tire

Abstract

The tire of the present invention maintains off-road performance and improves noise performance. The tire (1) is provided with shoulder longitudinal grooves (3), crown longitudinal grooves (4) and middle transverse grooves (5). The middle transverse grooves (5) include an outer portion (10) and an inner portion (11) inclined in the same direction as the first inclined portion (6) of the shoulder longitudinal grooves (3), and an intermediate portion (12) inclined in the opposite direction to the outer portion (10) and the inner portion (11). The outer portion (10) is smoothly continuous with the first inclined portion (6). The groove width WA1 of the outer portion (10) at the outer end position (10e) is greater than the groove width WA2 of the outer portion (10) at the inner end position (10i), and the groove width WB1 of the inner portion (11) at the outer end position (11e) is greater than the groove width WB2 of the inner portion (11) at the inner end position (11i).

Description

Technical Field

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

[0002] Patent Document 1 below describes a pneumatic tire having a middle land portion divided by a shoulder main groove and a center main groove in a tread portion. The middle land portion is provided with outer middle lug grooves extending from the shoulder main grooves, inner middle lug grooves extending from the center main grooves, and longitudinal narrow grooves connecting the outer middle lug grooves and the inner middle lug grooves.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2014-162388

[0004] In recent years, there has been a growing demand for reducing noise during vehicle travel. In this regard, the tire of Patent Document 1 has room for improvement in noise performance. Summary of the invention

[0005] The present invention has been made in view of the above-mentioned actual situation, and a main object of the present invention is to provide a tire capable of maintaining off-road performance and improving noise performance.

[0006] The tire involved in the present invention has a tread portion, wherein the tread portion is provided with: shoulder longitudinal grooves extending continuously in a zigzag shape in the tire circumferential direction, crown longitudinal grooves adjacent to the shoulder longitudinal grooves and extending in the tire circumferential direction, and a plurality of middle lateral grooves connecting the shoulder longitudinal grooves and the crown longitudinal grooves, the shoulder longitudinal grooves having a plurality of first inclined portions inclined relative to the tire circumferential direction, the middle lateral grooves respectively including an outer portion communicating with the shoulder longitudinal grooves, an inner portion connected to the crown longitudinal grooves, and an intermediate portion connecting the outer portion with the inner portion, the outer portion and the inner portion being axially opposite to the tire. The above-mentioned first inclined portion is inclined in the same direction, the above-mentioned middle portion is inclined in the opposite direction to the above-mentioned outer portion and the above-mentioned inner portion relative to the tire axial direction, the above-mentioned outer portions of the above-mentioned middle lateral grooves are smoothly continuous with the above-mentioned first inclined portions of the shoulder longitudinal grooves, the groove width WA1 of the above-mentioned outer portion in the tire circumferential direction at the outer end position in the tire axial direction is greater than the groove width WA2 of the above-mentioned outer portion in the tire circumferential direction at the inner end position in the tire axial direction, and the groove width WB1 of the above-mentioned inner portion in the tire circumferential direction at the outer end position in the tire axial direction is greater than the groove width WB2 of the above-mentioned inner portion in the tire circumferential direction at the inner end position in the tire axial direction.

[0007] In the tire according to the present invention, it is preferred that, when the tread is viewed from above, an extended region formed by extending the pair of groove edges of the outer portion toward the crown longitudinal groove at respective slopes does not overlap with the inner portion.

[0008] In the tire according to the present invention, it is preferable that the groove width WB2 of the inner portion is 0.7 to 0.9 times the groove width WB1 of the inner portion.

[0009] In the tire according to the present invention, it is preferable that the length of the intermediate portion in the tire axial direction is 0.05 to 0.15 times the length of the intermediate lateral groove in the tire axial direction.

[0010] In the tire according to the present invention, it is preferable that the width of the middle portion in a direction perpendicular to the longitudinal direction is smaller than the width of the inner portion in a direction perpendicular to the longitudinal direction and the width of the outer portion in a direction perpendicular to the longitudinal direction.

[0011] In the tire according to the present invention, it is preferable that the angle of the outer portion with respect to the tire circumferential direction is 70 degrees or more.

[0012] The tire involved in the present invention is preferably: the above-mentioned tread portion includes a middle land portion divided by the above-mentioned crown longitudinal groove and the above-mentioned shoulder longitudinal groove, and a knife groove extending from the above-mentioned shoulder longitudinal groove is provided in the above-mentioned middle land portion, and the angle of the knife groove relative to the tire circumference is less than 70 degrees.

[0013] In the tire according to the present invention, it is preferable that the sipe is displaced from the middle lateral groove in the tire circumferential direction and connected to the first inclined portion.

[0014] In the tire of the present invention, the shoulder longitudinal groove preferably includes a second inclined portion inclined in a direction opposite to the first inclined portion with respect to the tire axial direction, and a circumferential portion connecting the first inclined portion and the second inclined portion and extending in the tire circumferential direction.

[0015] The tire according to the present invention is preferably provided with a plurality of shoulder lateral grooves extending from the shoulder longitudinal grooves toward the tread end sides in the tread portion, wherein the shoulder lateral grooves are smoothly connected to the second inclined portions of the shoulder longitudinal grooves.

[0016] In the tire according to the present invention, it is preferable that the groove width WA2 of the inner portion is 0.7 to 0.9 times the groove width WA1 of the inner portion.

[0017] The present invention adopts the above-mentioned structure, thereby maintaining off-road performance and improving noise performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a plan view of a tread portion according to an embodiment of the present invention that is developed and enlarged.

[0019] Figure 2 It is a top view of the tread portion.

[0020] Figure 3 This is a top view of the middle land portion.

[0021] Figure 4 This is a top view of the middle land portion.

[0022] Figure 5 It is a top view of the tread portion.

[0023] Description of Reference Numerals

[0024] 1…tire; 3…shoulder longitudinal groove; 4…crown longitudinal groove; 5…middle transverse groove; 6…first inclined portion; 10…outer portion; 10e…outer end position of the outer portion; 10i…inner end position of the outer portion; 11…inner portion; 11e…outer end position of the inner portion; 11i…inner end position of the inner portion. DETAILED DESCRIPTION

[0025] Hereinafter, one embodiment of the present invention will be described based on the drawings.

[0026] Figure 1 FIG. 2 is a plan view of the tread portion 2 of the tire 1 according to the present embodiment, which is unfolded and enlarged. Figure 1 The tread portion 2 of the pneumatic tire is shown in FIG. The present invention is suitable for use in, for example, a passenger car, and is particularly suitable for use in tires of a sports utility vehicle (SUV) that is often driven in the wild, such as muddy ground, in addition to paved roads. In addition, the present invention can also be used for heavy-duty tires and tires of other categories.

[0027] like Figure 1 As shown, the tread portion 2 of the tire 1 is provided with a shoulder longitudinal groove 3, a crown longitudinal groove 4, and a plurality of middle lateral grooves 5. The shoulder longitudinal groove 3 extends in a zigzag shape in the tire circumferential direction. The crown longitudinal groove 4 is adjacent to the shoulder longitudinal groove 3 and extends in the tire circumferential direction. The middle lateral groove 5 connects the shoulder longitudinal groove 3 with the crown longitudinal groove 4.

[0028] The shoulder longitudinal groove 3 is inclined relative to the tire circumferential direction (at Figure 1 The shoulder longitudinal groove 3 in this embodiment includes a first inclined portion 6 that is inclined in the opposite direction to the first inclined portion 6 relative to the tire circumferential direction (in Figure 1 A second inclined portion 7 (declining to the right in the middle), and a circumferential portion 8 connecting the first inclined portion 6 and the second inclined portion 7 and extending in the tire circumferential direction.

[0029] The middle lateral grooves 5 each include an outer portion 10 communicating with the shoulder longitudinal grooves 3 , an inner portion 11 communicating with the crown longitudinal grooves 4 , and a middle portion 12 connecting the outer portion 10 and the inner portion 11 .

[0030] The outer side portion 10 and the inner side portion 11 are axially oriented in the same direction as the first inclined portion 6 (in Figure 1The middle portion 12 is inclined in the opposite direction to the outer portion 10 and the inner portion 11 relative to the tire axial direction. As a result, when the middle lateral groove 5 contacts the road surface, the timing of the groove edges 10a to 12a of each portion 10 to 12 contacting the road surface is dispersed. As a result, the impact sound caused by the middle lateral groove 5 is reduced.

[0031] The outer portion 10 is continuously inclined in the same direction as the first inclined portion 6, for example, between the outer end position 10e in the tire axial direction and the inner end position 10i in the tire axial direction. The inner portion 11 is continuously inclined in the same direction as the first inclined portion 6, for example, between the outer end position 11e in the tire axial direction and the inner end position 11i in the tire axial direction. The middle portion 12 is continuously inclined in the opposite direction to the first inclined portion 6 (between the inner end position 10i of the outer portion 10 and the outer end position 11e of the inner portion 11). Figure 1 , descending to the right) with a continuous tilt.

[0032] The outer side portion 10 is smoothly continuous with each first inclined portion 6 of the shoulder longitudinal groove 3. Thus, a large traction force is exerted by the outer side portion 10 and the first inclined portion 6. The above-mentioned "smoothly continuous" in this specification means that the intersection angle α1 between the imaginary line 10n formed by extending the groove center line 10c of the outer side portion 10 toward the first inclined portion 6 and the groove center line 6c of the first inclined portion 6 is 10 degrees or less.

[0033] The groove width WA1 of the outer portion 10 at the outer end position 10e in the tire circumferential direction is formed larger than the groove width WA2 of the inner end position 10i of the outer portion 10. Thus, mud and the like in the outer portion 10 are smoothly discharged to the shoulder longitudinal groove 3 side.

[0034] It is generally believed that the inner portion 11 has a greater ground contact pressure than the outer portion 10, so that the vibration of the air in the inner portion 11 becomes greater than the vibration of the air in the outer portion 10. Therefore, in order to improve the noise performance, it is important to reduce the resonance sound in the inner portion 11. For this reason, in this embodiment, the groove width WB1 of the inner portion 11 in the tire circumferential direction at the outer end position 11e is formed to be larger than the groove width WB2 of the inner portion 11 in the tire circumferential direction at the inner end position 11i. As a result, the relatively large resonance sound in the inner portion 11 is suppressed from flowing into the crown longitudinal groove 4. As a result, the resonance sound caused by the middle lateral groove 5 is reduced.

[0035] Figure 2It is a top view between the tread ends Te and Te of the tread portion 2. The above-mentioned "tread end" in the case of a pneumatic tire refers to the outermost contact position in the axial direction of the tire when the tire 1 is installed on a regular rim (not shown), filled with a regular internal pressure, and in a normal state without load, and is loaded with a regular load and contacts the flat surface at a camber angle of 0°. The distance between the tread ends Te and Te in the tire axial direction is the tread width TW. In this specification, unless otherwise specified, the dimensions of various parts of the tire 1 are values ​​in the normal state.

[0036] "Regular rims" refer to rims whose specifications are specified for each tire in the specification system including the specifications to which the tire is based. For example, if it is JATMA, it is a "standard rim", if it is TRA, it is a "design rim", and if it is ETRTO, it is a "measuring rim".

[0037] "Normal internal pressure" refers to the air pressure specified for each tire in the specification system including the specifications on which the tire is based. If it is JATMA, it is the "maximum air pressure". If it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". If it is ETRTO, it is "INFLATION PRESSURE".

[0038] "Normal load" refers to the load specified for each tire in the specification system including the specifications to which the tire is based. If it is JATMA, it is the "maximum load capacity". If it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIATION COLD INFLATION PRESSURES". If it is ETRTO, it is "LOADCAPACITY".

[0039] like Figure 2 As shown, the shoulder longitudinal groove 3 is arranged on the side closest to the tread end Te in the present embodiment. The shoulder longitudinal groove 3 and the crown longitudinal groove 4 are arranged on both sides of the tire equator C, for example.

[0040] The first inclined portion 6 of the shoulder longitudinal groove 3 of the present embodiment extends in an arc shape that is convex toward the outer side in the axial direction of the tire. The second inclined portion 7 of the present embodiment extends in an arc shape that is convex toward the inner side in the axial direction of the tire. The circumferential portion 8 of the present embodiment extends in a straight line. The length of the circumferential portion 8 in the tire circumferential direction is, for example, formed to be larger than the first inclined portion 6 and the second inclined portion 7. The first inclined portion 6, the second inclined portion 7 and the circumferential portion 8 are not limited to such a form. Such a shoulder longitudinal groove 3 reduces the resonance sound in the shoulder longitudinal groove 3.

[0041] In this embodiment, the circumferential portion 8 includes an outer circumferential portion 8A disposed axially outward from the tire, and an inner circumferential portion 8B disposed axially inward from the outer circumferential portion 8A. The outer circumferential portion 8A and the inner circumferential portion 8B are alternately disposed in the tire circumferential direction, for example.

[0042] The crown longitudinal groove 4 of the present embodiment extends continuously in a zigzag shape in the tire circumferential direction. In addition, the crown longitudinal groove 4 may also be a shape that is interrupted in the tire circumferential direction. In the present embodiment, the crown longitudinal groove 4 includes a crown first inclined portion 15, a crown second inclined portion 16, and a crown circumferential portion 17. The crown first inclined portion 15 is inclined to one side relative to the tire circumferential direction, for example, in the same direction as the first inclined portion 6. The crown second inclined portion 16 is inclined, for example, relative to the tire circumferential direction in a direction opposite to the crown first inclined portion 15. The crown circumferential portion 17, for example, connects the crown first inclined portion 15 and the crown second inclined portion 16 and extends along the tire circumferential direction. The length of the crown circumferential portion 17 in the tire circumferential direction is, for example, formed to be larger than the crown first inclined portion 15 and the crown second inclined portion 16. The crown first inclined portion 15, the crown second inclined portion 16, and the crown circumferential portion 17 are not limited to such a form.

[0043] In the present embodiment, the crown circumferential portion 17 includes a crown outer circumferential portion 17A disposed on the outer side in the tire axial direction, and a crown inner circumferential portion 17B disposed on the inner side in the tire axial direction than the crown outer circumferential portion 17A. The crown outer circumferential portion 17A and the crown inner circumferential portion 17B are alternately disposed in the tire circumferential direction, for example.

[0044] Although not particularly limited, the groove width Wa of the shoulder longitudinal groove 3 and the crown longitudinal groove 4 is preferably, for example, 2.5% to 6.5% of the tread width TW. The groove depth (not shown) of the shoulder longitudinal groove 3 and the crown longitudinal groove 4 is preferably, for example, 8.0 to 10.0 mm. The zigzag amplitude centerline 3c of the shoulder longitudinal groove 3 is preferably, for example, arranged at an axial distance La of 20% to 30% of the tread width TW from the tire equator C to the outside of the tire axial direction. The zigzag amplitude centerline 4c of the crown longitudinal groove 4 is preferably, for example, arranged at an axial distance Lb of 3% to 10% of the tread width TW from the tire equator C to the outside of the tire axial direction.

[0045] Thus, the tread portion 2 is divided into a pair of middle land portions 20, a pair of shoulder land portions 21, and a crown land portion 22. The middle land portion 20 is formed between the shoulder longitudinal groove 3 and the crown longitudinal groove 4. The shoulder land portion 21 is formed between the shoulder longitudinal groove 3 and the tread end Te. The crown land portion 22 is formed between the crown longitudinal grooves 4, 4.

[0046] like Figure 1As shown, it is preferred that the groove width WB2 of the inner portion 11 of the middle lateral groove 5 is 0.7 to 0.9 times the groove width WB1 of the inner portion 11. If the groove width WB2 of the inner portion 11 is 0.7 times or more of the groove width WB1 of the inner portion 11, mud and the like in the inner portion 11 can be smoothly discharged to the crown longitudinal groove 4 side. If the groove width WB2 of the inner portion 11 is 0.9 times or less of the groove width WB1 of the inner portion 11, the resonance sound in the inner portion 11 can be suppressed from flowing into the crown longitudinal groove 4.

[0047] In order to effectively exert the above-mentioned effect, the groove width WA2 of the outer portion 10 is preferably 0.7 to 0.9 times the groove width WA1 of the outer portion 10. The groove width WA1 of the outer portion 10 is preferably 30% to 50% of the length Lm of the middle lateral groove 5.

[0048] Generally speaking, when turning, a greater lateral force acts on the outer portion 10 than on the inner portion 11. In order to utilize such lateral force to effectively discharge mud and the like in the middle lateral groove 5 to the shoulder longitudinal groove 3, in this embodiment, the groove width WA1 of the outer portion 10 is formed to be greater than the groove width WB1 of the inner portion 11. In this embodiment, the groove width WA2 of the outer portion 10 is formed to be greater than the groove width WB2 of the inner portion 11. It is preferred that the groove width WA2 of the outer portion 10 is smaller than the groove width WB1 of the inner portion 11.

[0049] Figure 3 20 is a top view of the middle land portion 20. Figure 3 As shown, in the middle land portion 20 of this embodiment, the extended area 10R formed by extending the pair of groove edges 10a, 10a of the outer portion 10 toward the crown longitudinal groove 4 according to the slope does not overlap with the inner portion 11. This can further reduce the resonance sound in the middle lateral groove 5. Figure 3 In the figure, the extended region 10R is indicated by hatching. In the present specification, the extended region 10R is a region sandwiched between tangent lines 10b, 10b at the inner end position 10i of each groove edge 10a.

[0050] The outer portion 10 preferably has an angle θ1 of 70 degrees or more relative to the tire circumferential direction. Since the angle θ1 of the outer portion 10 is 70 degrees or more, high traction is achieved in the field. Therefore, the angle θ1 of the outer portion 10 is more preferably 75 degrees or more. In order to reduce the resonance sound in the middle lateral groove 5, the angle θ1 of the outer portion 10 is preferably less than 90 degrees, and more preferably less than 85 degrees.

[0051] The outer side portion 10 and the shoulder longitudinal groove 3 form, for example, a trident-shaped intersection K1. The trident-shaped intersection K1 refers to a state in which a lateral groove extending from the shoulder longitudinal groove 3 to the shoulder land portion 21 is not formed at the same position as the opening position of the outer side portion 10 at the shoulder longitudinal groove 3 in the tire circumferential direction. The above-mentioned "lateral groove" refers to the tire axial length Ws ( Figure 2 Grooves that are more than 20% of the axial length of the tire).

[0052] The absolute value of the difference between the angle θ2 of the inner portion 11 with respect to the tire circumferential direction and the angle θ1 of the outer portion 10 |θ2-θ1| is preferably 10 degrees or less, more preferably 5 degrees or less. Such an inner portion 11 ensures a rigid balance on both sides of the middle land portion 20 in the tire axial direction, thereby maintaining high off-road performance.

[0053] In order to effectively exert the above-mentioned effects, it is preferred that the axial length L1 of the outer portion 10 is substantially the same as the axial length L2 of the inner portion 11. "Substantially the same" means that the ratio (L1 / L2) of the length L1 of the outer portion 10 to the length L2 of the inner portion 11 is between 80% and 125%.

[0054] It is preferred that the length L3 of the middle portion 12 in the tire axial direction is 0.05 to 0.15 times the length Lm of the middle lateral groove 5 in the tire axial direction. Since the length L3 of the middle portion 12 is 0.05 times or more of the length Lm of the middle lateral groove 5, the resonance sound can be greatly reduced in the middle portion 12. Since the length L3 of the middle portion 12 is 0.15 times or less of the length Lm of the middle lateral groove 5, the mud and the like in the middle lateral groove 5 can be smoothly discharged. From this viewpoint, the length L3 of the middle portion 12 is more preferably 0.07 times or more of the length Lm of the middle lateral groove 5, and more preferably 0.12 times or less.

[0055] It is preferred that the width W3 of the middle portion 12 in the direction perpendicular to the longitudinal direction is smaller than the width W1 of the outer portion 10 in the direction perpendicular to the longitudinal direction and the width W2 of the inner portion 11 in the direction perpendicular to the longitudinal direction. This increases the effect of reducing resonance sound. Although not particularly limited, the width W3 of the middle portion 12 is preferably 60% or more of the width W2 of the inner portion 11, more preferably 65% ​​or more, preferably 80% or less, and more preferably 75% or less.

[0056] In order to maintain high off-road performance and improve noise performance, the angle θ3 of the middle portion 12 with respect to the tire circumferential direction is preferably 60 degrees or less, more preferably 55 degrees or less, and even more preferably 50 degrees or less.

[0057] Figure 4 20 is a top view of the middle land portion 20. Figure 4As shown, in the present embodiment, the middle land portion 20 is divided into a plurality of middle blocks 24 by the plurality of middle lateral grooves 5 .

[0058] The middle land portion 20 is provided with a sipe 25 extending from the shoulder longitudinal groove 3. The sipe 25 reduces the land portion rigidity of the middle land portion 20 and reduces the impact sound caused by the middle lateral groove 5. In this specification, the sipe is a groove-shaped body with a width of less than 1.5 mm, and is clearly distinguished from groove-shaped bodies such as the shoulder longitudinal groove 3 and the middle lateral groove 5 with a groove width of 1.5 mm or more.

[0059] In the present embodiment, the sipes 25 are offset in the tire circumferential direction from the middle lateral grooves 5. Such sipes 25 suppress a localized significant decrease in the land portion rigidity of the middle land portion 20, thereby maintaining high off-road performance.

[0060] The angle θ4 of the sipe 25 relative to the tire circumferential direction is preferably 70 degrees or less. Since such a sipe 25 has a large tire circumferential component, the block rigidity of the middle block 24 is reduced in a large area in the tire circumferential direction to reduce the impact sound of the middle lateral groove 5. As a result, the noise performance is further improved. In order to suppress the excessive reduction in the rigidity of the middle block 24, the angle θ4 of the sipe 25 is preferably 40 degrees or more.

[0061] In the present embodiment, the sipe 25 connects the shoulder longitudinal groove 3 and the crown longitudinal groove 4. The sipe 25 connects, for example, the intersection of the first inclined portion 6 and the outer circumferential portion 8A and the intersection of the crown second inclined portion 16 and the crown outer circumferential portion 17A. In the present embodiment, the sipe 25 is inclined in the same direction as the middle portion 12 in the tire circumferential direction.

[0062] Figure 5 2 is a top view of the tread portion 2. Figure 5 As shown, the shoulder land portion 21 is provided with a plurality of shoulder lateral grooves 28 extending from the shoulder longitudinal grooves 3 toward the tread end Te side.

[0063] The shoulder lateral groove 28 is smoothly connected to the second inclined portion 7 of the shoulder longitudinal groove 3. As a result, a large traction force is exerted by the shoulder lateral groove 28 and the second inclined portion 7. In this specification, the above-mentioned "smoothly continuous" means the intersection angle α2 ( Figure 4 The shape is below 10 degrees.

[0064] The shoulder lateral groove 28 and the shoulder longitudinal groove 3 form, for example, a trident-shaped intersection K2. The trident-shaped intersection K2 refers to a form in which a lateral groove extending from the shoulder longitudinal groove 3 to the middle land portion 20 is not formed at the same position in the tire circumferential direction as the opening position of the shoulder lateral groove 28 at the shoulder longitudinal groove 3. The above-mentioned "lateral groove" refers to a groove having an axial length of the tire of more than 20% of the axial length Wm of the middle land portion 20.

[0065] For example, the shoulder lateral groove 28 has a tire circumferential width WC that increases continuously from the shoulder longitudinal groove 3 to the tread end Te. Such a shoulder lateral groove 28 maintains higher off-road performance. Although not particularly limited, the tire circumferential width WC2 at the tire axial inner end position 28i of the shoulder lateral groove 28 is preferably 0.25 to 0.50 times the tire circumferential width WC1 at the tire axial outer end position 28e (tread end Te) of the shoulder lateral groove 28.

[0066] The shoulder land portion 21 includes, for example, a shoulder short lateral groove 30 that terminates in the shoulder land portion 21 and a longitudinal sipe 31 that extends in the tire circumferential direction.

[0067] In this embodiment, the shoulder short lateral groove 30 includes a first portion 30A connected to the tread end Te and a second portion 30B connecting the first portion 30A to the longitudinal groove 31 and having a smaller groove width than the first portion 30A. The first portion 30A and the second portion 30B are connected via a widened portion 32 where the groove width changes greatly, for example.

[0068] The longitudinal groove 31 connects, for example, the shoulder lateral grooves 28, 28. In the present embodiment, the longitudinal groove 31 is preferably located at a position where the distance Lc in the tire axial direction from the tread end Te is between 7% and 18% of the tread width TW.

[0069] The crown land portion 22 of the present embodiment is provided with a crown lateral groove 33 extending from the crown longitudinal groove 4 toward the tire equator C and terminating in the crown land portion 22. In the present embodiment, the crown lateral groove 33 terminates before reaching the tire equator C.

[0070] As mentioned above, although the tire which concerns on one embodiment of this invention was demonstrated in detail, this invention is not limited to the said specific embodiment, It can be implemented by changing into various forms.

[0071] [Example]

[0072] Based on the specifications in Table 1, we have produced Figure 2 The basic pattern size of the pneumatic tire for passenger cars is 265 / 55R19. In addition, the noise performance and off-road performance of each test tire were tested. The common specifications and test methods of each test tire are as follows.

[0073] <Noise performance>

[0074] Each test tire was mounted on all wheels of the following vehicle. The vehicle was driven by a test driver on a test track with a dry asphalt surface. The noise generated by the tires during driving was evaluated by the test driver's senses. The results were expressed as a score with Comparative Example 1 being 100. The larger the value, the better.

[0075] Vehicle: SUV with a displacement of 3000cc

[0076] Rim: 7.5J

[0077] Internal pressure: 200kPa

[0078] WA2=WB1

[0079] WA1 / Lm: 20%

[0080] <Off-road performance>

[0081] The test driver drove the vehicle on a muddy test track. The test driver evaluated the handling stability and traction at this time using his sensory organs. The results were expressed as a score where Comparative Example 1 was 100. The larger the value, the better.

[0082] The test results are shown in Table 1.

[0083]

Table 1

[0084]

[0085] As a result of the test, it can be understood that the tire of the example maintains off-road performance and improves noise performance.

Claims

1. A tire having a tread portion, wherein: The tread portion is provided with: a shoulder longitudinal groove extending continuously in a zigzag shape in the tire circumferential direction, a crown longitudinal groove adjacent to the shoulder longitudinal groove and extending in the tire circumferential direction, and a plurality of middle lateral grooves connecting the shoulder longitudinal groove and the crown longitudinal groove. The shoulder longitudinal groove has a plurality of first inclined portions inclined relative to the tire circumferential direction. The middle lateral grooves each include an outer portion communicating with the shoulder longitudinal grooves, an inner portion connected with the crown longitudinal grooves, and an intermediate portion where a pair of groove edges connect the pair of groove edges of the outer portion with the pair of groove edges of the inner portion. The outer portion and the inner portion are inclined in the same direction as the first inclined portion with respect to the tire axial direction. The middle portion is inclined in a direction opposite to the outer portion and the inner portion with respect to the tire axial direction. Each of the outer side portions of the middle lateral grooves is smoothly continuous with each of the first inclined portions of the shoulder longitudinal grooves, wherein the smooth continuity means that an intersection angle between an imaginary line extending the groove center line of the outer side portion toward the first inclined portion and the groove center line of the first inclined portion is 10 degrees or less, The groove width WA1 of the outer portion in the tire circumferential direction at the outer end position in the tire axial direction is greater than the groove width WA2 of the outer portion in the tire circumferential direction at the inner end position in the tire axial direction. A groove width WB1 of the inner portion in the tire circumferential direction at an outer end position in the tire axial direction is greater than a groove width WB2 of the inner portion in the tire circumferential direction at an inner end position in the tire axial direction.

2. The tire according to claim 1, wherein: When the tread is viewed from above, an extended region formed by extending the pair of groove edges of the outer portion toward the crown longitudinal groove side according to respective slopes does not overlap with the inner portion.

3. The tire according to claim 1 or 2, wherein: The groove width WB2 of the inner portion is 0.7 to 0.9 times the groove width WB1 of the inner portion.

4. The tire according to claim 1 or 2, wherein: The length of the middle portion in the tire axial direction is 0.05 to 0.15 times the length of the middle lateral groove in the tire axial direction.

5. The tire according to claim 1 or 2, wherein: The width of the intermediate portion in the direction perpendicular to the longitudinal direction is smaller than the width of the inner portion in the direction perpendicular to the longitudinal direction and the width of the outer portion in the direction perpendicular to the longitudinal direction.

6. The tire according to claim 1 or 2, wherein: The angle of the outer portion with respect to the tire circumferential direction is 70 degrees or more.

7. The tire according to claim 1 or 2, wherein: The tread portion includes a middle land portion divided by the crown longitudinal groove and the shoulder longitudinal groove, The middle land portion is provided with a sipe extending from the shoulder longitudinal groove. The angle of the sipe with respect to the tire circumferential direction is 70 degrees or less.

8. The tire according to claim 7, wherein: The sipe is displaced from the middle lateral groove in the tire circumferential direction and connected to the first inclined portion.

9. The tire according to claim 1 or 2, wherein: The shoulder longitudinal groove includes a second inclined portion inclined in a direction opposite to the first inclined portion with respect to the tire axial direction, and a circumferential portion connecting the first inclined portion and the second inclined portion and extending in the tire circumferential direction.

10. The tire according to claim 9, wherein: The tread portion is provided with a plurality of shoulder lateral grooves extending from the shoulder longitudinal grooves toward the tread end sides. The shoulder lateral grooves are smoothly connected to the second inclined portions of the shoulder longitudinal grooves.

11. The tire according to claim 1 or 2, wherein: The groove width WA2 of the outer portion is 0.7 to 0.9 times the groove width WA1 of the outer portion.

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