JP5980489B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire in which a block is formed on a tread and a countermeasure against stone biting is taken.

  A pneumatic tire having a block pattern tread has a problem in stone biting property under poor pavement conditions. In particular, the large stone bite increases the damage to the tire belt, and there is a need for improvement.

  As a countermeasure against this stone biting, Patent Document 1 discloses a pneumatic tire that raises the bottom of the lug groove. However, if the tire groove is raised, the tire life is shortened due to wear.

JP 2010-069956 A

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a pneumatic tire with improved stone bite regardless of whether the bottom of the tire groove is raised or not.

The pneumatic tire according to claim 1 of the present invention includes a plurality of block rows that are provided on the tread and are formed by blocks partitioned by a plurality of tire circumferential grooves and tire width grooves, each extending in the tire circumferential direction. The tire circumferential groove is divided into a first circumferential groove and a second circumferential groove across the tire width groove, and the first circumferential groove opens into the tire width groove. The first opening and the second circumferential groove are arranged at positions separated from each other in the tire width direction by the second opening where the second circumferential groove opens in the tire width direction groove, and the first circumferential direction is provided in all the tire circumferential grooves. A groove portion and the second circumferential groove portion are formed , and the angle between the kicking side block tread surface and the groove wall is larger than the angle between the stepping side block tread surface and the groove wall across the tire width direction groove. .

  Next, the operation of the pneumatic tire according to claim 1 will be described.

According to the above configuration, all the tire circumferential grooves have the first circumferential groove portion and the second circumferential groove portion that open to the tire width direction groove at positions separated in the tire width direction. The groove becomes discontinuous at the position of the groove in the tire width direction. Therefore, compared with the case where the tire circumferential groove has a straight line shape continuous in one block, it is possible to suppress biting of large stones.

The pneumatic tire according to claim 2 of the present invention is characterized in that a groove width of the tire circumferential groove is not less than 1 mm and not more than 5 mm.

  By setting the groove width of the circumferential groove to 5 mm or less, it is possible to suppress biting of stones larger than this size. The reason why the groove width of the circumferential groove is 1 mm or more is to prevent the groove from being closed at the time of ground contact and to ensure drainage.

The pneumatic tire according to claim 3 of the present invention is a shoulder circumferential groove disposed closest to a tire shoulder among a distance between the first opening and the second opening, and the shoulder circumferential direction. When the distance of the second circumferential groove disposed on the tire equatorial plane side from the shoulder circumferential grooves with adjacent grooves and X, the tread width of the tread and TW, TW / 150 ≦ X ≦ TW / It satisfies the relationship of 25.

When the distance X is smaller than TW / 150, the shoulder circumferential groove and the second circumferential groove have high continuity in the circumferential direction, so that large stones are likely to be bitten. Stones with a large circumferential size are often large in the depth direction and are liable to damage the belt. Further, if the distance X is larger than TW / 25, the amount of protrusion in the tire width direction of the block defined by the shoulder circumferential groove and the second circumferential groove becomes large, the block rigidity becomes uneven, and the protruding portion Block breaks and tear defects are likely to occur.
Therefore, by setting X ≦ TW / 25, it is possible to effectively prevent large stones from being bitten by setting TW / 150 ≦ X while suppressing non-uniform block rigidity.

  In the pneumatic tire according to claim 4 of the present invention, among the distances between the first opening and the second opening, the distance with respect to the central tire circumferential groove disposed on the tire equatorial plane is B. When the tread width of the tread is TW, the relationship of TW / 150 ≦ B ≦ TW / 15 is satisfied.

If the distance B is smaller than TW / 150, the circumferential continuity of the central tire circumferential groove is increased, so that large stones are likely to be caught. Stones with a large circumferential size are often large in the depth direction and are liable to damage the belt. Also, if the distance B is greater than TW / 15, the amount of protrusion in the tire width direction of the block defined by the central tire circumferential groove becomes large, the block rigidity becomes uneven, and the block is missing at the protruding portion. And tears are more likely to occur.
Therefore, by setting B ≦ TW / 15, it is possible to effectively suppress large stone biting by setting TW / 150 ≦ B while suppressing non-uniform block rigidity.

  The pneumatic tire according to claim 5 of the present invention is a pair of centers formed on both sides in the tire width direction of the central tire circumferential groove formed in the tire width direction center of the plurality of tire circumferential grooves. The block row is divided into each block by a straight central tire width direction groove that is continuous from one end in the tire width direction of the pair of central block rows to the other other end. .

  According to the above configuration, since the central tire width direction groove is continuously formed in the block row of the row arranged in the tire width direction center of the tread having a high contact pressure, the function of the edge component simultaneously occurs when traction / brake occurs. It can be used to improve the traction and braking function. Moreover, since the central tire width direction groove | channel is continuously formed, drainage is good and wet performance can also be improved.

  In the pneumatic tire according to claim 6 of the present invention, blocks adjacent to each other in the tire width direction overlap with each other in the tire width direction so that the tire circumferential groove is not transparent in the tire circumferential direction. It is characterized by that.

  Here, non-penetration means that when a tire circumferential line is drawn in the groove, there is no part that is transparent (a part that can pass without being blocked by the block), and there is always a part that is blocked by hitting the block. Say.

  According to the said structure, since there is no penetration part in a tire circumferential direction groove | channel, stone biting can be suppressed more reliably.

In the pneumatic tire according to claim 7 of the present invention, the second width direction groove disposed from the shoulder circumferential direction groove to the second circumferential direction groove is the center of the tire width direction groove with respect to the tire width direction. The shoulder width direction groove that is inclined in the direction opposite to the tire width direction groove and is arranged from the tread ground contact end to the shoulder circumferential direction groove is inclined in the direction opposite to the second width direction groove with respect to the tire width direction .
In the pneumatic tire according to claim 8 of the present invention, if the pattern pitch length of the tread is P, 0.16 TW <P <0.26 TW.

  As described above, since the pneumatic tire according to claim 1 has the above configuration, it is possible to suppress biting of large stones.

  Since the pneumatic tire according to claim 2 has the above-described configuration, it is possible to suppress the closing of the circumferential groove at the time of ground contact while suppressing the biting of a large stone.

  Since the pneumatic tire according to claim 3 has the above-described configuration, it is possible to effectively suppress the biting of large stones while suppressing unevenness in block rigidity.

  Since the pneumatic tire according to claim 4 has the above-described configuration, it is possible to effectively prevent large stones from being bitten while suppressing unevenness in block rigidity.

  Since the pneumatic tire according to claim 5 has the above-described configuration, the traction and brake function can be improved and the wet performance can also be improved.

  Since the pneumatic tire according to claim 6 has the above-described configuration, it is possible to more reliably suppress stone biting.

It is a tire radial direction half section view of the pneumatic tire concerning this embodiment. It is a top view of the tread of the pneumatic tire concerning this embodiment. It is a partial expansion perspective view of the tread of the pneumatic tire concerning this embodiment. It is a partial expansion perspective view of the tread of the pneumatic tire concerning this embodiment. It is a partial cross section figure of the tire width direction groove of the pneumatic tire concerning this embodiment. It is a top view of the tread of the pneumatic tire concerning a comparative example.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The position of each part of the pneumatic tire defined in this embodiment (tread grounding end, etc.) is mounted on a standard rim defined in JATMA YEAR BOOK (2011 edition, Japan Automobile Tire Association Standard), and JATMA YEAR. Applicable size / ply rating in BOOK with 100% internal pressure of the air pressure (maximum air pressure) corresponding to the maximum load capacity (bold load in the internal pressure-load capacity correspondence table) is there. When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  FIG. 1 shows a sectional view in the tire radial direction of the pneumatic tire 10 according to the present embodiment (only one side with the tire equatorial plane CL in between). The pneumatic tire 10 according to the present embodiment includes a pair of bead parts 12, a pair of sidewall parts 14, and a tread part 16.

  In the bead portion 12, at least one annular bead core 18 is embedded. A carcass 15 is provided between the pair of bead cores 18 so as to straddle a toroidal shape. The carcass 15 is wound around the bead core 18 from the inside to the outside. A belt layer 19 is provided on the outer side of the carcass 15 in the tire radial direction.

  The tread depth OTD (Original Tread Depth) of the present embodiment is preferably 17 mm or more. The OTD generally refers to the groove depth of the circumferential groove in which the tread wear indicator is disposed. In this embodiment, the OTD refers to the groove depth of the second circumferential groove 24 as shown in FIG. . By setting the OTD to 17 mm or more, a deep groove pattern can be formed and the wear resistance can be improved.

  Further, the pneumatic tire 10 of this embodiment is mounted so that the tire rotation direction is the direction indicated by the arrow R (the upper side of the block in FIG. 2 is the stepping side and the lower side is the kicking side). .

  As shown in FIG. 2, five tire circumferential grooves are formed in the tread 16 of the pneumatic tire 10 of the present embodiment. What is arranged on the tire equatorial plane CL is the central tire circumferential groove 20, and then what is closest to the tire equatorial plane CL is the second circumferential grooves 22, 24, closest to the tread ground contact E (E1, E2) side. What is arranged is referred to as shoulder circumferential grooves 26, 28. The groove widths of the central tire circumferential groove 20, the second circumferential grooves 22, 24, and the shoulder circumferential grooves 26, 28 are preferably 1 mm or more and 5 mm or less. This is because if it is less than 1 mm, the drainage cannot be ensured, and if it exceeds 5 mm, it is not possible to prevent biting of relatively large stones.

  A central block row 30 is formed between the central tire circumferential groove 20 and the second circumferential groove 22, and a central block row 32 is formed between the central tire circumferential groove 20 and the second circumferential groove 24. Yes. A second block row 34 is formed between the shoulder circumferential groove 26 and the second circumferential groove 22, and a second block row 36 is formed between the shoulder circumferential groove 28 and the second circumferential groove 24. A shoulder block row 38 is formed between the shoulder circumferential direction groove 26 on the outer side in the tire width direction X and the ground contact end E1, and between the shoulder circumferential direction groove 28 on the outer side in the tire width direction X and between the ground contact end E2. A shoulder block row 39 is formed.

  The central block rows 30 and 32 are divided into a plurality of central blocks 30B and 32B by a central tire width direction groove 40. The central tire width direction groove 40 is formed from the second circumferential direction groove 24 to the second circumferential direction groove 22 and has a straight line shape inclined with respect to the tire width direction. Therefore, the edge components in the tire width direction of the central block rows 30 and 32 can be simultaneously functioned, and the traction performance and the brake performance can be improved. Moreover, since the center tire width direction groove | channel 40 is continuously formed ranging over two rows of blocks, drainage is good and wet performance can also be improved.

  The central tire circumferential groove 20 has a bowl shape, and is open to the central tire width direction groove 40 at a position where one end in the tire circumferential direction is closer to the central block 30B side than the tire equatorial plane CL (central opening 20A). ). The central opening 20A is located at a position where the groove width center line of the central tire width direction groove 40 and the groove width center line of the central tire circumferential direction groove 20 (both shown by dotted lines in the figure). . The central tire circumferential groove 20 is bent at an intermediate portion at a different angle and straddles the tire equator plane CL, and further bent at a different angle and the other end side in the tire circumferential direction is a central block than the tire equator plane CL. It opens to the central tire width direction groove 40 at a position close to the 32B side (central opening 20B). The central opening 20B is also at a position where the groove width center line of the central tire width direction groove 40 and the groove width center line of the center tire circumferential direction groove 20 intersect. The central opening 20A and the central opening 20B are separated from each other in the tire width direction, and the distance is 20AB. Accordingly, the central tire circumferential groove 20 is divided and discontinuous across the central tire width direction groove 40 in the tire circumferential direction, and is extended so as to cross the central tire width direction groove 40. It arrange | positions so that it may collide with the center block 30B or the center tire block 32B.

Here, if 20AB is the distance B, the relationship between the distance B and the tread width TW preferably satisfies the formula (1).

TW / 150 ≦ B ≦ TW / 15 (Formula 1)

When the distance B is smaller than TW / 150, the circumferential continuity of the central tire circumferential groove 20 is increased, so that large stones are likely to be bitten. Stones with a large circumferential size are often large in the depth direction and are liable to damage the belt. Also, if the distance B is greater than TW / 15, the amount of protrusion in the tire width direction of the block defined by the central tire circumferential groove 20 becomes large, the block rigidity becomes uneven, and the block at the protruding portion becomes uneven. Chipping and tear defects are likely to occur.
Therefore, by setting B ≦ TW / 15, it is possible to effectively prevent large stones from being bitten by setting TW / 150 ≦ B while suppressing non-uniform block rigidity.

  The side wall of the central block 30B along the second circumferential groove 22 has a central protruding wall surface portion 30C that protrudes toward the second circumferential groove 22 on the side where the angle with the central tire width direction groove 40 is an acute angle in the tire circumferential direction. It has become. The side of the side wall that has an obtuse angle with the central tire width direction groove 40 is a second wall surface portion 30 </ b> E that faces the second circumferential groove 22. A step 30D is formed between the central protruding wall surface portion 30C and the second wall surface portion 30E.

  Similarly, with respect to the side wall along the second circumferential groove 24 of the central block 32 </ b> B, the central projection in which the angle with the central tire width direction groove 40 in the tire circumferential direction protrudes toward the second circumferential groove 24 is the same. It is a wall surface portion 32C. The side of the side wall that has an obtuse angle with the central tire width direction groove 40 is a second wall surface portion 32 </ b> E that faces the second circumferential groove 24. A step 32D is formed between the central protruding wall surface portion 32C and the second wall surface portion 32E.

  The second block row 34 is divided into a plurality of second blocks 34B by a second width direction groove 42. The second width direction groove 42 is formed in a straight line extending from the shoulder circumferential direction groove 26 to the second circumferential direction groove 22 and inclined in the direction opposite to the central tire width direction groove 40 with respect to the tire width direction.

  Both side walls along the tire circumferential direction of the second block 34B (side walls along the second circumferential groove 22 and side walls along the shoulder circumferential groove 26) have an acute angle with the second width direction groove 42 in the tire circumferential direction. The side which becomes will protrude toward the adjacent circumferential groove | channel (the second circumferential groove | channel 22 and the shoulder circumferential groove | channel 26), and it becomes the 2nd protrusion wall surface part 34CI and 34CO, respectively. The side of the side wall where the angle with the second width direction groove 42 is an obtuse angle is a second wall surface portion 34EI, 34EO that faces the adjacent circumferential groove (second circumferential groove 22, shoulder circumferential groove 26), respectively. It has become. A step 34DI is formed between the second protruding wall surface portion 34CI and the second wall surface portion 34EI. A step 34DO is formed between the second protruding wall surface portion 34CO and the second wall surface portion 34EO.

  The second block row 36 is also divided into a plurality of second blocks 36B by the second width direction groove 44. The second width direction groove 44 is formed in a straight line extending from the shoulder circumferential direction groove 28 to the second circumferential direction groove 24 and inclined in the direction opposite to the central tire width direction groove 40 with respect to the tire width direction.

Both side walls of the second block 36B along the tire circumferential direction (side walls along the second circumferential groove 24 and side walls along the shoulder circumferential groove 28) have an acute angle with the second width direction groove 44 in the tire circumferential direction. The side which becomes is protruded toward the adjacent circumferential groove | channel (the second circumferential groove | channel 24, the shoulder circumferential groove | channel 28), and becomes the 2nd protrusion wall surface part 36CI and 36CO, respectively. In the tire circumferential direction of the side wall, the side where the angle with the second width direction groove 44 becomes an obtuse angle is a second wall surface portion facing the adjacent circumferential groove (second circumferential groove 24, shoulder circumferential groove 28). 36EI and 36EO. Between the second protruding wall portion 36CI and the second wall surface portion 36EI, step 36 D I is formed. A step 36DO is formed between the second protruding wall surface portion 36CO and the second wall surface portion 36EO.

  The shoulder block row 38 is divided into a plurality of shoulder blocks 38 </ b> B by a shoulder width direction groove 46. The shoulder width direction groove 46 extends from the ground contact end E1 to the second circumferential groove 22 and is inclined in the direction opposite to the second width direction groove 42 with respect to the tire width direction.

  The side wall along the shoulder circumferential groove 26 of the shoulder block 38B has a shoulder protruding wall surface 38C that protrudes toward the shoulder circumferential groove 26 on the side where the angle with the shoulder width direction groove 46 is an acute angle in the tire circumferential direction. It has become. The side of the side wall that forms an obtuse angle with the shoulder width direction groove 46 is a second wall surface portion 38 </ b> E that faces the shoulder circumferential direction groove 26. A step 38D is formed between the shoulder protruding wall surface portion 38C and the second wall surface portion 38E.

  The shoulder block row 39 is also divided into a plurality of shoulder blocks 39B by a shoulder width direction groove 48. The shoulder width direction groove 48 extends from the ground contact E2 to the second circumferential groove 24 and is inclined in the direction opposite to the second width direction groove 44 with respect to the tire width direction.

  The side wall of the shoulder block 39B along the shoulder circumferential groove 28 has a shoulder protruding wall surface 39C that protrudes toward the shoulder circumferential groove 28 on the side where the angle with the shoulder width direction groove 46 is an acute angle in the tire circumferential direction. It has become. The side of the side wall where the angle with the shoulder width direction groove 48 is an obtuse angle is a second wall surface portion 39 </ b> E that faces the shoulder circumferential direction groove 28. A step 39D is formed between the shoulder protruding wall surface portion 39C and the second wall surface portion 39E.

As shown in FIG. 3, a first circumferential groove 22A that is a part of the second circumferential groove 22 is between the second protruding wall surface portion 34CI of the second block 34B and the second wall surface portion 30E of the central block 30B. Is formed. The first circumferential groove 22A opens to the central tire width direction groove 40 at the first opening A1, and opens to the second width direction groove 42 at the first opening A2.
The first opening A1 is a position where the groove width center line of the first circumferential groove portion 22A and the groove width center line of the center tire width direction groove 40 (both are indicated by dotted lines in the figure). Yes, the first opening A2 intersects the groove width center line of the first circumferential groove portion 22A and the groove width center line of the second width direction groove 42 (both are shown by dotted lines in the figure). is there.

A second circumferential groove 22B, which is a part of the second circumferential groove 22, is formed between the second wall surface 34EI of the second block 34B and the central protruding wall surface 30C of the central block 30B. The second circumferential groove 22B opens to the central tire width direction groove 40 at the second opening B1, and opens to the second width direction groove 42 at the second opening B2.
The second opening B1 intersects the groove width center line of the second circumferential groove portion 22B and the groove width center line of the center tire width direction groove 40 (both shown by dotted lines in the figure). The second opening B2 intersects the groove width center line of the second circumferential groove portion 22B and the groove width center line of the second width direction groove 42 (both are indicated by dotted lines in the drawing). It is.

  The first opening A1 and the second opening B1 are separated by a distance AB1 in the tire width direction. The first opening A2 and the second opening B2 are separated by a distance AB2 in the tire width direction. Accordingly, the second circumferential groove 22 is divided and discontinuous across the second width direction groove 42 and the central tire width direction groove 40 in the tire circumferential direction, and the second width direction groove 42 or the central tire width direction groove. When extended so as to cross 40, the second block 34 </ b> B or the central block 30 </ b> B is disposed. In other words, the central block 30B and the second block 34B adjacent to each other in the tire width direction are overlapped in the tire width direction when viewed from the tire circumferential direction, and the second circumferential groove 22 is not transparent in the tire circumferential direction ( Not familiar).

A first circumferential groove 24A, which is a part of the second circumferential groove 24, is formed between the second protruding wall surface portion 36CI of the second block 36B and the second wall surface portion 32E of the central block 32B. The first circumferential groove 24A opens to the central tire width direction groove 40 at the first opening A3, and opens to the second width direction groove 44 at the first opening A4.
The first opening A3 is a position where the groove width center line of the first circumferential groove portion 24A and the groove width center line of the central tire width direction groove 40 (both are indicated by dotted lines in the drawing). Yes, the first opening A4 intersects the groove width center line of the first circumferential groove 24A and the groove width center line of the second width groove 44 (both are shown by dotted lines in the figure). is there.

A second circumferential groove 24B, which is a part of the second circumferential groove 24, is formed between the second wall surface 36EI of the second block 36B and the central protruding wall surface 32C of the central block 32B. The second circumferential groove 24B opens to the central tire width direction groove 40 at the second opening B3, and opens to the second width direction groove 44 at the second opening B4.
The second opening B3 is a position where the groove width center line of the second circumferential groove portion 24B and the groove width center line of the central tire width direction groove 40 (both are indicated by dotted lines in the drawing). Yes, the second opening B4 intersects the groove width center line of the second circumferential groove portion 24B and the groove width center line of the second width direction groove 44 (both are shown by dotted lines in the figure). is there.

  As shown in FIG. 4, the first opening A3 and the second opening B3 are separated by a distance AB3 in the tire width direction. Further, the first opening A4 and the second opening B4 are separated by a distance AB4 in the tire width direction. Therefore, in the tire circumferential direction, the second circumferential groove 24 is divided and discontinuous across the second width groove 44 and the central tire width groove 40, and the second circumferential groove 44 or the central tire width groove When it extends so as to cross 40, it is arranged so as to hit the second block 36B or the central tire block 32B. In other words, the central block 32B and the second block 36B adjacent to each other in the tire width direction are overlapped in the tire width direction when viewed from the tire circumferential direction, and the second circumferential groove 24 is not transparent in the tire circumferential direction ( Not familiar).

A first circumferential groove 26A, which is a part of the shoulder circumferential groove 26, is formed between the second protruding wall surface portion 34CO of the second block 34B and the second wall surface portion 38E of the shoulder block 38B. The first circumferential groove 26A opens to the second width direction groove 42 at the first opening C1, and opens to the shoulder width direction groove 46 at the first opening C2.
The first opening C1 is a position where the groove width center line of the first circumferential groove portion 26A and the groove width center line of the second width direction groove 42 (both are indicated by dotted lines in the drawing). The first opening C2 is a position where the groove width center line of the first circumferential groove portion 26A and the groove width center line of the shoulder width direction groove 46 (both are indicated by dotted lines in the figure). .

A second circumferential groove 26B, which is a part of the shoulder circumferential groove 26, is formed between the second wall surface 34EO of the second block 34B and the shoulder protruding wall surface 38C of the shoulder block 38B. The second circumferential groove 26B opens to the second width direction groove 42 at the second opening D1, and opens to the shoulder width direction groove 46 at the second opening D2.
The second opening D1 is a position where the groove width center line of the second circumferential groove portion 26B intersects with the groove width center line of the second width direction groove 42 (both are indicated by dotted lines in the drawing). The second opening D2 is a position where the groove width center line of the second circumferential groove portion 26B and the groove width center line of the shoulder width direction groove 46 (both are indicated by dotted lines in the figure). .

  The first opening C1 and the second opening D1 are separated by a distance CD1 in the tire width direction. Further, the first opening C2 and the second opening D2 are separated by a distance CD2 in the tire width direction. Accordingly, the shoulder circumferential groove 26 is divided and discontinuous across the second width direction groove 42 and the shoulder width direction groove 46 in the tire circumferential direction, and the second width direction groove 42 or the shoulder width direction groove 46 is separated. When extending so as to cross, the second block 34B or the shoulder block 38B is disposed. In other words, the shoulder block 38B and the second block 34B adjacent to each other in the tire width direction overlap in the tire width direction when viewed from the tire circumferential direction, and the shoulder circumferential groove 26 is not transparent in the tire circumferential direction ( Not familiar).

A first circumferential groove 28A, which is a part of the shoulder circumferential groove 28, is formed between the second protruding wall surface 36CO of the second block 36B and the second wall surface 39E of the shoulder block 39B. The first circumferential groove 28A opens to the second width direction groove 44 at the first opening C3, and opens to the shoulder width direction groove 48 at the first opening C4.
The first opening C3 is a position where the groove width center line of the first circumferential groove 28A and the groove width center line of the second width groove 44 (both are indicated by dotted lines in the drawing). The first opening C4 is a position where the groove width center line of the first circumferential groove 28A and the groove width center line of the shoulder width direction groove 48 (both are indicated by dotted lines in the figure). .

A second circumferential groove 28B that is a part of the shoulder circumferential groove 28 is formed between the second wall surface 36EO of the second block 36B and the shoulder protruding wall surface 39C of the shoulder block 39B. The second circumferential groove 28B opens to the second width direction groove 44 at the second opening D3, and opens to the shoulder width direction groove 48 at the second opening D4.
The second opening D3 is a position at which the groove width center line of the second circumferential groove 28B and the groove width center line of the second width groove 44 (both are shown by dotted lines in the drawing). The second opening D4 is a position where the groove width center line of the second circumferential groove portion 28B and the groove width center line of the shoulder width direction groove 48 (both shown by dotted lines in the figure). .

  The first opening C3 and the second opening D3 are separated by a distance CD3 in the tire width direction. Further, the first opening C4 and the second opening D4 are separated by a distance CD4 in the tire width direction. Therefore, the shoulder circumferential groove 28 is divided and discontinuous across the second width direction groove 44 and the shoulder width direction groove 48 in the tire circumferential direction, and the second width direction groove 44 or the shoulder width direction groove 48 is separated. When extending so as to cross, the second block 36B or the shoulder block 39B is disposed. In other words, the shoulder block 39B and the second block 36B adjacent to each other in the tire width direction overlap in the tire width direction when viewed from the tire circumferential direction, and the shoulder circumferential groove 28 is not transparent in the tire circumferential direction ( Not familiar).

  Here, it is preferable that the relationship between the distances AB1, AB2, CD1, CD2, (these are collectively referred to as the distance X) and the tread width TW satisfy the formula (2).

  TW / 150 ≦ X ≦ TW / 25 (Formula 2)

If the distance X is smaller than TW / 150, the shoulder circumferential grooves 26 and 28 and the second circumferential grooves 22 and 24 have high continuity in the circumferential direction, so that large stones are likely to be caught. End up. Stones with a large circumferential size are often large in the depth direction and are liable to damage the belt. Further, when the distance X is larger than TW / 25, the protruding amount in the tire width direction of the block defined by the shoulder circumferential grooves 26 and 28 and the second circumferential grooves 22 and 24 becomes large, and the block rigidity is uneven. As a result, the chipped portion of the projecting portion and the tear are liable to occur.
Therefore, by setting X ≦ TW / 25, it is possible to effectively suppress the biting of large stones by setting TW / 150 ≦ X while suppressing non-uniform block rigidity.

  The second block 34B of the second block row 34, the second block 36B of the second block row 36, the shoulder block 38B of the shoulder block row 38, and the shoulder block 39B of the shoulder block row 39 are arranged in the tire circumferential direction with the same period. They are arranged so that their positions in the direction are different (different phases). The maximum of the straight portions of the central tire circumferential groove 20, the second circumferential grooves 22, 24, and the shoulder circumferential grooves 26, 28 is a distance L as shown in FIG.

As shown in FIG. 5, the central tire width direction groove 40, the second width direction grooves 42, 44, and the shoulder width direction grooves 46, 48 have different groove walls before and after the tire rotation direction R (FIG. 5). Then, the central tire width direction groove 40 is shown as an example). When the angle between the kick-out block tread surface and the groove wall 50 across the width direction groove is θk, and the angle between the tread-side block tread surface and the groove wall 52 is θf, θk> θf. Thus, by increasing the kicking side angle θk, the block kicking side rigidity is increased, and uneven wear, particularly pumping wear (uneven wear where the block becomes uneven) can be suppressed. In addition, since the inclination angles of the groove wall 50 and the groove wall 52 are different, even when stones enter, the force that the stones receive from the groove walls becomes non-uniform, and stone biting can be suppressed.

  As shown in FIG. 5, the groove widths W of the second width direction grooves 42 and 44 and the shoulder width direction grooves 46 and 48 are 4 mm or less at a depth position 2 mm above the groove bottom 54. Preferably there is. If it exceeds 4 mm, a relatively large stone may be allowed to enter.

  The pattern pitch length P (see FIG. 2) of the tread portion 16 of the pneumatic tire 10 is preferably larger than 0.16 TW and smaller than 0.26 TW as a ratio to the tread width TW. By setting the pattern pitch length P within this range, the traction property and the WET property can be effectively exhibited.

(Function)
Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.

  In the pneumatic tire 10 of this embodiment, the tire circumferential groove (the central tire circumferential groove 20, the second circumferential grooves 22, 24, and the shoulder circumferential grooves 26, 28 are tires at positions separated in the tire width direction. Since it opens to the width direction groove | channel (40, 42, 44, 46), a tire circumferential direction groove | channel becomes discontinuous in the position of a tire width direction groove | channel, and a linear part becomes the distance L. Therefore, a tire circumferential direction Compared with the case where the groove is a continuous straight line in one block, it is possible to suppress the biting of large stones.

  In order to confirm the effect of the present invention, pneumatic tires (Example 1 and Example 2) having the tread pattern of the present embodiment shown in FIG. 2 and pneumatic tires having the tread pattern of the comparative example shown in FIG. The tire was tested for stone biting and uneven wear. The tread 60 shown in FIG. 6 has five tire circumferential grooves as a central tire circumferential groove 120, second circumferential grooves 122 and 124, shoulder circumferential grooves 126 and 128, and six rows of blocks. Block rows 130 and 132, second block rows 134 and 136, and shoulder block rows 138 and 139 are provided. Each of these block rows is divided into blocks 130B to 139B by a central tire width direction groove 140, second width direction grooves 142 and 144, and shoulder width direction grooves 146 and 148, respectively. The conditions such as the groove width of the tread patterns of Example 1, Example 2, and Comparative Example are as shown in Table 1.

The tire size, test conditions, and method are as follows.

[Tire size]: 295 / 80R22.5
[Rim, internal pressure, load]: Attached to the actual vehicle under the internal pressure and load conditions of the ETROTO regular rim.
[Vehicle / Mounting position]: Semi-trailer type 6x2 tractor drive shaft [Test method]: Check the number of stone bites after 6 months of driving with GENERAL CARGO USER, the belt arrival point of damage, the number of pumping wear [Number of test vehicles]: AB method (left and right scratch test) × 12 units (24 units for the comparative example). The pneumatic tire of the example and the pneumatic tire of the comparative example are mounted coaxially and a comparative test is performed.

  The test results are as shown in Table 2.

From Table 2, it can be seen that the pneumatic tires having the treads according to Examples 1 and 2 are superior in the comparative example in terms of the number of stone bites, the damaged portion reaching the belt, and uneven wear.

10 Pneumatic tire 20AB Distance 20 Central tire circumferential groove 20A, 20B Central opening 22 Second circumferential groove 22A First circumferential groove 22B Second circumferential groove 24 Second circumferential groove 24A First circumferential groove 24B Second circumference Direction groove 26 shoulder circumferential groove 26A first circumferential groove 26B second circumferential groove 28 shoulder circumferential groove 28A first circumferential groove 28B second circumferential groove 30, 32 central block rows 30B, 32B central blocks 34, 36 Second block row 34B, 36B Second block 34CI, 34CO, 36CI, 36CO Second protrusion wall surface 34DI, 34DO, 36DI, 36DO Step 34EI, 34EO, 36EI, 36EO Second wall surface 38, 39 Shoulder block row 38B, 39B Shoulder block 38C , 39C Shoulder protruding wall surface portions 38D, 39D Steps 38E, 39E Second wall surface portion 40 Central tire width direction grooves 42, 44 Second width direction grooves 46, 48 Shoulder width direction grooves A1-4, C1-4 First openings B1-4 D1-4 Second opening CL Tire equatorial plane

Claims (8)

Provided on the tread, comprising a plurality of block rows formed by blocks partitioned by a plurality of tire circumferential direction grooves and tire width direction grooves, each extending in the tire circumferential direction ,
The tire circumferential groove is divided into a first circumferential groove and a second circumferential groove across the tire width groove,
The first opening in which the first circumferential groove portion opens in the tire width direction groove and the second opening in which the second circumferential groove portion opens in the tire width direction groove are arranged at positions separated in the tire width direction. And
The first circumferential groove portion and the second circumferential groove portion are formed in all the tire circumferential grooves, and the angle between the block tread surface on the kick-out side and the groove wall is depressed with the tire width direction groove interposed therebetween. A pneumatic tire that is larger than the angle between the side block tread and the groove wall .   The pneumatic tire according to claim 1, wherein a groove width of the tire circumferential groove is 1 mm or more and 5 mm or less.   Of the distance between the first opening and the second opening, the shoulder circumferential groove disposed closest to the tire shoulder, and the tire equator more adjacent to the shoulder circumferential groove than the shoulder circumferential groove The relationship of TW / 150 ≦ X ≦ TW / 25 is satisfied, where X is a distance about a second circumferential groove disposed on the surface side, and TW is a tread width of the tread. The pneumatic tire according to claim 2.   Of the distances between the first opening and the second opening, TW / 150, where B is the distance with respect to the central tire circumferential groove disposed on the tire equatorial plane and TW is the tread width of the tread. The pneumatic tire according to claim 3, wherein a relationship of ≦ B ≦ TW / 15 is satisfied.   A pair of central block rows formed on both sides in the tire width direction of the central tire circumferential groove formed in the tire width direction center of the plurality of tire circumferential grooves is one of the pair of central block rows. The pneumatic tire according to claim 4, wherein the pneumatic tire is divided into blocks by a straight central tire width direction groove that extends from one end in the tire width direction to the other end.   The tire circumferential direction groove is characterized in that blocks adjacent in the tire width direction are overlapped in the tire width direction when viewed from the tire circumferential direction so as not to be transparent in the tire circumferential direction. A pneumatic tire given in any 1 paragraph.   Of the tire width direction grooves, a second width direction groove arranged from the shoulder circumferential direction groove to the second circumferential direction groove is inclined in a direction opposite to the central tire width direction groove with respect to the tire width direction, and is a tread grounding end. The pneumatic tire according to claim 5, wherein the shoulder width direction groove disposed from to the shoulder circumferential groove is inclined in a direction opposite to the second width direction groove with respect to the tire width direction. The pneumatic tire according to any one of claims 1 to 7 , wherein when the pattern pitch length of the tread is P, 0.16TW <P <0.26TW.