JP5997729B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire having improved performance on snow while maintaining dry performance and wet performance.

  For example, Patent Document 1 below proposes a pneumatic tire in which the shape of the groove wall of the main groove is improved in order to improve the performance on snow. Specifically, the main groove of the pneumatic tire of Patent Document 1 has an upper wall surface portion extending from the edge of the groove and a smaller inclination angle than the upper wall surface portion in the tire radial direction in a cross section orthogonal to the groove. It has a lower wall surface part. In addition, convex portions having a triangular cross section are provided in the tire circumferential direction on the lower wall surface portion.

  When such a main groove travels on snow, the convex portion strongly presses and solidifies the snow in the groove, and a large snow column shearing force is obtained.

JP 2009-090680 A

  However, the main groove of Patent Document 1 has a tendency to have low drainage because a convex portion is provided in the groove. Moreover, since the main groove of Patent Document 1 has a large opening width on the tread surface, there is a tendency to reduce the land ratio of the tire and consequently to the steering stability on the dry road surface.

  The present invention was devised in view of the actual situation as described above, and on the basis of improving the cross-sectional shape of the main groove provided in the tread portion, while maintaining dry performance and wet performance, performance on snow The main purpose is to provide a pneumatic tire with improved performance.

According to a first aspect of the present invention, a shoulder main groove that is provided in the tread portion at the most tread end side and extends continuously in the tire circumferential direction, and continuously in the tire circumferential direction on the tire equator side of the shoulder main groove. A pneumatic tire including a center main groove extending, and a middle land portion divided between the shoulder main groove and the center main groove , wherein the shoulder main groove is in a meridian cross section including a tire rotation axis. an inner groove wall of the tire equator side includes an outer groove wall angle of inclination than the inner groove wall is greater the tread end side, in the middle land portion communicates with the shoulder main grooves and the tire axial direction A first middle sipe having a terminal portion whose inner end terminates in the middle land portion, and a second middle sipe that communicates between the shoulder main groove and the center main groove. Sipes and the second Midorusaipu is a bottom at the end of the shoulder main groove side is characterized by having a first shallow portion which is raised.

In the pneumatic tire of the present invention, the first middle sipe and the second middle sipe have a second shallow bottom portion whose bottom surface is raised on the tire equator side with respect to the first shallow bottom portion, and the first middle sipe of the first middle sipe The second shallow bottom portion is provided between the first shallow bottom portion and the end portion, and the second shallow bottom portion of the second middle sipe is provided at an end portion on the center main groove side. Is desirable.

According to a second aspect of the present invention, a shoulder main groove that is provided on the tread end side and extends continuously in the tire circumferential direction, a middle land portion adjacent to the tire equator side of the shoulder main groove, A pneumatic tire including a shoulder land portion on an outer side in a tire axial direction of the shoulder main groove, wherein the shoulder main groove includes an inner groove wall on a tire equator side and the inner groove in a meridian section including a tire rotation axis. An outer groove wall on the tread end side having a larger inclination angle than the wall, and the middle land portion is provided with a sipe communicating with the shoulder main groove, and the sipe is an end portion on the shoulder main groove side. The shoulder land portion has a plurality of shoulder lateral grooves extending in the tire axial direction and the shoulder lateral grooves adjacent to each other in the tire circumferential direction. And the shoulder longitudinal sipe is provided for communicating, said shoulder longitudinal sipe is characterized by having a shallow portion of the bottom surface is raised at the end of the tire circumferential direction.

In the pneumatic tire of the present invention, the shoulder vertical sipe has a pair of first shallow bottom portions whose bottom surfaces are raised at both end portions in the tire circumferential direction, and a bottom surface is raised between the pair of first shallow bottom portions. It is desirable to have a second shallow bottom portion .

In the pneumatic tire of the present invention, the shoulder lateral groove extends from the tread end in the tire axial direction and has a terminal portion that terminates in the shoulder land portion, and the shoulder vertical sipe is the terminal end of the shoulder lateral groove. It is desirable to communicate with the part .

  The pneumatic tire of the present invention includes a main groove provided between the tire equator and the tread end and continuously extending in the tire circumferential direction, and a land portion divided by the main groove. The main groove includes an inner groove wall on the tire equator side and an outer groove wall on the tread end side having a larger inclination angle than the inner groove wall in a meridian cross section including the tire rotation axis. Such a shoulder main groove takes in a large amount of snow into the groove from the outer groove wall side and travels on the snow, and strongly presses the snow that has been taken in by the inner groove wall. For this reason, a hard snow column is formed in the main groove, and as a result, the performance on snow is improved.

  The land portion includes an inner land portion adjacent to the tire equator side of the main groove. A sipe communicating with the main groove is provided in the inner land portion. Such a sipe relaxes the compressive stress at the time of ground contact of the inner land portion, and suppresses uneven wear. In addition, such sipe edges scratch the road surface and increase the frictional force on wet road surfaces and ice road surfaces.

  The sipe has a shallow bottom portion with a raised bottom at the end on the main groove side. Such a shallow bottom portion maintains the rigidity of the inner land portion and maintains steering stability on a dry road surface. In addition, such a shallow bottom part also suppresses deformation on the inner groove wall side of the inner land part at the time of ground contact, so that the snow in the groove is more strongly compressed when running on snow, forming a stronger snow column To help.

  As described above, the pneumatic tire of the present invention can improve on-snow performance while maintaining dry performance and wet performance.

It is an expanded view of the tread part of the pneumatic tire of one embodiment of the present invention. It is the sectional view on the AA line of FIG. It is an enlarged view of the middle land part of FIG. FIG. 4 is a cross-sectional view of the first middle sipe of FIG. 3 taken along the line BB. It is CC sectional view taken on the line of the 2nd middle sipe of FIG. It is an enlarged view of the shoulder land part of FIG. It is the DD sectional view taken on the line of the shoulder lateral groove of FIG. It is the EE sectional view taken on the line of the shoulder vertical sipe of FIG. It is an enlarged view of the center land part of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a development view of a tread portion 2 of a pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment. The pneumatic tire 1 of the present embodiment is suitably used as a passenger car tire, for example.

  As shown in FIG. 1, the tread portion 2 includes a main groove 3 provided between the tire equator C and the tread end Te and continuously extending in the tire circumferential direction, and a land portion divided by the main groove 3. 5 is provided. The tread portion 2 of the present embodiment has, for example, a substantially point-symmetric tread pattern centered on a point on the tire equator C.

  The “tread end Te” is a rim assembled on a normal rim (not shown) and filled with a normal internal pressure. Further, the normal load 1 is loaded with a normal load and a flat surface with a camber angle of 0 ° is applied. This is the ground contact position on the outermost side in the tire axial direction when grounded.

  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, “Design Rim” for TRA, If there is "Measuring Rim".

  “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. “JAMATA” is the “highest air pressure”, TRA is the table “TIRE LOAD LIMITS AT” The maximum value described in “VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO.

  “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. “JATMA” is “Maximum load capacity”, TRA is “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO.

  The main groove 3 includes, for example, a pair of shoulder main grooves 7 and 7 and a pair of center main grooves 8 and 8. Each shoulder main groove 7 is provided, for example, on the most tread end Te side. For example, one center main groove 8 is provided between the pair of shoulder main grooves 7 and 7 and on both sides of the tire equator C.

  The shoulder main groove 7 and the center main groove 8 extend linearly, for example. The shoulder main groove 7 and the center main groove 8 are not limited to such an embodiment, and may extend in a zigzag shape or a wave shape.

  The groove width W1 of the shoulder main groove 7 and the groove width W2 of the center main groove 8 are, for example, 5.0 to 8.0% of the tread ground contact width TW. The tread contact width TW is a distance in the tire axial direction between the tread ends Te and Te of the tire 1 in the normal state. The shoulder main groove 7 and the center main groove 8 as described above exhibit excellent performance on snow while maintaining steering stability on the dry road surface. In a preferred embodiment, the groove width W2 of the center main groove 8 is formed larger than the groove width W1 of the shoulder main groove 7. Such a center main groove 8 effectively improves wet performance and performance on snow.

  In order to improve the steering stability on the dry road surface and the wet performance in a well-balanced manner, the total width (W1 + W2) × 2 of the shoulder main groove 7 and the center main groove 8 is preferably 0.2 of the tread ground contact width TW. Times or more, more preferably 0.22 times or more, preferably 0.3 times or less, more preferably 0.28 times or less.

  2 shows a cross-sectional view of the shoulder main groove 7 and the center main groove 8 of FIG. As shown in FIG. 2, the shoulder main groove 7 includes an inner groove wall 12 on the tire equator C side and an outer groove wall 13 on the tread end Te side having a larger inclination angle than the inner groove wall 12. The inclination angle of the groove wall is an angle with respect to the tread normal 14 standing on the tread surface passing through the groove edge. Such a shoulder main groove 7 takes in a large amount of snow into the groove from the outer groove wall 13 side and travels on the snow, and strongly pushes the taken snow with the inner groove wall 12. For this reason, a hard snow column is formed in the shoulder main groove 7, and as a result, the performance on snow is improved.

  In a preferred embodiment, the inclination angle θ1 of the inner groove wall 12 is, for example, 10 to 14 °. Similarly, the inclination angle θ2 of the outer groove wall 13 is, for example, 12 to 18 °.

  The angle difference θ2-θ1 between the inclination angle θ2 of the outer groove wall 13 and the inclination angle θ1 of the inner groove wall 12 is preferably 4 ° or more, more preferably 5 ° or more, preferably 8 ° or less, more preferably It is 7 degrees or less. When the angle difference θ2−θ1 is smaller than 4 °, the above-described effect may be reduced. When the angle difference θ2−θ1 is larger than 8 °, the groove volume of the shoulder main groove 7 becomes too large, and the steering stability on the dry road surface may be lowered.

  The center main groove 8 of the present embodiment has the same inclination angle θ3 of the groove walls 10 and 10 on both sides. In a preferred embodiment, the inclination angle θ3 of the groove wall 10 of the center main groove 8 is, for example, 10 to 14 °. As described above, in the present embodiment, the configuration of the outer groove wall 13 and the inner groove wall 12 having different inclination angles described above is employed only in the shoulder main groove 7, but may be employed in the center main groove 8. good.

  FIG. 3 shows an enlarged view of the inner land portion 15 adjacent to the tire equator C side of the shoulder main groove 7. The inner land portion 15 of the present embodiment is a middle land portion 16 divided between the shoulder main groove 7 and the center main groove 8.

  The middle land portion 16 is provided with a sipe 19 communicating with the shoulder main groove 7. In this specification, “sipe” means a cut having a width of 1.5 mm or less, and is distinguished from a drainage groove.

  The sipe 19 relaxes the compressive stress at the time of the ground contact of the inner land portion 15 and suppresses uneven wear at the inner land portion 15. Moreover, the edge of the sipe 19 scratches the road surface and increases the frictional force on the wet road surface and the ice road surface.

  The sipe 19 includes, for example, a first middle sipe 21 having an inner end 20 whose inner end in the tire axial direction terminates in the middle land portion 16, and a second middle sipe that communicates between the shoulder main groove 7 and the center main groove 8. 22 is included.

  The first middle sipes 21 and the second middle sipes 22 are provided alternately in the tire circumferential direction, for example. The first middle sipe 21 and the second middle sipe 22 as described above bring the rigidity distribution of the middle land portion 16 close to uniform and effectively suppress the uneven wear.

  In order to enhance the frictional force in the tire circumferential direction and the tire axial direction in a well-balanced manner, the angles θ6 and θ7 of the first middle sipe 21 and the second middle sipe 22 with respect to the tire axial direction are preferably 10 ° or more, more preferably 15 ° or more. Yes, preferably 30 ° or less, more preferably 25 ° or less.

  4 is a cross-sectional view taken along line BB along the length direction of the first middle sipe 21 of FIG. 3, and FIG. A cross-sectional view taken along line C is shown. As shown in FIGS. 4 and 5, the first middle sipe 21 and the second middle sipe 22 have a shallow bottom portion 25 in which a bottom surface 24 is raised.

  The shallow portion 25 includes at least a first shallow portion 26 in which a bottom surface 24 is raised at an end portion on the shoulder main groove 7 side. Such a shallow bottom portion 25 maintains the rigidity of the inner land portion 15 and maintains steering stability on a dry road surface. Moreover, such a shallow bottom portion 25 also suppresses deformation on the inner groove wall 12 side of the middle land portion 16 at the time of ground contact, so that the snow in the groove is more strongly pressed and hardened when running on snow. Useful for snow column formation.

  The first shallow bottom portion 26 includes, for example, a top portion 30 that extends along the tread surface 15s of the inner land portion 15, and an inclined portion 31 that is continuous with the top portion 30 and is inclined with respect to the tread surface 15s.

  The depth d1 from the tread surface 15s to the top 30 of the sipe 19 is preferably 1.0 mm or more, more preferably 1.3 mm or more, preferably 2.0 mm or less, more preferably 1.7 mm or less. The first shallow bottom portion 26 increases the sipe edge effect while maintaining the rigidity of the inner groove wall 12.

  From the same viewpoint, the length W4 of the top portion 30 along the length direction of the sipe is preferably 2.0 mm or more, more preferably 2.3 mm or more, preferably 3.0 mm or less, more preferably 2. 7 mm or less.

  In FIG. 4, the angle θ5 of the inclined portion 31 with respect to the depth direction of the sipe perpendicular to the tread surface 15s is preferably 20 ° or more, more preferably 25 ° or more, preferably 40 ° or less, more preferably 35. ° or less. The inclined portion 31 of the present embodiment extends from the top portion 30 at a substantially constant angle, for example. Such an inclined part 31 makes the change of the rigidity of a land part moderate, and suppresses the uneven wear.

  The shallow bottom portion 25 of the present embodiment includes second shallow bottom portions 27a and 27b in which the bottom surface 24 is raised on the tire equator C side with respect to the first shallow bottom portion 26 described above. Such a second shallow bottom portion 27 makes the rigidity of the middle land portion 16 uniform, and suppresses uneven wear of the land portion while improving steering stability during dry traveling.

  As shown in FIG. 4, the second shallow bottom portion 27 a provided in the first middle sipe 21 is provided between the first shallow bottom portion 26 and the inner end 20 of the sipe 19. The second shallow bottom portion 27 a of the first middle sipe 21 has a top portion 32 extending along the land tread surface 15 s and a pair of inclined portions 33, 33 connected to both sides of the top portion 32. Such a second shallow bottom portion 27a suppresses excessive opening of the sipe at the time of grounding, and exhibits an excellent edge effect.

  The depth d2 from the tread surface 15s to the top portion 32 of the second shallow bottom portion 27a is preferably larger than the depth d1 of the top portion 30 of the first shallow bottom portion 26, for example. Since the second shallow bottom portion 27a suppresses the opening of the sipe while maintaining the water absorption of the sipe, the ice road surface can be firmly scratched, and the performance on ice can be effectively enhanced. In a preferred embodiment, the depth d2 is, for example, 3.0 to 4.5 mm.

  From the same viewpoint, the length W5 of the top portion 32 of the second shallow bottom portion 27a is preferably smaller than the length W4 of the top portion 30 of the first shallow bottom portion 26. In a preferred embodiment, the length W5 is, for example, 0.5 to 1.5 mm.

  The inclined portion 33 of the second shallow bottom portion 27a extends, for example, with respect to the tread surface 15s. In the present embodiment, the inclined portion 33 is concavely curved toward the inner side in the tire radial direction and toward the top portion 32 side. Such an inclined portion 33 smoothes the change in rigidity of the middle land portion 16 at the sipe position.

  As shown in FIG. 5, the second shallow bottom portion 27 b provided in the second middle sipe 22 is provided at an end portion on the center main groove 8 side. Such a second middle sipe 22 effectively maintains the rigidity of the middle land portion 16 on the inner side in the tire axial direction, and improves steering stability during dry travel.

  The second shallow bottom portion 27b has substantially the same shape as the first shallow bottom portion 26, for example. Thereby, the opening of the both ends of the sipe is effectively suppressed, and the steering stability during dry running is improved.

  As shown in FIG. 1, the land portion 5 further includes a shoulder land portion 35 on the outer side in the tire axial direction of the shoulder main groove 7, and a center land portion 36 between the pair of center main grooves 8, 8. Yes.

  FIG. 6 shows an enlarged view of the shoulder land portion 35. As shown in FIG. 6, the shoulder land portion 35 is provided with, for example, a plurality of shoulder lateral grooves 38 extending in the tire axial direction and a plurality of shoulder sipes 39.

  The shoulder lateral groove 38 has, for example, an inner end 40 extending inward in the tire axial direction from the tread end Te and terminating in the shoulder land portion 35.

  The shoulder lateral groove 38 extends, for example, at an angle of 0 to 5 ° with respect to the tire axial direction. In the shoulder lateral groove 38 of the present embodiment, the angle θ8 with respect to the tire axial direction gradually increases toward the inner side in the tire axial direction.

  FIG. 7 is a sectional view taken along the line DD along the length direction of the shoulder lateral groove 38 of FIG. As shown in FIG. 7, the shoulder lateral groove 38 has a terminal portion 42 formed with an inclined surface 41 in which the groove depth gradually decreases toward the inner end 40. Such a terminal portion 42 changes the rigidity of the shoulder land portion 35 smoothly, thereby suppressing uneven wear.

  An angle θ9 of the inclined surface 41 with respect to the tread normal 43 that passes through the inner end 40 of the shoulder lateral groove 38 and is perpendicular to the tread surface is, for example, 40 to 50 °. Such an inclined surface 41 can suppress uneven wear of the shoulder land portion 35 while maintaining the groove volume of the shoulder lateral groove 38.

  As shown in FIG. 6, the shoulder sipe 39 includes, for example, a shoulder connection sipe 44 that communicates between the shoulder lateral groove 38 and the shoulder main groove 7, and each shoulder lateral groove 38, 38 adjacent to each other in the tire circumferential direction. And a shoulder lateral sipe 46 extending in the tire axial direction between the shoulder lateral grooves 38, 38.

  For example, the shoulder connection sipe 44 communicates with the inner end 40 of the shoulder lateral groove 38 in the tire axial direction, and communicates with the shoulder main groove 7 along the extension line of the shoulder lateral groove 38. Such a shoulder connection sipe 44 can exhibit an excellent edge effect while maintaining the rigidity inside the shoulder land portion 35.

  As shown in FIG. 1, in order to make the wear of the groove edges on both sides of the shoulder main groove 7 uniform, the inner end 44i of the shoulder connecting sipe 44 in the tire axial direction and the outer side of the second middle sipe 22 in the tire axial direction are shown. The ends 22o are preferably close to each other in the tire circumferential direction. Specifically, the distance L1 in the tire circumferential direction between the inner end 44i of the shoulder connection sipe 44 and the outer end 22o of the second middle sipe 22 is preferably 0.5 times or less the groove width W1 of the shoulder main groove 7. More preferably, it is 0.3 times or less.

  As shown in FIG. 6, the shoulder vertical sipe 45 extends linearly along the tire circumferential direction, for example. Such a shoulder vertical sipe 45 exhibits a large frictional force with respect to the tire axial direction when traveling on ice, for example, and improves skid resistance.

  The shoulder vertical sipe 45 is desirably communicated with the end portion 42 side of the shoulder lateral groove 38, for example. Thereby, the partial wear near the edge part of the shoulder vertical sipe 45 is suppressed.

  FIG. 8 is a cross-sectional view taken along the line E-E along the length direction of the shoulder vertical sipe 45 of FIG. As shown in FIG. 8, the shoulder vertical sipe 45 has a shallow bottom portion 50 with a raised bottom surface.

  The shallow portion 50 includes, for example, a pair of first shallow portions 51 and 51 provided at both ends in the tire circumferential direction, and a second shallow portion 52 provided therebetween. Such a shallow bottom portion 50 effectively maintains the rigidity of the shoulder land portion 35, particularly the rigidity between the shoulder vertical sipe 45 and the shoulder main groove 7, and improves the steering stability on the dry road surface.

  The first shallow bottom portion 51 of the shoulder vertical sipe 45 has, for example, the same shape and size as the first shallow bottom portion 26 of the above-described first middle sipe 21 (shown in FIG. 4 and hereinafter the same). Can be done. Similarly, the second shallow bottom portion 52 of the shoulder vertical sipe 45 may have the same shape and size as the second shallow bottom portion 27a of the first middle sipe 21 described above, for example.

  As a particularly preferable aspect, the depth d3 of the first shallow bottom portion 51 of the shoulder vertical sipe 45 is desirably equal to the depth d4 at the position where the shoulder vertical sipe 45 of the inclined surface 41 of the shoulder lateral groove 38 is connected. Such a shoulder vertical sipe 45 can further suppress uneven wear.

  As shown in FIG. 6, one or two shoulder lateral sipes 46 are provided in each region between the shoulder lateral grooves 38, 38. The shoulder lateral sipe 46 is provided, for example, on the outer side in the tire axial direction of the shoulder longitudinal sipe 45 and extends along the shoulder lateral groove 38.

  The shoulder lateral sipe 46 is, for example, a full closed sipe whose both ends are terminated in the shoulder land portion 35. Such a shoulder lateral sipe 46 increases the frictional force on the wet road surface and the ice road surface while maintaining the rigidity of the shoulder land portion 35.

  FIG. 9 shows an enlarged view of the center land portion 36. As shown in FIG. 9, the center land portion 36 is, for example, a rib extending continuously in the tire circumferential direction. Such a center land portion 36 effectively enhances steering stability on a dry road surface.

  The center land portion 36 is provided with a plurality of center sipes 55 that communicate with the center main groove 8 and terminate in the center land portion 36, for example. Such a center sipe 55 suppresses distortion of the ground contact surface of the center land portion 36 and suppresses uneven wear.

  The center sipe 55 includes, for example, a first center sipe 56 extending from one center main groove and a second center sipe 57 extending from the other center main groove 8. In the present embodiment, a center sipe pair 58 composed of a first center sipe 56 and a second center sipe 57 that are adjacent to each other in the tire axial direction is spaced apart in the tire circumferential direction.

  Each center sipe 55 preferably terminates without straddling the tire equator C. Such a center sipe 55 effectively maintains the rigidity of the center land portion 36.

  For example, the center sipe 55 is preferably inclined at an angle θ10 of 30 to 50 ° with respect to the tire axial direction. Such a center sipe 55 exhibits an edge effect with a good balance with respect to the tire circumferential direction and the tire axial direction.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to illustrated embodiment, It can deform | transform and implement in a various aspect.

A pneumatic tire of size 215 / 55R16 having the basic pattern of FIG. 1 was prototyped based on the specifications in Table 1. As a comparative example, a tire in which the inner groove wall and the outer groove wall of the shoulder main groove have the same inclination angle and the middle sipe is not provided with a shallow bottom portion was prototyped. Each test tire was tested for handling stability on a dry road surface, wet performance, and performance on snow. The common specifications and test methods for each test tire are as follows.
Wearing rim: 16 × 6.5J
Tire internal pressure: front wheel 210 kPa, rear wheel 200 kPa

<Operation stability on dry road>
The driving stability of the following test vehicle when driving on a dry road test course was evaluated based on the driver's sensuality. A result is a score which sets the comparative example 1 to 100, and shows that steering stability is excellent, so that a numerical value is large.
Test vehicle: 2000cc displacement, front-wheel drive vehicle Test tire mounting position: all wheels

<Wet performance>
The test vehicle traveled on an asphalt road surface with a radius of 100 m provided with a puddle having a depth of 5 mm and a length of 20 m, and the lateral acceleration (lateral G) of the front wheels was measured. The result is an average lateral G at a speed of 50 to 80 km / h, and is represented by an index with the value of Comparative Example 1 being 100. Larger values indicate better wet performance.

<Snow performance>
The performance on the snow when running on a snowy road with the test vehicle was evaluated by the driver's sensuality. A result is a score which sets comparative example 1 to 100, and shows that performance on snow is excellent, so that a numerical value is large.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the pneumatic tire of the example improved the performance on snow while maintaining the dry performance and the wet performance.

1 Pneumatic tire 2 Tread part 3 Main groove
5 Land part 12 Inner groove wall 13 Outer groove wall 15 Inner land part 19 Sipe 25 Shallow part

Claims (5)

A shoulder main groove provided on the tread portion closest to the tread end and extending continuously in the tire circumferential direction, a center main groove extending continuously in the tire circumferential direction on the tire equator side of the shoulder main groove, and the shoulder main A pneumatic tire including a middle land portion divided between a groove and the center main groove ,
The shoulder main grooves includes at meridian section including the tire rotational axis, and the inner groove wall of the tire equator side and an outer groove wall angle of inclination than the inner groove wall is greater the tread end side,
The middle land portion includes a first middle sipe that has a terminal portion that communicates with the shoulder main groove and whose inner end in the tire axial direction terminates in the middle land portion, and between the shoulder main groove and the center main groove. And a second middle sipe communicating with
The pneumatic tire according to claim 1, wherein each of the first middle sipe and the second middle sipe has a first shallow bottom portion whose bottom surface is raised at an end of the shoulder main groove . The first middle sipe and the second middle sipe have a second shallow bottom portion whose bottom surface is raised on the tire equator side from the first shallow bottom portion,
The second shallow bottom portion of the first middle sipe is provided between the first shallow bottom portion and the terminal portion,
The pneumatic tire according to claim 1, wherein the second shallow bottom portion of the second middle sipe is provided at an end portion on the center main groove side. A shoulder main groove provided on the tread portion closest to the tread end and continuously extending in the tire circumferential direction, a middle land portion adjacent to the tire equator side of the shoulder main groove, and an outer side in the tire axial direction of the shoulder main groove A pneumatic tire including a shoulder land portion of
The shoulder main groove, in a meridian cross section including a tire rotation axis, includes an inner groove wall on the tire equator side, and an outer groove wall on the tread end side having a larger inclination angle than the inner groove wall,
The middle land portion is provided with a sipe communicating with the shoulder main groove,
The sipe has a shallow bottom portion with a raised bottom at an end on the shoulder main groove side,
The shoulder land portion is provided with a plurality of shoulder lateral grooves extending in the tire axial direction and shoulder longitudinal sipes communicating between the shoulder lateral grooves adjacent to each other in the tire circumferential direction,
The shoulder longitudinal sipe has a shallow bottom portion with a raised bottom surface at an end portion in the tire circumferential direction. The shoulder vertical sipe includes a pair of first shallow bottom portions whose bottom surfaces are raised at both ends in the tire circumferential direction, and a second shallow bottom portion whose bottom surface is raised between the pair of first shallow bottom portions. The pneumatic tire according to claim 3. The shoulder lateral groove extends from the tread end in the tire axial direction, and has a terminal portion that terminates in the shoulder land portion,
The pneumatic tire according to claim 3 or 4, wherein the shoulder vertical sipe communicates with the end portion of the shoulder lateral groove.

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