tire

Abstract

The present invention provides a tire having excellent drainage performance. The tire (1) has a tread portion (2). The tread portion (2) is formed with a first circumferential groove (10) and a second circumferential groove (20) extending along the tire circumference, and a transverse groove (40) connecting the first circumferential groove (10) and the second circumferential groove (20). The first circumferential groove (10) extends in a zigzag shape. The first circumferential groove (10) includes a first portion (11) with the smallest width and a second portion (12) arranged on the inner side of the tire radial direction than the first portion (11) and having a width greater than the first portion (11).

Description

Technical Field

[0001] The present invention relates to a tire. Background Art

[0002] Conventionally, tires are known in which ridges protrude in opposite directions from both opposing sidewall surfaces of adjacent ridge-shaped land portions across a circumferential groove and extend in the tread circumferential direction (see, for example, Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-202956 Summary of the Invention

[0004] However, even in the tire disclosed in Patent Document 1, further improvement in drainage performance is required.

[0005] The present invention has been proposed in view of the above-mentioned actual situation, and its main object is to provide a tire having excellent drainage performance at the end of wear.

[0006] The present invention is a tire having a tread portion, in which a first circumferential groove and a second circumferential groove extending along the circumference of the tire, and a transverse groove connecting the first circumferential groove and the second circumferential groove are formed. The first circumferential groove extends in a zigzag shape, and the first circumferential groove includes a first part with the smallest width and a second part arranged on the inner side of the tire radial direction than the first part and with a width greater than the first part.

[0007] In the tire of the present invention, preferably, the first circumferential groove includes a first proximity portion that is a portion closest to the second circumferential groove, and the depth of the first proximity portion is equal to or less than the depth of the second circumferential groove.

[0008] In the tire of the present invention, preferably, the transverse groove communicates with the first proximal portion.

[0009] In the tire of the present invention, preferably, the second circumferential groove includes a second proximal portion that is a portion closest to the first circumferential groove, and the transverse groove communicates with the second proximal portion.

[0010] In the tire of the present invention, preferably, the tread portion includes: a first land portion, which is closer to the first circumferential groove side than the second circumferential groove; and a second land portion, which is closer to the side opposite to the first land portion, and the transverse groove extends from the first land portion beyond the second circumferential groove and terminates in the second land portion.

[0011] In the tire of the present invention, preferably, the width W1 of the first portion is 1 mm to 2 mm.

[0012] In the tire of the present invention, preferably, the maximum width W2 of the second portion is 2 mm to 12 mm.

[0013] In the tire of the present invention, preferably, the maximum width W2 of the second portion is 2 to 6 times the width W1 of the first portion.

[0014] In the tire of the present invention, preferably, the depth H1 of the first circumferential groove and the minimum length H2 in the tire radial direction from the groove bottom of the first circumferential groove to the first portion satisfy the following relationship.

[0015] 1 / 3≤H2 / H1≤2 / 3

[0016] In the tire of the present invention, preferably, the first circumferential groove includes a third portion that is arranged outside the first portion in the tire radial direction and has a width that increases in a tapered shape toward the outside in the tire radial direction.

[0017] The tire of the present invention preferably further includes a first sipe connecting the first circumferential groove and the second circumferential groove.

[0018] In the tire of the present invention, it is preferable that the second circumferential groove is arranged on the outer side in the tire axial direction than the first circumferential groove.

[0019] In the tire of the present invention, preferably, the first circumferential grooves are arranged on both sides of the tire equator, and the tire further includes a third circumferential groove extending in the tire circumferential direction between the first circumferential grooves.

[0020] The tire of the present invention preferably further includes a second sipe connecting the first circumferential groove and the third circumferential groove.

[0021] In the tire of the present invention, preferably, the tread portion includes a plurality of reinforcement layers overlapping in the tire radial direction, and the outer end of the outermost layer of the reinforcement layer arranged at the outermost side in the tire radial direction is closer to the outside of the tire axial direction than the circumferential groove arranged at the outermost side in the tire axial direction.

[0022] In the tire of the present invention, the second portion provided in the first circumferential groove ensures drainage performance at the end of wear. In addition, the transverse groove allows water to flow from the first circumferential groove to the second circumferential groove, thereby improving drainage performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a cross-sectional view of a tire showing one embodiment of the tire of the present invention.

[0024] Figure 2 Yes Figure 1 Expanded view of the tread portion.

[0025] Figure 3 yes Figure 2 AA line section view in.

[0026] Figure 4 It is an enlarged cross-sectional view showing the first circumferential groove.

[0027] Figure 5 It is an enlarged cross-sectional view showing a modified example of the first circumferential groove.

[0028] Figure 6 Yes Figure 2 An expanded view of a modified example of the tread portion.

[0029] Figure 7 yes Figure 6 A cross-sectional view of the tread portion.

[0030] Figure 8 Yes Figure 6 An expanded view of a modified example of the tread portion.

[0031] Figure 9 yes Figure 8 Cross-sectional view of the tread portion.

[0032] Description of labels

[0033] 1: tire; 2: tread portion; 9: reinforcement layer; 9E: outer end; 10: first circumferential groove; 11: first portion; 12: second portion; 13: third portion; 15: first approach portion; 20: second circumferential groove; 21: second approach portion; 30: third circumferential groove; 40: transverse groove; 41: first sipe; 42: second sipe; 51: first land portion; 52: second land portion; CL: tire equator; D1: depth; D2: depth; D3: depth. DETAILED DESCRIPTION

[0034] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0035] Figure 1 It is a meridian cross-sectional view including the tire rotation axis (not shown) in the standard state of the tire 1 according to the present embodiment.

[0036] In this embodiment, as an example of a tire 1, a pneumatic tire for heavy loads is preferably used. The tire 1 is not limited to heavy load pneumatic tires and can also be applied to pneumatic tires for passenger cars or motorcycles, for example. Furthermore, the present invention is not limited to pneumatic tires and can also be applied to airless tires, for example.

[0037] The "standard state" refers to the tire 1 being assembled on a standard rim (see Figure 2), and filled with standard internal pressure, in a state without load. In the present invention, unless otherwise specified, the dimensions of various parts of the tire 1 are values measured under the standard state.

[0038] "Standard rim" refers to a rim whose specifications are prescribed for the tire in a standard system including the standards based on which the tire 1 is based, for example, "Standard rim" in JATMA, "Design rim" in TRA, and "Measuring rim" in ETRTO.

[0039] "Standard internal pressure" refers to the air pressure specified for each tire specification within the standard system, including the standard to which tire 1 is based. For JATMA, this is the "maximum air pressure," for TRA, the maximum value listed in the table "TIRE LOAD LIMITS ATVARIOUSCOLD INFLATION PRESSURES," and for ETRTO, the "INFLATION PRESSURE." For a passenger car tire, the standard internal pressure may be, for example, 180 kPa.

[0040] The tire 1 includes a tread portion 2 , a pair of bead cores 5 , a carcass layer 6 , and a belt layer 7 .

[0041] Each bead core 5 is arranged in one of the pair of bead portions 4. The bead core 5 is formed into a polygonal cross-section by, for example, winding steel bead wires in multiple rows and multiple layers.

[0042] The carcass layer 6 includes at least one carcass ply 6A. The carcass ply 6A is formed, for example, by an array of carcass cords covered with rubber. The carcass cords may be made of organic fibers such as polyester, nylon, rayon, polyethylene naphthalate, and aramid fibers, or steel wire.

[0043] The carcass ply 6A is arranged across the pair of bead cores 5 via the tread portion 2 and the pair of sidewall portions 3. The carcass layer 6 may be a structure in which a plurality of carcass plies are stacked.

[0044] The belt layer 7 is arranged radially outward of the carcass layer 6. The belt layer 7 is composed of at least one belt ply. In this embodiment, it is composed of four belt plies, 7A, 7B, 7C, and 7D, stacked in the tire radial direction. The belt plies 7A, 7B, 7C, and 7D are formed, for example, by an array of belt cords covered with rubber. The belt cords of the belt plies 7A, 7B, 7C, and 7D are preferably made of a highly elastic material such as steel cord.

[0045] A band ply may be disposed radially outside the belt layer 7. The band ply is composed of, for example, at least one band ply formed by arranging organic fiber cords at a small angle, such as 10 degrees or less, relative to the tire circumferential direction. The band ply may be a seamless band or ply formed by splicing together band cords or belt-shaped plies wound in a spiral.

[0046] Figure 2 The tread portion 2 of the tire 1 of this embodiment is shown. The tread portion 2 includes a first circumferential groove 10 and a second circumferential groove 20 extending in the tire circumferential direction, and a transverse groove 40 connecting the first circumferential groove 10 and the second circumferential groove 20.

[0047] The first circumferential groove 10 extends in a zigzag pattern. Specifically, the centerline of the first circumferential groove 10 in the width direction extends in a zigzag pattern relative to the tire circumferential direction. "Zigzag-shaped" means that the centerline of the first circumferential groove 10 in the width direction oscillates relative to the tire circumferential direction while extending along the tire circumferential direction. Therefore, in addition to repeatedly bending a straight groove, this also includes repeatedly bending a curved groove in a wavy pattern.

[0048] Figure 3 express Figure 2 The first circumferential groove 10 includes a first portion 11 having the smallest width and a second portion 12 having a width greater than that of the first portion 11. The second portion 12 is disposed on the inner side of the first portion 11 in the tire radial direction.

[0049] In the present embodiment, the first circumferential groove 10 has a flask-shaped cross section. This cross-sectional shape can alleviate stress applied to the sidewalls of the land portion even when a large load is applied to the tread portion 2.

[0050] In this embodiment, the first portion 11 opens toward the tread of a new tire. Therefore, during the initial stages of wear of the tread portion 2, the first circumferential groove 10 that appears in the tread is the first portion 11. The first portion 11 is closed by the load applied to the tread portion 2, thereby enhancing the axial rigidity of the tread portion 2. In this embodiment, the first portion 11 extends in a zigzag pattern relative to the tire circumference. Therefore, the land portions on both sides of the first portion 11 mesh with each other, thereby enhancing the circumferential rigidity of the tread portion 2.

[0051] On the other hand, as the tread portion 2 wears, the tread moves inward in the tire radial direction, and the opening of the first circumferential groove 10 changes from the first portion 11 to the second portion 12. Therefore, as wear progresses, the width of the first circumferential groove 10 increases, and the drainage performance of the tread portion 2 is maintained at a high level at the end of wear (for example, when the remaining groove of the first circumferential groove 10 reaches 3 mm, indicating that the tread portion 2 is in a worn state).

[0052] In addition, if Figure 2 As shown, the transverse grooves 40 improve the drainage performance of the tread portion 2, thereby improving cornering performance during wet driving. The first circumferential grooves 10 and the second circumferential grooves 20 are connected by the transverse grooves 40. Therefore, water flows from the first circumferential grooves 10 to the second circumferential grooves 20 through the transverse grooves 40, thereby improving the drainage performance of the tread portion 2.

[0053] The serrated first circumferential groove 10 includes a first approach portion 15, which is the portion closest to the second circumferential groove 20. The depth D1 of the first approach portion 15 is preferably less than or equal to the depth D2 of the second circumferential groove 20. By setting the depth D1 to less than or equal to the depth D2, water within the first circumferential groove 10 easily flows to the second circumferential groove 20 via the transverse groove 40 during wet driving. This prevents water from stagnating within the first circumferential groove 10 and improves the drainage performance of the tread portion 2. Furthermore, the axial rigidity of the tread portion 2 can be increased. Furthermore, the rubber volume of the tread portion 2 can be easily maintained. Consequently, the wear resistance of the tire 1 is improved.

[0054] The depth D1 of the first approach portion 15 is preferably at least 80% of the depth D2 of the second circumferential groove 20. By setting the depth D1 at least 80% of the depth D2, water flow in the first circumferential groove 10 is improved, particularly improving drainage performance of the tread portion 2 at the end of wear.

[0055] The depth D3 of the transverse groove 40 is preferably 70% to 90% of the depth D1 of the first approach portion 15. By setting the depth D3 to at least 70% of the depth D1, water within the first circumferential groove 10 easily flows into the transverse groove 40, preventing water from stagnating within the first circumferential groove 10 and improving the drainage performance of the tread portion 2. Furthermore, the drainage performance of the tread portion 2 at the end of wear can be improved. Furthermore, by setting the depth D3 to no more than 90% of the depth D1, the circumferential rigidity of the tread portion 2 can be increased. Furthermore, the rubber volume of the tread portion 2 can be easily maintained. Consequently, the wear resistance of the tire 1 is improved.

[0056] The transverse groove 40 preferably communicates with the first circumferential groove 10 at the first proximal portion 15. This shortens the distance from the first circumferential groove 10 to the second circumferential groove 20, allowing water in the first circumferential groove 10 to more easily flow to the second circumferential groove 20 via the transverse groove 40 during wet driving, thereby improving the drainage performance of the tread portion 2. This also improves the drainage performance of the tread portion 2 by allowing water in the first circumferential groove 10 to more easily flow to the transverse groove 40 during wet driving.

[0057] The second circumferential groove 20 preferably extends in a zigzag pattern. That is, the center line of the second circumferential groove 20 in the width direction extends in a zigzag pattern relative to the tire circumferential direction. This can easily improve the turning performance during wet driving.

[0058] The zigzag-shaped second circumferential groove 20 includes a second proximal portion 21, which is the portion closest to the first circumferential groove 10. Furthermore, the transverse groove 40 preferably communicates with the second circumferential groove 20 at the second proximal portion 21. This shortens the distance between the first circumferential groove 10 and the second circumferential groove 20, allowing water within the first circumferential groove 10 to more easily flow through the transverse groove 40 to the second circumferential groove 20 during wet driving, thereby improving the drainage performance of the tread portion 2. Furthermore, water within the transverse groove 40 also easily flows to the second circumferential groove 20 during wet driving, thereby improving the drainage performance of the tread portion 2.

[0059] The distance L1 between the first proximal portion 15 and the second proximal portion 21 in the tire circumferential direction is preferably 5 mm to 20 mm. When the distance L1 is greater than 5 mm, the inclination angle of the transverse groove 40 relative to the tire axial direction increases, thereby promoting water flow within the transverse groove 40. When the distance L1 is less than 20 mm, the axial rigidity of the tread portion 2 is improved. Furthermore, it is easier to maintain the rubber volume of the tread portion 2. As a result, the wear resistance of the tire 1 is improved.

[0060] The transverse grooves 40 preferably extend in a straight line. This allows for smoother water flow within the transverse grooves 40 during wet driving. Furthermore, the shorter transverse grooves 40 facilitate water flow from the first circumferential grooves 10 to the second circumferential grooves 20 during wet driving. This improves drainage performance of the tread portion 2.

[0061] The tread portion 2 includes a first land portion 51 located closer to the first circumferential groove 10 than the second circumferential groove 20 and a second land portion 52 located on the opposite side of the first land portion 51. The first land portion 51 is sandwiched between the first circumferential groove 10 and the second circumferential groove 20.

[0062] Preferably, the transverse groove 40 extends from the first land portion 51 beyond the second circumferential groove 20 and terminates within the second land portion 52. That is, in this embodiment, the transverse groove 40 includes an extension 44 extending to the second land portion 52. Providing the extension 44 in the second land portion 52 improves drainage performance.

[0063] Figure 4 The first circumferential groove 10 is further enlarged. The width W1 of the first portion 11 is preferably 1 mm to 2 mm. By setting the width W1 to be greater than 1 mm, water easily flows from the first portion 11 to the second portion 12 when driving on wet roads, making it easy to ensure sufficient drainage performance. On the other hand, by setting the width W1 to be less than 2 mm, when a load is applied to the tread portion 2 in the early stage of wear, the first portion 11 is easily blocked by the ground contact pressure, thereby improving the axial rigidity of the tread portion 2. In addition, it is easy to ensure the rubber volume of the tread portion 2. As a result, the wear resistance of the tire 1 is improved.

[0064] The maximum width W2 of the second portion 12 is preferably between 2 mm and 12 mm. By setting the maximum width W2 to 2 mm or greater, the width of the first circumferential groove 10 can be easily maintained even at the end of wear, ensuring sufficient drainage performance. On the other hand, by setting the maximum width W2 to 12 mm or less, the rubber volume of the tread portion 2 can be easily maintained. This improves the wear resistance of the tire 1.

[0065] The maximum width W2 is preferably 2 to 6 times the width W1. By setting the maximum width W2 to be at least 2 times the width W1, the width of the first circumferential groove 10 can be easily maintained even at the end of wear, ensuring sufficient drainage performance. By setting the maximum width W2 to be no more than 6 times the width W1, the rubber volume of the tread portion 2 can be easily maintained. This improves the wear resistance of the tire 1.

[0066] In the first circumferential groove 10 of this embodiment, it is more preferable that the width W1 be 1 mm or greater, the maximum width W2 be 2 mm or greater, and the maximum width W2 be at least twice the width W1. Such a first circumferential groove 10 can easily ensure sufficient drainage performance even at the end of wear. Furthermore, in the tread portion 2, it is preferable that the width W1 be 2 mm or less, the maximum width W2 be 12 mm or less, and the maximum width W2 be no more than six times the width W1. Such a first circumferential groove 10 can easily ensure the rubber volume of the tread portion 2, thereby improving the wear resistance of the tire 1.

[0067] The depth H1 of the first circumferential groove 10 and the minimum length H2 in the tire radial direction from the groove bottom of the first circumferential groove 10 to the first portion 11 preferably satisfy the following relationship.

[0068] 1 / 3≤H2 / H1≤2 / 3

[0069] By setting the ratio H2 / H1 to 1 / 3 or greater, the groove volume of the second portion 12 can be easily maintained, ensuring sufficient drainage performance at the end of wear. Setting H2 / H1 to 2 / 3 or less improves the axial rigidity of the tread portion 2 at the beginning of wear. Furthermore, it is easier to maintain the rubber volume of the tread portion 2. Consequently, the wear resistance of the tire 1 is improved.

[0070] In the first circumferential groove 10 of this embodiment, it is more preferable that the maximum width W2 be 2 to 6 times the width W1 and have a cross-sectional shape that satisfies the relationship 1 / 3 ≤ H2 / H1 ≤ 2 / 3. By setting the maximum width W2 to at least 2 times the width W1 and H2 / H1 to at least 1 / 3, sufficient drainage performance can be easily ensured at the end of wear. By setting the maximum width W2 to no more than 6 times the width W1 and H2 / H1 to no more than 2 / 3, the rubber volume of the tread portion 2 can be easily maintained, thereby improving the wear resistance of the tire 1.

[0071] exist Figure 2 The width W3 of the second circumferential groove 20 is preferably the tread contact width TW (refer to Figure 1 The "tread contact width TW" is the distance in the tire axial direction between the tread contact edges TE1 and TE2.

[0072] Tread contact edges TE1 and TE2 refer to the axially outermost tread contact edges of the tire 1 when a standard load is applied to the tire 1 and the tire is in contact with a flat surface at a camber angle of 0°. The standard condition herein refers to the unloaded state in which the tire 1 is assembled on a standard rim (not shown) and filled to a standard internal pressure. Unless otherwise specified, the dimensions of various components of the tire 1 are values measured under this standard condition.

[0073] By setting the width W3 to be at least 2% of the tread contact width TW, the drainage performance of the tread portion 2 can be improved. On the other hand, by setting the width W3 to be at most 6% of the tread contact width TW, the rubber volume of the tread portion 2 can be easily ensured. This improves the wear resistance of the tire 1.

[0074] The width W4 of the transverse groove 40 is preferably between 2 mm and 12 mm. By setting the width W4 to 2 mm or greater, water flows smoothly from the first circumferential groove 10 to the second circumferential groove 20, easily improving the drainage performance of the tread portion 2. On the other hand, by setting the width W4 to 12 mm or less, the circumferential rigidity of the tread portion 2 can be increased. Furthermore, the rubber volume of the tread portion 2 can be easily maintained. Consequently, the wear resistance of the tire 1 is improved.

[0075] Figure 5 The first circumferential groove 10A is shown in enlarged form as a modified example of the first circumferential groove 10. The structure of the first circumferential groove 10 described above can be adopted for portions of the first circumferential groove 10A that are not described below.

[0076] The first circumferential groove 10A includes a third portion 13 located radially outward of the first portion 11. The width of the third portion 13 tapers toward the outside in the tire radial direction. The third portion 13 increases the volume of the first circumferential groove 10A during the initial wear phase. Furthermore, the third portion 13 increases the amount of water flowing from the first portion 11 into the second portion 12, thereby improving the drainage performance of the tread portion 2.

[0077] The maximum width W2 of the second portion 12 is preferably greater than the maximum width W5 of the third portion 13. This makes it easier to ensure the groove volume of the first circumferential groove 10A in the second portion 12 and ensure sufficient drainage performance of the tread portion 2 at the end of wear.

[0078] A plurality of the first circumferential grooves 10, the second circumferential grooves 20, and the transverse grooves 40 may be formed in the tread portion 2. In addition, the first circumferential grooves 10, the second circumferential grooves 20, and the transverse grooves 40 may be used in combination with other grooves.

[0079] For example, Figure 6 Express as Figure 2 The tread portion 2A shown is a modified example of the tread portion 2. The structure of the tread portion 2 described above can be adopted for portions of the tread portion 2A that are not described below.

[0080] The tread portion 2A includes a pair of first circumferential grooves 10 and a pair of second circumferential grooves 20. Each first circumferential groove 10 is located on either side of the tire equator CL. Furthermore, each second circumferential groove 20 is located on either side of the tire equator. The second circumferential grooves 20 are located axially outward of the first circumferential grooves 10. As a result, the ground contact pressure around the first circumferential grooves 10 is higher than the ground contact pressure around the second circumferential grooves 20. This facilitates occlusion of the first portion 11 during initial wear, improving the axial rigidity of the tread portion 2.

[0081] The tread portion 2A includes third circumferential grooves 30 extending in the tire circumferential direction between the first circumferential grooves 10 .

[0082] In the present embodiment, the third circumferential groove 30 is formed on the tire equator CL. Such third circumferential groove 30 can improve drainage performance in the crown portion of the tread portion 2A.

[0083] In the tread 2A of this embodiment, when new, the second and third circumferential grooves 30 form a four-line tread pattern, improving wear resistance. Meanwhile, at the end of wear, the first, second, and third circumferential grooves 10, 30 form a six-line tread pattern, improving drainage during wet driving.

[0084] The width W6 of the third circumferential groove 30 is preferably 2% to 6% of the tread contact width TW. By setting the width W6 to at least 2% of the tread contact width TW, the drainage performance of the tread portion 2 is improved. On the other hand, by setting the width W6 to no more than 6% of the tread contact width TW, the rubber volume of the tread portion 2 can be easily maintained. This improves the wear resistance of the tire 1.

[0085] The first land portion 51 is provided with a first sipe 41 connecting the first circumferential groove 10 and the second circumferential groove 20. The first sipe 41 is closed by the ground contact pressure of the tire 1 and is a narrow groove having a width of 2.0 mm or less.

[0086] The first sipes 41 generate an edge effect to improve traction performance during wet driving. The first sipes 41 of this embodiment extend in a zigzag shape, thereby further improving the rigidity of the first land portion 51 when closed.

[0087] The zigzag first circumferential groove 10 includes a third proximal portion 16, which is the portion closest to the third circumferential groove 30. The first sipe 41 preferably communicates with the third proximal portion 16. This shortens the first sipe 41 and improves the rigidity of the first land portion 51.

[0088] Figure 7 : shows a cross section of the tread portion 2A. The depth D5 of the third circumferential groove 30 is preferably greater than the depth D4 of the third proximal portion 16. By making the depth D5 greater than the depth D4, the drainage performance of the tread portion 2 can be improved.

[0089] The third land portion 53 between the first circumferential groove 10 and the third circumferential groove 30 is provided with a second sipe 42 connecting the first circumferential groove 10 and the second circumferential groove 20. The second sipe 42 is closed by the ground contact pressure of the tire 1 and is a narrow groove with a width of 2.0 mm or less.

[0090] The second sipes 42 generate an edge effect to improve traction performance during wet driving. The second sipes 42 of this embodiment extend in a zigzag shape, thereby further improving the rigidity of the third land portion 53 when closed.

[0091] The third circumferential groove 30 extends in a zigzag shape and includes a fourth proximal portion 31 closest to the first circumferential groove 10. The second sipe 42 preferably communicates with the fourth proximal portion 31. This shortens the second sipe 42 and improves the rigidity of the third land portion 53.

[0092] The tread portion 2A includes a plurality of reinforcing layers 9 stacked in the tire radial direction. In the tire 1, the belt 7, which is composed of stacked belt plies 7A, 7B, 7C, and 7D, corresponds to the reinforcing layer 9. In an embodiment in which a cap ply is formed on the outer side of the belt 7 in the tire radial direction, the belt 7 and the cap ply correspond to the reinforcing layer 9.

[0093] In the tread portion 2A, the axially outer end 9E of the outermost layer (the belt ply 7D in this embodiment) of the reinforcement layer 9, which is located radially outward, is preferably positioned axially outward of the first circumferential groove 10. Extending the reinforcement layer 9 axially outward of the first circumferential groove 10 increases the rigidity of the tread portion 2. This improves drainage performance and cornering performance during wet driving.

[0094] In the tread portion 2A, the outer end 9E of the reinforcing layer 9 is preferably located axially outward of the circumferential groove (the second circumferential groove 20 in this embodiment) located axially outward of the tire. Extending the reinforcing layer 9 to the axially outward of the second circumferential groove 20 further increases the rigidity of the tread portion 2. This further enhances drainage performance and improves cornering performance during wet driving.

[0095] Figure 8 、 9 Express as Figure 6 、 7 The tread portion 2B is a modified example of the tread portion 2A. The structure of the tread portion 2A can be adopted for portions of the tread portion 2B that are not described below.

[0096] The tread portion 2B includes a pair of first circumferential grooves 10A and a pair of second circumferential grooves 20. Figure 5 As shown, the first circumferential groove 10A includes a third portion 13 disposed radially outward of the first portion 11. The width of the third portion 13 tapers toward the outside of the tire radial direction. The third portion 13 improves drainage performance of the first circumferential groove 10A during initial wear.

[0097] As mentioned above, the tire 1 of the present invention has been described in detail, but the present invention is not limited to the specific embodiment described above, and can be implemented in various modified forms.

[0098] [Example]

[0099] Based on the specifications in Table 1, we have produced Figure 2 Wet performance was evaluated for pneumatic tires with a basic tread size of 315 / 70R22.5, both when new and at the end of wear. Wet performance at the end of wear was also tested using tires with rubber removed from the tread by buffing and polishing until the remaining groove in the second circumferential groove was 3 mm (the same applies hereinafter). Specifications not listed in Table 1 for each test tire were the same. The testing method is as follows.

[0100] <Wet Road Performance>

[0101] Each test tire was mounted on all wheels of a test vehicle with a load of 75% of the standard load, and a wet road performance test was carried out. That is, the vehicle was driven to a test route on a wet road with a water depth of 0.5mm to 2.0mm, and the turning performance was evaluated by testing the driver's senses. The results are as follows: the total score of 20 people's evaluations was calculated with a full score of 1 to 5 points (5-level evaluation), and based on Comparative Example 1, the result was indexed in a manner that gave a result proportional to the total score. In addition, each value was rounded off in a multiple of 5. For example, if the value below the unit digit is greater than 0.0 and less than 2.5, it is rounded off to 0, if it is greater than 2.5 and less than 7.5, it is rounded to 5, and if it is greater than 7.5, it is rounded to 0. The larger the value, the better, indicating that the wet road performance is better.

[0102]

Table 1

[0103] Comparative Example 1 Comparative Example 2 Example 1 First circumferential groove (serrated) have have have Part 1 have have have Part 2 none have have Second circumferential groove have have have Horizontal groove have none have New product wet road performance (rating) 100 90 110 Final wet road performance (rating) 100 100 110

[0104] From Table 1, it can be confirmed that the tires of the examples have significantly improved wet performance compared to the comparative examples.

[0105] Based on the specifications in Table 2, we have produced Figure 2 Pneumatic tires with a basic tread size of 315 / 70R22.5 were evaluated for wet performance and wear resistance at the end of wear. Specifications not listed in Table 2 were the same for each test tire. The test method is as follows.

[0106] <Wet Road Performance>

[0107] The wet performance test of each test tire was carried out in the same manner as described above. The results were indexed to multiples of 5, with Example 4 being 100, with larger values indicating better wet performance.

[0108] <Abrasion resistance>

[0109] The wear of each test tire was measured after the vehicle had traveled a certain distance. The results were expressed as an index rounded to a multiple of 5, with Example 4 being 100. Larger values indicate better wear resistance.

[0110]

Table 2

[0111] Example 2 Example 3 Example 4 Example 5 Example 6 First circumferential groove (serrated) have have have have have Part 1 have have have have have Part 2 have have have have have Second circumferential groove have have have have have Horizontal groove have have have have have D1 / D2 (%) 70 80 90 100 110 Final wet road performance (rating) 90 95 100 105 110 Wear resistance (index) 110 105 100 95 90

[0112] Based on the specifications in Table 3, we have produced Figure 2 Pneumatic tires with a basic tread size of 315 / 70R22.5 were evaluated for wet performance and wear resistance at the end of wear. Specifications not listed in Table 3 were the same for each test tire. The test method is as follows.

[0113] <Wet Road Performance>

[0114] The wet performance test of each test tire was carried out in the same manner as described above. The results were indexed to multiples of 5, with Example 9 being 100, with larger values indicating better wet performance.

[0115] <Abrasion resistance>

[0116] The wear of each test tire was measured in the same manner as described above. The results are expressed as indices rounded to multiples of 5, with Example 9 being 100. Larger values are better, indicating better wear resistance.

[0117]

Table 3

[0118] Example 7 Example 8 Example 9 Example 10 Example 11 First circumferential groove (serrated) have have have have have Part 1 have have have have have Part 2 have have have have have Second circumferential groove have have have have have Horizontal groove have have have have have D3 / D1 (%) 65 70 80 90 95 Final wet road performance (rating) 90 95 100 105 110 Wear resistance (index) 110 105 100 95 90

[0119] Based on the specifications in Table 4, a prototype with Figure 2 Wet performance at the end of wear was evaluated for pneumatic tires with a basic tread size of 315 / 70R22.5. Specifications not listed in Table 4 were the same for each test tire. The test method is as follows.

[0120] <Wet Road Performance>

[0121] The wet performance test of each test tire was carried out in the same manner as described above. The results are indexed by rounding to multiples of 5, with Example 12 being 100, with larger values indicating better wet performance.

[0122]

Table 4

[0123]

[0124] Based on the specifications in Table 5, we have produced Figure 2 Wet performance at the end of wear was evaluated for pneumatic tires with a basic tread size of 315 / 70R22.5. Specifications not listed in Table 5 were the same for each test tire. The test method is as follows.

[0125] <Wet Road Performance>

[0126] The wet performance test of each test tire was carried out in the same manner as described above. The results were indexed to multiples of 5, with Example 14 being 100, with larger values indicating better wet performance.

[0127]

Table 5

[0128]

[0129] Based on the specifications in Table 6, a prototype with Figure 2 Wet performance at the end of wear was evaluated for pneumatic tires with a basic tread size of 315 / 70R22.5. Specifications not listed in Table 6 were the same for each test tire. The test method is as follows.

[0130] <Wet Road Performance>

[0131] The wet performance test of each test tire was carried out in the same manner as described above. The results were indexed to multiples of 5, with Example 16 being 100, with larger values indicating better wet performance.

[0132]

Table 6

[0133] Example 16 Example 17 First circumferential groove (serrated) have have Part 1 have have Part 2 have have Second circumferential groove have have Horizontal groove have have Extension have none Final wet road performance (rating) 100 95

[0134] Based on the specifications in Table 7, a prototype with Figure 2 We evaluated the wet performance and wear resistance of new pneumatic tires with a basic tread size of 315 / 70R22.5. Specifications not listed in Table 7 were the same for each test tire. The test method is as follows.

[0135] <Wet Road Performance>

[0136] The wet performance test of each test tire was carried out in the same manner as described above. The results are indices rounded to multiples of 5, with Example 20 being 100, with larger values indicating better wet performance.

[0137] <Abrasion resistance>

[0138] The wear of each test tire was measured in the same manner as described above. The results are expressed as indices rounded to multiples of 5, with Example 20 being 100. Larger values are better, indicating better wear resistance.

[0139]

Table 7

[0140] Example 18 Example 19 Example 20 Example 21 Example 22 First circumferential groove (serrated) have have have have have Part 1 have have have have have Part 2 have have have have have Second circumferential groove have have have have have Horizontal groove have have have have have W1(mm) 0.5 1 1.5 2 3 New product wet road performance (rating) 90 95 100 105 110 Wear resistance (index) 110 105 100 95 90

[0141] Based on the specifications in Table 8, we have produced Figure 2 Pneumatic tires with a basic tread size of 315 / 70R22.5 were evaluated for wet performance and wear resistance at the end of wear. Specifications not listed in Table 8 were the same for each test tire. The test method is as follows.

[0142] <Wet Road Performance>

[0143] The wet performance test of each test tire was carried out in the same manner as described above. The results were indexed to multiples of 5, with Example 25 being 100, with larger values indicating better wet performance.

[0144] <Abrasion resistance>

[0145] The wear of each test tire was measured in the same manner as described above. The results are expressed as indices rounded to multiples of 5, with Example 25 being 100. Larger values are better, indicating better wear resistance.

[0146]

Table 8

[0147] Example 23 Example 24 Example 25 Example 26 Example 27 First circumferential groove (serrated) have have have have have Part 1 have have have have have Part 2 have have have have have Second circumferential groove have have have have have Horizontal groove have have have have have W2(mm) 1 2 7 12 15 Final wet road performance (rating) 80 90 100 110 120 Wear resistance (index) 120 110 100 90 80

[0148] Based on the specifications in Table 9, we have produced Figure 2 Pneumatic tires with a basic tread size of 315 / 70R22.5 were evaluated for wet performance and wear resistance at the end of wear. Specifications not listed in Table 9 were the same for each test tire. The test method is as follows.

[0149] <Wet Road Performance>

[0150] The wet performance test of each test tire was carried out in the same manner as described above. The results are indices rounded to multiples of 5, with Example 30 being 100, with larger values indicating better wet performance.

[0151] <Abrasion resistance>

[0152] The wear of each test tire was measured in the same manner as described above. The results are expressed as indices rounded to multiples of 5, with Example 30 being 100. Larger values are better, indicating better wear resistance.

[0153]

Table 9

[0154] Example 28 Example 29 Example 30 Example 31 Example 32 First circumferential groove (serrated) have have have have have Part 1 have have have have have Part 2 Ding have have have have Second circumferential groove have have have have have Horizontal groove have have Ding have have W2 / W1 1.5 2 4 6 8 Final wet road performance (rating) 80 90 100 110 120 Wear resistance (index) 120 110 100 90 80

[0155] Based on the specifications in Table 10, we have produced Figure 2 Pneumatic tires with a basic tread size of 315 / 70R22.5 were evaluated for wet performance and wear resistance at the end of wear. Specifications not listed in Table 10 were the same for each test tire. The test method is as follows.

[0156] <Wet Road Performance>

[0157] The wet performance test of each test tire was carried out in the same manner as described above. The results are indices rounded to multiples of 5, with Example 35 being 100, and larger values being better, indicating better wet performance.

[0158] <Abrasion resistance>

[0159] The wear of each test tire was measured in the same manner as described above. The results are expressed as indices rounded to multiples of 5, with Example 35 being 100. Larger values are better, indicating better wear resistance.

[0160]

Table 10

[0161] Example 33 Example 34 Example 35 Example 36 Example 37 First circumferential groove (serrated) have have have have have Part 1 have have have have have Part 2 have have have have have Second circumferential groove have have have have have Horizontal groove have have have have have H2 / H1 1 / 6 1 / 3 1 / 2 2 / 3 5 / 6 Final wet road performance (rating) 80 90 100 110 120 Wear resistance (index) 120 110 100 90 80

[0162] Based on the specifications in Table 11, we have produced Figure 2 Pneumatic tires with a basic tread size of 315 / 70R22.5 were evaluated for wet performance and wear resistance at the end of wear. Specifications not listed in Table 11 were the same for each test tire. The test method is as follows.

[0163] <Wet Road Performance>

[0164] The wet performance test of each test tire was carried out in the same manner as described above. The results are indices rounded to multiples of 5, with Example 40 being 100, and larger values being better, indicating better wet performance.

[0165] <Abrasion resistance>

[0166] The wear of each test tire was measured in the same manner as described above. The results are expressed as indices rounded to multiples of 5, with Example 40 being 100. Larger values are better, indicating better wear resistance.

[0167]

Table 11

[0168]

[0169] Based on the specifications in Table 12, a prototype with Figure 2 Pneumatic tires with a basic tread size of 315 / 70R22.5 were evaluated for wet performance and wear resistance at the end of wear. Specifications not listed in Table 12 were the same for each test tire. The test method is as follows.

[0170] <Wet Road Performance>

[0171] The wet performance test of each test tire was carried out in the same manner as described above. The results are indices rounded to multiples of 5, with Example 45 being 100, and larger values being better, indicating better wet performance.

[0172] <Abrasion resistance>

[0173] The wear of each test tire was measured in the same manner as described above. The results are expressed as indices rounded to multiples of 5, with Example 45 being 100. Larger values are better, indicating better wear resistance.

[0174]

Table 12

[0175] Example 43 Example 44 Example 45 Example 46 Example 47 First circumferential groove (serrated) have have have have have Part 1 have have have have have Part 2 have have have have have Second circumferential groove have have have have have Horizontal groove have have have have have W1(mm) 0.5 1 1.5 2 2.5 W2(mm) 0.8 2 7 12 20 W2 / W1 1.6 2 4 6 8 Final wet road performance (rating) 85 90 100 110 115 Wear resistance (index) 115 110 100 90 85

[0176] Based on the specifications in Table 13, a prototype with Figure 2 Pneumatic tires with a basic tread size of 315 / 70R22.5 were evaluated for wet performance and wear resistance at the end of wear. Specifications not listed in Table 13 were the same for each test tire. The test method is as follows.

[0177] <Wet Road Performance>

[0178] The wet performance test of each test tire was carried out in the same manner as described above. The results are indices rounded to multiples of 5, with Example 52 being 100, and larger values being better, indicating better wet performance.

[0179] <Abrasion resistance>

[0180] The wear of each test tire was measured in the same manner as described above. The results are expressed as indices rounded to multiples of 5, with Example 52 being 100. Larger values are better, indicating better wear resistance.

[0181]

Table 13

[0182] Example 48 Example 49 Example 50 Example 51 Example 52 First circumferential groove (serrated) have have have have have Part 1 have have have have have Part 2 have have have have have Second circumferential groove have have have have have Horizontal groove have have have have have W2 / W1 1.5 1.5 2 2 4 H2 / H1 1 / 6 1 / 3 1 / 6 1 / 3 1 / 2 Final wet road performance (rating) 70 75 75 80 100 Wear resistance (index) 130 125 125 120 100

[0183] Example 53 Example 54 Example 55 Example 56 First circumferential groove (serrated) have have have have Part 1 have have have have Part 2 have have have have Second circumferential groove have have have have Horizontal groove have have have have W2 / W1 6 6 8 8 H2 / H1 2 / 3 5 / 6 2 / 3 5 / 6 Final wet road performance (rating) 120 125 125 130 Wear resistance (index) 80 75 75 70

Claims

1. A tire having a tread portion, wherein: The tread portion includes: Two first circumferential grooves and two second circumferential grooves, both of which extend in the tire circumferential direction, one of the two first circumferential grooves and one of the two second circumferential grooves being arranged on one side of the tire equator, and the other of the two first circumferential grooves and the other of the two second circumferential grooves being arranged on the other side of the tire equator; a first transverse groove connecting one of the two first circumferential grooves and one of the two second circumferential grooves; as well as The second transverse groove connects the other of the two first circumferential grooves and the other of the two second circumferential grooves, wherein Each of the two first circumferential grooves includes: a radially outer first portion having a groove width; and a radially inner second portion located inside the radially outer first portion in the tire radial direction and having a groove width wider than the groove width of the radially outer first portion, in, One of the two first circumferential grooves is a sawtooth groove and includes a first approach portion at which one of the two first circumferential grooves is closest to one of the two second circumferential grooves, and the other of the two first circumferential grooves is a sawtooth groove and includes another first approach portion at which the other of the two first circumferential grooves is closest to the other of the two second circumferential grooves. The depth of each first approach portion is smaller than the depth of one of the two second circumferential grooves, the depth of each further first approach portion being smaller than the depth of the other of the two second circumferential grooves, Each first transverse groove is connected to a corresponding first approach portion, Each second transverse groove is connected to a corresponding other first approach portion, The depth of each first transverse groove is 70% to 90% of the depth of the first approach portion. The depth of each second transverse groove is 70% to 90% of the depth of the other first approach portion, wherein one of the two second circumferential grooves is a serrated groove and is arranged axially outside one of the two first circumferential grooves. The other of the two second circumferential grooves is a serrated groove and is provided axially outside the other of the two first circumferential grooves, and The third circumferential groove is provided between the two first circumferential grooves, and the third circumferential groove is a sawtooth groove. One of the two second circumferential grooves extends in a zigzag shape and has a second approach portion closest to one of the two first circumferential grooves, and the other of the two second circumferential grooves extends in a zigzag shape and has another second approach portion closest to the other of the two first circumferential grooves. One of the two first circumferential grooves extends in a zigzag shape and has a third approach portion closest to the third circumferential groove. The other of the two first circumferential grooves extends in a zigzag shape and has another third approach portion closest to the third circumferential groove. The third circumferential groove is formed on the tire equator. The depth of the third circumferential groove is greater than the depth of the third approach portion.

2. The tire according to claim 1, wherein The tread portion is further formed with a first sipe extending from one of the two first circumferential grooves to one of the two second circumferential grooves and another first sipe extending from the other of the two first circumferential grooves to the other of the two second circumferential grooves.

3. The tire according to claim 2, wherein: The tread portion is further formed with a second sipe extending from the third circumferential groove to one of the two first circumferential grooves and another second sipe extending from the third circumferential groove to the other of the two first circumferential grooves.

4. The tire according to claim 3, wherein: The third circumferential groove extends in a zigzag shape and has a fourth approach portion closest to one of the two first circumferential grooves and another fourth approach portion closest to the other of the two first circumferential grooves. The first sipe extends between the first approach portion and the second approach portion, and the further first sipe extends between the further first approach portion and the further second approach portion. Furthermore, the second sipe extends between the third proximal portion and the fourth proximal portion, and the other second sipe extends between the other third proximal portion and the other fourth proximal portion.

5. The tire according to claim 4, wherein: Each of the first sipes and each of the further first sipes is a serrated sipe, Furthermore, each of the second sipes and each of the additional second sipes are serrated sipes.

6. The tire according to claim 1, wherein The tread portion is further formed with a reinforcement layer, the reinforcement layer including a radially outermost layer, The radially outermost layer extends in the tire axial direction so that axially outer ends of the radially outermost layer are respectively located axially outside the two first circumferential grooves.

7. The tire according to claim 1, wherein: Each of the two first circumferential grooves extends in a smooth, zigzag-like curve. Furthermore, the sawtooth amplitude of each of the two first circumferential grooves is larger than the sawtooth amplitude of each of the two second circumferential grooves and the sawtooth amplitude of the third circumferential groove.

8. The tire according to claim 7, wherein: One of the two second circumferential grooves includes a second approach portion, the second approach portion being closest to one of the two first circumferential grooves, The other of the two second circumferential grooves comprises a further second approach portion, the further second approach portion being closest to the other of the two first circumferential grooves, Each first transverse groove is connected to a corresponding second approach portion, Furthermore, each second transverse groove is connected to a corresponding other second proximal portion.

9. The tire according to claim 8, wherein: The tread portion also includes: a first land portion, which is arranged on one side of one of the two second circumferential grooves and located between one of the two second circumferential grooves and one of the two first circumferential grooves; and a second land portion, which is arranged on the other side of one of the two second circumferential grooves; another first land portion, which is arranged on one side of the other of the two second circumferential grooves and located between the other of the two second circumferential grooves and the other of the two first circumferential grooves; and another second land portion, which is arranged on the other side of the other of the two second circumferential grooves, and the first transverse groove extends from the first land portion beyond one of the two second circumferential grooves and terminates in the second land portion, and the second transverse groove extends from the other first land portion beyond the other of the two second circumferential grooves and terminates in the other second land portion.

10. The tire according to claim 7, wherein: The groove width of the radially outer first portion is 1 mm to 2 mm.

11. The tire according to claim 10, wherein: The maximum groove width of the radially inner second portion is 2 mm to 12 mm.

12. The tire according to claim 11, wherein The maximum groove width of the radially inner second portion is 2 to 6 times the groove width of the radially outer first portion.

13. The tire according to claim 10, wherein: A distance in the tire radial direction from the groove bottom of each of the two first circumferential grooves to the radially inner end of the radially outer first portion is within a range of 1 / 3 to 2 / 3 of the depth of each of the two first circumferential grooves.

14. The tire according to claim 13, wherein: Each of the two first circumferential grooves includes a third portion that is provided outside the radially outer first portion in the tire radial direction, and a groove width of the third portion gradually increases toward the outer side in the tire radial direction.

15. The tire according to claim 12, wherein: The two first circumferential grooves each have a flask-shaped cross-section, wherein the radially outer first portion has a substantially constant minimum width of the two first circumferential grooves, The radially inner second portion comprises: a groove bottom portion having an arc-shaped cross-section; and The middle portion extends from the groove bottom portion to the radially outer first portion, and the groove width gradually decreases.

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