JP3431871B2 - Pneumatic tire - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire suitable for use as, for example, a radial tire for heavy loads, which can improve wear resistance while improving running performance on a snowy road.

[0002]

2. Description of the Related Art In recent years,
Studless tires are being widely used when traveling on ice and snow roads. Such studless tires generally use a relatively soft rubber material for the tread rubber and a block pattern with high snow-biting characteristics on the tread surface in order to improve the running performance on ice and snow roads, and the vertical groove. , The width of the lateral groove is increased, and the land ratio (ratio of contact area) is greatly reduced. That is, a large driving force and a large braking force are obtained by pressing a large amount of snow in the groove to form a snow pillar and shearing the snow pillar when cutting the snow pillar. Further, by providing a large number of sipes or the like in each block, the edge component scratching the road surface is increased, and the running performance on an icy road is improved.

By the way, in recent years, studless tires have been worn and worn continuously not only in winter, but also in summer. Therefore, it is necessary to improve wear resistance in consideration of running other than winter. . However,
Studless tires have low block rigidity due to flexible tread rubber, reduction of land ratio on the tread surface, and engraving of many sipings, etc., and there is a problem that tire life is short when worn on dry roads and tire life is short. is there. In particular, when the above technology is applied to the tread pattern of a heavy duty radial tire with a high ground contact pressure, it causes uneven wear and a significant decrease in tire life, and when the land ratio is further reduced, it is called a mirror surface. There is a problem that the grip performance on the frozen ice surface is deteriorated.

The present invention has been made in view of the above problems, and an object thereof is to provide a pneumatic tire capable of improving wear resistance while improving grip performance on a snowy road or an icy road. I am trying.

[0005]

According to a first aspect of the present invention, a tread surface is provided with a longitudinal groove extending in the tire circumferential direction and a plurality of lateral grooves extending in a direction intersecting with the longitudinal groove. A pneumatic tire in which a plurality of block rows in which blocks are arranged in a tire circumferential direction are formed, wherein the block rows are provided at substantially intermediate positions in the circumferential direction of a block vertical wall surface facing the vertical grooves, and the vertical grooves are provided. A first block row composed of a block with convex portions provided with convex portions projecting to the side, and a block with concave portions having a concave portion concaved toward the inside of the block at a substantially intermediate position in the circumferential direction of the vertical wall surface of the block. A second block row in which the concave portions are arranged in the convex portions of the block with convex portions at positions facing each other through vertical grooves, and the maximum width in the tire axial direction of the block with convex portions is provided on the tread surface. The ratio of the amount of projection WP of B1 and the convex portion (W
P / WB1), and the ratio (WH / W) of the maximum width WB2 in the tire axial direction of the block with concave portions to the concave amount WH of the concave portions.
B2) is 0.04 to 0.15, and the ratio of the maximum circumferential length LB1 of the block with convex portions to the maximum circumferential length LP of the convex portions (LP / LB1), And the maximum length LH in the tire circumferential direction of the block with concave portions
To the tire circumferential direction length LB2 of the recess (LH / LB
All of 2) are characterized by being 0.3 to 0.4.

As described above, by providing the convex portions and the concave portions having a certain size in the blocks facing each other with the vertical groove interposed therebetween, the edge component of the vertical groove can be increased and the running performance on the icy road can be improved. sell. Further, by disposing the convex portion and the concave portion of each block so as to face each other, the snow column shearing force in the vertical groove can be secured even if the vertical groove is linear, and the snow ratio can be maintained without changing the land ratio. Not only can grip performance on the road be improved, but wet grip performance can be secured without blocking the flow of drainage. Further, by disposing the convex portion and the concave portion at positions facing each other and limiting the size and the like of the block, deterioration of wear resistance can be suppressed.

According to a second aspect of the present invention, in the block with projections, both ends in the circumferential direction of the block vertical wall surface are inclined toward the inside of the block from the groove bottom side of the vertical groove toward the tread surface side. The convex portion is formed between the inclined surfaces by notching the inclined surface, and the block with concave portions extends from the groove bottom side of the vertical groove toward the tread surface side in the circumferential intermediate portion of the block vertical wall surface. The pneumatic tire according to claim 1, wherein the concave portion is formed by cutting out a sloped surface that is inclined toward the inside of the block.

According to a third aspect of the invention, the vertical groove is
The pneumatic tire according to claim 1 or 2, wherein the groove width on the tread surface is substantially constant.

According to a fourth aspect of the present invention, the block with a convex portion extends from both circumferential edges of the convex portion and crosses the inside of the block so that the block with the convex portion is substantially 3 times.
In addition to the first sipe that equally divides, the recessed block has a second sipe that extends from both circumferential edges of the recess and traverses the inside of the block so as to divide the recessed block into approximately three equal parts. The pneumatic tire according to any one of claims 1 to 3, further comprising:

The invention according to claim 5 is characterized in that the length of the convex portion and the concave portion in the tire radial direction is 40 to 50% of the depth of the vertical groove. The pneumatic tire according to any one of 1 to 4.

According to a sixth aspect of the present invention, the depth of the first siping and the second siping is greater than the length of the convex portion and the concave portion in the tire radial direction and the depth of the vertical groove. 5. It is 60% or less of
It is the pneumatic tire described.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a development view of the tread surface 2 of the pneumatic tire of this embodiment. The pneumatic tire of this example is a heavy-duty radial tire used for, for example, trucks and buses, and has a vertical groove 3 extending in the tire circumferential direction on a tread surface 2 and a plurality of vertical tires that intersect with the vertical groove 3. A lateral groove 4 is provided.

The vertical groove 3 of this example includes one internal vertical groove 3a extending linearly in the tire circumferential direction on the tire equator C and external vertical grooves 3b arranged on both outer sides thereof. Three are illustrated. In addition, the lateral groove 4 includes an inner vertical groove 3a and an outer vertical groove 3b.
And an outer lateral groove 4b that joins between the outer vertical groove 3b and the tread end E. As a result, the tread surface 2 is formed with a plurality of block rows in which substantially rectangular blocks are arranged in the tire circumferential direction, that is, four row in this example. The vertical groove 3 has a groove width measured on the tread surface 2 of, for example, 2.5 to 7.
It is preferably about 0%, more preferably 3.5 to 6%, and further preferably 4.5 to 6.0%.

As shown in FIGS. 1 and 2, the block row is located at a substantially intermediate position in the tire circumferential direction of the block vertical wall surface 5 facing the vertical groove 3 (in this example, the outer vertical groove 3b side) in this example. The first block row R1 and R1 formed of a block B1 having a convex portion provided with a convex portion 6 projecting to the vertical groove 3 side, and the block vertical wall surface 5 is recessed toward the inside of the block at a substantially intermediate position in the tire circumferential direction. The block B2 with a concave portion provided with the concave portion 7 is formed on the convex portion 6 of the block B1 with the convex portion.
And a second block row R2 arranged at a position facing each other through the outer vertical groove 3b.

The first block row R1, R1 of this example is formed between the inner vertical groove 3a and the outer vertical groove 3b, and the second block row R2 is formed by the outer vertical groove 3a. Groove 3b
And the tread edge E. Therefore, the first block row R1 and the second block row R2 are adjacent to each other on either side of the tire equator C with the outer vertical groove 3b interposed therebetween.

The block with convex portion B1 is shown in FIG.
As shown schematically in FIG. 3, both end portions in the circumferential direction of the block vertical wall surface 5 are inclined in this example by slopes SP, SP that are inclined from the groove bottom side of the outer vertical groove 3b toward the tread surface 2 side toward the inside of the block. It is illustrated that the convex portion 6 is formed between the slopes SP, SP by the notch. As a result, step surfaces X1 and X1 having a substantially triangular shape and continuing to the slope SP are formed on both sides of the convex portion 6. In addition, the block B2 with concave portions is a block in which the intermediate portion in the tire circumferential direction of the block vertical wall surface 5 is directed from the groove bottom side of the outer vertical groove 3b toward the tread surface 2 side, as schematically shown in FIG. 2B. The figure shows that the concave portion 7 is formed by notching the inclined surface SH that is inclined inward. Further, step surfaces X2, X2 having a substantially triangular shape and continuing to the block vertical side surface 5 are formed on both sides of the slope SH.

Thus, by providing the convex portions 6 and the concave portions 7 on the blocks B1 and B2 which are adjacent to each other with the outer vertical groove 3b interposed therebetween, the edge component on the tread surface 2 is increased and the running performance on the icy road is increased. In addition to increasing the height, the step surface X of the convex portion 6
1. Due to the step surface X2 of the concave portion 7 and the like, a shearing force that cuts the snow pillar pressed in the outer vertical groove 3b in the advancing direction is generated, and in combination with the snow pillar shearing force by the lateral groove 4, snow is generated. It can greatly increase the grip power while driving on the road. Further, as a result of the convex portion 6 and the concave portion 7 being arranged at positions facing each other via the outer vertical groove 3b, for example, it becomes possible to secure a substantially constant groove width of the outer vertical groove 3b. Wet grip performance can be secured without impairing the drainage property inside. In addition, arranging the convex portion 6 and the concave portion 7 at positions facing each other means that the lengths LP and L of the convex portion 6 and the concave portion 7 are, for example, as shown in FIG.
It is particularly preferable that H is the same and the phases thereof are aligned. In addition to this, as shown in FIG.
The length LH of the concave portion is made larger than the length LP of the concave portion 7 so that the convex portion 6 is included in the concave portion 7, or the convex portion 6 and the concave portion 7 are mostly formed as shown in FIG. Those facing each other are also included in the embodiments of the present invention.

Further, in this embodiment, the maximum width WB of the block B1 with the protrusions in the tire axial direction on the tread surface 2 is large.
1 and the protrusion amount WP of the convex portion 6 (WP / WB1), and the maximum width WB of the concave block B2 in the tire axial direction.
The ratio (WH / WB2) between 2 and the recess amount WH of the recess 7 is 0.04 to 0.15. If the value of each ratio is less than 0.04, the effect of improving the performance on snow and the performance on ice is poor, and on the contrary, if it exceeds 0.15, the rigidity of the block becomes uneven and causes uneven wear. In addition, with respect to the convex portion 6, there is a tendency that the drainage effect of the vertical groove G1 is obstructed and the wet grip performance is deteriorated.
Further, regarding the concave portion 7, the reduction of the ground contact area of the block is too large, and the abrasion resistance performance is likely to be adversely affected. From such a viewpoint, the ratio (WP / WB1) and the ratio (WH
/ WB2) is preferably 0.048 to 0.143, and more preferably 0.06 to 0.09.

The ratio (LP / LB1) of the maximum circumferential length LB1 of the block B1 with convex portions (shown in FIG. 1) to the maximum circumferential length LP of the convex portions 6 (LP / LB1), and the concave portion The ratio (LH / LB2) between the maximum tire circumferential direction length LB2 (shown in FIG. 1) of the attached block B2 and the tire circumferential direction length LH of the concave portion 7 is 0.3 to 0.4 in all cases. . When the value of each ratio is less than 0.3, the convex portion 6 or the concave portion 7 is too small to enhance the running performance on an ice and snow road, and even if it exceeds 0.4, each block B1, B
Similarly, since the other portions of 2 become smaller, it is difficult to exhibit the above-described running performance and uneven wear may occur. From such a viewpoint, the ratio (LP / LB1) and the ratio (LH
/ LB2) is preferably 0.3 to 0.4, and more preferably 0.33 to 0.36.

As described above, the convex portion 6 and the concave portion 7 are arranged at positions facing each other through the outer vertical groove 3b, and the size with respect to the block B1 or B2 is limited, so that the convex block B1 and the concave portion are formed. The wear resistance of the attached block B2 can be improved.

Further, in this embodiment, the protrusion amount WP of the convex portion 6 and the concave amount WH of the concave portion 7, and the length LP of the convex portion 6 and the length LH of the concave portion 7 are substantially the same,
As a result, the outer vertical groove 3b exemplifies a groove width of the tread surface 2 that is substantially constant. Such an outer vertical groove 3b does not impede the flow of drainage in the vertical groove 3b, for example, on a wet road surface, and can sufficiently secure wet grip performance.

Further, the block with convex portion B1 extends from both edges of the convex portion 6 in the tire circumferential direction and crosses the inside of the block to divide the block with convex portion B1 into approximately three equal parts S1. , S1. The concave block B2 extends from both edges of the concave portion 7 in the tire circumferential direction and traverses the inside of the block so that the concave block B2 is divided into approximately three equal parts S2, S2.
It is equipped with

As a result, both the convex portion 6 and the concave portion 7 can move independently of the other portions divided by siping when they come into contact with the road surface, and the snow column shearing force is further increased to improve the snow column shearing force. While further improving the running performance, the edges of the sipings S1 and S2 scratch the ice surface, and moisture is absorbed into the respective sipings S1 and S2, whereby the grip performance during traveling on the ice surface can be further improved. Further, the first and second sipings S1 and S2 are the blocks B1 and
By dividing B2 into approximately three equal parts in the tire circumferential direction, it is possible to prevent a significant decrease in the rigidity of each block, an uneven rigidity of each part divided by siping, and the like, and to help prevent deterioration of wear resistance. . In addition, each siping S1, S2
Can be formed in various shapes, but it is desirable that they are formed substantially parallel to the groove edge line of the lateral groove 4b that is closest to and adjacent to it, for example, and is a straight line in this example. Each of the sipings S1 and S2 may include not only a linear shape but also a bent portion that bends in a zigzag shape, a wavy shape, or the like.

Further, in this embodiment, the convex portion 6,
The recess 7 has groove edges Be1 and Be2 that are substantially parallel to the block vertical wall surface 5 on the tread surface 2. This allows
On the tread surface 2, the outer edge profile of the outer vertical groove 3b has a shape in which a part of the vertical groove 3 is translated parallel to the outer side in the tire axial direction at a position where the convex portion 6 and the concave portion 7 face each other. By forming the convex portion 6 and the concave portion 7 in such a shape, the respective edge components can be increased and the snow column shearing force can be strengthened, and at the same time, the increase in the edge component caused by these increases on the ice road surface. Also effective in improving grip performance.

In addition, in the case of a heavy duty tire of the studless type in recent years, after being used in winter, it is used as it is on the normal road surface from spring to summer of the following year, and it is used so-called crushing that will end its life by the next winter. The form is becoming common. Therefore, according to such usage patterns,
After finishing the winter season, in order to further improve the wear resistance for dry road surfaces, the sipes S1 and S2 and the recesses 7 that reduce the block rigidity are in use, and more specifically, outside the vertical direction. It is desirable to configure the groove 3b to disappear by the time of wear of about 50 to 60%.

In this example, as shown in FIGS. 2A and 2B, the depth DS1 of the first siping S1 and the depth DS2 of the second siping S2 are both the depth of the outer vertical groove 3b. GD is 50 to 60%, and the lengths DP and DH of the convex portion 6 and the concave portion 7 in the tire radial direction are both 50% or less of the groove depth of the outer vertical groove 3b. Thus, it is desirable that the depths DS1 and DS2 of the sipings S1 and S2 be larger than the lengths DP and DH of the convex portions 6 and the concave portions 7 in the tire radial direction. As a result, the convex portion 6 or the concave portion 7 can be flexibly moved by siping until the convex portion 6 or the concave portion 7 completely disappears due to wear, which can contribute to improvement of the running performance on the ice and snow road to the end.

[0027]

EXAMPLES In order to confirm the effect of the present invention, a radial tire for heavy load having a tire size of 11R22.5 was prototyped and tested on ice, snow performance, wet performance, uneven wear resistance, and wear resistance. . The tire of the example was formed by the tread surface shown in FIGS. 1 and 4.

The tread surface shown in FIG. 4 has five vertical grooves 3, and the central vertical groove 3a passing through the tire equator C is formed in a straight line along the tire circumferential direction, and the first vertical groove 3a is arranged on the outer side thereof. The outer vertical groove 3b1 and the second outer vertical groove 3b2 arranged outside thereof are both formed in a zigzag shape. Lateral groove 4
6 is formed by connecting the vertical grooves 3, 3 or the vertical grooves 3 and the tread edge E to each other by bending appropriately. The dimensions of the groove widths 3, 4, etc. are as shown in FIG.

Further, the block with convex portion B1 is the first block.
The convex portions 6 are arranged so as to protrude toward the outer vertical groove 3b1 and the blocks B1 are arranged in the tire circumferential direction to form the first block row R1. Further, the block B2 with concave portions is formed on the outer side in the tire axial direction of the first outer vertical groove 3b1 so that the concave portion 7 faces the convex portion 6 of the block B1 with convex portion, so that the second block row R2 is formed. Make up. Each of these blocks B1, B2
Is schematically shown in FIGS. 5 (A) and 5 (B).

The convex portion 6 and the concave portion 7 face each other, and their respective positions in the tire circumferential direction are the same. Further, the convex portion 6 and the concave portion 7 of this example have edge portions Be1 and Be2 that are substantially parallel to the groove edges of the first outer vertical groove 3b1 other than the convex portion 6 and the concave portion 7, respectively. The portion sandwiched between the convex portion 6 and the concave portion 7 has a shape obtained by moving a part of the first outer vertical groove 3b1 in parallel to the outer side in the tire axial direction. Further, as shown in FIG. 5 (A), the block B1 with a convex portion has a block vertical wall surface 5 formed in a zigzag convex top portion T1 protruding outward of the block B1 by the zigzag of the vertical groove 3b1. In addition, the block B2 with concave portions is, as shown in FIG.
The block vertical wall surface 5 is formed in the zigzag concave top portion T2 which is recessed inward of the block B1 by the zigzag of the vertical groove 3b2. By forming the convex portion 6 and the concave portion 7 on such a block vertical wall surface 5, respectively, the effect of the convex portion 6 and the concave portion 7 is more remarkably exhibited.

The blocks B1 and B2 are substantially divided into three equal parts in the tire circumferential direction by the first and second sipings S1 and S2 extending from both circumferential edges of the convex portion 6 or the concave portion 7. Each of the sipings S1 and S2 is formed in a shape along the edge of the lateral groove closest to it.

For comparison, tires of the same size as those of Comparative Examples 1 to 3 having tread surfaces shown in FIGS. 6 to 8 were also prototyped and their performances were compared. Next, the test contents will be described.

(Performance on ice) A test tire was mounted on a rim (7.50).
X22.5) with rim assembled and filled with internal pressure of 800 (kPa) and mounted on all wheels of a displacement 2 / 2-D vehicle (maximum loading capacity 10t) and locked from 30km / h on ice. This was done by measuring the braking distance of. The evaluation was performed by the index obtained by the following formula. The larger the value, the better. Performance on ice = {(braking distance of Comparative Example 1) / (obtained braking distance)} × 100

(Performance on snow) Using a test vehicle equipped with the above-mentioned test tire, a snow-covered road surface having a thickness of 10.0 cm (temperature: −
13.5 ℃, ice temperature: -5.0 ℃, snow temperature: -8.0 ℃), while feeling the driver,
The evaluation was carried out focusing on braking, acceleration, turning, etc. The results are expressed as an index with 100 of Comparative Example 1 being set, and the larger the value, the better.

(Wet Performance) It was carried out by measuring the braking distance when the asphalt road surface with a water film of 0.3 cm was locked from 40 km / h using the above test vehicle. The evaluation was performed by the index obtained by the following formula. The larger the value, the better. Wet performance = {(braking distance of Comparative Example 1) / (obtained braking distance)} × 100

(Uneven wear resistance performance) A test vehicle under the same conditions as described above was used to run 3000 km on a general road and a highway for a total of 3,000 km, and uneven wear (heel and toe wear, mainly on blocks with convex portions and blocks with concave portions) was performed. Edge wear, wear on one side, etc.) was visually observed, and Comparative Example 1 was set to 1
It is indicated by an index of 00. The larger the value, the better.

(Abrasion resistance performance) After the uneven wear resistance test, the average depth of the flutes of the test tire was determined and expressed as an index with Comparative Example 1 being 100. The larger the value, the better. The test results are shown in Table 1.

[0038]

[Table 1]

[0039]

As described above, according to the first aspect of the present invention, by providing the convex portion and the concave portion in the blocks adjacent to each other with the vertical groove interposed therebetween, the edge component on the tread surface is increased, and In addition to improving the running performance of the snow, even if it is a straight vertical groove due to the unevenness formed by the convex portion and the concave portion, it is possible to generate a snow column shearing force in the vertical groove, and in combination with the snow column shearing force by the lateral groove. It is possible to greatly improve the grip force while traveling on a snowy road. Moreover, as a result of the convex portion and the concave portion being arranged at positions facing each other through the vertical groove, for example, it becomes possible to secure a substantially constant groove width of the outer vertical groove, which hinders drainage in the vertical groove. Wet grip performance can be secured without doing. Thereby, the pneumatic tire of the present invention can improve on-ice performance, on-snow performance, wet performance, uneven wear resistance, and wear resistance in a well-balanced manner.

According to the second aspect of the present invention, in the block with convex portions, both end portions in the circumferential direction of the vertical wall surface of the block are cut by slopes inclined from the groove bottom side of the vertical groove toward the tread surface side toward the inside of the block. Due to the lack, a convex portion is formed between the slopes, and as a result, a step surface that connects to the slope can be formed on both sides of the convex portion. Further, the block with a concave portion forms the concave portion by notching the intermediate portion in the tire circumferential direction of the block vertical wall surface by notching by a slope inclined from the groove bottom side of the vertical groove toward the tread surface side into the block, and as a result. On both sides of this slope, a step surface can be formed that extends to the vertical side surface of the block. With these step surfaces, the snow column shearing force in the vertical groove can be further enhanced and the gripping force on the snowy road is improved.

Further, in the invention according to claim 4, both the convex portion and the concave portion can move independently of both side portions in the tire circumferential direction at the time of contact with the ground, and the shear force of the snow column is further enhanced to improve the snow column. While further improving the running performance, the edge of the siping scratches the ice surface, and moisture is absorbed into each of the sipings, so that the grip performance when traveling on the ice surface can be further improved. In addition, the first and second provided in each block
The siping of each block divides each block into three equal parts in the tire circumferential direction to prevent a significant decrease in block rigidity and uneven rigidity of each part divided by siping, thereby suppressing deterioration of wear resistance. sell.

Further, in the invention according to claim 5, the length of the convex portion and the concave portion in the tire radial direction is 40 to 50% of the depth of the vertical groove. It disappears afterwards, and wear resistance can be further improved for running on a dry road surface.

According to a sixth aspect of the present invention, in the first siping and the second siping, the depth is larger than the length of the convex portion and the concave portion in the tire radial direction. The effect of the recesses can be effectively maintained until they disappear.

[Brief description of drawings]

FIG. 1 is a development view of a tread surface showing an embodiment of the present invention.

FIG. 2A is a perspective view of the block with a convex portion,
(B) is a perspective view of the block with concave portions.

FIG. 3 is a schematic plan view showing a convex portion and a concave portion in an enlarged manner.

FIG. 4 is a development view of a tread pattern of a tire showing another embodiment of the present invention.

FIG. 5 (A) is a perspective view of the block with convex portions,
(B) is a perspective view of the block with concave portions.

FIG. 6 is a development view of a tread surface of a comparative example.

FIG. 7 is a development view of a tread surface of a comparative example.

FIG. 8 is a development view of a tread surface of a comparative example.

[Explanation of symbols]

2 tread surface 3 vertical grooves 4 lateral grooves 5 blocks vertical wall 6 convex 7 recess B1 Block with convex part B2 Block with recess C tire equator R1 First block row R2 second block row S1 First siping S2 second siping SP, SH slope

Claims (6)

(57) [Claims] Claims: 1. A tread surface having a vertical groove extending in the tire circumferential direction and a plurality of lateral grooves extending to intersect the vertical groove, thereby forming a plurality of block rows in which blocks are arranged in the tire circumferential direction. In the filled tire, the block row is a first block including a convex portion provided with a convex portion protruding toward the vertical groove, at a substantially middle position in a circumferential direction of a block vertical wall surface facing the vertical groove. It is composed of a block row and a block with a concave portion, which is provided at a substantially intermediate position in the circumferential direction of the vertical wall surface of the block, with a concave portion that is concave toward the inside of the block, and the concave portion faces the convex portion of the block with a convex portion through a vertical groove. A second block row arranged at a position, and the ratio of the maximum width WB1 in the tire axial direction of the block with convex portions to the protrusion amount WP of the convex portion on the tread surface (WP /
WB1), and the ratio of the maximum width WB2 in the tire axial direction of the block with concave portions to the concave amount WH of the concave portions (WH / WB
2) is 0.04 to 0.15, and the ratio of the maximum circumferential length LB1 of the block with convex portions to the maximum circumferential length LP of the convex portions (LP / LB).
1), and the ratio (L of the maximum length LH in the tire circumferential direction of the block with concave portions to the length LB2 of the concave portion in the tire circumferential direction).
H / LB2) was set to 0.3 to 0.4 in all cases. 2. The block with convex portions is formed by notching both end portions in the circumferential direction of the vertical wall surface of the block by slanting surfaces that are inclined toward the inside of the block from the groove bottom side of the vertical groove toward the tread surface side, The convex portion is formed between the slopes, and the block with the concave portion is inclined from the groove bottom side of the vertical groove toward the tread surface side toward the inside of the block in the circumferential middle portion of the block vertical wall surface. 2. The recess is formed by notching with a slope.
Pneumatic tire described. 3. The pneumatic tire according to claim 1, wherein the vertical groove has a groove width substantially constant on the tread surface. 4. The block with projections comprises first sipings which extend from both circumferential edges of the projections and traverse the inside of the block to divide the block with projections into approximately three equal parts. 4. The block with recesses comprises second sipes extending from both circumferential edges of the recess and traversing the inside of the block to divide the block with recesses into approximately three equal parts. The pneumatic tire according to any one of 1. 5. The convex portion and the concave portion have a length in the tire radial direction which is 40 to 50% of the depth of the vertical groove, according to any one of claims 1 to 4. Pneumatic tires. 6. The depth of each of the first siping and the second siping is greater than the length of the convex portion and the concave portion in the tire radial direction and 60% or less of the depth of the vertical groove. The pneumatic tire according to claim 4, wherein