JP5695613B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which drainage performance, snow road performance, and ice road performance are improved in a balanced manner.

Winter pneumatic tires run not only on snowy and icy roads but also on wet roads. Therefore, the winter pneumatic tire is required to have good drainage performance.
For example, it has been proposed to increase the contact area of the tread portion for the purpose of increasing the frictional force on an icy road. However, in this method, the groove width of the main groove or the lateral groove of the tread portion is reduced. For this reason, there existed a problem that drainage performance and snowy road performance deteriorated. Thus, the ice road performance, the drainage performance, and the snow road performance have a reciprocal relationship, and it has been difficult to improve all these performances in a well-balanced manner. Related technologies include the following.

JP 2008-308010 A

  The present invention has been devised in view of the actual situation as described above, and is based on specifying the shape of the shoulder lateral groove and the like, and has improved the drainage performance, snow road performance, and ice road performance in a well-balanced manner. The main purpose is to provide tires.

Among the present inventions, the invention according to claim 1 is a tire shaft extending from the shoulder main groove to the tread grounding end with a pair of shoulder main grooves extending continuously in the tire circumferential direction at the tread portion. A pneumatic tire in which a plurality of shoulder blocks are arranged along the tread grounding end by providing a shoulder lateral groove extending in a direction,
The shoulder lateral groove is inclined at an angle of 5 to 15 ° with respect to the tire axial direction,
In addition, the shoulder lateral groove includes an inner groove portion that extends from the shoulder main groove with a substantially constant groove width, and an outer groove portion that is continuous with the inner groove portion and extends to the tread grounding end side with a substantially constant groove width that is larger than the inner groove portion. Including
Wherein the groove portion and the outer groove are each at least one saw including a shift unit that is displaced in the one side in the tire circumferential direction,
The outer groove portion includes fewer shift portions than the inner groove portion .

  In the invention according to claim 2, the shift portion includes a short side portion extending at an angle larger than 45 ° with respect to the tire axial direction, and 30 ° with respect to the tire axial direction from both ends of the short side portion. The pneumatic tire according to claim 1, comprising a pair of long side portions extending at the following angles and having a length longer than that of the short side portions.

In the invention according to claim 3, the shoulder block is divided into an inner block piece on the inner side in the tire axial direction and an outer block piece on the outer side in the tire axial direction by a shoulder narrow groove extending in the tire circumferential direction.
3. The pneumatic tire according to claim 1, wherein the shoulder narrow groove communicates between the inner groove portion and the outer groove portion of the shoulder lateral groove.

In the invention according to claim 4, the shoulder block is divided into an inner block piece on the inner side in the tire axial direction and an outer block piece on the outer side in the tire axial direction by a shoulder narrow groove extending in the tire circumferential direction.
The inner block piece and the outer block piece are each formed with a plurality of semi-open type shoulder sipes whose one end communicates with the shoulder narrow groove and the other end terminates inside the block. A pneumatic tire according to any one of the above.

  According to a fifth aspect of the present invention, there is provided a widened portion communicating with the tread grounding end with a larger groove width than the outer groove portion on the outer side in the tire axial direction of the outer groove portion of the shoulder lateral groove. The pneumatic tire according to any one of 1 to 4.

  The invention according to claim 6 is the pneumatic tire according to any one of claims 1 to 5, wherein each of the inner groove portion and the outer groove portion includes 1 to 5 shift portions.

The invention according to claim 7 is the pneumatic tire according to any one of claims 1 to 6 , wherein the shift portion of the outer groove portion is one less than the shift portion of the inner groove portion .

The invention according to claim 8 is the air according to any one of claims 1 to 7 , wherein the groove depth of the outer groove portion is 1.4 to 1.6 times the groove depth of the inner groove portion. This is a tire.

  In the pneumatic tire of the present invention, the shoulder lateral grooves are inclined at an angle of 5 to 15 ° with respect to the tire axial direction. Such a shoulder lateral groove has an edge component that exerts frictional force in the tire axial direction while maintaining drainage, and improves turning performance on snow.

  The shoulder lateral groove includes an inner groove portion that extends from the shoulder main groove with a substantially constant groove width, and an outer groove portion that continues to the inner groove portion and extends with a substantially constant width that is larger than the inner groove portion. Such an inner groove portion and an outer groove portion secure a ground contact area on the inner side in the tire axial direction of the shoulder block, and a sufficient frictional force on an ice road is ensured. Further, the outer groove portion effectively drains the water film outward in the tire axial direction during wet running, and improves drainage performance.

  Further, each of the inner groove portion and the outer groove portion includes at least one shift portion that is displaced to one side in the tire circumferential direction. Such a shift portion has an edge component that exerts a frictional force in the tire axial direction, and improves snow road performance and ice road performance.

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

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment is suitably used as, for example, a winter tire. The tread portion 2 of the tire 1 has a pair of shoulder main grooves 3 and 3 extending continuously in the tire circumferential direction on the tread grounding end Te side, and an inner side in the tire axial direction of the shoulder main grooves 3 in the tire circumferential direction. A pair of extending center main grooves 4 and 4 are provided.

  The “tread grounding end” Te is grounded on a flat surface at a camber angle of 0 ° by applying a normal load to an unloaded normal tire that is assembled with a normal rim (not shown) and filled with a normal internal pressure. It means the ground contact position on the outermost side in the tire axial direction. A distance in the tire axial direction between the tread ground contact Te and Te is determined as a tread ground contact width TW. Unless otherwise specified, the dimensions and the like of each part of the tire are values measured in a normal state.

  The “regular rim” is a rim defined for each tire in the standard system including the standard on which the tire is based. “Standard Rim” for JATMA, “Design Rim” for TRA For ETRTO, "Measuring Rim". In addition, “regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based, and is “maximum air pressure” for JATMA, and “TIRE” for TRA. Maximum value described in “LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO, but 180 kPa for tires for passenger cars.

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

  The shoulder main groove 3 and the center main groove 4 of the present embodiment extend in a zigzag shape in the tire circumferential direction. Such shoulder main groove 3 and center main groove 4 increase an edge component that exerts a frictional force in the tire circumferential direction. For this reason, snow column shearing force, driving force, braking force, etc. become large, and snowy road performance and icy road performance are improved.

  FIG. 2 is a sectional view taken along line XX in FIG. As shown in FIG. 1 and FIG. 2, the groove width W1 of the shoulder main groove 3 (meaning the groove width perpendicular to the longitudinal direction of the groove) and the groove depth D1, and the groove width W2 and the groove of the center main groove 4 are shown. The depth D2 can be variously determined in accordance with common practice. However, when these groove widths or groove depths are small, drainage performance and snow road performance may be deteriorated. On the contrary, when these groove widths or groove depths are large, the contact area and rigidity of the tread portion 2 are lowered, and there is a possibility that the ice road performance is deteriorated. For this reason, the groove width W1 of the shoulder main groove 3 and the groove width W2 of the center main groove 4 are preferably 3 to 9% of the tread grounding width TW, for example. The groove depth D1 of the shoulder main groove 3 and the groove depth D2 of the center main groove 4 are preferably 6 to 15 mm, for example.

  As shown in FIG. 1, the tread portion 2 includes a center land portion 5 sandwiched between a pair of center main grooves 4, 4, a pair of middle land portions 6 sandwiched between the center main groove 4 and the shoulder main grooves 3, 6 and a pair of shoulder land portions 7 and 7 sandwiched between the shoulder main groove 3 and the tread grounding end Te.

  The land ratio of the tread portion 2 defined by each groove and each land portion is preferably 68% or more, and preferably 72% or less. Thereby, compared with the conventional winter tire, a ground contact area becomes large and ice road performance improves. The “land ratio” means the ratio of the actual ground contact area to the total area of the virtual ground contact surface filling all the grooves between the tread ground contact Te and Te.

  The shapes and the like of the center land portion 5 and the middle land portion 6 are appropriately set according to the custom. For example, if the width W3 of the center land portion 5 in the tire axial direction and the width W4 of the middle land portion 6 in the tire axial direction are reduced, the deformation of the land portion may be increased, and the steering stability may be reduced. The drainage performance may be reduced. From such a viewpoint, the width W3 and the width W4 are preferably 0.14 times or more, more preferably 0.16 times or more, more preferably 0.22 times or less, more preferably the tread grounding width TW. Preferably it is 0.20 times or less.

  The center land portion 5 is divided into center blocks 9 spaced in the tire circumferential direction by center lateral grooves 8 extending in the tire axial direction. Similarly, the middle land portion 6 is divided into middle blocks 11 spaced in the tire circumferential direction by middle lateral grooves 10 extending in the tire axial direction. The shoulder land portion 7 is divided into shoulder blocks 12 that are spaced apart in the tire circumferential direction by shoulder lateral grooves 13 extending in the tire axial direction.

  FIG. 3 shows a partially enlarged view of the shoulder land portion 7. As shown in FIG. 3, the shoulder land portion 7 includes a shoulder lateral groove 13 extending from the shoulder main groove 3 to the tread ground contact Te in the tire axial direction. Further, the shoulder lateral grooves 13 are spaced apart in the tire circumferential direction, so that a plurality of shoulder blocks 12 are spaced apart in the tire circumferential direction along the tread ground contact Te.

  The shoulder lateral grooves 13 are inclined at an angle of 5 to 15 ° with respect to the tire axial direction. Such a shoulder lateral groove 13 has an edge component that exerts a frictional force in the tire axial direction while maintaining drainage, and improves turning performance on ice.

  If the angle θ1 of the shoulder lateral groove 13 with respect to the tire axial direction increases, the drainage performance may decrease, and if it decreases, the turning performance on snow may decrease. For this reason, the angle θ1 is preferably 7 ° or more, more preferably 9 ° or more, and preferably 13 ° or less, more preferably 11 ° or less. Note that the shoulder lateral groove 13 is non-linear because it includes a shift portion described later. Therefore, the angle θ1 means the angle of the center line 13c of the amplitude of the groove center line of the shoulder lateral groove 13 with respect to the tire axial direction.

  The shoulder lateral groove 13 includes an inner groove portion 13i and an outer groove portion 13o.

  The inner groove portion 13i communicates with the shoulder main groove 3 and extends outward from the shoulder main groove 3 in the tire axial direction with a substantially constant groove width W5. The outer groove portion 13o is connected to the inner groove portion 13i and extends toward the tread grounding end Te side with a substantially constant groove width W6 larger than the groove width W5 of the inner groove portion 13i.

  The “substantially constant groove width” means that the ratio Wmin / Wmax between the minimum value Wmin and the maximum value Wmax of the groove width is 0 when the groove width is constant and when the groove width changes. .95 or more.

  Such inner groove portion 13i and outer groove portion 13o ensure a ground contact area on the inner side in the tire axial direction of the shoulder block 12 and ensure a sufficient frictional force on an icy road. For this reason, ice road performance improves. Further, the outer groove 13o is wider than the inner groove 13i. Thereby, during wet running, the water film in the inner groove 13i is effectively discharged outward in the tire axial direction, and drainage performance is improved.

  When the groove width W5 of the inner groove portion 13i is reduced, the drainage performance may be reduced. When the groove width W5 is increased, the ground contact area of the shoulder block 12 may be reduced and the ice performance may be reduced. For this reason, the groove width W5 is preferably 0.15 times or more, more preferably 0.18 times or more of the maximum length L4 (shown in FIG. 1) of the shoulder block 12 in the tire circumferential direction. Also, it is preferably 0.25 times or less, more preferably 0.22 times or less.

  From the same viewpoint, the groove length L1 of the inner groove portion 13i in the tire axial direction is preferably 0.35 times or more, more preferably 0.40 times or more of the maximum width W7 of the shoulder block 12 in the tire axial direction. Moreover, Preferably it is 0.50 times or less, More preferably, it is 0.45 times or less.

  If the groove width W6 of the outer groove portion 13o is reduced, the drainage performance may be reduced, and if it is increased, the steering stability may be reduced. For this reason, the groove width W6 is preferably 1.40 times or more, more preferably 1.45 times or more, and preferably 1.60 times or less, more preferably 1.5 times or more of the groove width W5 of the inner groove portion 13i. 55 times or less.

  From the same viewpoint, the groove length L2 of the outer groove portion 13o is preferably 0.35 times or more, more preferably 0.40 times or more, and preferably 0.55 times the maximum width W7 of the shoulder block 12. Below, more preferably 0.50 times or less.

  As shown in FIG. 2, the groove depth D4 of the outer groove portion 13o is desirably larger than the groove depth D3 of the inner groove portion 13i. Further, the groove depth D4 of the outer groove portion 13o is preferably 1.40 times or more, more preferably 1.45 times or more, more preferably 1.60 times or less of the groove depth D3 of the inner groove portion 13i. More preferably, it is 1.55 times or less. Such an outer groove portion 13o discharges water in the inner groove portion 13i to the outer side in the tire axial direction more effectively while maintaining the rigidity of the shoulder block 12 on the inner side in the tire axial direction. For this reason, drainage performance is improved while maintaining ice performance.

  As shown in FIG. 3, each of the inner groove portion 13i and the outer groove portion 13o includes at least one shift portion 15 that is displaced to one side in the tire circumferential direction. Such a shift part 15 has an edge component which exhibits a frictional force in the tire axial direction, and improves snow road performance and ice road performance.

  The shift portion 15 of the present embodiment is formed to include a short side portion 16 and a pair of long side portions 17 and 17 connected to both ends of the short side portion 16.

  It is desirable that the short side portion 16 extends at an angle θ2 larger than 45 ° with respect to the tire axial direction. Such a short side part 16 exhibits a large frictional force in the tire axial direction and improves the performance on ice. In addition, the snow that has been compacted in the shoulder lateral groove 13 is sheared by the shift portion 15, thereby improving the performance on snow. From such a viewpoint, the angle θ2 of the short side portion 16 is more preferably 50 ° or more, and further preferably 55 ° or more. Further, when the angle θ2 is increased, the drainage performance may be deteriorated. For this reason, the angle θ2 is preferably 75 degrees or less, more preferably 70 degrees or less.

  If the length L3 in the tire circumferential direction of the short side portion 16 is reduced, the frictional force in the tire axial direction may be reduced, and if it is increased, the drainage performance may be reduced. For this reason, the length L3 is preferably 0.05 times or more, more preferably 0.07 times or more, and preferably 0.07 times or more of the maximum length L4 (shown in FIG. 1) of the shoulder block 12 in the tire circumferential direction. It is 0.12 times or less, more preferably 0.10 times or less. The length L3 is preferably 1.0 to 2.0 mm. Thereby, for example, stone biting in the shoulder lateral groove 13 is also suppressed.

  The long side portion 17 preferably extends from both ends of the short side portion 16 at an angle θ3 of 30 degrees or less with respect to the tire axial direction. Such a long side portion 17 effectively discharges the water film in the shoulder lateral groove 13 to the outer side in the tire axial direction. From such a viewpoint, the angle θ3 of the long side portion 17 is more preferably 15 degrees or less, and further preferably 13 degrees or less. Further, when the angle θ3 is reduced, the frictional force in the tire axial direction is reduced. Therefore, the angle θ3 is preferably 5 degrees or more, more preferably 7 degrees or more.

  Each long side portion 17 is preferably longer than the short side portion 16. Such a long side part 17 exhibits a frictional force in the tire circumferential direction and improves snowy road performance. Further, if the length L5 in the tire axial direction of each long side portion 17 is reduced, the frictional force in the tire circumferential direction may be reduced. If the length L5 is increased, the length of the shift portion 15 that can be disposed in the shoulder lateral groove 13 is increased. There is a risk that the number will decrease and snow road performance and ice road performance will deteriorate. For this reason, the length L5 is preferably at least 0.12 times, more preferably at least 0.15 times, and preferably at most 0.25 times, more preferably at least 0.12 times the maximum width W7 of the shoulder block 12. 22 times or less.

  The length L5 of each long side portion 17 varies depending on the number of shift portions 15. For example, when the two shift portions 15 are arranged as in the inner groove portion 13i of the present embodiment, the length L5 of the long side portion 17 is 0.12 to 0. 0 of the maximum width W7 of the shoulder block 12. It is preferably 21 times. Further, when one shift portion 15 is arranged as in the outer groove portion 13o of the present embodiment, the length L5 of the long side portion 17 is 0.17 to 0. 0 of the maximum width W7 of the shoulder block 12. It is desirable that it is 25 times.

  If the number of the shift portions 15 is small, the above-described effects may be small, and if the number is large, there is a possibility that damage is caused to the groove edge of the shoulder lateral groove 13. From such a viewpoint, the number Ni of the shift portions 15 of the inner groove portion 13i and the number No of the shift portions 15 of the outer groove portion 13o are each preferably 1 or more, more preferably 2 or more, and preferably 5 or less. More preferably, it is desirable to provide three or less shift portions 15.

The outer groove 13o is that not comprise a small number of shift portion 15 than the inner groove portion 13i. Such an outer groove portion 13o suppresses block chipping on the outer side in the tire axial direction of the shoulder block 12 while maintaining snow road performance and ice road performance. Furthermore, such an outer groove 13o improves drainage of the shoulder lateral groove 13 and improves drainage .

  It is desirable that a widened portion 18 communicating with the tread ground contact Te with a groove width W8 larger than that of the outer groove portion 13o is provided on the outer side in the tire axial direction of the outer groove portion 13o. Such a widened portion 18 discharges the water film in the shoulder lateral groove 13 more effectively to the outer side in the tire axial direction, and improves drainage. Such a widened portion 18 is also useful for improving the wandering performance.

  If the groove width W8 of the widened portion 18 is small, the above-described effects may not be obtained. If the groove width W8 is large, the shoulder lateral grooves 13 may be easily bitten by stones. From such a viewpoint, the groove width W8 is preferably 1.70 times or more, more preferably 1.75 times or more, and more preferably 1.90 times or less, more preferably, the groove width W6 of the outer groove portion 13o. Is 1.85 times or less.

  FIG. 4 shows a partially enlarged view of the shoulder block 12. As shown in FIG. 4, the maximum width W7 of the shoulder block 12 in the tire axial direction is set to 0.20 to 0.25 times the tread ground contact width TW (shown in FIG. 1), for example. Further, the maximum length L4 of the shoulder block 12 in the tire circumferential direction is set to 0.80 to 0.90 times the maximum width W7, for example.

  The shoulder block 12 has a shoulder inner vertical edge 19 that is an end edge on the tire equator C side, and a shoulder outer vertical edge 20 that is an end edge on the tread ground contact end Te side.

  The shoulder inner vertical edge 19 of the present embodiment includes a plurality of circumferential pieces 21 inclined at an angle θ4 of 3 to 15 ° with respect to the tire circumferential direction, and the circumferential piece 21 between the circumferential pieces 21 and 21. Concavities and convexities are formed by a plurality of axial pieces 22 that are joined with opposite inclinations. Due to such irregularities, an edge component that exerts a frictional force in the tire circumferential direction of the shoulder block 12 becomes large.

  If the angle θ4 of the circumferential piece 21 with respect to the tire circumferential direction is small, the edge component may be small, and if it is large, the drainage performance of the shoulder main groove 3 may be deteriorated. For this reason, the said angle (theta) 4 of the circumferential piece 21 becomes like this. Preferably it is 5 degrees or more, Preferably it is 13 degrees or less.

  The circumferential length L6 of the circumferential piece 21 is preferably at least 0.10 times, more preferably at least 0.12 times, preferably at least 0.12 times the maximum length L4 of the shoulder block 12 in the tire circumferential direction. 20 times or less, more preferably 0.18 times or less. Such a circumferential piece 21 suppresses biting of the shoulder main groove 3 while suppressing damage to the shoulder inner vertical edge 19.

  It is desirable that the axial piece 22 that connects between the circumferential pieces 21 and 21 extends while inclining with respect to the tire axial direction. Further, the angle θ5 of the axial piece 22 with respect to the tire axial direction is preferably 10 ° or more, more preferably 20 ° or more, and preferably 35 ° or less, more preferably 25 ° or less. Such an axial piece 22 effectively exhibits a frictional force in the tire circumferential direction while suppressing the occurrence of cracks in the shoulder inner vertical edge 19.

  The shoulder outer vertical edge 20 preferably extends linearly along the tread grounding end Te. Such a shoulder outer vertical edge 20 exhibits a large frictional force with respect to the tire axial direction while suppressing block breakage of the shoulder block 12.

  The shoulder block 12 includes a shoulder narrow groove 23 extending in the tire circumferential direction. Thus, the shoulder block 12 is divided into an inner block piece 24 on the inner side in the tire axial direction and an outer block piece 25 on the outer side in the tire axial direction.

  The shoulder narrow groove 23 is preferably communicated between the inner groove portion 13 i and the outer groove portion 13 o of the shoulder lateral groove 13. Such shoulder narrow grooves 23 assist drainage of the shoulder lateral grooves 13 and improve drainage performance.

  The angle θ6 (not shown) of the shoulder narrow groove 23 with respect to the tire circumferential direction is preferably 10 ° or less, more preferably 5 ° or less. More preferably, the shoulder narrow groove 23 extends parallel to the tire circumferential direction. Such shoulder narrow grooves 23 make the shape of the inner block piece 24 and the outer block piece 25 close to a rectangle, and as a result, ensure the rigidity of the shoulder block 12. For this reason, ice road performance improves.

  The shoulder narrow groove 23 preferably extends with a substantially constant groove width W9. The groove width W9 is, for example, preferably 0.15 times or more, more preferably 0.20 times or more, and preferably 0.30 times or less, more preferably, the groove width W1 of the shoulder main groove 3. It is 0.25 times or less. Such shoulder narrow grooves 23 improve drainage performance while maintaining the rigidity of the shoulder block 12.

  The width W10 in the tire axial direction of the inner block piece 24 and the width W11 in the tire axial direction of the outer block piece 25 are each preferably 0.40 times or more, more preferably, the maximum width W7 of the shoulder block 12 in the tire axial direction. It is 0.45 times or more, preferably 0.60 times or less, more preferably 0.55 times or less. Such an inner block piece 24 and an outer block piece 25 make the rigidity distribution of the shoulder block 12 appropriate, and improve steering stability while suppressing block chipping.

  As shown in FIG. 4, a plurality of shoulder sipes 26 are formed on the inner block piece 24 and the outer block piece 25.

  The shoulder sipe 26 is a semi-open type sipe whose one end communicates with the shoulder narrow groove 23 and the other end terminates inside the block. Such a shoulder sipe 26 increases an edge component that exerts a frictional force in the tire circumferential direction while maintaining the rigidity of the shoulder block 12. For this reason, snowy road performance improves, maintaining ice road performance.

  The shoulder sipe 26 is desirably inclined in the same direction with respect to the shoulder lateral groove 13 adjacent to the tire circumferential direction and the tire axial direction. Such a shoulder sipe 26 makes the rigidity distribution of the shoulder block 12 uniform and suppresses block chipping.

  The shoulder sipe 26 of the present embodiment includes a wave-like portion 27 extending in a wave shape, and straight portions 28 and 28 connected to both ends of the wave-like portion 27. Such a shoulder sipe 26 exhibits a frictional force not only in the tire circumferential direction but also in the tire axial direction, and improves snow road performance and ice road performance.

  As mentioned above, although the pneumatic tire of this invention was demonstrated in detail, it cannot be overemphasized that this invention can be changed into various aspects, without being limited to said specific embodiment.

  A pneumatic tire of size 195 / 80R15 based on the specifications in Table 1 was prototyped based on the specifications in Table 1, and the drainage performance, ice performance (braking force) and snow performance of each sample tire were tested.

  The tread pattern of Comparative Example 1 is shown in FIG. The shoulder lateral groove of Comparative Example 1 does not have a shift portion. Moreover, the tread pattern of the comparative example 2 is provided with the shift part only in the inner groove part of the tread pattern of FIG. Further, the tread pattern of Example 1 is the same as the tread pattern shown in FIG. In Comparative Examples 3 to 5 and Examples 2 to 25, a part of the configuration of the tread pattern shown in FIG. 1 is changed. The common specifications are as follows.

Tread contact width TW: 162mm
Shoulder main groove width W1: 4.9-6.1 mm
Shoulder main groove depth D1: 12.5mm
Center main groove width W2: 3.9 to 5.0 mm
Center main groove depth D2: 12.5mm
The test method is as follows.

<Snow road performance>
Each sample tire was mounted on all wheels of a 2700cc four-wheel drive vehicle under the following conditions, and was run on a snowy road test course by one driver. The driving characteristics at this time, such as steering response, rigidity, and grip, were evaluated by the driver's sensuality. The results are displayed with a score of Comparative Example 1 being 100. The larger the value, the better.
Rim 15 × 6J
Internal pressure: 350 kPa (front wheel)
Internal pressure: 425 kPa (rear wheel)
Load: 4.9kN

<Ice performance (braking force)>
The test vehicle traveled on an icy road test course, suddenly braked from a speed of 30 km / h, and the braking distance until stopping was measured. The result is displayed as an index with the reciprocal of the braking distance of Comparative Example 1 as 100. The larger the value, the better.

<Drainage performance>
The test vehicle was run on a wet asphalt road test course having a total length of 2000 m, and the running time at that time was measured. In order to make the wet conditions the same, the water depth on the road surface was unified to 5 mm immediately before traveling. The result is displayed as an index with the reciprocal of the traveling time of Comparative Example 1 as 100. The larger the value, the better.

  As a result of the test, it was confirmed that the drainage performance, snowy road performance, and icy road performance of the tires of the examples were significantly improved as compared with the comparative example.

2 Tread portion 3 Shoulder main groove 12 Shoulder block 13 Shoulder lateral groove 13i Inner groove portion 13o Outer groove portion 13 Shoulder lateral groove 15 Shift portion

Claims (8)

By providing the tread portion with a pair of shoulder main grooves extending continuously in the tire circumferential direction from the most tread ground end side and a shoulder lateral groove extending in the tire axial direction from the shoulder main groove to the tread ground end, A pneumatic tire in which a plurality of shoulder blocks are arranged along the tread ground end,
The shoulder lateral groove is inclined at an angle of 5 to 15 ° with respect to the tire axial direction,
In addition, the shoulder lateral groove includes an inner groove portion that extends from the shoulder main groove with a substantially constant groove width, and an outer groove portion that is continuous with the inner groove portion and extends to the tread grounding end side with a substantially constant groove width that is larger than the inner groove portion. Including
Wherein the groove portion and the outer groove are each at least one saw including a shift unit that is displaced in the one side in the tire circumferential direction,
The pneumatic tire according to claim 1, wherein the outer groove portion includes fewer shift portions than the inner groove portion .   The shift portion includes a short side portion extending at an angle larger than 45 ° with respect to the tire axial direction, an angle of 30 ° or less with respect to the tire axial direction from both ends of the short side portion, and the short side portion. The pneumatic tire according to claim 1, comprising a pair of long side portions having a length longer than that of the pneumatic tire. The shoulder block is divided into an inner block piece on the inner side in the tire axial direction and an outer block piece on the outer side in the tire axial direction by a shoulder narrow groove extending in the tire circumferential direction,
The pneumatic tire according to claim 1 or 2, wherein the shoulder narrow groove communicates between the inner groove portion and the outer groove portion of the shoulder lateral groove. The shoulder block is divided into an inner block piece on the inner side in the tire axial direction and an outer block piece on the outer side in the tire axial direction by a shoulder narrow groove extending in the tire circumferential direction,
The inner block piece and the outer block piece are each formed with a plurality of semi-open type shoulder sipes whose one end communicates with the shoulder narrow groove and the other end terminates inside the block. The pneumatic tire according to any one of the above.   The air according to any one of claims 1 to 4, wherein a widened portion that communicates with the tread ground contact end with a larger groove width than the outer groove portion is provided on the outer side in the tire axial direction of the outer groove portion of the shoulder lateral groove. Enter tire.   The pneumatic tire according to any one of claims 1 to 5, wherein each of the inner groove portion and the outer groove portion includes 1 to 5 shift portions. The pneumatic tire according to any one of claims 1 to 6 , wherein the shift portion of the outer groove portion is one less than the shift portion of the inner groove portion . The pneumatic tire according to any one of claims 1 to 7 , wherein a groove depth of the outer groove portion is 1.4 to 1.6 times a groove depth of the inner groove portion .

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