JP4778866B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and in particular, air in which a width direction sipe extending in a tread width direction is formed in a plurality of blocks formed by a plurality of grooves extending in a tire circumferential direction and a tire width direction. Related to tires.

  Various proposals have been made for pneumatic tires that improve grip performance (so-called edge effect) and improve driving performance on wet and icy roads, such as steering stability, acceleration performance, braking performance, and traction performance. Has been made. For example, a pneumatic tire is disclosed in which a plurality of blocks formed by a plurality of grooves extending in the tire circumferential direction and the tire width direction are formed with a plurality of width direction sipes extending in the tread width direction. (For example, refer to Patent Document 1).

In this pneumatic tire, the center block located on the tire equator line side among the plurality of blocks is set smaller than the shoulder block arranged on the outer side in the tread width direction than the center block, so that the vicinity of the tire equator line In this case, the edge effect can be sufficiently exhibited, and the running performance can be improved.
Japanese Patent Laid-Open No. 2001-191740 (pages 2 to 3 and FIG. 1)

  However, in the conventional pneumatic tire described above, the center block is formed by forming a center block smaller than the shoulder block in addition to the width direction sipe formed in the block (center block and shoulder block). As a result, the center block is deformed and the driving performance on the dry road surface, the wet road surface, and the ice / snow road surface, in particular, the steering stability, acceleration performance, and braking performance are deteriorated.

  Further, in the conventional pneumatic tire, as the deformation of the center block increases, the edge effect due to the width direction sipe is reduced, and the running performance on the wet road surface and the icy / snow road surface is deteriorated.

  Therefore, the present invention has been made in view of such problems, and improves driving performance on dry road surfaces, wet road surfaces, and icy and snowy road surfaces, particularly handling stability, acceleration performance, and braking performance on icy and snowy road surfaces. An object of the present invention is to provide a pneumatic tire that can be used.

In order to solve the above situation, the present invention has the following features. First, the invention according to the first feature of the present invention is the width direction extending in the tread width direction in the plurality of blocks formed by the plurality of grooves extending in the tire circumferential direction and the tire width direction on the tread surface. A pneumatic tire in which a sipe is formed, and a center block located on the tire equator line side among a plurality of blocks is smaller than a shoulder block arranged on the outer side in the tread width direction than the center block, and the center block is At least a part of the groove to be formed is formed by a bottom upper bottom surface having a depth shallower than a depth from the tread tread surface to the bottom surface in the groove forming the shoulder block, and at least one of the plurality of adjacent center blocks. The block is a triangular block composed of triangles in a tread plan view, At least one groove of the grooves forming a square block, with bottom is inclined, and gist being formed by a thin inclined narrow groove than the other grooves forming the triangle blocks.
Further, the present invention includes a plurality of adjacent center blocks each including an inner block and an outer block arranged on the outer side in the tread width direction than the inner block, and between the inner block and the outer block. Is formed with a groove having the bottom upper surface, and the inclined narrow groove is formed between the inner block and the triangular block and between the outer block and the triangular block. This is the gist.
Further, according to the present invention, the inner block includes a circumferential groove extending in the tire circumferential direction, a bottom upper groove having the bottom upper bottom surface that is shallower than the circumferential groove, and a depth shallower than the bottom groove. The outermost block is formed by the uppermost bottom groove having the uppermost bottom surface and the inclined narrow groove, and the outer block includes the circumferential groove, a widthwise groove extending in the tread width direction, and the circumferential direction. The gist of the present invention is that the groove is formed by the bottom upper groove having the bottom top bottom surface that is shallower than the groove and shallower than the widthwise groove, and the inclined narrow groove.

  According to such a feature, at least a part of the groove forming the center block is formed by the bottom upper bottom surface, so that the rigidity of the center block and the rigidity of the shoulder block are equalized, and the dry road surface, the wet road surface, the ice and snow Driving performance on the road surface, in particular, steering stability, acceleration performance, and braking performance on icy and snowy road surfaces can be improved.

  In addition, the sipe in the width direction is formed in the block (center block and shoulder block), so that the grip force (so-called edge effect) on the snowy and snowy road surface is improved, and the steering stability and acceleration performance on the snowy and snowy road surface, In addition to improving braking performance, water and snow on the ground contact surface (between the tread tread and the road surface) can escape to the sipe in the width direction, preventing hydroplaning, a phenomenon that lifts the tire. .

  Furthermore, the center block is positioned on the tire equator line side with respect to the shoulder block, thereby ensuring the volume of the groove forming the shoulder block and reducing the shear strength (shearing force) by the snow column in the shoulder block. Therefore, driving performance such as steering stability, acceleration performance, braking performance, traction performance on dry road surfaces, wet road surfaces, and icy and snowy road surfaces can be improved.

  The invention according to the second aspect of the present invention is such that at least a part of a groove forming one center block among a plurality of adjacent center blocks has a depth shallower than a depth to the bottom upper bottom surface. The gist is that it is formed.

  According to such a feature, at least a part of the groove forming one center block among the plurality of adjacent center blocks is formed on the bottom uppermost bottom surface, thereby further suppressing the reduction in rigidity of the center block. Further, it is possible to further improve driving performance such as driving stability, acceleration / braking performance, traction performance on dry road surfaces, wet road surfaces, and icy and snowy road surfaces.

  The gist of the invention according to the third feature of the present invention is that the shoulder block is formed with a circumferential sipe extending in the tire circumferential direction.

  According to such a feature, the circumferential sipe is formed on the shoulder block, so that the friction of the ground contact surface at the time of cornering can be increased, the side slip at the time of cornering can be prevented, and the wet road surface, ice and snow can be prevented. Hydroplaning during cornering on the road surface can be prevented.

  In the invention according to the fourth feature of the present invention, at least one of the plurality of adjacent center blocks is a triangular block made of a triangle in plan view of the tread, and at least one side of a groove forming the triangular block has a bottom surface. The gist of the present invention is that it is inclined and formed with an inclined narrow groove that is thinner than the groove.

  The invention according to the fifth feature of the present invention is summarized in that a narrow hole is formed in the triangular block and extends from the tread surface to the inner side in the tire radial direction.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can improve the driving | running | working performance on a dry road surface, a wet road surface, and an icy and snowy road surface, especially the steering stability, acceleration performance, and braking performance on an icy and snowy road surface can be provided.

  Next, an example of a pneumatic tire according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

  FIG. 1 is a development view showing a tread pattern of a pneumatic tire according to the present embodiment, and FIG. 2 is a perspective view of a block constituting a tread surface of the pneumatic tire according to the present embodiment. 3 is a cross-sectional view in the tread width direction of the pneumatic tire according to the present embodiment (A-A cross-sectional view in FIG. 1), and FIG. 4 is a cross-sectional view in the tread width direction of the pneumatic tire according to the present embodiment. FIG. 5 is a tire circumferential direction sectional view (CC sectional view of FIG. 1) of the pneumatic tire according to the present embodiment.

  The pneumatic tire according to the present embodiment is a general radial tire (studless tire) including a bead portion, a carcass layer, and a belt layer (not shown). Moreover, the pneumatic tire according to the present embodiment is mounted on a passenger car.

  As shown in FIGS. 1 and 2, the tread tread surface 1 in the pneumatic tire includes a plurality of circumferential grooves 3 extending in the tire circumferential direction and a plurality of circumferential grooves 3 extending in the tread width direction. A width direction groove 5 is formed.

  On the tire tread surface 1 on the tire equator line CL side, a plurality (three in the drawing) of center blocks 7 formed by a plurality of circumferential grooves 3 and a plurality of widthwise grooves 5 are arranged adjacent to each other. On the outer side in the tread width direction of the center block 7, a shoulder block 9 formed by a plurality of circumferential grooves 3 and a plurality of width direction grooves 5 and larger than the center block 7 is disposed. That is, the center block 7 is smaller than the shoulder block 9 disposed outside the center block 7 in the tread width direction.

  The center block 7 is formed with a width direction sipe 11 extending in a zigzag shape in the tread width direction. Further, the shoulder block 9 is formed with a width direction sipe 11 extending while repeating a zigzag shape toward the tread width direction and a circumferential direction sipe 13 extending while repeating a zigzag shape toward the tread circumferential direction. Yes.

  As shown in FIGS. 3 to 5, at least a part of the grooves (circumferential groove 3 and width groove 5) forming the center block 7 is a groove (circumferential groove 3 and width groove) forming the shoulder block 9. The bottom upper bottom surface 15a has a depth (D2) shallower than the depth from the tread tread surface 1 to the bottom surface in 5) (hereinafter, outer groove depth (D1)). Further, at least a part of the groove forming one center block 7 among the plurality of adjacent center blocks 7 is formed by the bottom uppermost bottom surface 17a having a depth shallower than the depth (D2) to the bottom upper bottom surface 15a. Has been.

  Specifically, first, at least one of the center blocks 7 positioned on the inner side in the tread width direction (most on the tire equator line CL side) of the upper bottom groove 15 extending in the tire circumferential direction, that is, at least one of the adjacent center blocks 7 is shown. The “inner block 7A” will be described.

  As shown in FIGS. 3 to 5, the inner block 7A includes a circumferential groove 3 having a bottom surface having the same depth as the outer groove depth (D1) and a depth shallower than the outer groove depth (D1) ( D2) a bottom top groove 15 having a bottom top bottom surface 15a, a bottom top groove 17 having a bottom top bottom surface 17a having a depth (D3) shallower than a depth (D2) to the bottom top bottom surface 15a, and an inclination It is formed by the narrow groove 19 (D1> D2> D3).

  The inclined narrow groove 19 is a groove (for example, a width of 1.5 mm or less) that is narrower than the grooves (circumferential groove 3 and width direction groove 5) while the bottom surface is inclined upward toward an obtuse corner. ) And may be made of sipe or the like.

  The bottom upper groove 15 having the bottom upper bottom surface 15a is located on the outer side of the inner block 7A in the tread width direction and on the opposite side of the tire rotation direction R. The bottom-most upper groove 17 having the bottom-most upper bottom surface 17a is located on the opposite side of the tire rotation direction R. Further, the inclined narrow groove 19 is located on the tire rotation direction R side.

  Next, an “outer block 7B” indicating at least one of the center blocks 7 located on the outer side in the tread width direction (most outer side in the tread width direction) of the bottom upper groove 15 extending in the tire circumferential direction, that is, the center blocks 7 adjacent to each other. Will be described.

  As shown in FIGS. 3 to 5, the outer block 7 </ b> B includes a circumferential groove 3 and a width direction groove 5 having a bottom surface having the same depth as the outer groove depth (D1), and an outer groove depth (D1). The upper bottom groove 15 having the bottom upper bottom surface 15a having a shallow depth (D2) and the inclined narrow groove 19 are formed (D1> D2).

  The bottom upper groove 15 having the bottom upper bottom surface 15a is located inside the inner block 7A in the tread width direction. The inclined narrow groove 19 is located on the tire rotation direction R side.

  Next, a description will be given of the center block 7 that is triangular in the tread plan view and is located closest to the tire rotation direction R, that is, the “triangular block 7C” that indicates at least one of the plurality of adjacent center blocks 7.

  As shown in FIGS. 3 to 5, the triangular block 7 </ b> C includes a circumferential groove 3 and a widthwise groove 5 having a bottom surface having the same depth as the outer groove depth (D <b> 1), and an outer groove depth (D <b> 1). The upper bottom groove 15 having the bottom upper bottom surface 15a having a shallow depth (D2) and the inclined narrow groove 19 are formed (D1> D2). That is, at least one side of the groove forming the triangular block 7 </ b> C is formed by the inclined narrow groove 19.

  The bottom upper groove 15 having the bottom upper bottom surface 15a is located on the tire rotation direction R side. Further, the inclined narrow groove 19 is located on the opposite side of the tire rotation direction R side.

  In the triangular block 7C, a narrow hole 21 extending from the tread surface 1 toward the inner side in the tire radial direction is formed. Note that the triangular block 7C does not necessarily have a triangular shape in a tread plan view, and may of course be a quadrangle in a tread plan view.

  Thus, at least a part of the grooves forming the center block 7 (the inner block 7A, the outer block 7B, and the triangular block 7C) has a depth (D2) shallower than the outer groove depth (D1). 15a. Further, at least a part of the groove forming one center block 7 (that is, the inner block 7A) among the plurality of adjacent center blocks 7 is shallower than the depth (D2) to the bottom upper bottom surface 15a (D3). ) And the bottom uppermost bottom surface 17a.

(Action / Effect)
According to the pneumatic tire according to the present embodiment described above, at least part of the grooves (circumferential groove 3 and width groove 5) forming the center block 7 is formed by the bottom upper bottom surface 15a. The rigidity of the center block 7 and the rigidity of the shoulder block 9 are equalized, so that driving performance on dry road surfaces, wet road surfaces and icy and snowy road surfaces, in particular, steering stability, acceleration performance and braking performance on icy and snowy road surfaces can be improved. it can.

  In addition, the sipe 11 in the width direction is formed on the blocks (the center block 7 and the shoulder block 9), thereby improving the grip force (so-called edge effect) on the snowy and snowy road surface, Acceleration and braking performance can be improved, and water and snow on the contact surface (between the tread tread and the road surface) can escape to the sipe in the width direction, preventing hydroplaning, a phenomenon of tire lifting. be able to.

  Furthermore, the center block 7 is positioned on the tire equator line CL side with respect to the shoulder block 9, so that the volume of the groove forming the shoulder block 9 is secured and the shear strength (shearing force) by the snow column in the shoulder block 9 is secured. Since it is not lowered, driving performance such as steering stability, acceleration performance, braking performance, and traction performance on dry road surfaces, wet road surfaces, and icy and snow road surfaces can be improved.

  In addition, the rigidity of the center block 7 is reduced by forming at least a part of the groove forming one center block 7 (that is, the inner block 7A) among the plurality of adjacent center blocks 7 by the uppermost bottom surface 17a. , And driving performance such as steering stability, acceleration / braking performance, and traction performance on dry road surfaces, wet road surfaces, and ice and snow road surfaces can be further improved.

  Further, since the circumferential sipe 13 is formed on the shoulder block 9, it is possible to increase the friction of the ground contact surface at the time of cornering, to prevent a side slip at the time of cornering, and at the wet road surface and the ice and snow road surface. Hydroplaning during cornering can be prevented.

  Further, since the triangular block 7C is triangular in the tread plan view, the penetration force of the triangular block 7C on the snowy and snowy road surface is increased, and the running performance on the snowy and snowy road surface (for example, steering stability, acceleration / braking performance, traction) Performance) can be further improved.

  Further, since the narrow hole 21 is formed in the triangular block 7C, it is possible to suppress a decrease in rigidity of the triangular block 7C as compared with the sipe (the width direction sipe 11 and the circumferential direction sipe 13), and the ground contact surface. Since water, snow, etc. can escape to the narrow hole 21, it is possible to further improve driving performance such as steering stability, acceleration / braking performance, traction performance on dry road surfaces, wet road surfaces, and icy and snow road surfaces.

  In addition, since the triangular block 7C is a triangle in the tread plan view, the rigidity of the obtuse corner may be reduced. However, in addition to the fact that the bottom surface of the inclined narrow groove 19 is inclined upward from the tire equator line CL side toward the outer side in the tread width direction, the narrow hole 21 having higher rigidity than the sipe is arranged, so that the triangle The rigidity of the block 7C can be ensured.

  Thereby, since deformation of the center block 7 on the tire equator line CL side, which is smaller than the shoulder block 9 and the load is likely to concentrate, can be suppressed, the rigidity on the tire equator line CL side in the center block 7 can be reduced. It is possible to improve driving performance on dry roads, wet roads, icy and snowy roads, and driving performance such as acceleration / braking performance and traction performance can be further improved.

[Other embodiments]
As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention.

  Specifically, although the pneumatic tire according to the present embodiment has been described as a general radial tire including a bead portion, a carcass layer, and a belt layer (not shown), it is not limited thereto. Alternatively, a tire other than a radial tire (for example, a bias tire) may be used.

  Further, the pneumatic tire according to the present embodiment has been described as being mounted on a passenger car, but is not limited thereto, and is mounted on a vehicle other than a passenger car (for example, a bus / truck). There may be.

  Furthermore, in the pneumatic tire according to the present embodiment, the description has been given assuming that the three center blocks 7 of the inner block 7A, the outer block 7B, and the triangular block 7C are adjacent to each other, but the present invention is not limited to this. Instead, for example, it may consist of one center block 7, any two center blocks 7 may be adjacent, or three or more center blocks 7 may be adjacent.

  From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  Next, in order to further clarify the effects of the present invention, the results of tests performed using pneumatic tires according to the following comparative examples and examples will be described. In addition, this invention is not limited at all by these examples.

  Data on each pneumatic tire was measured under the following conditions.

・ Tire size: 195 / 65R15
・ Wheel size: 15 × 6JJ
・ Internal pressure condition: 200kPa
・ Vehicle conditions: FR vehicle (displacement 2500cc)
・ Load conditions: 1 driver + 60kg (equivalent to 2 passengers)
First, the structure of the pneumatic tire which concerns on a comparative example and an Example is demonstrated. Each pneumatic tire has the same conditions except for the depth from the tread surface to the bottom surface in the groove described below.

  In the pneumatic tire according to the comparative example, all the depths from the tread surface to the bottom surface in the grooves (circumferential groove and width groove) forming the center block and the shoulder block are the same. The pneumatic tire according to this comparative example has the following conditions.

・ Negative rate of tread: 28%
・ Circumferential groove width: 9.5 mm (on the tire equator line), 5.0 mm (shoulder side)
・ Circumferential groove depth: 8.9 mm
・ Width of width direction groove: 7.0mm
・ Depth of width direction groove: 8.9mm
・ Circumferential sipe width: 1.0 mm
・ Width of sipe in width direction: 0.4mm
・ Width of narrow groove: 1.5mm
・ Diameter of narrow hole: ψ1.5mm
The pneumatic tire according to the example is the pneumatic tire according to the above-described embodiment (see FIGS. 1 to 5). The pneumatic tire according to this example has the following conditions.

・ Negative rate of tread: 28%
・ Circumferential groove width: 9.5 mm (on the tire equator line), 5.0 mm (shoulder side)
・ Circumferential groove depth: 8.9 mm
・ Width of width direction groove: 7.0mm
・ Depth of width direction groove: 8.9mm
・ Depth to bottom bottom: 7.0mm
・ Depth to bottom and top bottom: 3.5mm
・ Circumferential sipe width: 1.0 mm
・ Width of sipe in width direction: 0.4mm
・ Inclined narrow groove width: 1.5mm
・ Diameter of narrow hole: ψ1.5mm
Refer to Table 1 for the handling stability on the dry road surface, the handling stability and hydroplaning on the wet road surface, the acceleration performance on the snowy and snowy road surface, the braking performance, and the steering stability of the pneumatic tires according to the comparative examples and the examples. While explaining.

<Operation stability on dry road>
Each pneumatic tire is mounted on a vehicle, runs on a test course on a dry road surface at a constant speed, the handling stability of the pneumatic tire according to the comparative example is set to “100”, and the handling stability of the pneumatic tire according to the embodiment is stabilized. The feeling was evaluated by a professional driver. The larger the index, the better the steering stability.

  As a result, it was found that the pneumatic tire according to the example was superior in steering stability on the dry road surface as compared with the pneumatic tire according to the comparative example.

<Operation stability on wet road>
Each pneumatic tire is mounted on a vehicle, runs on a test course on a wet road surface at a constant speed, the handling stability of the pneumatic tire according to the comparative example is set to “100”, and the handling stability of the pneumatic tire according to the example is achieved. The feeling was evaluated by a professional driver. The larger the index, the better the steering stability.

  As a result, it was found that the pneumatic tire according to the example was superior in steering stability on the wet road surface as compared with the pneumatic tire according to the comparative example.

<Hydroplaning on wet road>
Each pneumatic tire is mounted on a vehicle, and the pneumatic tire according to the comparative example is raised at a speed of 5 km / h on a wet road test course (R = 100 m J-turn), and line tracing during cornering is impossible. The maximum speed was set to “100”, and the maximum speed at which line tracing was impossible during cornering of the pneumatic tire according to the example was displayed as an index. In addition, hydroplaning can be prevented, so that an index | exponent is large.

  As a result, it was found that the pneumatic tire according to the example can prevent hydroplaning during cornering on the wet road surface as compared with the pneumatic tire according to the comparative example.

<Acceleration performance on snowy and snowy road>
Each pneumatic tire is mounted on a vehicle, and the acceleration time until the speed of the pneumatic tire according to the comparative example reaches 0 km / h to 20 km / h is set to “100” in a test course on an icy and snowy road. The acceleration time of entering tires was displayed as an index. The larger the index, the better the acceleration performance.

  As a result, it was found that the pneumatic tire according to the example was superior in acceleration performance on an icy and snowy road surface as compared with the pneumatic tire according to the comparative example.

<Brake performance on snowy and snowy road>
Each pneumatic tire is mounted on a vehicle, and on a icy and snowy road test course, the stopping distance from when the pneumatic tire according to the comparative example is run at a speed of 20 km / h and the vehicle is braked to 0 km / h. Was set to "100", and the stop distance of the pneumatic tire according to the example was displayed as an index. The larger the index, the better the braking performance.

  As a result, it was found that the pneumatic tire according to the example was superior in braking performance on an icy and snowy road surface as compared with the pneumatic tire according to the comparative example.

<Steering stability on ice and snow>
Each pneumatic tire is mounted on a vehicle, runs on a test course on an icy and snowy road surface at a constant speed, the handling stability of the pneumatic tire according to the comparative example is set to “100”, and the handling stability of the pneumatic tire according to the embodiment is stabilized. The feeling was evaluated by a professional driver. The larger the index, the better the steering stability.

  As a result, it was found that the pneumatic tire according to the example is superior in handling stability on the icy and snowy road surface as compared with the pneumatic tire according to the comparative example.

It is an expanded view which shows the tread pattern of the pneumatic tire which concerns on this Embodiment. It is a perspective view of the block which comprises the tread surface of the pneumatic tire which concerns on this Embodiment. It is a tread width direction sectional view (AA sectional view of Drawing 1) of the pneumatic tire concerning this embodiment. It is a tread width direction sectional view (BB sectional view of Drawing 1) of the pneumatic tire concerning this embodiment. It is tire peripheral direction sectional drawing (CC sectional drawing of FIG. 1) of the pneumatic tire which concerns on this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Tread tread surface, 3 ... Circumferential groove, 5 ... Width direction groove, 7 ... Center block, 7A ... Inner area | region, 7B ... Outer area | region, 7C ... Triangle area | region, 9 ... Shoulder block, 11 ... Width direction sipe, 13 ... Circumferential sipe, 15 ... bottom groove, 15a ... bottom top bottom surface, 17 ... bottom bottom top groove, 17a ... bottom bottom top groove, 19 ... inclined bottom groove, 21 ... narrow hole, CL ... tire equator line, R ... tire rotation direction ,

Claims (6)

In the tread surface, a pneumatic tire in which a plurality of blocks formed by a plurality of grooves extending in the tire circumferential direction and the tire width direction are formed with a width sipe extending in the tread width direction,
The center block located on the tire equator line side among the plurality of blocks is smaller than the shoulder block arranged on the outer side in the tread width direction than the center block,
At least a part of the groove forming the center block is formed of a bottom upper surface that is shallower than the depth from the tread tread surface to the bottom surface in the groove forming the shoulder block ,
At least one of the plurality of adjacent center blocks is a triangular block made of a triangle in a tread plan view,
The pneumatic tire is characterized in that at least one of the grooves forming the triangular block has a slanted narrow groove that has a slanted bottom surface and is thinner than other grooves that form the triangular block . The plurality of adjacent center blocks include an inner block, and an outer block disposed outside the inner block in the tread width direction,
  Between the inner block and the outer block, a groove having the bottom upper surface is formed,
The pneumatic tire according to claim 1, wherein the inclined narrow groove is formed between the inner block and the triangular block and between the outer block and the triangular block.   The inner block includes a circumferential groove extending in the tire circumferential direction, a bottom upper groove having the bottom upper bottom surface having a shallower depth than the circumferential groove, and a topmost bottom having a shallower depth than the bottom groove. Formed by an uppermost groove having a bottom surface and the inclined narrow groove;
  The outer block includes the circumferential groove, a widthwise groove extending in a tread width direction, a depth shallower than the circumferential groove, and a depth shallower than the widthwise groove. The pneumatic tire according to claim 2, wherein the pneumatic tire is formed by the bottom upper groove and the inclined narrow groove. At least a part of a groove forming one center block among a plurality of adjacent center blocks is formed by an uppermost bottom surface that is shallower than a depth to the bottom upper surface. The pneumatic tire according to claim 1 . The pneumatic tire according to any one of claims 1 to 4 , wherein a circumferential sipe extending in a tire circumferential direction is formed in the shoulder block. The pneumatic tire according to any one of claims 1 to 5 , wherein a narrow hole is provided in the triangular block and extends from the tread tread surface toward the inside in the tire radial direction.

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