JP5399823B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire including both regions outside the position corresponding to 80% of the tread contact width centered on the tire equatorial plane as shoulder regions, and at least a plurality of blocks in the shoulder region. In particular, it is intended to achieve both wet performance and dry performance.

  One important performance in terms of tire safety is wet performance. As a technique for improving the wet performance, a technique is known in which a sipe is cut into a block land portion constituting a block system pattern to increase a pattern edge (for example, Patent Document 1).

  However, carving a sipe in the block land portion leads to a decrease in block rigidity, which is effective for wet performance but adversely affects dry performance such as steering stability on a dry road surface.

JP-A-2005-145128

  Therefore, the inventor diligently studied to achieve both of the conflicting performances, and by reducing the size of each block constituting the block pattern and consolidating a large number of them, the decrease in block rigidity is suppressed to some extent. The knowledge that the block edge can be increased was obtained.

  However, when the inventor prototyped a pneumatic tire using such a block pattern and repeated the experiment, it was confirmed that the wet performance was significantly improved compared to the conventional sipe type block pattern, but still the block edge It has been found that there is a possibility that the effect of improving the wet performance commensurate with the increased amount of is not sufficiently exhibited.

  Therefore, the present invention provides a pneumatic tire capable of realizing both wet performance and dry performance at a high level by improving wet performance commensurate with the increase in pattern edge due to dense arrangement of blocks. It is in.

  The present invention has been made to solve the above-described problems, and the pneumatic tire of the present invention has both the outer side in the tire width direction than the position corresponding to 80% of the tread contact width with the tire equatorial plane as the center. In the pneumatic tire in which each region is a shoulder region and a plurality of blocks are densely arranged in at least the shoulder region, the block extends across the ground contact edge in the tire width direction of the tread in at least one shoulder region. A plurality of outer blocks arranged side by side in the tire circumferential direction, and inner blocks arranged at least in the shoulder region and constituting a part of the blocks are arranged in the tire circumferential direction. A plurality of inner block rows arranged in a block group, and the outer block row The distance between the outer block and the inner block in the first inner block row that is the inner block row adjacent to the inner side in the tire width direction of the outer block row, and the inner block in the first inner block row, It is characterized in that it is larger than the distance formed by the inner block in the second block row which is the inner block row adjacent to the inner side in the tire width direction of the first inner block row.

  Here, the “tread contact width” is an industrial standard valid for the region where the tire is produced or used, for example, “Year Book” of The Tire and Rim Association Inc. in the United States, and The European Tire and Rim Technical Organization in Europe. “Standard Manual” of Japan, and in Japan, tires are assembled to standard rims at the applicable size of the standard described in the “JATMA Year Book” of the Japan Automobile Association, and the maximum load (maximum load capacity) and maximum of the single wheel at the applicable size of such standard The maximum width of the surface where the tire surface contacts the ground in the state where the air pressure corresponding to the load is applied. The “landing end” in the tire width direction refers to the outermost position in the tire width direction of the tread contact width.

  In such a pneumatic tire, a block group in which blocks are densely arranged is provided in a shoulder region on the outer side in the tire width direction from a position corresponding to 80% of a tread contact width centering on the tire equator plane. Therefore, it is possible to increase the block edge while avoiding a decrease in block rigidity to some extent.

Here, the inventor conducted research on the cause of the insufficient wet performance improvement effect commensurate with the increase in block edge due to the dense arrangement of blocks in the block group. The groove surrounding the inner block is partially closed and the adjacent blocks are integrated, so that the function as the block edge is reduced, or the water removed by the block is not effectively drained outside the tread. I found out that there was an approach between the surface and the road surface. The mechanism for closing the groove when the tire contacts the ground is as follows. That is, as shown in FIG. 3, when the tire contacts the ground, vertical load F _P from the rim, the bead portion 4, is converted into a horizontal direction parallel to the road surface through the sidewall portion 3 and the shoulder portion 2, of the tread the near ground terminal TE in the tire width direction side force P _H is generated toward the tire width direction inner side. And this lateral force P _H is allowed to block the groove (groove, especially a circumferentially extending) surrounding these blocks by shear deformation of the block in the vicinity of ground terminal TE, is cause integrate the adjacent blocks to each other. Therefore, the groove closing amount of the groove surrounding the block increases as it approaches the grounding end TE.

  Therefore, the inventor, based on these findings, the distance between the outer block in the outer block row and the inner block in the first inner block row that is the inner block row adjacent to the inner side in the tire width direction of the outer block row, The distance between the inner block in the first inner block row and the inner block in the second block row, which is the inner block row adjacent to the inner side in the tire width direction of the first inner block row, is larger. . As a result, the groove edge between the blocks near the grounding end of the tread can be suppressed and the block edge can function reliably, and the original function of the groove can be exhibited. The effect of improving wet performance commensurate with the increase in edge can be exhibited.

  Therefore, according to the pneumatic tire of the present invention, it is possible to improve the wet performance commensurate with the increase in the block edge due to the dense arrangement of the blocks by suppressing the groove closing in the block group at the time of tire contact. Therefore, both wet performance and dry performance can be realized at a high level.

  In the pneumatic tire of the present invention, the block group has a third inner block row that is an inner block row adjacent to the inner side in the tire width direction of the second inner block row, The distance between the inner block in the inner block row and the inner block in the second inner block row is greater than the distance between the inner block in the second inner block row and the inner block in the third inner block row. Larger is preferred.

Further, in the pneumatic tire of the present invention, the width of the block group is W (mm), the reference pitch length of the inner block in any inner block row in the block group is PL (mm), and the block group When the number of inner blocks existing in the reference area of the block group divided by the width W of the block and the reference pitch length PL is a (number), and the negative rate in the reference area is N (%), The block number density S (units / mm ² ) per unit actual ground contact area of the block group given by S = a / {PL × W × (1−N / 100)} is 0.003 to 0.04. It is preferable to be within the range.

  The “block group width” herein refers to the length of the block group along the tire width direction. The “reference pitch length of the inner block” refers to a minimum unit or a plurality of units of a repeating pattern in the tire circumferential direction in an arbitrary inner block row. For example, one inner block is adjacent to the inner block. If the pattern of the tire circumferential pattern is defined by the groove, the inner block reference pitch is the sum of the tire circumferential length of one inner block and the groove width of the groove adjacent to the inner block. It can be a length. The “block number density” is a density representing how many inner blocks exist per actual ground contact area (total surface area of all inner blocks in the reference area) in the reference area.

  According to the present invention, a pneumatic tire capable of achieving both wet performance and dry performance at a high level by improving wet performance commensurate with the increase in block edge due to dense block arrangement is provided. Is possible.

It is sectional drawing of the tire width direction which assembled | attached the pneumatic tire of embodiment according to this invention to the rim | limb, and applied the predetermined | prescribed internal pressure, (a) shows the state which is not grounding, (b) shows the state which grounded, respectively It is. It is the partial expanded view which showed the tread pattern of the tire of one Embodiment (Example 1 tire) according to this invention. It is sectional drawing of the tire width direction when the pneumatic tire which has a block in a shoulder area | region is assembled | attached to a rim, and a predetermined internal pressure is applied, (a) is the state which is not grounding, (b) is the state which grounded. Each is shown. It is the partial expanded view which showed the tread pattern of the pneumatic tire (tire of Example 2) of other embodiment according to this invention. It is the partial expanded view which showed the tread pattern of the pneumatic tire of the prior art (tire of the prior art example 1). It is the partial expanded view which showed the tread pattern of the pneumatic tire (tire of the comparative examples 1 and 2) as a comparison.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view in the tire width direction in which a pneumatic tire (hereinafter simply referred to as “tire”) according to an embodiment of the present invention is assembled to a rim and a predetermined internal pressure is applied, and (a) is grounded. FIG. 2 (b) shows a grounded state, and FIG. 2 is a partial development view showing a tread pattern of a tire according to an embodiment of the present invention.

  As shown in FIG. 1, the tire according to this embodiment includes a tread portion 1 that forms a tread surface of the tire, a pair of sidewall portions 3 that are connected to the outer side in the width direction of the tread portion 1 via a shoulder portion 2, and these A carcass 5 that includes a pair of bead portions 4 disposed on the radially inner side of the sidewall portion 3 and extends in a toroidal shape between the pair of bead portions 4 and 4 inside the tire, and a radially outer side of the crown region of the carcass 5 And a belt layer 6 disposed on the tire.

  As shown in FIG. 2, in the tire, in the tread portion 1, both regions outside the tire width direction from the position corresponding to 80% of the tread contact width TW centering on the tire equator plane are set as shoulder regions Rs, An inner side in the tire width direction from the shoulder region Rs is a center region Rc, and at least the shoulder region Rs (here, the shoulder region Rs and the center region Rc) includes a block pattern having a plurality of blocks 8 partitioned by vertical grooves 7a and horizontal grooves 7b. .

  In each shoulder region Rs, a plurality of outer blocks 8a extending across the ground contact edge TE in the tire width direction of the tread portion 1 are arranged side by side in the tire circumferential direction to form an outer block row L1. Further, a plurality of inner blocks 8b are arranged on the inner side in the tire width direction of the outer block row L1, and a plurality of inner block rows L2 to L7 are formed side by side in the tire circumferential direction. Here, the inner side block row | line | column inside the tire width direction of the outer side block row | line | column L1 is made into inner side block row | line | columns L2-L7 in order toward the inner side from the tire width direction outer side. The inner blocks 8b in the inner block rows L2 to L5 constitute a block group G described later.

  The surface contour shape of the inner block 8b can be any shape, but the inner block 8b in the block group G is particularly preferably a polygon (here, substantially octagonal). This is because a sufficient contact area on the tire surface can be ensured by adopting this shape. Moreover, it is because the inner block 8b can mutually support the fall-down of the inner block 8b while making each inner block 8b movable independently.

  The inner blocks 8b in the block group G are arranged in a staggered manner. That is, the inner blocks 8b forming the inner block rows L2 to L5 adjacent in the tire width direction are arranged so that the phases are different in the tire circumferential direction. Here, “the phases are different in the tire circumferential direction” means that, for example, in the example of FIG. 2, the inner block 8b of the first inner block row L2 and the inner block 8b of the second inner block row L3 are half It means the state shifted in the tire circumferential direction by pitch. By adopting such a staggered arrangement, the block number density in the block group G can be easily increased, and the contact timing in the tire width direction of the inner block 8b in the block group G can be shifted. Therefore, pattern noise can be reduced.

として表される、ブロック群Ｇの単位実接地面積当りの内側ブロック８ｂの個数（ブロック個数密度Ｓ）は、０．００３（個／ｍｍ^２）以上０．０４（個／ｍｍ^２）以下である。ブロック個数密度Ｓは、ブロック群Ｇ内の全ての内側ブロック８ｂの実接地面積（溝分を除いた面積）中の単位面積（ｍｍ^２）当りに何個の内側ブロック８ｂがあるかということを密度として表現したものである。ちなみに、例えば通常のスタッドレスタイヤの場合には、この密度Ｓは概ね０．００２以下となる。なお、ブロック群Ｇの基準区域Ｚ内の内側ブロック８ｂの個数ａをカウントするに際して、内側ブロック８ｂが基準区域Ｚの内外に跨って存在し、１個として数えることができない場合は、基準区域Ｚを跨る内側ブロック８ｂの表面積に対する、基準区域内に残った内側ブロック８ｂの残存面積の比率を用いて数えることとする。例えば、基準区域Ｚの内外に跨り、基準区域Ｚ内にその半分しか存在しない内側ブロック８ｂの場合は、１／２個と数えることができる。 The smaller the size of the inner block 8b in the block group G and the higher the density, the larger the block edges in the pattern, but the preferred range of the block number density is as follows. . That is, the reference pitch length in the tire circumferential direction of the inner block 8b in any inner block row L2 to L5 of the block group G is PL (mm), and the width of each block group G is W (mm). The number of the inner blocks 8b existing in the reference area Z (area shown by hatching in FIG. 2) divided by the pitch length PL and the block group W is a (number), and the negative rate in each reference area Z Is N (%),

The number (block number density S) of the inner blocks 8b per unit actual ground contact area of the block group G is 0.003 (pieces / mm ² ) or more and 0.04 (pieces / mm ² ) or less. . The block number density S is the number of inner blocks 8b per unit area (mm ² ) in the actual ground contact area (area excluding the groove) of all inner blocks 8b in the block group G. It is expressed as density. Incidentally, for example, in the case of a normal studless tire, this density S is approximately 0.002 or less. When counting the number a of the inner blocks 8b in the reference zone Z of the block group G, if the inner block 8b exists across the reference zone Z and cannot be counted as one, the reference zone Z It is counted using the ratio of the remaining area of the inner block 8b remaining in the reference area to the surface area of the inner block 8b straddling the block. For example, in the case of the inner block 8b straddling the inside and outside of the reference area Z and having only half of the reference area Z, it can be counted as 1/2.

When the block number density S in the block group G is less than 0.003 (pieces / mm ² ), it is difficult to increase the block edge without forming sipes, while the block number density S is 0.04. If it exceeds (pieces / mm ² ), the size of the inner block 8b becomes too small, and it is difficult to achieve the required block rigidity. Further, if the block number density S in the block group G is in the range of 0.0035 to 0.03 / mm ² , it is possible to achieve both higher levels of block rigidity and increased block edge. it can.

  The negative rate N in the block group G is preferably 5% to 50%. When the negative rate N in the block group G is less than 5%, the groove area is too small and the drainage is insufficient, and the size of each of the inner blocks 8b is too large, and the block that the present invention aims at. This is because it is difficult to increase the edge. On the other hand, if it exceeds 50%, the ground contact area becomes too small and the steering stability may be lowered.

In this embodiment, the surface area of the inner blocks 8b of the inner block rows L6 and L7 of the center region Rc is larger than the surface area of the inner blocks 8b of the inner block rows L2 to L5 constituting the block group G. The block number density S of the block rows L6 and L7 is outside the range of 0.003 to 0.04 (pieces / mm ² ), but the block number density S is also 0.003 to 0.04 (in the center region Rc). Blocks / mm ² ) may be provided.

  The features of this tire are that, in each shoulder region Rs, the outer block 8a in the outer block row L1 and the first inner block that is the inner block row adjacent to the inner side in the tire width direction of the outer block row L1. The distance d1 (minimum value) between the inner block 8b in the row L2 is the inner block row adjacent to the inner block 8b in the first inner block row L2 and the inner side in the tire width direction of the first inner block row L2. It is larger than the distance d2 (minimum value) formed by the inner block 8b in the second block row L3.

  Further, in this tire, the distance d2 (minimum value) between the inner block 8b in the first inner block row L2 and the inner block 8b in the second inner block row L3 is the inner side in the second inner block row L3. It is larger than the distance d3 (minimum value) formed between the block 8b and the inner block 8b in the third inner block row L4.

In the tire of this embodiment, the block number density is 0.003 to 0.04 in the shoulder region Rs on the outer side in the tire width direction from the position corresponding to 80% of the tread contact width with the tire equatorial plane as the center. (Blocks / mm ² ) and the block group G formed by densely arranging the blocks 8a and 8b is provided, so that block rigidity is reduced to some extent (that is, dry performance is ensured), and the block edge is increased. can do. Moreover, since the surface area of the inner block 8b can be made sufficiently small in the block group G as compared with the prior art, the ground contact property of the inner block 8b is improved and the distance from the central area to the peripheral edge on the surface of the inner block 8b. The water film in the center area of the block surface can be efficiently removed when the block is grounded.

Further, a distance d1 between the outer block 8a in the outer block row L1 and the inner block 8b in the first inner block row L2 that is an inner block row adjacent to the inner side in the tire width direction of the outer block row L1 More than the distance d2 between the inner block 8b in one inner block row L2 and the inner block 8b in the second block row L3 that is an inner block row adjacent to the inner side in the tire width direction of the first inner block row L2. from what has been increased, as shown in FIG. 1 (b), even when subjected to lateral force P _H that occurs near the tread edge as described above, between the ground terminal TE nearby blocks of the tread (outer block 8a and the inner block 8b Between the inner block 8b and the inner block 8b), and the function of the block edge is exhibited by suppressing the closing of the vertical groove 7a. In addition, since the original function of the groove can be exhibited, the effect of improving the wet performance corresponding to the increase in the block edge due to the dense arrangement of the inner blocks 8b in the block group G can be exhibited.

  Therefore, according to this tire, it is possible to improve the wet performance commensurate with the increase in the block edge due to the dense arrangement of the blocks by suppressing the closing of the grooves in the block group G at the time of tire contact. Performance and dry performance can be achieved at a high level.

  Further, according to the tire of this embodiment, the distance d2 formed by the inner block 8b in the first inner block row L2 and the inner block 8b in the second inner block row L3 is set to the second inner block row L3. Since the distance d3 between the inner block 8b at the inner block 8b and the inner block 8b at the third inner block row L3 is larger than the distance d3, the groove closing becomes longer as the tread grounding end TE is approached. Since the groove width of the groove 7a can be set, the wet performance can be improved more effectively.

Furthermore, a tire provided with a block group having a block number density of 0.003 to 0.04 (pieces / mm ² ) in the shoulder region Rc is very advantageous in reducing rolling resistance. This is because by providing such a relatively small inner block 8b, it is possible to subdivide the tread portion 1 in the vicinity of the belt end that is dominant in the rolling resistance (that is, to make the tread portion in the vicinity of the belt end flexible) and to increase the tire load. This is because the energy loss of the tread portion 1 during rolling can be significantly reduced.

  Next, another embodiment of the present invention will be described with reference to FIG. The tire shown in this figure has a circumferential main groove 10 extending along the tire circumferential direction adjacent to the inner side in the tire width direction of the shoulder region Rs of the tread portion 1. The block height of the outer block 8a and the inner block 8b is preferably 60 to 100% of the groove depth of the circumferential main groove 10, and more preferably 70 to 90%. Inner block rows L2 to L4 constituting the block group G are arranged on the outer side in the tire width direction of the circumferential main groove 10. The distance d1 (minimum value) between the outer block 8a in the outer block row L1 and the inner block 8b in the first inner block row L2, which is the inner block row, is the inner block 8b in the first inner block row L2. , Larger than the distance d2 (minimum value) between the second block row L3 and the inner block 8b, and the distance d2 (minimum value) is larger than the inner block 8b in the second inner block row L3, It is larger than the distance d3 (minimum value) formed by the inner block 8b in the third inner block row L4. According to this, since sufficient drainage can be ensured by the circumferential main groove 10, the wet performance can be further enhanced.

  Next, tires of Examples 1 and 2 according to the present invention, tires of Conventional Example 1 according to the prior art, and tires of Comparative Examples 1 and 2 were respectively prototyped and subjected to various performance evaluations.

  The tire of Example 1 is a 195 / 65R15 size radial tire for passenger cars having the tread pattern shown in FIG. 2 in the tread portion. This tire has a plurality of independent inner sides defined by vertical grooves 7a and horizontal grooves 7b between a position corresponding to 70% of the tread contact width centered on the tire equator plane and a contact end TE in the tire width direction. It has a block group G in which the blocks 8b are densely arranged. In the center region Rc, rectangular blocks 8b (30 mm in the tire circumferential direction and 20 mm in the tire width direction) that are partitioned by the vertical grooves 7a and the horizontal grooves 7b are disposed. The block height of the inner block 8a and the outer block 8b is 6.7 mm. In the block group G, the distance d1 (minimum value) between the outer block 8a in the outer block row L1 and the inner block 8b in the first inner block row L2, which is the inner block row, is the first inner block row. The distance d2 (minimum value) between the inner block 8b in L2 and the inner block 8b in the second block row L3 is larger, and the distance d2 (minimum value) is larger in the second inner block row L3. It is larger than the distance d3 (minimum value) formed by the inner block 8b and the inner block 8b in the third inner block row L4. Other specifications are as shown in Table 1.

  The tire of Example 2 is a 195 / 65R15 size radial tire for passenger cars having the tread pattern shown in FIG. 4 in the tread portion. This tire has a plurality of independent inner sides defined by vertical grooves 7a and horizontal grooves 7b between a position corresponding to 70% of the tread contact width centered on the tire equator plane and a contact end TE in the tire width direction. It has a block group G in which the blocks 8b are densely arranged. The block height of the inner block 8a and the outer block 8b is 6.7 mm. In the block group G, the distance d1 (minimum value) between the outer block 8a in the outer block row L1 and the inner block 8b in the first inner block row L2, which is the inner block row, is the first inner block row. The distance d2 (minimum value) between the inner block 8b in L2 and the inner block 8b in the second block row L3 is larger, and the distance d2 (minimum value) is larger in the second inner block row L3. It is larger than the distance d3 (minimum value) formed by the inner block 8b and the inner block 8b in the third inner block row L4. This tire also extends along the tire circumferential direction at both positions corresponding to 65% of the tread contact width with the tire equatorial plane as the center, and has a circumferential width of 12 mm and a groove depth of 8.3 mm. The grooves 10 are respectively arranged. Other specifications of the tire of Example 2 are as shown in Table 1.

  For comparison, a 195 / 65R15 size radial tire for passenger cars and a tire of Conventional Example 1 having a tread pattern shown in FIG. Although the tire of Conventional Example 1 has the same configuration as the tire of Example 2 and the center region Rc, a rib-like land portion 15 extending along the tire circumferential direction is arranged in the shoulder region Rs instead of the block group. . A large number of sipes 16 extending in the tire width direction are engraved in the rib-like land portion 15.

  For comparison, the tires of Comparative Examples 1 and 2 which are 195 / 65R15 size radial tires for passenger cars and have the tread pattern shown in FIG. The tires of Comparative Examples 1 and 2 have the same basic configuration of the tread portion as the tire of Example 2, but have the same distances d1, d2, and d3. The tires of Comparative Example 1 and Comparative Example 2 have different distances d1, d2, and d3. Other specifications are shown in Table 1.

(Performance evaluation)
About each said test tire, the following tests were done and performance was evaluated.

(1) Wet brake performance evaluation test Wet brake performance was assembled on a rim of size 6JJ × 15 and mounted on a vehicle equipped with an anti-lock brake system at 210kPa (relative pressure). The braking distance when a 0 mm wet road surface was fully braked from 80 km / h was measured and evaluated from the measured distance. The evaluation results are shown in Table 2. The evaluation in Table 2 is the index of the tires of Examples 1 and 2 and the tires of Comparative Examples 1 and 2 with the result of Conventional Example 1 being 100. The larger the value, the better the wet brake performance. It shows that.

(2) Rolling resistance evaluation test The rolling resistance was measured with an indoor drum tester at a rolling resistance value of 80 km / h under conditions of an air pressure of 210 kPa (relative pressure) and a load of 4.41 kN. The evaluation results are shown in Table 2. The evaluation in Table 2 is expressed as an index for the tires of Examples 1 and 2 and the tires of Comparative Examples 1 and 2 with the conventional example 1 being 100, and the larger the value, the better the rolling resistance. .

(3) Wear resistance performance evaluation test Wear resistance performance was assembled on a rim of size 6JJ × 15, mounted on the vehicle at 210kPa (relative pressure), and traveled 10,000km under the riding load of one driver (general road: 40%, Expressway: 50%, Yamasaka Road: 10%), and the remaining groove amount at that time was measured and evaluated. The evaluation results are shown in Table 2. The evaluation in Table 2 is expressed as an index for the tires of Examples 1 and 2 and the tires of Comparative Examples 1 and 2 with the conventional example 1 being 100, and the larger the value, the better the wear resistance performance. Show.

  From the results shown in Table 2, it was found that the wet performance was improved by applying the present invention as compared with the tire of Comparative Example 1. It can also be seen that the wear resistance performance is lowered if the distances d1, d2, and d3 are simply increased as in the tire of Comparative Example 2. Therefore, it can be seen that by setting d1> d2> d3 as in Examples 1 and 2, the wet brake performance can be improved while ensuring the wear resistance performance.

  Thus, according to the present invention, wet performance and dry performance can be achieved at a high level by improving wet performance commensurate with the increase in pattern edge due to dense block arrangement.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Shoulder part 3 Side wall part 4 Bead part 5 Carcass 6 Belt layer 7a Vertical groove 7b Horizontal groove 8a Outer block 8b Inner block 10 Circumferential main groove

Claims (3)

In a pneumatic tire in which both regions outside the position corresponding to 80% of the tread contact width centered on the tire equator plane are in the tire width direction as shoulder regions, and at least a plurality of blocks are densely arranged in the shoulder region ,
In at least one shoulder region, an outer block row that extends across the contact edge in the tire width direction of the tread and constitutes a part of the block, and a plurality of outer block rows arranged side by side in the tire circumferential direction,
A block group composed of a plurality of rows of inner block rows arranged at least in the shoulder region and arranged in a row in the tire circumferential direction.
The distance between the outer block in the outer block row and the inner block in the first inner block row that is the inner block row adjacent to the inner side in the tire width direction of the outer block row is the inner side in the first inner block row. Greater than the distance between the block and the inner block in the second block row that is the inner block row adjacent to the inner side in the tire width direction of the first inner block row ,
In the block group, having a third inner block row that is an inner block row adjacent to the inner side in the tire width direction of the second inner block row,
The distance between the inner block in the first inner block row and the inner block in the second inner block row is the inner block in the second inner block row and the inner block in the third inner block row. Pneumatic tire characterized by being larger than the distance between The width of the block group is W (mm), the reference pitch length of the inner block in an arbitrary inner block row in the block group is PL (mm), and the width W of the block group and the reference pitch length PL are S = a / {PL × W × (1−) where the number of inner blocks existing in the reference area of the block group to be partitioned is a (number) and the negative rate in the reference area is N (%). ^2. The air according to claim 1 , wherein a block number density S (pieces / mm ² ) per unit actual ground contact area of the block group given by N / 100)} is within a range of 0.003 to 0.04. Enter tire. In a pneumatic tire in which both regions outside the position corresponding to 80% of the tread contact width centered on the tire equator plane are in the tire width direction as shoulder regions, and at least a plurality of blocks are densely arranged in the shoulder region ,
In at least one shoulder region, an outer block row that extends across the contact edge in the tire width direction of the tread and constitutes a part of the block, and a plurality of outer block rows arranged side by side in the tire circumferential direction,
A block group composed of a plurality of rows of inner block rows arranged at least in the shoulder region and arranged in a row in the tire circumferential direction.
The distance between the outer block in the outer block row and the inner block in the first inner block row that is the inner block row adjacent to the inner side in the tire width direction of the outer block row is the inner side in the first inner block row. Greater than the distance between the block and the inner block in the second block row that is the inner block row adjacent to the inner side in the tire width direction of the first inner block row,
The width of the block group is W (mm), the reference pitch length of the inner block in an arbitrary inner block row in the block group is PL (mm), and the width W of the block group and the reference pitch length PL are S = a / {PL × W × (1−) where the number of inner blocks existing in the reference area of the block group to be partitioned is a (number) and the negative rate in the reference area is N (%). N / 100)}, the block number density S (pieces / mm ² ) per unit actual contact area of the block group is within a range of 0.003 to 0.04. .

Images