JPWO2010131474A1 - Pneumatic tire - Google Patents

Abstract

In a pneumatic tire provided with a block group partitioned by a narrow groove and a thick groove, a pneumatic tire in which the collapse of the block is suppressed is provided. A block group G formed by densely arranging a plurality of mutually independent polygonal blocks 4 each having a number of pentagons or more, which is partitioned by the narrow grooves 3 and the thick grooves 2 extending linearly, A projection line or projection of a thick groove on an arbitrary projection plane provided outside the block 4 adjacent to the thick groove 2, which is provided in the tread portion and formed continuously at both ends of the thick groove 2. Each narrow groove 3 is disposed at a position where at least one of the narrow grooves 3 does not overlap with the same projection line or projection point with respect to a point.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire in which block rigidity of a block defined by a groove is increased.

  In a conventional pneumatic tire, for example, as described in Patent Document 1, three main grooves extending linearly in the tread circumferential direction are provided in a tread portion, and a block is formed by a plurality of sub grooves between the main grooves. In general, it is widely practiced to form a polygonal shape to improve driving performance, braking performance and turning performance with respect to the road surface.

  However, in general, such a tire forms a block with a main groove having a wide groove width and a sub groove having a narrow groove width in order to enhance drainage and block rigidity, so that the collapse of the block narrows the main groove. In the case of the falling and deforming in the direction, the block wall surface cannot be supported by the adjacent block, and the amount of the falling deformation may be increased, and as a result, the steering stability may be decreased. On the other hand, in order to suppress the collapse of the block, when the block is partitioned only by the narrow groove, the drainage property or the water absorption property is lowered, and the steering stability on the wet road surface may be lowered.

Japanese Patent Laid-Open No. 2003-154813

  The inventor has provided a polygonal block defined by two sub-grooves (thin grooves) continuous at both ends of the main groove (thick groove), and in a conventional tire, the direction in which the block collapses and the grooves The projection directions on the virtual projection plane outside the block coincide with each other, and as shown in FIG. 12, each narrow groove on any projection plane virtually outside the thick groove block is shown. Acquired the knowledge that any collapsed deformation of a block cannot be supported by an adjacent block if the projection line or projection point extends overlapping with a similar projection line or projection point of a large groove .

  Accordingly, the present invention is to provide a pneumatic tire in which collapse of the block is suppressed, particularly in a pneumatic tire provided with a block group partitioned by narrow grooves and thick grooves.

  A pneumatic tire according to the present invention is formed by arranging a plurality of polygonal blocks independent of each other and having a number of pentagons or more divided by narrow grooves and thick grooves extending linearly. A block group is provided at least in part, and each thin groove is formed continuously at both ends of the thick groove, and to an arbitrary projection plane virtually outside the block adjacent to the thick groove Each of the narrow grooves is arranged at a position where at least one of the narrow grooves does not overlap with the projection line or projection point of the thick groove. is there.

Here, “thin groove” means a groove where the opposing groove walls contact each other within the ground contact surface during rolling of the tire, while “thick groove” means that the opposing groove walls contact each other within the ground contact surface. It shall mean a groove that does not.
“Both ends of thick groove” means the position of a line segment drawn at a right angle to the tangent of the side of the block adjacent to the thick groove, and adjacent to the thick groove on both sides. When the lengths of the opposing sides of each block are different, the block is for the longer side.
“Projection plane” is an industrial standard effective in the region where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK, in Europe, ETRTO (European Tire and Rim Technical Organization) STANDARDDS MANUAL In the United States, TRA (THE TIRE and RIM ASSOCIATION INC.) YEAR BOOK, etc., the tire is assembled to the rim, filled with the highest air pressure specified according to the tire size in the standards such as JATMA, It is assumed that the thick groove is perpendicular to the projection direction when projected in an arbitrary direction outside the block.
“A position where at least one of both narrow grooves does not overlap with the same projection line or projection point” means that the projection point or the like of one narrow groove overlaps the projection surface or the like of the large groove, but the other fine groove does not overlap. It shall mean that the grooves do not overlap.

  In such a tire, it is more preferable that one or more circumferential grooves extending in the tread circumferential direction and / or a plurality of lateral grooves extending in the tread width direction are disposed on the tread surface.

Here, the “circumferential groove” can be extended not only in a linear shape but also in a main groove shape such as a zigzag shape, a wavy line shape, a curved shape, or a crank shape.
A “lateral groove” is a groove having a longer extension in the tread width direction than the extension length in the tread circumferential direction, and is inclined at an acute angle or an angle of 90 ° with respect to the tread circumferential direction. It can be extended not only in a linear shape but also in a groove shape such as a zigzag shape, a wavy line shape, a curved shape, or a crank shape. The lateral groove can also be formed continuously in the shape of a V, an arrow, or a step over the entire tread surface.

Preferably, the groove defining one block includes at least three narrow grooves.
Preferably, three or more narrow grooves that contribute to the division of one block are provided by extending the thick grooves in the tread width direction or the tread circumferential direction.

で与えられる、ブロック群の単位実接地面積当たりのブロック個数密度Ｓを０．００３〜０．０４個／ｍｍ^２の範囲とすることが好ましい。By the way, when the reference pitch length of the polygon block in the block group is P (mm) and the width of the block group is W (mm), the block group defined by the reference pitch length P and the width W The number of blocks in the reference area is a (piece), the negative rate in the reference area is N (%),

It is preferable that the block number density S per unit actual ground contact area of the block group is in the range of 0.003 to 0.04 / mm ² .

  Here, the “reference pitch length of the block” refers to the minimum unit of the repeated pattern of the block in one block row constituting the block group. For example, the pattern is defined by one block and a groove defining the block. If a repetitive pattern is specified, the reference pitch length of the block is the sum of the tread circumferential length of one block and the tread circumferential length of one groove adjacent to the tread circumferential direction of this block. To do. Note that “the number of blocks a in the reference area of the block group” is the number of blocks remaining in the reference area with respect to the surface area of the block, when the block exists inside and outside the reference area and cannot be counted as one. For example, in the case of a block straddling the inside and outside of the reference area and having only half of the reference area, it is counted as 1/2.

  The “width W of the block group” refers to the length in the tread width direction of the block group formed by densely arranging the blocks. For example, when the block group exists in the entire tread, the tread ground width is assumed. “Actual contact area” of a block group refers to the total surface area of all blocks in the reference area of the block group, that is, the reference area defined by the product of the reference pitch length P and the width W. The area obtained by subtracting the area of the groove that divides each block from the area of.

Preferably, the polygonal blocks are arranged in a zigzag pattern in the tread circumferential direction.
And preferably, the groove width of the narrow groove is in the range of 0.1 to 2.0 mm.

  In the pneumatic tire of the present invention, as shown in FIG. 1, each narrow groove is continuously formed from both ends of the thick groove, and is projected onto an arbitrary projection plane outside the block adjacent to the thick groove. By disposing each narrow groove at a position where the similar projection line or projection point of at least one of the two narrow grooves does not overlap with the projection line or projection point of the thick groove, Even if the block is deformed so as to close the thick groove, regardless of the deformation direction, the block is supported by at least one adjacent block, preventing the block from falling down. can do. As a result, steering stability on dry and wet road surfaces is improved.

  In addition, by providing a large groove in the tread portion, when the large groove is grounded, water can be retained in the thick groove to improve water absorption, and deformation of the block adjacent to the thick groove is ensured. The grounding property can be improved, and as a result, the steering stability can be improved.

It is a figure which shows typically the state which projected the groove | channel of the pneumatic tire of this invention on the outer side of a block. It is a partial development view of a tread pattern showing one embodiment of a pneumatic tire of the present invention. It is a partial expanded view of the tread pattern which shows other embodiment of the pneumatic tire of this invention. It is a partial expanded view of the tread pattern which shows other embodiment of the pneumatic tire of this invention. It is a partial expanded view of the tread pattern which shows other embodiment of the pneumatic tire of this invention. It is a partial expanded view of the tread pattern which shows other embodiment of the pneumatic tire of this invention. It is a partial expanded view of the tread pattern of the conventional pneumatic tire. It is a partial expanded view of the tread pattern of the conventional pneumatic tire. It is a partial expanded view of the tread pattern of the conventional pneumatic tire. It is a partial expanded view of the tread pattern of the conventional pneumatic tire. It is a partial expanded view of the tread pattern of the conventional pneumatic tire. It is a figure which shows typically the state which projected the groove | channel of the conventional pneumatic tire on the outer side of a block.

Hereinafter, the pneumatic tire of the present invention will be described in detail with reference to the drawings.
FIG. 2 is a partial development view of a tread pattern showing an embodiment of the pneumatic tire of the present invention. Since the reinforcing structure inside the tire is the same as that of a general radial tire or bias tire, illustration is omitted.

In the figure, reference numeral 1 denotes a tread tread. The tread tread 1 has a plurality of horizontally long straight thick grooves 2 extending in the tread width direction and 10 t with respect to the tread circumferential direction from the ends of the thick grooves 2. A linear narrow groove 3 that is inclined in a range of ˜80 ° and extends in four directions is provided. In the figure, a block 4 having an octagonal outline is defined by four thick grooves 2 and four narrow grooves 3, and a block group G is formed by concentrating these blocks 4. , Present on the entire tread surface 1.
Here, the respective blocks 4 are arranged in a staggered manner in the tread circumferential direction.

Here, each of the thick grooves 2 has, for example, a groove width BGL of 1.2 to 10 mm and a groove depth of 2 to 11 mm, and the narrow groove 3 has, for example, a groove width BGO of 0.1 to 1. 2 mm, the groove depth is 1 to 10 mm, and the extended length of the groove is 1 to 15 mm. Further, the tread circumferential length BL of the block 4 is 5 to 25 mm, the tread width direction length BW is 5 to 25 mm, the surface area is 25 to 330 mm ² , and the distance BGW between adjacent blocks in the tread width direction is 2. It can be set to a range of 5 to 10 mm.

  Here, each shape of the block 4 is an octagonal shape with an inner angle larger than 90 °, and the groove facing the side wall adjacent to the side wall on the thick groove 2 side of the block 4 forms the narrow groove 3. Is arranged.

  In such a tire, the block 4 is densely arranged while securing a sufficient groove area in the block group G, so that the total edge length and edge direction of each block 4 (in different directions). The number of facing edges) can be increased, and an excellent edge effect can be exhibited. In addition, since the size of the block 4 is reduced, it is possible to improve the ground contact performance of each block. Can be improved. In addition, by reducing the size of each block 4, the distance from the central area of the block 4 to the block periphery can be reduced, and the water film removal effect of the block 4 can be improved.

  In this pneumatic tire, the narrow grooves 3 are continuously formed at both ends of the thick grooves 2, and the thick grooves 2 are projected onto an arbitrary projection plane virtually outside the block 4 adjacent to the thick grooves 2. Each of the narrow grooves 3 is positioned at a position where at least one of the narrow grooves 3 does not overlap with the projection line or the projection point with respect to the line or the projection point. Even if the tire is arranged longer than the groove width (tread circumferential direction length) of the thick groove 2 and the small block 4 having low block rigidity is arranged, the collapse of the block 4 is suppressed and the steering stability is suppressed. Can be improved.

  In such a pneumatic tire, preferably, the groove defining one block 4 is composed of at least three narrow grooves 3, so that the collapse deformation of the block 4 is reduced and the steering stability on the dry road surface and the wet road surface is improved. Can be improved.

として表される、ブロック群Ｇの単位実接地面積当たりのブロック個数密度Ｓ（個／ｍｍ^２）、すなわち接地面積（溝分を除いた）中の単位面積（ｍｍ）当たり小ブロックが配置された部分のブロック個数は、０．００３〜０．０４個／ｍｍ^２、好ましくは０．００３〜０．０３５個／ｍｍ^２の範囲で形成する。Preferably, in the tire, the reference pitch length of the block 4 in the block group G is P (mm), and the width of the block group G is W (mm) (in this embodiment, the block 4 is disposed on the entire tread portion 1. Since it is arranged, it is equal to the tread ground contact width.) Of the block 4 existing in the reference zone Z (area shown by hatching in the figure) of the block group G, which is divided by the reference pitch length P and the width W. When the number is a (pieces) and the negative rate in the reference zone Z is N (%),

The block number density S (units / mm ² ) per unit actual ground contact area of the block group G, that is, represented by as follows: small blocks are arranged per unit area (mm) in the ground contact area (excluding the groove) The number of blocks in the portion is 0.003 to 0.04 / mm ² , preferably 0.003 to 0.035 / mm ² .

According to such a configuration, for example, the density S of the tire of the present invention is increased as compared with the density of s = 0.002 pieces / mm ² or less of the conventional studless tire, and excellent grounding property and edge effect are ensured. By realizing the efficient removal of the water film by the block 4, it is possible to achieve both the block rigidity and the edge effect at a higher level, and to dramatically improve the performance on ice.

  That is, when S is less than 0.003, the surface area of the block 4 is increased, and there is a possibility that the ground contact property of the tread surface 1 cannot be improved. On the other hand, when S exceeds 0.04, the block 4 Even if the sipe is not disposed, the desired block rigidity tends to be difficult to achieve.

  By the way, the negative rate N of the block group G is preferably 5% to 50%, and by setting this range, the steering stability can be improved. That is, when the negative rate N is less than 5%, the groove area is too small and the drainage performance is insufficient, and the size of each block may be too large, making it difficult to achieve the required edge effect. On the other hand, if it exceeds 50%, the ground contact area becomes too small, and the steering stability tends to decrease.

  By arranging the blocks 4 in a zigzag pattern in the tread circumferential direction, it is possible to exert a more excellent edge effect by causing each edge to act sequentially while forming more blocks 4 during tire rolling. At the same time, the ground contact timing to the road surface can be shifted between the blocks 4 adjacent in the tread width direction, so that pattern noise can be reduced. In the tire as shown in FIG. 2, the support block rigidity and the on-ice performance of the adjacent blocks 4 can be improved when a high load is applied.

  By the way, by setting the groove width of the narrow groove 3 to be in the range of 0.1 to 2.0 mm, the narrow groove 3 can support the block 4 while ensuring the flexible grounding property.

  That is, if it is less than 0.1 mm, the flexibility of the block 4 is reduced. On the other hand, if it exceeds 2.0 mm, the support between adjacent blocks is lost and the block rigidity tends to decrease.

FIG. 3 is a partial development view of a tread pattern showing another embodiment of the pneumatic tire of the present invention. In addition, the same code | symbol is attached | subjected to the element similar to the tire shown in the previous figure, and the description is abbreviate | omitted.
In this embodiment, the extending length of the thick groove 12 in the tread circumferential direction is made longer than the groove width of the thick groove 12 (length in the tread width direction). With this configuration, the drainage in the tread circumferential direction can be improved, and the pattern noise can be reduced by shortening the extending length in the tread width direction.

FIG. 4 is a partial development view of a tread pattern showing another embodiment of the pneumatic tire of the present invention. In addition, the same code | symbol is attached | subjected to the element similar to the tire shown in the previous figure, and the description is abbreviate | omitted.
In this embodiment, one or more circumferential grooves extending in the tread circumferential direction are arranged on the tread tread surface 1, and in the figure, one circumferential groove 22 is arranged in the vicinity of the tire equator line. Each block row 23 is partitioned between the circumferential groove 22 and the tread side edge.

In the block row 23, a plurality of linear thick grooves 24 extending in the tread width direction, and extending in the tread width direction in the figure longer than the groove width (length in the tread circumferential direction), and this A linear narrow groove 25 that is inclined in the range of 10 to 80 ° from the end of the thick groove 24 and extends in four directions is provided. In the figure, a block 26 having an octagonal outline is defined by four thick grooves 24 and four narrow grooves 25, and a block group G is formed by densely gathering these blocks 26. , Present on the entire tread surface 1.
Here, the respective blocks 26 are arranged in a staggered manner in the tread circumferential direction.

Here, for example, the circumferential groove 22 has a groove width of 3 to 50 mm and a groove depth of 2 to 15 mm, and each thick groove 24 has a groove width BGL of 1.2 to 10 mm and a groove depth of 2. The narrow groove 5 has, for example, a groove width BGO of 0.1 to 1.2 mm, a groove depth of 1 to 10 mm, and a groove extension length of 1 to 15 mm. Further, the tread circumferential length BL of the block 26 is 5 to 25 mm, the tread width direction length BW is 5 to 25 mm, the surface area is 25 to 330 mm ² , and the distance BGW between adjacent blocks in the tread width direction is 2. It can be set to a range of 5 to 10 mm.

Thus, by providing the circumferential groove 22, it is possible to achieve a good balance between the drainage in the front-rear direction of the tire and the steering stability.
In addition, by providing the thick groove 24, water can be retained in the thick groove 24 at the time of ground contact and the driving stability of the wet road surface can be improved. By providing the thin groove 25, the thick groove can be narrowed. Compared with a case where the groove 26 is not divided, the decrease in block rigidity can be reduced, and the grounding property of the block 26 can be improved.

  Here, the circumferential groove 22 has, for example, a groove width of 3 to 50 mm and a groove depth of 2 to 15 mm, and each thick groove 24 has a groove width of 2.5 to 10 mm and a groove depth, for example. The length of the groove is 2 to 11 mm and the extension length of the groove is 1.2 to 10 mm. The narrow groove 25 is inclined from the end of the thick groove 24 in the range of 10 to 80 ° with respect to the tread circumferential direction, for example. Can be arranged.

FIG. 5 is a partial development view of a tread pattern showing another embodiment of the pneumatic tire of the present invention. In addition, the same code | symbol is attached | subjected to the element similar to the tire shown in the previous figure, and the description is abbreviate | omitted.
In this embodiment, the extended length of the thick groove 34 in the tread circumferential direction is made longer than the groove width of the thick groove 34 (length in the tread width direction).
With this configuration, the drainage in the tread circumferential direction can be improved, and the pattern noise can be reduced by shortening the extending length in the tread width direction.

  Here, the circumferential groove 32 has, for example, a groove width of 3 to 50 mm and a groove depth of 2 to 15 mm, and each thick groove 34 has a groove width of 2.5 to 10 mm and a groove depth, for example. The length of the groove is 2 to 11 mm, and the extension length of the groove is 1.2 to 10 mm. The narrow groove 35 is inclined from the end of the thick groove 34 in the range of 10 to 80 ° with respect to the tread circumferential direction, for example. Can be arranged.

FIG. 6 is a partial development view of a tread pattern showing another embodiment of the pneumatic tire of the present invention. In addition, the same code | symbol is attached | subjected to the element similar to the tire shown in the previous figure, and the description is abbreviate | omitted.
In this embodiment, the lateral groove 42 that is inclined and extended in the tread width direction is formed in a V shape over the tread surface 1 with the tire equatorial plane as the center. With this configuration, drainage to the side of the tire can be performed, and drainage performance and steering stability can be well balanced.

  Here, for example, the lateral groove 42 is inclined in a range of 3 to 20 mm, a groove depth of 2 to 15 mm, an extension length of the groove of 20 to 300 mm, and a range of 10 to 80 ° with respect to the tread circumferential direction. Each of the thick grooves 24 has, for example, a groove width of 2.5 to 10 mm, a groove depth of 2 to 11 mm, and an extended length of the groove of 1.2 to 10 mm. The thick groove 44 can be disposed so as to incline within a range of 10 to 80 ° with respect to the tread circumferential direction.

  Preferably, the thick groove extends in the tread width direction or the tread circumferential direction, and three or more narrow grooves that contribute to the section of one block are provided, so that the continuous narrow grooves are inclined and arranged. Thus, the block rigidity in the circumferential direction of the tread is increased, and the steering stability on the dry road surface and the wet road surface can be improved.

  When the block group G is arranged on the tread tread or the entire block row, it is possible to improve the performance of the ice road surface in particular. For example, by placing the block group G on a part of the tread tread, Both can be achieved.

  Next, radial tires having a structure as shown in the figure and having a size of 205 / 55R16 were prototyped, and as shown in Table 1, Example tires 1 and 2 in which various specifications were changed, and comparative examples For each of the tires 1 to 5, the steering stability on the dry road surface, the steering stability on the wet road surface, and the water absorption were measured. In addition, since the comparative example tire does not require modification about structures other than the tread portion, it was assumed to conform to the example tire.

[Operation stability on dry road surface]
Each of Example Tires 1 and 2 and Comparative Example Tires 1 to 5 was assembled to a rim of size 6.5J × 16, mounted on a vehicle with an internal pressure of 220 kPa, and ran on an asphalt test course in various driving modes. This was done by comprehensively evaluating the braking performance, acceleration performance, straight travel performance, and cornering performance of the test driver. The evaluation results are shown in Table 2. In addition, the index value in a table | surface was calculated | required as a control using the value of the comparative example tire 1, and it shows that the steering stability of a dry road surface is excellent, so that an index is large.

[Operation stability on wet road surface]
Each of Example tires 1 and 2 and Comparative tires 1 to 5 is assembled to a rim having a size of 6.5 J × 16 and mounted on a vehicle with an internal pressure of 220 kPa, and various test modes of a wet asphalt road test course are provided. This was done by comprehensively evaluating the braking performance, acceleration performance, straight travel performance, and cornering performance of the test driver when driving on the road. The evaluation results are shown in Table 2.
In addition, the index value in a table | surface is calculated | required using the value of the comparative example tire 1 as control, and it shows that the steering stability of a wet road surface is excellent, so that an index | exponent is large.

[Water absorption]
Each of Example tires 1 and 2 and Comparative tires 1 to 5 was assembled on a rim of size 6.5J × 16, mounted on a vehicle with an internal pressure of 220 kPa, and traveled straight on a wet road surface with a water depth of 5 mm. The critical speed at which the planing phenomenon occurred was measured and evaluated from the measured critical speed. The evaluation results are shown in Table 2.
In addition, the index value in a table | surface is calculated | required using the value of the comparative example tire 1 as control, and it shows that water absorption is excellent, so that an index | exponent is small.

  From the results of Table 2, Example Tires 1 and 2 were able to improve the handling stability of the dry road surface, the steering stability of the wet road surface, and the water absorption compared to Comparative Example Tires 1-5.

Example tires 3 to 5 and comparative tires 6 to 5 having a structure as shown in the drawings and having a size of 205 / 55R16 manufactured as a prototype and having various specifications changed as shown in Table 3 For each of No. 8, the driving stability on the dry road surface, the steering stability on the wet road surface, and the water absorption were measured.
In addition, since the comparative example tire does not require modification about structures other than the tread portion, it was assumed to conform to the example tire.

[Operation stability on dry road surface]
Each of Example tires 3 to 5 and Comparative tires 6 to 8 was assembled to a rim having a size of 6.5 J × 16, mounted on a vehicle with an internal pressure of 220 kPa, and traveled on an asphalt test course in various travel modes. This was done by comprehensively evaluating the braking performance, acceleration performance, straight travel performance, and cornering performance of the test driver. The evaluation results are shown in Table 3.
In addition, the index value in a table | surface is calculated | required by using the value of the comparative example tire 6 as control, and it shows that the steering stability of a dry road surface is excellent, so that an index is large.

[Operation stability on wet road surface]
Example tires 3 to 5 and comparative example tires 6 to 8 are each assembled to a rim of size 6.5J × 16, attached to a vehicle with an internal pressure of 220 kPa, and various test modes for wet asphalt road test courses. This was done by comprehensively evaluating the braking performance, acceleration performance, straight travel performance, and cornering performance of the test driver when driving on the road. The evaluation results are shown in Table 4.
In addition, the index value in a table | surface is calculated | required using the value of the comparative example tire 6 as control, and it shows that the steering stability of a wet road surface is excellent, so that an index | exponent is large.

[Water absorption]
Each of Example tires 3 to 5 and Comparative tires 6 to 8 is assembled to a rim having a size of 6.5 J × 16, attached to a vehicle with an internal pressure of 220 kPa, and runs straight on a wet road surface having a water depth of 5 mm. The critical speed at which the planing phenomenon occurred was measured and evaluated from the measured critical speed. The evaluation results are shown in Table 4.
In addition, the index value in a table | surface is calculated | required using the value of the comparative example tire 6 as control, and shows that water absorption is excellent, so that an index | exponent is small.

  From the results of Table 4, it was possible to improve the handling stability of the dry road surface, the handling stability of the wet road surface, and the water absorption of the Example tires 3 to 5 and the comparative example tires 6 to 8.

1 Tread tread 2, 12, 24, 34, 44 Thick groove 3, 13, 25, 35, 45 Narrow groove 4, 14, 26, 36, 46 Block 22, 32 Circumferential groove 23, 33, 43 Block row 42 Horizontal groove G Block group P Reference pitch length of block group W Block group width Z Reference area

Claims (8)

  At least a part of a block group in which a plurality of polygonal blocks independent from each other and having a number of pentagons or more, which are partitioned by narrow grooves and thick grooves extending in a straight line, are arranged closely together. In the provided pneumatic tire, a thin groove projection line or projection onto an arbitrary projection plane formed by continuously forming the respective narrow grooves at both ends of the thick groove and outside the block adjacent to the thick groove. A pneumatic tire, wherein each narrow groove is disposed at a position where a similar projection line or projection point does not overlap at least one of the two narrow grooves with respect to a point.   The pneumatic tire according to claim 1, wherein one or more circumferential grooves extending in a tread circumferential direction are disposed on the tread surface.   The pneumatic tire according to claim 1 or 2, wherein a plurality of lateral grooves extending in the tread width direction are provided on the tread surface.   The pneumatic tire according to any one of claims 1 to 3, wherein the groove defining one block includes at least three narrow grooves.   The pneumatic tire according to any one of claims 1 to 4, wherein the thick grooves are extended in the tread width direction or the tread circumferential direction, and three or more narrow grooves contributing to a section of one block are provided. The reference area of the block group defined by the reference pitch length P and the width W, where P (mm) is the reference pitch length of the polygon block in the block group and W (mm) is the width of the block group The number of blocks existing in a is a (piece), the negative rate in the reference area is N (%),

The pneumatic tire according to any one of claims 1 to 5, wherein the block number density S per unit actual ground contact area of the block group is within a range of 0.003 to 0.04 / mm ² .   The pneumatic tire according to any one of claims 1 to 6, wherein the polygonal blocks are arranged in a staggered manner in the tread circumferential direction.   The pneumatic tire according to any one of claims 1 to 7, wherein a groove width of the narrow groove is in a range of 0.1 to 2.0 mm.

Images