, from the main tank 2 (21) side, not from the land section 3 (31 or 32) side)). The lower tank wall portions 2a1 and 2b1 are connected to the upper tank wall portions 2au and 2bu, and the upper tank wall portions 2au and 2bu are connected to the tank bottom 2c via the lower tank wall portions 2a1 and 2b1.

[0078] exist Figure 4 (a) and Figure 3In the example shown in (b), the upper groove wall portions 2au and 2bu extend from the tread surface 1 in a straight line (i.e., with a curvature of 0 and a radius of curvature of ∞) in the tire width direction section. However, in the tire width direction section, the upper groove wall portions 2au and 2bu can extend from the tread surface 1 in an arc shape with a constant curvature (the center of curvature is on the groove side (in the example shown, on the side of the meandering main groove 21) (that is, the protrusion is on the land side (in the example shown, on the side of the first land 31 or the second land 32)). Additionally, in Figure 4 (a) and Figure 4 In the example shown in (b), as described above, in the cross-section along the tire width, the lower groove wall portion 2a1 of the first groove wall 2a extends continuously from the upper groove wall portion 2au and has a constant curvature arc shape (the center of curvature is on the groove side) (that is, the protrusion is on the land side (in the example shown, on the first land side 31)), and the constant curvature is greater than the curvature of the upper groove wall portion 2au (which is 0 in the example). Similarly, in Figure 4 (a) and Figure 4 In the example shown in (b), in the cross section in the tire width direction, the lower groove wall portion 2bl of the second groove wall 2b extends continuously from the upper groove wall portion 2bu and is an arc shape with a constant curvature (the center of curvature is on the groove side) (that is, the protrusion is on the land side (in the example shown, on the second land 32 side)), and the constant curvature is greater than the curvature of the upper groove wall portion 2bu (which is 0 in the example).

[0079] It should be noted that in this embodiment, the upper groove wall portion 2au and the lower groove wall portion 2al of the first groove wall 2a have different curvatures (and thus different radii of curvature), but are smoothly connected at their boundary edges (hereinafter referred to as the upper edge 2ale of the lower groove wall) (i.e., they share a common tangent at their boundary edges (in the illustrated example, the upper groove wall portion 2au is tangent to the lower groove wall portion 2al at the upper edge 2ale of the lower groove wall)). This results in a smooth connection between the upper groove wall portion 2au and the lower groove wall portion 2al. The same applies to the upper groove wall portion 2bu and the lower groove wall portion 2bl of the second groove wall 2b.

[0080] In this embodiment, as described above, such as Figure 4 (a) and Figure 4As shown in (b), the upper groove wall portion 2au of the first groove wall 2a and the upper groove wall portion 2bu of the second groove wall 2b are connected to the groove bottom 2c via lower groove wall portions 2al and 2bl, respectively. That is, the upper groove wall portions 2au and 2bu are smoothly connected to the groove bottom 2c via the lower groove wall portions 2al and 2bl, respectively, and the lower groove wall portions 2al and 2bl extend continuously from the upper groove wall portions 2au and 2bu in an arc shape with a certain curvature (the center of curvature is located on the groove side). In this embodiment, as shown, the groove bottom 2c extends continuously from the lower groove wall portions 2al and 2bl in the tire width direction section. However, the upper groove wall portions 2au and 2bu can be connected to the groove bottom 2c via other groove wall portions that have a similar structure to the lower groove wall portions 2al and 2bl, a curvature greater than that of the lower groove wall portions 2al and 2bl, and extend downward from the lower groove wall portions 2al and 2bl in the groove depth direction. However, from the perspective of a simpler construction of the meandering main channel 2, it is preferable that, as in the example shown, the upper channel wall portions 2au and 2bu are connected to the channel bottom 2c only via the lower channel wall portions 2al and 2bl, respectively.

[0081] In this embodiment, in the cross-section along the tire width, the upper groove wall portion 2au and the groove bottom 2c of the first groove wall 2a are smoothly connected at their boundary edges (that is, they share a common tangent at their boundary edges). (In the example shown, the straight groove bottom 2c is tangent to the lower groove wall portion 2al at the aforementioned boundary edge). This results in a smooth connection between the lower groove wall portion 2al and the groove bottom 2c. The same applies to the lower groove wall portion 2bl and the groove bottom 2c of the second groove wall 2b.

[0082] Here, the term "groove bottom (2c)" in this document refers to the portion of the groove surface where the groove depth is greatest. The groove bottom 2c may have a width in the tire width direction (≠0) or may not have a width in the tire width direction at various positions in the tire circumferential direction (i.e., the width in the tire width direction can be 0). That is, the groove bottom 2c does not have a width in the tire width direction; therefore, for example, the deepest portion of the lower groove wall portions 2a1 and 2b1 in the groove depth direction can be the groove bottom 2c. In this embodiment, as... Figure 4 , Figure 4 (a) and Figure 4 As shown in (b), the groove bottom 2c has a width (≠0) in the tire width direction at various positions in the tire circumferential direction. When the groove bottom 2c has a width (≠0) in the tire width direction, the groove bottom 2c is a straight line in the tire width direction section (i.e., the curvature is 0 and the radius of curvature is ∞).

[0083] In this embodiment, as described above, the upper groove wall portion 2au and the lower groove wall portion 2al of the first groove wall 2a are smoothly connected at their boundary edges (hereinafter referred to as the upper edge 2ale of the lower groove wall) in the tire width direction section. Therefore, the upper edge 2ale of the lower groove wall at the minimum groove wall angle portion Pamin of the first groove wall 2a (see below) Figure 4 (b) The height of the lower wall 2a at the maximum wall angle Pamax, as described below, where the height of the lower wall 2c is higher than that of the first wall 2a, is (see below) Figure 3 (a) The height of 2c from the bottom of the tank.

[0084] On the other hand, in this embodiment, the upper edge 2ble of the lower groove wall of the second groove wall 2b described below (see...) Figure 4 (a) and Figure 4 (b) The height of the lower upper edge 2ble of the second groove wall 2b from the bottom 2c is constant along the tire circumference. In this embodiment, the height of the lower upper edge 2ale of the second groove wall 2b from the bottom 2c is: lower than the height of the lower upper edge 2ale of the first groove wall 2a at the minimum groove wall angle Pamin from the bottom 2c, and higher than the height of the lower upper edge 2ale of the first groove wall 2a at the maximum groove wall angle Pamax from the bottom 2c.

[0085] For reference here Figure 4 , Figure 4 (a) and Figure 4 (b) In this disclosure, in the tire width direction section, the groove wall angles (2au and 2bu) of the upper groove wall portion (2au and 2bu) on the tread surface 1 (in other words, at the upper groove wall upper edges 2aue and 2bue as described below) relative to the normal on the tread surface 1 are called "upper groove wall angles (θ2a and θ2b)"; the edges formed by connecting the upper ends (each upper end is located in the upper groove wall portion in the tire width direction section) along the tire circumference (i.e., to the two groove opening edges on the tread surface), and the boundaries (each boundary in the tire... In the width direction section, the edges formed by connecting the upper groove wall portions (2au and 2bu) and the lower groove wall portions (2al and 2bl) along the tire circumference are respectively called the "upper groove wall upper edge (2aue and 2bue)" (i.e., the two groove openings to the tread surface) and the "lower groove wall upper edge (2ale and 2ble)"; and furthermore, the distance in the tire width direction between the upper edges (2ale and 2ble) of the lower groove wall in the two groove walls (2a and 2b) of the meandering main groove 21 is called the "groove wall spacing (Ww)". Here, the upper groove wall angles θ2a and θ2b are considered to be: when... Figure 4 (a) and Figure 3As shown in (b), the upper groove wall portion 2au or 2bu is positive when it tilts closer to the groove side (in the example shown, closer to the meandering main groove 21) as it moves from the upper edge 2aue or 2bue of the upper groove wall towards the groove bottom 2c; and negative when it tilts closer to the land portion (in the example shown, the first land portion 31 or the second land portion 32). This positive or negative value should be taken into account when determining the relationship between the angles of the upper groove wall portion 2au or 2bu at various positions in the tire circumferential direction.

[0086] In this embodiment, such as Figure 4 , Figure 4 (a) and Figure 4 As shown in (b), the first groove wall 2a of the meandering main groove 21 has a lower groove wall upper edge 2ale. In the tread surface view, the lower groove wall upper edge 2ale extends along the tire circumference in a wavy line (i.e., repeatedly bending with circular bends), that is, meanders along the tire circumference so that the minimum groove wall angle Pamin, where the upper groove wall angle θ2a is the smallest, and the maximum groove wall angle Pamax, where the upper groove wall angle θ2a is the largest, alternate along the tire circumference at a predetermined repeating cycle. Here, "minimum groove wall angle (Pamin and Pbmin)" in this text refers to the position in the meandering main groove where the upper groove wall angle (θ2a and θ2b) in the tire circumference direction is the smallest, while "maximum groove wall angle (Pamax and Pbmax)" refers to the position in the meandering main groove where the upper groove wall angle (θ2a and θ2b) in the tire circumference direction is the largest. Figure 4 (a) and Figure 3 (b) shows the tire width direction sections of the meandering main groove 21 at the maximum groove wall angle Pamax and the minimum groove wall angle Pamin of the first groove wall 2a.

[0087] It should be noted that in this embodiment, the above-mentioned upper groove wall angle θ2a changes smoothly along the tire circumference between the minimum groove wall angle Pamin and the maximum groove wall angle Pamax.

[0088] In this embodiment, the aforementioned "predetermined repetition period" is constant in the tire circumferential direction. However, the aforementioned "predetermined repetition period" can vary in the tire circumferential direction. However, from the perspective of rigidity balance in the tire circumferential direction, it is preferable that the aforementioned "predetermined repetition period" is constant in the tire circumferential direction. Furthermore, in this embodiment, as... Figure 4As shown, the upper edge 2ale of the lower groove wall extends along the tire circumference in a smooth wavy line in the tread surface view (i.e., it repeatedly bends with circular curves without any straight sections), meaning it smoothly meanders along the tire circumference. However, the upper edge 2ale of the lower groove wall only needs to extend as a wavy line, not necessarily as a smooth wavy line. However, from the perspective of more efficient correction to obtain better drainage performance, it is preferable that the upper edge 2ale of the lower groove wall extends as a smooth wavy line.

[0089] Note that in this embodiment, such as Figure 4 As shown, the upper edge 2ale of the lower groove wall of the first groove wall 2a and the boundary edge between the lower groove wall portion 2al and the groove bottom 2c extend along the tire circumference in a wavy (winding) manner, such that they are furthest from the second groove wall 2b side at the minimum groove wall angle Pamin and closest to the second groove wall 2b side at the maximum groove wall angle Pamax. In other words, in this embodiment, the upper edge 2ale of the lower groove wall of the first groove wall 2a and the boundary edge between the lower groove wall portion 2al and the groove bottom 2c extend along the tire circumference with the same repeating period.

[0090] In this embodiment, the upper wall angle θ2a at the maximum wall angle Pamax of the first wall 2a of the meandering main channel 21 (see...) Figure 4 (a) is preferably 25° or less, more preferably 20° or less. Furthermore, the upper tank wall angle θ2a is preferably 10° or greater, more preferably 15° or greater. If the upper tank wall angle θ2a at the maximum tank wall angle portion Pamax is 25° or less, the tank cross-sectional area will not be less than the necessary range, which in turn ensures sufficient drainage performance; if the angle is 10° or greater, the rigidity of the adjacent land portion can be ensured. Figure 4 In the example shown in (a), the upper tank wall angle θ2a is set to approximately 17°.

[0091] Additionally, the upper wall angle θ2a at the minimum wall angle Pamin of the first wall 2a of the meandering main channel 21 (see...) Figure 3 (b) is preferably 15° or less, more preferably 10° or less. Furthermore, the upper tank wall angle θ2a is preferably 0° or greater, more preferably 5° or greater. If the upper tank wall angle θ2a at the minimum tank wall angle portion Pamin is 15° or less, the tank cross-sectional area will not be less than the necessary range, which in turn ensures sufficient drainage performance, while if the angle is 0° or greater, the rigidity of the adjacent land portion can be ensured. Figure 3 In the example shown in (b), the upper tank wall angle θ2a is set to approximately 7°.

[0092] In this embodiment, such as Figure 4 , Figure 4 (a) andFigure 4 As shown in (b), similar to the first groove wall 2a described above, the second groove wall 2b of the meandering main groove 21 also has a lower groove wall upper edge 2ble, which extends along the tire circumference in a wavy line (i.e., repeatedly bending with a circular bend) in the tread surface view. However, in this embodiment, the second groove wall 2b differs from the first groove wall 2a in that the upper groove wall angle θ2b does not change in the tire circumference and is constant. However, the second groove wall 2b may have an upper groove wall angle θ2b that changes in the tire circumference, as shown below. Figure 4 The second embodiment described is the same.

[0093] Note that in this embodiment, such as Figure 3 As shown, the upper edge 2ble of the lower groove wall of the first groove wall 2a and the second groove wall 2b, as well as the boundary edge between the lower groove wall portion 2bl and the groove bottom 2c, extend along the tire circumference in a wavy (winding) manner, such that they are furthest from the first groove wall 2a side at the minimum groove wall angle Pamin, and closest to the first groove wall 2a side at the maximum groove wall angle Pamax. In other words, in this embodiment, the upper edge 2ble of the lower groove wall of the second groove wall 2b and the boundary edge between the lower groove wall portion 2bl and the groove bottom 2c extend along the tire circumference with the same repeating period.

[0094] In this embodiment, the upper edge 2ble of the lower groove wall of the second groove wall 2b extends in a wavy pattern along the tire circumference in the tread surface view, and this extension is similar to the extension of the upper edge 2ale of the lower groove wall of the first groove wall 2a, except for the amplitude in the tire width direction as described below. Therefore, we omit its description.

[0095] It should be noted that in this embodiment, the upper wall angle θ2b of the second wall 2b of the meandering main groove 21 (which is constant) can be, for example, 10° to 20°, more specifically, 13° to 17°, etc.

[0096] In this embodiment, when points on the first groove wall 2a at any height from the groove bottom 2c, except for the upper edge of the upper groove wall (i.e., the opening edge of the meandering main groove 21 to the side of the tread surface 1) 2aue, are connected along the tire width direction to form a line, this line extends in a wavy (meandering) manner along the tire circumference in the tread surface view (when the upper edge 2aue of the upper groove wall extends in a wavy or serrated manner, the aforementioned line extends in the tire circumference in the tire surface view with an amplitude greater than that in the tire width direction at the upper edge 2aue of the upper groove wall). For example, a line formed by connecting points on the first groove wall 2a at a height of 10% of the groove depth (maximum depth) D from the groove bottom 2c along the tire width direction extends in a wavy (meandering) manner along the tire circumference in the tread surface view. In other words, except for the upper edge 2aue of the upper groove wall, the entire first groove wall 2a extends in a wavy (winding) manner (when the upper edge 2aue of the upper groove wall extends in a wavy or serrated line, the groove wall extends along the tire circumference in the tread surface view, and its amplitude is greater than the amplitude in the tire width direction at the upper edge 2aue of the upper groove wall).

[0097] Furthermore, in this embodiment, when points on the second groove wall 2b at any height from the groove bottom 2c are connected along the tire width direction to form a line, this line extends in a wavy (winding) manner along the tire circumference in the tread surface view. For example, a line formed by connecting points on the second groove wall 2b at a height of 10% of the groove depth (maximum depth) D from the groove bottom 2c along the tire circumference extends in a wavy (winding) manner along the tire circumference in the tread surface view. In other words, except for the upper edge 2bue of the upper groove wall, the entire second groove wall 2b extends in a wavy (winding) manner.

[0098] The above-described structure in this embodiment ensures more reliable drainage performance.

[0099] In this embodiment, the amplitude in the tire width direction at the upper edge 2ale of the lower groove wall of the first groove wall 2a of the meandering main groove 21 is smaller than the amplitude in the tire width direction at the upper edge 2ble of the lower groove wall of the second groove wall 2b of the meandering main groove 21. Here, as used herein, the "amplitude in the tire width direction" of the upper groove wall or the upper edge of the lower groove wall, etc., refers to the distance in the tire width direction between the tire width direction position when the edge, etc., extending in the tire circumferential direction, is located on its most landward side and the tire width direction position when the edge, etc., is located on the most groove side (for example, see...). Figure 4 (The attached figure is labeled "Wa").

[0100] In this embodiment, such as Figure 4As shown, the wide groove segment Pwb, where the minimum groove wall angle Pamin of the first groove wall 2a of the meandering main groove 21 and the groove wall spacing Ww of the meandering main groove 21 (the distance in the tire width direction between the upper edge 2ale of the lower groove wall of the first groove wall 2a and the upper edge 2ble of the lower groove wall of the second groove wall 2b) are at the same position in the tire circumferential direction, is located at the same position. Conversely, the narrow groove segment Pwn, where the maximum groove wall angle Pamax of the first groove wall 2a of the meandering main groove 21 and the groove wall spacing Ww of the meandering main groove 21 are at the same position in the tire circumferential direction, is located at the same position. In other words, "wide groove segment Pwb" refers to the position in the meandering main groove 21 where the groove wall spacing Ww in the tire circumferential direction has the maximum value Wwmax, and "narrow groove segment Pwn" refers to the position in the meandering main groove 21 where the groove wall spacing Ww in the tire circumferential direction has the minimum value Wwmin.

[0101] As described above, in this embodiment, the minimum wall angle Pamin of the first wall 2a of the meandering main groove 21 is located at the same position in the tire circumferential direction as the wide groove section Pwb, while the maximum wall angle Pamax of the first wall 2a of the meandering main groove 21 is located at the same position in the tire circumferential direction as the narrow groove section Pwn. In other words, in this embodiment, as... Figures 6 to 7 As shown, the upper edge 2ale of the lower groove wall of the first groove wall 2a and the upper edge 2ble of the lower groove wall of the second groove wall 2b extend in a wavy line (meander) along the tire circumference in the same repeating cycle but with phases staggered by 180° from each other.

[0102] It should be noted that the above-mentioned "same position in the tire circumferential direction" means that the position should be substantially the same. For example, a tire circumferential deviation of 5% or less of the repeating period (length in the tire circumferential direction) of the aforementioned upper groove wall angle θ2a should be allowed.

[0103] In this embodiment, such as Figure 3 As shown, in the tread surface view, the upper edge 2aue of the upper groove wall 2a of the first groove wall 2a of the meandering main groove 21 (i.e., one of the two opening edges of the meandering main groove 21 to the tread surface 1 (i.e., in the example shown, on the outer side in the tire width direction)) extends along the tire circumference in a straight line, wavy line or serrated line, with a magnitude in the tire width direction smaller than that of the upper edge 2ale of the lower groove wall 2a of the first groove wall 2a in the tire width direction.

[0104] More specifically, in this embodiment, such as Figure 3As shown, the upper edge 2aue of the upper groove wall 2a of the first groove wall 21 extends in a straight line (i.e., the amplitude in the tire width direction is 0) along the tire circumference in the tread surface view. However, the upper edge 2aue of the upper groove wall 2a can extend in a wavy or serrated line along the tire circumference, as long as its amplitude in the tire width direction is less than the amplitude Wa of the upper edge 2ale of the lower groove wall in the tire width direction. However, from the perspective of more effectively controlling the deterioration of noise performance, it is preferable that the upper edge 2aue of the upper groove wall 2a extends in a straight line along the tire circumference.

[0105] In addition, in this embodiment, such as Figure 3 As shown, in the tread surface view, the upper edge 2bue of the upper groove wall 2b of the second groove wall 2b of the meandering main groove 21 (i.e., the other side of the two opening edges of the meandering main groove 21 to the tread surface 1 (i.e., in the example shown, the inner side in the tire width direction)) extends along the tire circumference in a wavy line (more specifically, in a smooth wavy line). However, as described below... Figure 3 As described in the second embodiment, the upper edge 2bue of the upper groove wall of the second groove wall 2b can extend in a straight line, for example, along the tire circumference. However, from the perspective of more effectively improving drainage performance, it is preferable that the upper edge 2bue of the upper groove wall of the second groove wall 2b extends in a wavy line along the tire circumference.

[0106] In this embodiment, as described above, such as Figure 3 As shown in the tread surface view, the upper edge 2aue of the upper wall of the first groove wall 2a of the meandering main groove 21 (i.e., the opening edge of the meandering main groove 21 to the tread surface 1 on the outer side in the tire width direction) extends in a straight line along the tire circumference, while the upper edge 2bue of the upper wall of the second groove wall 2b of the meandering main groove 21 (i.e., the opening edge of the meandering main groove 21 to the tread surface 1 on the inner side in the tire width direction) extends in a wavy line along the tire circumference. In other words, in this embodiment, the opening edges (2aue and 2bue) of the meandering main groove 21 to the tread surface 1 are straight on the outer opening edge (2aue) in the tire width direction, and wavy on the inner opening edge (2bue) in the tire width direction. In this case, when the rigidity of the land portion in the tire circumferential direction changes, the opening edge adjacent only to the land portion in the tire width direction (i.e., the tire shoulder side) (where uneven wear is more likely to occur than in the tire width direction) is made straight. This prevents the rigidity of the adjacent land portion in the tire circumferential direction from changing, thereby improving drainage performance, while effectively controlling not only the deterioration of noise performance but also the deterioration of resistance to uneven wear.

[0107] In addition, in this embodiment, such as Figure 3As shown, the upper edge 2bue of the upper groove wall of the second groove wall 2b of the meandering main groove 21 (i.e., the opening edge of the other side of the two opening edges of the meandering main groove 21 to the tread surface 1 (in the illustrated example, i.e., the inner side in the tire width direction) extends along the tire circumference in a wavy line, such that it is furthest from the first groove wall 2a side at the minimum groove wall angle Pamin of the first groove wall 2a, and closest to the first groove wall 2a side at the maximum groove wall angle Pamax of the first groove wall 2a. In other words, in this embodiment, the upper edge 2bue of the upper groove wall of the second groove wall 2b extends along the tire circumference with the same repeating period as the following edges: the upper edge 2ale of the lower groove wall of the first groove wall 2a; the boundary edge between the lower groove wall portion 2al and the groove bottom 2c of the first groove wall 2a; the upper edge 2ble of the lower groove wall of the second groove wall 2b; and the boundary edge between the lower groove wall portion 2bl and the groove bottom 2c of the second groove wall 2b.

[0108] Furthermore, in this embodiment, such as Figure 3 As shown, the position of the meandering main groove 21 in the tire circumferential direction with the maximum groove opening width Wo is located in the wide groove section Pwb (and therefore in the minimum groove wall angle Pamin), while the position of the meandering main groove 21 in the tire circumferential direction with the minimum groove opening width Wo is located in the narrow groove section Pwn (and therefore in the maximum groove wall angle Pamax). Furthermore, the position of the meandering main groove 21 in the tire circumferential direction with the maximum groove bottom width Wb is located in the wide groove section Pwb (and therefore in the minimum groove wall angle Pamin), while the position of the meandering main groove 21 in the tire circumferential direction with the minimum groove bottom width Wb is located in the narrow groove section Pwn (and therefore in the maximum groove wall angle Pamax).

[0109] In this embodiment, from the perspective of more effectively balancing improved drainage and ensured land rigidity, the ratio of the maximum value Womax to the minimum value Womin of the channel opening width Wo of the meandering main channel 21, Womax / Womin, is preferably 1.25 to 1.50, more preferably 1.30 to 1.45. Figures 6 to 7 In the example shown, Womax / Womin is set to approximately 1.38.

[0110] In this embodiment, such as Figure 3 As shown, in the meandering main groove 21, the groove opening width Wo is greater than the groove wall spacing Ww at all locations in the tire circumferential direction. Similarly, in the meandering main groove 21, the groove opening width Wo is greater than the groove bottom width Wb at all locations in the tire circumferential direction. These constructions ensure sufficient rigidity for the land portion 3 adjacent to the meandering main groove 21.

[0111] In this embodiment, such as Figure 3 , Figure 3 of (a),Figures 3 to 4 (b) and Figure 3 As shown, the meandering main groove 21 has a ridge 5 that bulges outward toward the radial direction of the tire at the bottom 2c of the groove. In this embodiment, the ridge 5 is formed in a region including the wide groove segment Pwb in the tire circumferential direction.

[0112] Therefore, in this embodiment, a ridge 5 is formed in the bottom 2c of the meandering main groove 21, in the region including the wide groove section Pwb, such that the ridge 5 bulges outward in the radial direction of the tire. Thus, due to the ridge 5, water flowing near the wide groove section Pwb in the meandering main groove 21 can easily flow along the first groove wall 2a and the second groove wall 2b, which in turn effectively improves drainage performance.

[0113] However, the meandering main channel 21 need not have a ridge 5. However, from the perspective of effectively improving drainage performance, the meandering main channel 21 preferably has a ridge 5, as in this embodiment.

[0114] In this embodiment, such as Figure 3 As shown in the tread surface view, the side edge of the first groove wall 2a side of the ridge 5 extends in a curve along the first groove wall 2a (more specifically, the upper edge 2ale of the lower groove wall of the first groove wall 2a, and the boundary edge between the lower groove wall portion 2al and the groove bottom 2c of the first groove wall 2a, etc.), and the side edge of the second groove wall 2b side of the ridge 5 also extends in a curve along the second groove wall 2b (more precisely, the upper edge 2ble of the lower groove wall of the second groove wall 2b, and the boundary edge between the lower groove wall portion 2b1 and the groove bottom 2c of the second groove wall 2b, etc.).

[0115] The aforementioned construction of the ridge 5 allows water flowing near the wide trough section Pwb in the meandering main trough 21 to flow more easily along the first trough wall 2a and the second trough wall 2b, which in turn improves drainage performance.

[0116] In this embodiment, such as Figure 4 As shown, in the tread surface view, the ridge 5 is formed as a longitudinal shape along the tire circumference, and the length (maximum length) Lr in the tire circumference direction (see...) Figure 4 The width (maximum width) Wr, which is longer than the tire width direction (see...) Figure 5 (b)). More specifically, in the tread surface view, the ridge 5 is formed in a longitudinal shape, wherein the width in the tire width direction gradually narrows towards both ends of the ridge 5 in the tire circumferential direction. Furthermore, in this embodiment, the ridge 5 is formed in a simplified triangular shape in the tire width direction section, such as... Figure 3 As shown in (b), the height of the ridge 5 from the bottom of the groove 2c decreases towards both ends of the ridge 5 in the tire width direction. Furthermore, in this embodiment, as... Figure 3As shown, the ridge 5 is formed into a simplified triangular shape in the cross section of the tire circumferential direction, wherein the height of the ridge 5 from the bottom of the groove 2c gradually decreases towards both ends of the ridge 5 in the tire circumferential direction.

[0117] Due to the aforementioned construction of the ridge 5, the water flowing near the wide groove section Pwb in the meandering main groove 21 will not have its flow suddenly changed by the ridge 5, and can flow more easily along the first groove wall 2a and the second groove wall 2b, which further improves the drainage performance.

[0118] The height of the tire ridge 5 from the bottom of the groove 2c (maximum height) Hr (see Figure 5 (b) is not particularly restricted, but is preferably less than the groove depth (maximum depth) D of the meandering main groove 21 (see Figure 4 (b) 1 / 5. In this case, due to the presence of the ridge 5, the cross-sectional area of ​​the meandering main channel 21 will not decrease beyond the necessary range, which in turn ensures sufficient drainage performance.

[0119] Additionally, the width (maximum width) Wr of the rib 5 in the tire width direction (see...) Figure 4 (b) is not particularly limited, but is preferably less than 1 / 2 of the groove opening width (maximum width) Wo of the meandering main groove 21. In this case, due to the presence of the tire ridge 5, the cross-sectional area of ​​the meandering main groove 21 will not decrease beyond the necessary range, which in turn ensures sufficient drainage performance.

[0120] Then, as needed, the main effects of the first embodiment of this disclosure will be summarized again below.

[0121] First, in this embodiment, at least one main groove 2 is a meandering main groove, wherein, in a tread surface view, at least a portion of the groove surface extends along the tire circumference in a wavy line. This makes it easier to control the turbulence of the water flowing in the main groove and correct the flow, thereby controlling hydroplaning and improving drainage performance.

[0122] In this embodiment, both the first groove wall 2a and the second groove wall 2b in the meandering main groove 21 have an upper groove wall portion 2au and a lower groove wall portion 2al in the tire width direction section. The upper groove wall portion 2au extends from the tread surface in a straight line or in an arc shape with a constant curvature (the center of curvature is on the groove side). The lower groove wall portion 2al extends in an arc shape with a constant curvature (greater than the constant curvature of the upper groove wall portion 2au) and connects to the upper groove wall portion 2au. The upper groove wall portion 2au is connected to the groove bottom 2c via the lower groove wall portion 2al. Therefore, the upper groove wall portion 2au is smoothly connected to the groove bottom 2c via the lower groove wall portion 2al, which makes it easier to correct the water flowing in the meandering main groove 21 and effectively suppress groove bottom cracks that are prone to appear in the groove bottom 2c, especially near its two ends in the tire width direction.

[0123] Furthermore, in this embodiment, the first groove wall 2a of the meandering main groove 21 has a lower groove wall upper edge 2ale extending along the tire circumference in a wavy line in the tread surface view, so that the minimum groove wall angle Pamin and the maximum groove wall angle Pamax alternate along the tire circumference at a predetermined repeating cycle; the upper groove wall upper edge 2ble of the second groove wall 2b of the meandering main groove 21 extends along the tire circumference in a wavy line in the tread surface view; and the minimum groove wall angle Pamin of the first groove wall 2a of the meandering main groove 21 is located at the same position in the tire circumference as the wide groove section Pwb of the meandering main groove 21, and the maximum groove wall angle Pamax of the first groove wall 2a of the meandering main groove 21 is located at the same position in the tire circumference as the narrow groove section Pwn of the meandering main groove 21. These configurations make it easier and more effective to correct the water flowing in the meandering main groove 21.

[0124] Furthermore, in this embodiment, the upper edge 2aue of the upper groove wall 2a of the first groove wall 2a of the meandering main groove 21 extends along the tire circumference in a straight line, wavy line, or serrated line in the tread surface view, wherein the amplitude in the tire width direction is smaller than the amplitude in the tire width direction of the upper edge 2ale of the lower groove wall 2a of the first groove wall 2a. This can control the variation of the compressive stiffness of the first land portion 31 of the first groove wall 2a forming the meandering main groove 21 (and thus the entire land portion constituting the tread surface 1) in the tire circumference, and thus control the deterioration of the tire 10's noise performance due to at least one of the main grooves 2 being a meandering main groove.

[0125] As described above, according to this embodiment, the deterioration of noise performance can be controlled while improving drainage performance.

[0126] In this embodiment, the upper edge 2aue of the upper groove wall 2a of the first groove wall 2a of the meandering main groove 21 extends in a straight line along the tire circumference in the tread surface view.

[0127] In this configuration, the variation in compressive stiffness in the tire circumferential direction of the first land portion 31 (and thus the entire land portion constituting the tread surface 1) forming the first groove wall 2a of the meandering main groove 21 can be controlled, thus more effectively controlling the deterioration of noise performance. Furthermore, in this configuration, the rubber flow during tire manufacturing (particularly vulcanization molding) becomes more uniform, resulting in suppression and improved uniformity of the load-bearing structure.

[0128] In this embodiment, as described above, the upper wall angle θ2a at the maximum wall angle Pamax of the first wall 2a of the meandering main channel 21 (see...) Figure 5 (a) can be 25° or less.

[0129] In this case, the cross-sectional area of ​​the meandering main channel 21 will be no less than the necessary range, which will in turn ensure sufficient drainage performance and improve drainage performance more effectively.

[0130] In this embodiment, the upper edge 2bue of the upper groove wall 2b of the second groove wall 2b of the meandering main groove 21 extends in a wavy line along the tire circumference in the tread surface view.

[0131] In this case, it is easier to further correct the water flowing in the meandering main channel 21, which in turn improves drainage performance more effectively.

[0132] In this embodiment, the amplitude of the upper edge 2ale of the lower wall of the first groove wall 2a of the meandering main groove 21 in the tire width direction is smaller than the amplitude of the upper edge 2ble of the lower wall of the second groove wall 2b of the meandering main groove 21 in the tire width direction.

[0133] In this case, the cross-sectional area of ​​the meandering main channel 21 will be no less than the necessary range, which will in turn ensure sufficient drainage performance and improve drainage performance more effectively.

[0134] In this embodiment, the tire 10 has a plurality of main grooves 2, and among the plurality of main grooves 2, the meandering main groove is the outermost main groove 21 in the tire width direction on the inner side of the vehicle mounting.

[0135] Since tires are typically mounted on vehicles with a negative camber angle, the land on the inner side of the vehicle mount often experiences higher ground pressure than the land on the outer side. Therefore, as described above, by incorporating a meandering main groove on the outermost side of the tire in the tire width direction on the inner side of the vehicle mount, hydroplaning can be controlled more effectively, and drainage performance can be improved more effectively.

[0136] Other effects of this embodiment have been described above.

[0137] (Second Implementation)

[0138] Next, we will refer to Figure 4 A tire 20 according to a second embodiment of the present disclosure is described. Figure 4 It is similar to Figure 4 The enlarged view shows a portion of the tread surface of a tire according to a second embodiment of the present disclosure; Figure 4 (a) is along Figures 6 to 7 The cross-sectional view of line X3-X3 in the diagram; and Figure 6 (b) is along Figure 3 A cross-sectional view of line X4-X4 in the diagram. Here, in Figure 7 In the diagram, for ease of understanding, the outlines of the two opening edges of the main groove 2 on the tread surface 1 and the ridge 5 are drawn with fairly thick lines. The main groove 2 is a meandering main groove (hereinafter referred to as "meandering main groove 2"); while...Figure 6 The rather thin lines between them are edges (lines) formed along the tire circumference by connecting points where the curvature (and thus the radius of curvature) varies in the cross-section along the tire width. Note that in... Figure 7 In the middle, the horizontal groove 4 is also drawn with a slightly thicker line.

[0139] for Figure 6 ,and Figure 6 The same numbers / marks are used with Figure 6 The same parts and components are listed, and their descriptions are omitted.

[0140] The tire 20 according to the second embodiment of this disclosure differs from the tire 10 according to the first embodiment mainly in that the structure of the meandering main groove 2 is different. Figure 6 The structure of the meandering main groove 21 of the tire 10 according to the first embodiment of the present disclosure is shown, and is otherwise substantially the same as that of the tire 10 of the first embodiment.

[0141] The differences between the second embodiment and the first embodiment will be described in detail below.

[0142] The number of circumferential main grooves 2 in the tire 20 of the second embodiment is the same as that in the first embodiment, and the tire 20 should have at least one main groove.

[0143] Although not shown in the figure, in this embodiment, Figures 6 to 7 The position of the meandering main groove 2 on the tread surface can be arbitrary. That is, for example, as in the first embodiment (see...). Figures 1 to 5 As in (e.g., four), among multiple (e.g., four) main slots, the outermost main slot in the tire width direction on the inner side of the vehicle mounting can be a meandering main slot 2. Alternatively or additionally, at least one of the remaining main slots can be Figures 1 to 5 The meandering main channel 2 is shown.

[0144] Furthermore, in this embodiment, as in the first embodiment, the construction and presence of the transverse groove 4 are optional, and... Figures 2 to 5 In the example shown, the land portions 3 on both sides forming the meandering main channel 2 each have transverse channels 4 connected to the meandering main channel 2.

[0145] In this embodiment, such as Figure 6 , Figure 2 (a) and Figure 6 As shown in (b), unlike the meandering main channel 21 of the first embodiment, the meandering main channel 2 is symmetrical with respect to the center line of the channel, wherein the first channel wall 2a side and the second channel wall 2b side are formed asymmetrically with respect to each other.

[0146] More specifically, in this embodiment, compared with the first embodiment (see...)Figure 6 , Figure 6 (a) and Figure 7 Similar to (b)), the first groove wall 2a of the meandering main groove 2 is configured such that the minimum groove wall angle Pamin, where the upper groove wall angle θ2a is the smallest, and the maximum groove wall angle Pamax, where the upper groove wall angle θ2a is the largest, alternate along the tire circumference at a predetermined repeating cycle. On the other hand, unlike the first embodiment, the second groove wall 2b of the meandering main groove 2 is also configured such that the minimum groove wall angle Pbmin, where the upper groove wall angle θ2b is the smallest, and the maximum groove wall angle Pbmax, where the upper groove wall angle θ2b is the largest, alternate along the tire circumference at a predetermined repeating cycle.

[0147] In this embodiment, such as Figure 7 As shown, the repeating cycles of the changes in the upper groove wall angle θ2a of the first groove wall 2a and the upper groove wall angle θ2b of the second groove wall 2b are the same. This means that the minimum groove wall angle portion Pamin of the first groove wall 2a, the minimum groove wall angle portion Pbmin of the second groove wall 2b, and the wide groove segment Pwb are located at the same position in the circumferential direction of the tire in the meandering main groove 2, and the maximum groove wall angle portion Pamax of the first groove wall 2a, the maximum groove wall angle portion Pbmax of the second groove wall 2b, and the narrow groove segment Pwn are located at the same position in the circumferential direction of the tire in the meandering main groove 2. Furthermore, in this embodiment, the upper groove wall angle θ2a of the first groove wall 2a and the upper groove wall angle θ2b of the second groove wall 2b are the same at various positions in the circumferential direction of the tire. Figure 3 (a) shows a cross-sectional view of the meandering main groove 2 in the tire width direction at the maximum groove wall angle Pamax of the first groove wall 2a, and further shows a cross-sectional view of the meandering main groove 2 in the tire width direction at the maximum groove wall angle Pbmax of the second groove wall 2b. Figure 4 (b) shows a cross-sectional view of the meandering main groove 2 in the tire width direction at the minimum groove wall angle Pamin of the first groove wall 2a, and further shows a cross-sectional view of the meandering main groove 2 in the tire width direction at the minimum groove wall angle Pbmin of the second groove wall 2b.

[0148] In this embodiment, such as Figure 4 As shown, compared with the first embodiment (see...) Figure 6 The difference is that the amplitude of the upper edge 2ale of the lower groove wall of the first groove wall 2a in the tire width direction is the same as the amplitude of the upper edge 2ble of the lower groove wall of the second groove wall 2b in the tire width direction.

[0149] In addition, in this embodiment, such as Figure 7 As shown, compared with the first embodiment (see...) Figure 7Similar to the first embodiment, the upper edge 2aue of the upper wall of the first groove wall 2a of the meandering main groove 2 extends in a straight line along the tire circumference in the tread surface view. However, unlike the first embodiment, the upper edge 2bue of the upper wall of the second groove wall 2b of the meandering main groove 2 also extends in a straight line along the tire circumference in the tread surface view. Note that in this embodiment, the upper edge 2aue of the upper wall of the first groove wall 2a and the upper edge 2bue of the upper wall of the second groove wall 2b of the meandering main groove 2 can extend along the tire circumference in a wavy line or a serrated line, respectively, in the tread surface view. The amplitude in the tire width direction is smaller than the amplitude in the tire width direction of the lower edge 2ale of the first groove wall 2a or the lower edge 2ble of the second groove wall 2b, which is the same as the upper edge 2aue of the first groove wall portion 2a of the meandering main groove 21 in the first embodiment.

[0150] In this embodiment, such as Figure 6 , Figure 3 (a) and Figure 6 As shown in (b), the meandering main groove 2 has a ridge 5 that bulges outward toward the radial direction of the tire at the bottom 2c of the groove, as in the first embodiment. The ridge 5 is formed in the region including the wide groove segment Pwb in the tire circumferential direction, as in the first embodiment. As in the first embodiment, the ridge 5 is formed in a longitudinal shape along the tire circumferential direction in the tread surface view. However, in this embodiment, as... Figure 3 (a) and Figure 6 Figure 7 Figure 7 Figure 7 Figure 7 As shown in (b), unlike the first embodiment, the cross-sectional shape of the ridge 5 in the tire width direction is square (rectangular). Note that in this embodiment, the dimensions of the ridge 5 can be the same as those in the first embodiment.

[0151] The tire 20 of the second embodiment according to the present disclosure, constructed as described above, can also control the deterioration of noise performance while improving drainage performance in the same manner as the tire 10 according to the first embodiment described above. Comparing the tire 10 of the first embodiment with the tire 20 of the second embodiment, in the tire 10 of the first embodiment shown in the example above, the entire second groove wall 2b, including the upper edge 2bue of the upper groove wall, extends in a wavy line along the tire circumference in the tread surface view. This makes it easier to correct water entering the meandering main groove 21, which in turn provides better drainage performance. On the other hand, in the tire 20 of the second embodiment shown in the example above, the upper edge 2bue of the upper groove wall of the second groove wall 2b also extends in a straight line along the tire circumference in the tread surface view, just like the upper edge 2aue of the upper groove wall of the first groove wall 2a. This reduces the variation in compressive stiffness in the tire circumferential direction, and thus makes it easier to control the deterioration of noise performance.

[0152] The aforementioned ridge 5 formed in the tire 20 of the second embodiment also makes it easier for water that has entered the meandering main groove 2 to flow along the first groove wall 2a and the second groove wall 2b due to the ridge 5, which in turn can effectively improve drainage performance.

[0153] The tire 20 of this embodiment has the same other structure and effects as the tire 10 of the first embodiment described above.

[0154] Exemplary embodiments of this disclosure have been described above, and various changes may be made without departing from the scope of the claims.

[0155] For example, the tire 10 of the first embodiment described above is a tire whose vehicle mounting direction is specified by printing on the tire or in the instruction manual, etc., but the tire of this disclosure may also be a tire whose vehicle mounting direction is not specified.

[0156] Additionally, for example, in the tire 10 of the first embodiment described above, the first groove wall 2a with a varying groove wall angle is positioned relative to the second groove wall 2b on the vehicle mounting inner side and the outer side in the tire width direction. However, the tire width direction positions of the first groove wall 2a and the second groove wall 2b can be reversed, such that the first groove wall 2a is positioned relative to the second groove wall 2b on the vehicle mounting outer side and the inner side in the tire width direction.

[0157] Industrial availability

[0158] The tires disclosed herein can be suitably used for any type of pneumatic tire, such as passenger car pneumatic tires, truck and bus pneumatic tires, etc.

[0159] Explanation of reference numerals in the attached figures

[0160] 10, 20: Tire; 1: Tread surface; 2, 21, 22, 23, 24: Main groove; 2a: First groove wall; 2b: Second groove wall; 2c: Groove bottom; 2au, 2bu: Upper groove wall; 2aue, 2bue: Upper edge of upper groove wall; 2al, 2bl: Lower groove wall; 2ale, 2ble: Upper edge of lower groove wall; 3, 31, 32, 33, 34, 35: Land section; 4, 41, 42, 43, 44, 45, 46, 47: Lateral groove; 5: Ridge; CD: Tire circumferential direction; CL: Tire equatorial surface; D: Groove depth; I N: Inner side of vehicle mounting; Lr: Length of rib; Hr: Height of rib; OUT: Outer side of vehicle mounting; Pamin, Pbmin: Minimum groove wall angle; Pamax, Pbmax: Maximum groove wall angle; Pwb: Wide groove section; Pwn: Narrow groove section; TE: Tread end; WD: Tire width direction; Wa: Width; Wb: Groove bottom width; Wr: Ridge width; Wo: Groove opening width; Ww: Groove wall spacing; Wwmin: Minimum groove wall spacing; Wwmax: Maximum groove wall spacing; θ2a, θ2b: Upper groove wall angle.

Claims

1. A tire having one or more main grooves extending circumferentially along the tread surface, wherein, At least one of the one or more main grooves is a meandering main groove that extends in a wavy line along the tire circumference in a tread surface view, representing at least a portion of the groove surface. Both the first groove wall, which forms one side of the meandering main groove in the tire width direction, and the second groove wall, which forms the other side of the meandering main groove in the tire width direction, have an upper groove wall portion and a lower groove wall portion in the tire width direction cross-section. The upper groove wall portion extends from the tread surface in a straight line or in an arc shape with a constant curvature centered on the groove side. The lower groove wall portion extends in an arc shape with a constant curvature greater than that of the upper groove wall portion centered on the groove side and connects to the upper groove wall portion. The upper groove wall portion is connected to the groove bottom via the lower groove wall portion. When: in a cross-section along the tire width direction, the groove wall angle of the upper groove wall portion on the tread surface relative to the normal on the tread surface is called the upper groove wall angle; the edge formed by connecting the upper ends of each portion located in the upper groove wall portion along the tire circumference in the cross-section along the tire width direction, and the edge formed by connecting the boundaries between the upper and lower groove walls along the tire circumference in the cross-section along the tire width direction, are respectively called the upper edge of the upper groove wall and the upper edge of the lower groove wall; and the distance in the tire width direction between the upper edges of the lower groove walls of the two groove walls of the meandering main groove is called the groove wall spacing. In the tread surface view, the first groove wall of the meandering main groove has an upper edge of the lower groove wall extending in a wavy line along the tire circumference, such that a minimum groove wall angle portion where the upper groove wall angle is the smallest and a maximum groove wall angle portion where the upper groove wall angle is the largest alternate along the tire circumference at a predetermined repeating cycle. In the tread surface view, the second groove wall of the meandering main groove has an upper edge of the lower groove wall extending in a wavy line along the tire circumference. The minimum wall angle portion of the first groove wall of the meandering main groove and the wide groove section where the wall spacing of the meandering main groove is greatest are located at the same position in the tire circumferential direction, and the maximum wall angle portion of the first groove wall of the meandering main groove and the narrow groove section where the wall spacing of the meandering main groove is smallest are located at the same position in the tire circumferential direction, and In the tread surface view, the upper edge of the upper groove wall of the first groove wall of the meandering main groove extends along the tire circumference in a straight line, a wavy line, or a serrated line, and its amplitude in the tire width direction is smaller than that of the upper edge of the lower groove wall of the first groove wall in the tire width direction. The amplitude of the upper edge of the lower wall of the first groove wall of the meandering main groove in the tire width direction is smaller than the amplitude of the upper edge of the lower wall of the second groove wall of the meandering main groove in the tire width direction.

2. The tire of claim 1, wherein, in a tread surface view, the upper edge of the upper groove wall of the first groove wall of the meandering main groove extends in a straight line along the tire circumference.

3. The tire according to claim 1, wherein the upper groove wall angle in the maximum groove wall angle portion of the first groove wall of the meandering main groove is 25° or less.

4. The tire according to any one of claims 1 to 3, wherein, in a tread surface view, the upper edge of the upper groove wall of the second groove wall of the meandering main groove extends in a wavy line along the tire circumference.

5. The tire according to claim 1, having a plurality of said main grooves, and Of the plurality of main grooves, the meandering main groove is the outermost main groove in the tire width direction on the inner side of the vehicle mounting.

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