JP5476497B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire having improved drainage performance while maintaining uneven wear resistance.

  There is known a block pattern pneumatic tire in which a plurality of blocks are formed in a tread portion by a plurality of longitudinal grooves extending in the tire circumferential direction and a plurality of lateral grooves extending in the tire axial direction. In recent years, for such pneumatic tires, increasing the pattern rigidity of the block has been performed to improve uneven wear resistance.

  Generally, in order to increase the pattern rigidity, it is effective to reduce the groove width and depth of the vertical and horizontal grooves. However, if the groove width or groove depth of the vertical groove or horizontal groove is reduced, there is a problem that the groove volume is reduced and the drainage performance is deteriorated. In particular, in the shoulder lateral groove connected to the tread ground contact end, the contribution to drainage performance is large. Therefore, if the groove depth is simply reduced, the drainage performance is significantly deteriorated. Thus, there is a tradeoff between improving drainage performance and ensuring uneven wear resistance, and it has been difficult to achieve both. Related technologies include the following.

Japanese Patent Laid-Open No. 10-1000061 JP 2007-182094 A

  The present invention has been devised in view of the above-described problems, and bends the shoulder lateral groove and defines the arrangement angle within a certain range, and defines the bending position and the groove depth in association with each other. The main objective is to provide a pneumatic tire that can improve drainage performance while maintaining uneven wear resistance.

According to the invention described in claim 1 of the present invention, the tread portion is provided with a shoulder vertical groove extending continuously from the ground contact end side in the tire circumferential direction, and a shoulder horizontal groove extending from the shoulder vertical groove to the ground contact end. A pneumatic tire in which a plurality of shoulder blocks are partitioned between the shoulder longitudinal groove and the tread end, and the shoulder lateral groove is 70 degrees or more with respect to the tire circumferential direction from the shoulder longitudinal groove and A first portion that inclines at an angle of less than 90 degrees and extends outward in the tire axial direction, is connected to the first portion, is opposite to the first portion, and is inclined at an angle of 40 to 70 degrees with respect to the tire circumferential direction. And the shoulder lateral groove has a shallow bottom portion at which the groove depth is minimized at a connection portion between the first portion and the second portion, and the shallow transverse groove bottom Axially inside the groove depth is gradually increased to the outer groove depth of the shallow bottom, characterized in that the 30% to 50% of the groove depth of the shoulder circumferential grooves.

  According to a second aspect of the present invention, the groove depth at the outer end in the tire axial direction of the second portion is smaller than the groove depth at the inner end in the tire axial direction of the first portion. The pneumatic tire described.

  The invention according to claim 3 is the pneumatic tire according to claim 1 or 2, wherein the shoulder lateral groove has a constant groove width at least from the first part to the second part.

  The invention according to claim 4 is the pneumatic tire according to any one of claims 1 to 3, wherein each of the first portion and the second portion extends linearly.

  In the invention according to claim 5, the groove depth at the inner end in the tire axial direction of the first portion is 90 to 100% of the groove depth of the shoulder longitudinal groove. The pneumatic tire described in 1.

The invention according to claim 6 is the pneumatic tire according to claim 2, wherein the length of the second portion in the tire axial direction is 2 to 7 times the length of the first portion in the tire axial direction. . According to a seventh aspect of the invention, the shoulder lateral groove is connected to the second portion on the outer side in the tire axial direction of the second portion, and is opposite to the second portion and 60 to 90 with respect to the tire circumferential direction. The pneumatic tire according to claim 2 or 6, comprising a third portion extending outward in the tire axial direction at an angle of degrees. In the invention according to claim 8 , the groove depth at the outer end in the tire axial direction of the second portion is 50% to 80% of the groove depth of the shoulder longitudinal groove. A pneumatic tire according to claim 1.

  In the pneumatic tire of the present invention, the shoulder tread portion is provided with a shoulder vertical groove extending continuously from the ground contact end side in the tire circumferential direction and a shoulder horizontal groove extending from the shoulder vertical groove to the tread end. A plurality of shoulder blocks are partitioned between the longitudinal grooves and the tread ends. The shoulder lateral groove extends from the shoulder longitudinal groove at an angle of 70 degrees or more and less than 90 degrees with respect to the tire circumferential direction and extends outward in the tire axial direction, and is connected to the first part and the first part. It includes a second portion that is opposite to the portion and is inclined at an angle of 40 to 70 degrees with respect to the tire circumferential direction and extends outward in the tire axial direction. In such a shoulder lateral groove, the first portion is inclined at an angle of 70 degrees or more and less than 90 degrees with respect to the tire circumferential direction from the shoulder longitudinal groove, so that the water in the shoulder longitudinal groove utilizes a ground pressure difference. Drainage performance improves because it flows smoothly. Moreover, since the shoulder lateral groove is a bent groove in which the first portion and the second portion extend in opposite directions, the drainage performance can be exhibited without depending on the tire rotation direction. Further, since the first portion and the second portion are opposite to each other and the angle with respect to the tire circumferential direction is limited to the above range, the anisotropy of the shoulder block is reduced, thereby improving the uneven wear resistance.

  Further, the shoulder lateral groove has a shallow bottom portion where the groove depth is minimized at a connection portion between the first portion and the second portion, and the groove depth extends inward and outward in the tire axial direction from the shallow bottom portion. Increase gradually. Such a shoulder lateral groove has a groove depth that gradually increases in and out of the tire axial direction from the shallow bottom portion, so that the groove volume of the shoulder lateral groove is increased and a large amount of drainage is smoothly discharged to the ground contact end side. In addition, wear tends to concentrate on a portion where the groove angle changes, such as the connection portion between the first portion and the second portion, but by providing a shallow bottom portion in the connection portion as described above, Since rigidity is largely secured, uneven wear resistance is further improved.

It is an expanded view of the tread part which shows the pneumatic tire of one Embodiment of this invention. It is the elements on larger scale of FIG. It is XX sectional drawing of FIG. It is an expanded view of the tread part which shows a comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment is suitably used as a small truck, for example, and the tread portion 2 includes A pair of shoulder longitudinal grooves 3 extending continuously in the tire circumferential direction on the most ground contact end Te side and, for example, one center longitudinal groove 4 extending continuously on the tire equator C in the tire circumferential direction are provided. As a result, the tread portion 2 has a pair of shoulder land portions 5 extending between the shoulder vertical groove 3 and the ground contact Te, and a pair of center land extending between the center vertical groove 4 and the shoulder vertical groove 3. Part 6 is formed. Therefore, the tire 1 of the present embodiment includes a total of four land portions in the tread portion 2.

  In the shoulder land portion 5, shoulder lateral grooves 7 extending from the shoulder longitudinal groove 3 to the ground contact Te are provided in the tire circumferential direction. Thereby, the shoulder land portion 5 forms a block row in which a plurality of shoulder blocks 8 divided by the shoulder vertical grooves 3, the ground contact Te and the shoulder horizontal grooves 7 are arranged in the tire circumferential direction.

  Here, the “grounding end” Te is grounded on a flat surface at a camber angle of 0 degree by applying a normal load to the tire 1 in a normal state in which a normal rim is assembled with a normal rim and filled with a normal internal pressure. It is determined as the contact position on the outermost side in the tire axial direction. The distance in the tire axial direction between the ground contact Te and Te is determined as the ground contact width TW. Further, the dimensions and the like of each part of the tire are values in the normal state unless otherwise specified.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA and “Design Rim” for TRA. For ETRTO, use "Measuring Rim".

  The “regular internal pressure” is the air pressure defined by each standard for each tire in the standard system including the standard on which the tire is based, and is “maximum air pressure” for JATMA and table for TRA. The maximum value described in TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES is "INFLATION PRESSURE" for ETRTO, but 180 kPa for tires for passenger cars.

  Furthermore, “regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “Maximum load capacity” for JATMA, “TIRE” for TRA The maximum value described in “LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” is “LOAD CAPACITY” in the case of ETRTO.

  The shoulder longitudinal groove 3 and the center longitudinal groove 4 of this embodiment form a straight line along the tire circumferential direction. Each of the vertical grooves 3 and 4 suppresses unstable behavior such as vehicle wobbling or single flow during braking, and smoothly discharges the waste water in the vertical grooves 3 and 4 to the rear in the tire rotation direction. This is desirable in that it can improve maneuvering stability and drainage performance.

  Further, the width of the shoulder vertical groove 3 and the center vertical groove 4 (the groove width perpendicular to the longitudinal direction of the groove, hereinafter the same applies to other grooves) W1, W2 and groove depths D1, D2 (see FIG. 3) can be variously determined in accordance with common practice. However, if the groove widths W1 and W2 and / or the groove depths D1 and D2 are too large, the rigidity of the land portions 5 and 6 may be reduced. If the groove widths are too small, the drainage property may be deteriorated. For this reason, the groove widths W1 and W2 are preferably 2.5 to 7.5% of the grounding width TW, for example. The groove depths D1 and D2 are preferably 7.0 to 12.0 mm.

  As for the position of the shoulder longitudinal groove 3, for example, the tire axial distance L1 between the center line 1G and the tire equator C is preferably 15% or more, more preferably 20% or more of the ground contact width TW. Desirably, preferably 35% or less, more preferably 30% or less. By setting in such a range, the rigidity balance of the land portions 5 and 6 can be further improved, and uneven wear resistance performance, steering stability performance, and the like can be improved.

  Moreover, in order to exhibit the above-mentioned effect more, the ratio Ls / Lc between the land portion width Lc of the center land portion 6 and the land portion width Ls of the shoulder land portion 5 is preferably 100% or more, more preferably 115%. The above is desirable, preferably 145% or less, more preferably 130% or less.

  In addition, as shown in FIG. 2, the shoulder lateral groove 7 of the present embodiment is inclined at an angle θ1 of 70 degrees or more and less than 90 degrees with respect to the tire circumferential direction from the shoulder longitudinal groove 3 and extends outward in the tire axial direction. The first portion 11 and the second portion 12 that is connected to the first portion 11 and that is opposite to the first portion 11 and inclined at an angle θ2 of 40 to 70 degrees with respect to the tire circumferential direction and extends outward in the tire axial direction. And a third portion 13 that continues to the second portion 12 and extends outward in the tire axial direction.

Such a shoulder lateral groove 7 has the first portion 11 inclined from the shoulder longitudinal groove 3 with respect to the tire circumferential direction at the large angle θ1 so that the water in the shoulder longitudinal groove 3 is in contact with the ground pressure difference of the shoulder land portion 5. Improves the drainage performance because it flows smoothly. Moreover, since the shoulder lateral groove 7 has a bent portion because the first portion 11 and the second portion 12 extend in opposite directions, the drainage performance is exhibited without depending on the tire rotation direction. Furthermore, since the angles θ1 and θ2 between the first portion 11 and the second portion 12 are limited to the above range, the anisotropy of the shoulder block 8 is reduced, and the uneven wear resistance is improved. In particular, since the angle θ2 of the second portion 12 is inclined within the above range, drainage performance and uneven wear resistance are improved in a well-balanced manner.

  Here, when the angle θ1 of the first portion 11 is less than 70 degrees, drainage in the shoulder longitudinal groove 3 during turning becomes difficult to flow into the shoulder lateral groove 7. From such a viewpoint, the angle θ1 is more preferably 75 degrees or more. In addition, when the angle θ2 of the second portion 12 is less than 40 degrees, the anisotropy of the shoulder block 8 increases and the uneven wear resistance performance deteriorates. On the contrary, if the angle θ2 exceeds 70 degrees, the drainage in the second portion 12 cannot be smoothly discharged to the ground contact Te when traveling straight, and the resonance of air generated in the shoulder longitudinal groove 3 is not achieved. The discharge of vibration (air column resonance) to the ground contact Te side cannot be suppressed. From such a viewpoint, the angle θ2 is more preferably 45 degrees or more, and more preferably 65 degrees or less.

  Moreover, when the difference θ1-θ2 between the angles θ1 and θ2 is increased, the rigidity of the shoulder block 8 is decreased, and the uneven wear resistance may be deteriorated. For this reason, the angle difference θ1-θ2 is preferably 40 degrees or less, more preferably 30 degrees or less.

  As shown in FIGS. 2 and 3, the shoulder lateral groove 7 is formed at the connection portion K between the first portion 11 and the second portion 12 (that is, the bent portion in the embodiment of the present invention). A shallow bottom portion 15 having a minimum groove depth D3 is provided. Such a shallow bottom portion 15 increases the rigidity in the vicinity of the connection portion K where stress concentration tends to occur due to the bending of the groove, and improves the uneven wear resistance performance of the shoulder block 8. Further, as shown in FIG. 3, the groove depth D <b> 3 of the shoulder lateral groove 7 gradually increases from the shallow bottom portion 15 in and out of the tire axial direction. As a result, the decrease in the groove volume at the shallow bottom portion 15 is compensated, and the groove volume of the shoulder lateral groove 7 is maintained or increased in total, so that a large amount of drainage from the shoulder vertical groove 3 is smoothly discharged to the grounding end Te side. it can.

  As described above, in the tire 1 of the present invention, the arrangement angle between the first portion 11 and the second portion 12 of the shoulder lateral groove 7 provided in the shoulder land portion 5 is defined within a certain range and is bent in the opposite directions. In addition, by minimizing the groove depth at the bent position, the drainage performance from the shoulder lateral groove 7 is improved while maintaining the rigidity of the shoulder land portion 5, so that uneven wear resistance and drainage performance are improved in a well-balanced manner. To do.

Incidentally, if the groove depth D3a of the shallow bottom 15 is too small, the drainage performance of the shoulder lateral grooves 7 you decrease. Groove depth D3a of the shallow bottom part 15, at least 30% of the groove depth D1 of the sheet Yoruda circumferential grooves 3, 50% or less. The groove depth D3a of the shallow bottom portion 15 is preferably 40% or more, preferably 45% or less of the groove depth D1 of the shoulder longitudinal groove 3.

  Although not particularly limited, when the groove depth D3b (shown in FIG. 3) at the inner end 11i in the tire axial direction of the first portion 11 is increased, the rigidity of the shoulder land portion 5 on the inner side in the tire axial direction is increased. However, when the groove depth D3b is decreased, the shoulder volume of the shoulder lateral groove 7 is decreased and the drainage performance tends to be deteriorated. For this reason, the groove depth D3b is preferably 90% or more of the groove depth D1 of the shoulder longitudinal groove 3, more preferably 95% or more, and preferably 100% or less, more preferably 98% or less. . In the present embodiment, the bottom of the shoulder lateral groove 7 is smoothly connected to the bottom of the shoulder vertical groove 3.

  From the same viewpoint, the groove depth D3c (shown in FIG. 3) at the outer end 12e in the tire axial direction of the second portion 12 is preferably 50% or more of the groove depth D1 of the shoulder longitudinal groove 3, more preferably. 60% or more is desirable, preferably 80% or less, more preferably 70% or less. The groove depth D3c is larger than the groove depth D3b at the inner end 11i in the tire axial direction of the first portion 11 from the viewpoint of securing a large rigidity on the ground contact end Te side where a large lateral force acts during turning. Small is desirable.

  In the shoulder lateral groove 7 of the present embodiment, the groove width W3 of the first portion 11 and the second portion 12 groove width W4 are formed substantially constant. Such shoulder lateral grooves 7 prevent the groove volume from changing significantly and the drainage performance from deteriorating. Further, the rigidity of the shoulder land portion 5 is effectively increased without excessively passing air resonance vibration (air column resonance sound) generated in the shoulder longitudinal groove 3. Therefore, the pneumatic tire 1 of this embodiment improves drainage performance and uneven wear resistance performance without deteriorating noise performance. The “substantially constant” means that the groove widths W3 and W4 are the same, and the ratio W3 / W4 between the groove widths W3 and W4 is 80 to The range of 120% is included.

  The groove width W3 of the first portion 11 is preferably 10% or more, more preferably 12% or more, and preferably 15% of the tire circumferential pitch Pa of the shoulder lateral grooves 7 in order to exert the above-described effect. Below, more preferably 14% or less.

  Further, it is desirable that the first portion 11 and the second portion 12 each extend linearly as in the present embodiment. Thereby, since it can drain more smoothly and the rigidity of the shoulder land portion 5 is ensured, the uneven wear resistance performance and drainage performance are further enhanced.

  Further, the length L4 of the second portion 12 in the tire axial direction is preferably at least twice, more preferably at least three times, and preferably at most seven times the length L3 of the first portion in the tire axial direction. More preferably, 6 times or less is desirable. That is, if the length L4 exceeds 7 times the length L3, anisotropy is likely to occur in the rigidity of the shoulder block. Conversely, if the length L4 is less than 2 times, there is a possibility that water cannot be smoothly drained to the tread end Te.

  Further, it is desirable that the third portion 13 extends in an opposite direction to the second portion 12 and at an angle θ3 of 60 to 90 degrees with respect to the tire circumferential direction. The shoulder land portion 5 having such a third portion 13 further utilizes the ground pressure difference of the shoulder land portion 5 to smoothly drain the drainage of the shoulder lateral groove 7 to the ground end Te side without depending on the tire rotation direction. Can be discharged. In addition, when the angle θ3 is small, there is a possibility that the rigidity on the ground contact end Te side on which the lateral force during turning acts greatly decreases. For this reason, the angle θ3 is more preferably 65 degrees or more.

  In the present embodiment, the groove width W5 of the third portion 13 gradually increases toward the ground contact Te. Thereby, the drainage to the ground contact Te is further smoothly performed. In addition, from the viewpoint of ensuring drainage performance and uneven wear resistance performance, the groove width W5 of the third portion 13 is preferably 120% or more of the groove width W4 of the second portion 12, more preferably 140% or more, Further, it is preferably 200% or less, more preferably 180% or less. From the same viewpoint, the groove depth D5 (shown in FIG. 3) of the third portion 13 is preferably 70% or more, more preferably 80% or more of the groove depth D1 of the shoulder longitudinal groove 3, and preferably It is desirably 120% or less, more preferably 110% or less. The groove depth D5 is the depth at the ground contact Te.

  Further, the shoulder block 8 includes a plurality of semi-closed type in-shoulder sipes 16 extending from the outer edge 3e in the tire axial direction of the shoulder longitudinal groove 3 to the outer side in the tire axial direction and terminating without reaching the ground contact end Te (this embodiment) Two are provided in the form. The in-shoulder sipe 16 preferably has different lengths in the tire axial direction in order to secure a rigidity balance in the tire circumferential direction. For example, the ratio L6a / L6b between the length L6a of the shoulder sipe 16a on one side in the tire circumferential direction and the length L6b of the shoulder sipe 16b on the other side in the tire circumferential direction is preferably 0.80 or more. More preferably, it is 0.90 or more, preferably 1.25 or less, more preferably 1.15 or less.

  The shoulder block 8 includes a semi-closed type first shoulder sipe 17 that linearly extends inward in the tire axial direction from the ground contact end Te and terminates without reaching the outer edge, and is bent inward in the tire axial direction from the ground contact end Te. Then, a semi-closed type second shoulder sipe 18 that terminates without reaching the outer edge is provided.

  The inner end 17i in the tire axial direction of the first shoulder sipe 17 is disposed on the inner side in the tire axial direction from the outer end 16e of the shoulder inner sipe 16. Since the first shoulder sipe 17 as described above exhibits the edge effect of the first shoulder sipe 17 while ensuring the rigidity of the shoulder block 8, the steering stability performance and the uneven wear resistance performance are improved.

  The inner end 17i of the first shoulder sipe 17 is provided between the tire inner sipe 16a on the one side and the tire inner sipe 16b on the other side. Such a first shoulder sipe 17 further improves steering stability performance and uneven wear resistance performance.

  Further, the shoulder block 8 is provided with the second shoulder sipe 18 to further enhance drainage performance.

  In order to exert the above-described action, the width (not shown) of the in-shoulder sipe 16, the first shoulder sipe 17, and the second shoulder sipe 18 is preferably 0.2 mm or more, more preferably 0.5 mm or more. Further, it is preferably 1.5 mm or less, more preferably 1.0 mm or less. The sipe depth (not shown) is preferably 3.0 mm or more, more preferably 4.0 mm or more, and preferably 8.0 mm or less, more preferably 7.0 mm or less.

  Further, the center land portion 6 includes a first lug groove 20 that extends from the center vertical groove 4 toward the outer side in the tire axial direction with a small length and is inclined to one side with respect to the tire axial direction, and a shoulder vertical groove. 3 and a second lug groove 21 extending from one side toward the tire equator C side in a small length. Further, the center land portion 6 has a first main sipe 22 that connects the first lug groove 20 and the second lug groove 21 and is inclined to the one side, and the first lug groove 20 and the second lug groove 21. And a second main sipe 23 which is inclined to the other side with respect to the tire axial direction. Such a center land portion 6 effectively drains the water film of the center land portion 6 by the first and second lug grooves 20 and 21, and the center land portion by the first and second main sipes 22 and 23. The drainage performance is further improved without excessively reducing the rigidity of 6.

  The center land portion 6 includes a semi-closed type center edge sipe 24 extending from the both land portion edges 6e, 6e in the tire axial direction to the center side of the center land portion 6 in a small length, and the center first sipe 24. A closed-type center sub-sipe 25 is provided to straddle the main sipe 22 with a small length. Such center edge sipes 24 and center sub sipes 25 improve the drainage performance while securing the rigidity of the center land portion 6.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the illustrated embodiments, and can be implemented in various forms.

Pneumatic tires (size: 195 / 80R15 107 / 105L LT) having the pattern of FIG. 1 and based on the specifications in Table 1 were manufactured and tested for their respective performance. The common specifications are as follows.
Grounding width: 145mm
<Center vertical groove>
Groove width W1 / Grounding width TW: 4.0%
Groove depth D1: 9.7 mm
Angle relative to tire equator C: 0 degree <shoulder longitudinal groove>
Groove width W2 / Contact width TW: 5.5%
Groove depth D2: 9.7 mm
Angle relative to tire equator C: 0 degree <first part>
Groove width W3: 5.5 mm
<Second part>
Groove width W4: 5.5 mm
<Third part>
Groove width W5: 6.0 to 9.0 mm
Groove depth D5 / D1: 97% at the contact end
Other <each sipe>
Width: 0.3-0.5mm
Sipe depth: 5.5-8.5mm
The test method is as follows.

<Uneven wear resistance>
A sample tire was mounted on all wheels of a vehicle (domestic 2000cc, FR car) under the conditions of a rim of 6.0J and an internal pressure of 450kPa, and the tire test course was run for 30km by the limit running, and there was no chipping or uneven wear. Was observed visually. Evaluation is indicated by an index with Comparative Example 1 being 100, and the larger the value, the better the uneven wear resistance.

<Drainage performance>
In the above test vehicle, on the asphalt road surface with a radius of 100 m, on the course where a puddle with a depth of 10 mm and a length of 20 m was provided, the vehicle was entered while increasing the speed stepwise, and the lateral acceleration (lateral G) was measured. The average lateral G of the front wheels at a speed of 50 to 80 km / h was calculated. The results were expressed as an index with Comparative Example 1 as 100. The larger the value, the better.

<Noise performance>
In the above test vehicle, the noise in the car when traveling on the road noise measurement road (asphalt rough road) at a speed of 60 km / h was collected with a microphone installed at the driver's window side ear position. The sound pressure level at the peak value of the column resonance sound was measured. Evaluation is indicated by an index with Comparative Example 1 being 100, and the larger the value, the better.
The test results are shown in Table 1.

  As a result of the test, it can be confirmed that the tires of the examples have improved various performances as compared with the comparative examples.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Shoulder vertical groove 7 Shoulder lateral groove 8 Shoulder block 11 1st part 12 2nd part 15 Shallow bottom part C Tire equator K Connection part Te Grounding end

Claims (8)

The tread portion is provided with a shoulder vertical groove extending continuously from the ground contact end side in the tire circumferential direction, and a shoulder horizontal groove extending from the shoulder vertical groove to the ground contact end, whereby the shoulder vertical groove and the tread end are provided. A pneumatic tire with a plurality of shoulder blocks in between,
The shoulder transverse groove is inclined at an angle of 70 degrees or more and less than 90 degrees with respect to the tire circumferential direction from the shoulder longitudinal groove and extends outward in the tire axial direction, and is connected to the first part and the first part. A second portion that is opposite to the portion and inclined at an angle of 40 to 70 degrees with respect to the tire circumferential direction and extends outward in the tire axial direction,
The shoulder lateral groove has a shallow bottom portion that minimizes the groove depth at the connecting portion between the first portion and the second portion, and the groove depth gradually increases from the shallow bottom portion in and out of the tire axial direction. ,
The pneumatic tire according to claim 1, wherein a groove depth of the shallow bottom portion is 30% to 50% of a groove depth of the shoulder vertical groove .   The pneumatic tire according to claim 1, wherein a groove depth at an outer end in the tire axial direction of the second portion is smaller than a groove depth at an inner end in the tire axial direction of the first portion.   The pneumatic tire according to claim 1, wherein the shoulder lateral groove has a constant groove width at least from the first part to the second part.   The pneumatic tire according to claim 1, wherein each of the first portion and the second portion extends linearly.   The pneumatic tire according to any one of claims 1 to 4, wherein a groove depth at an inner end in the tire axial direction of the first portion is 90 to 100% of a groove depth of the shoulder vertical groove.   The pneumatic tire according to claim 2, wherein a length of the second portion in the tire axial direction is 2 to 7 times a length of the first portion in the tire axial direction.   The shoulder lateral groove is on the outer side in the tire axial direction of the second portion, is connected to the second portion, is opposite to the second portion, and is on the outer side in the tire axial direction at an angle of 60 to 90 degrees with respect to the tire circumferential direction. The pneumatic tire according to claim 2 or 6, comprising a third portion that extends. The pneumatic tire according to any one of claims 1 to 7, wherein a groove depth at an outer end in the tire axial direction of the second portion is 50% to 80% of a groove depth of the shoulder vertical groove.

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