JP2017124773A - Pneumatic tire - Google Patents

Abstract

A pneumatic tire capable of improving both dry performance and snow performance is provided. A pair of inner circumferential grooves 21 disposed on both sides of a tire equatorial plane CL in the tire width direction and a pair of outer circumferential grooves 21 disposed in the tire width direction. A center lug having an outer circumferential groove 25, both ends connected to the pair of inner circumferential grooves 21, and a circumferential extending portion 33 extending in the tire circumferential direction and a width extending portion 34 extending in the tire width direction. The groove 31, the center block 11 defined by the center lug groove 31 and the inner circumferential groove 21, and the circumferential extension portion 33 and the width extension portion are formed at positions on the minor angle side of the bent portion 32. 34 in a center region that is a region of 10% of the width of the center block 11 in the tire width direction with the center of the center block 11 in the tire width direction as the center. Contact area ratio is 70% or less than 30%. [Selection] Figure 2

Description

  The present invention relates to a pneumatic tire.

  Pneumatic tires have grooves on the tread surface mainly to ensure drainage, but if too many grooves are used, the rigidity of the land will decrease and steering stability and wear resistance will decrease. Some conventional pneumatic tires improve the contradictory performance by devising the arrangement of grooves. For example, in the pneumatic tire described in Patent Document 1, four circumferential grooves extending in a zigzag shape along the tire circumferential direction are arranged side by side in the tire width direction, and the tire width of the four circumferential grooves is Between the two inner circumferential grooves in the direction, a lug groove formed in a crank shape is arranged to improve traction and wear resistance on wet road surfaces.

JP 2006-111122 A

  Here, the grounding characteristics of pneumatic tires change depending on the weight of the vehicle during travel, but in particular for trucks and buses where the difference between the weight when the cargo is not loaded and the weight when the cargo is full is large. The change in the ground contact characteristic accompanying the change in the weight of the vehicle is remarkable. For example, in trucks and buses, vehicles that have multiple wheels mounted on top of each other are more suitable for pneumatic tires when they are not loaded with cargo than when they are loaded with cargo. The ground contact area to the road surface is reduced, and only the vicinity of the center region is grounded. As described above, when the ground contact area becomes small, slip is likely to occur between the tread surface of the pneumatic tire and the road surface. Therefore, in order to prevent the slip, it is better to reduce the groove area ratio near the center region. However, when the groove area ratio is reduced, the running performance on snowy roads is degraded.

  That is, the groove formed on the tread surface of the pneumatic tire contributes to snow performance, which is a running performance on a snowy road, in addition to drainage. However, the dry performance, which is the driving performance when driving on a dry road surface, can be improved by increasing the ground contact area, while the snow performance mainly increases the groove area and increases the snow area. In order to improve by increasing the column shearing force, etc., the dry performance and the snow performance are incompatible elements. For this reason, it is difficult to improve the dry performance and the snow performance, and in particular, the dry performance and the snow performance regardless of the cargo loading state, that is, regardless of whether the cargo is empty or loaded. It has been very difficult to achieve both.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can improve both dry performance and snow performance.

  In order to solve the above-described problems and achieve the object, a pneumatic tire according to the present invention is disposed on both sides of the tire equatorial plane in the tire width direction across the tire equatorial plane, and extends in the tire circumferential direction. Inner circumferential grooves, a pair of outer circumferential grooves disposed on the outer sides of the pair of inner circumferential grooves in the tire width direction and extending in the tire circumferential direction, and a pair of inner circumferential grooves at both ends. A plurality of center lug grooves having a circumferential extension portion extending in the tire circumferential direction and a width extension portion extending in the tire width direction by being bent at a plurality of positions, and the center lug groove, A center block, which is a land portion defined by an inner circumferential groove, and a recess formed in the center block at a position on the minor angle side of the bent portion of the center lug groove from the tread surface. And a bent portion concave portion connected to the circumferentially extending portion and the widthwise extending portion, and centering on the center of the center block in the tire width direction, the tire width direction of the center block The ground contact area ratio in the center region, which is a region having a width of 10%, is 30% to 70%.

  Moreover, the said pneumatic tire WHEREIN: It is preferable that the said circumferential direction extension part is located in the said center area | region.

  Moreover, the said pneumatic tire WHEREIN: It is preferable that the said bending part recessed part is formed by chamfering.

  Moreover, the said pneumatic tire WHEREIN: It is preferable that the said bending part recessed part is formed in the length in which the part connected to the said circumferential direction extension part and the part connected to the said width direction extension part are equal.

  In the pneumatic tire, it is preferable that the bent portion recess is formed so that a depth from the tread surface is in a range of 20% to 50% of a groove depth of the center lug groove.

  Further, in the pneumatic tire, the center block is provided on an extension line of the width direction extending portion, one end is connected to the bent portion, and the other end is terminated in the center block. Is preferably formed.

  Further, in the pneumatic tire, the center cutout portion has a length in a direction along a forming direction of the width direction extending portion of 10% or more and 20% or less of the width of the center block in the tire width direction. It is preferable to form within the range.

  Further, in the pneumatic tire, the bent portion recess and the center cutout portion are defined by an opening area A1 of the bent portion recess connected to the common bent portion and an opening area A2 of the center cutout portion. The relationship is preferably 3 ≦ (A2 / A1) ≦ 6.

  Further, in the pneumatic tire, a plurality of intermediate lug grooves whose both ends are connected to the adjacent inner circumferential groove and the outer circumferential groove, and the outer circumferential groove disposed outside the tire circumferential direction. A plurality of shoulder lug grooves, one end of which is connected to the outer circumferential groove, an intermediate block that is a land portion defined by the inner circumferential groove, the outer circumferential groove, and the intermediate lug groove; A shoulder block that is a land portion defined by an outer circumferential groove and the shoulder lug groove, and the intermediate block is provided on an extension line of the shoulder lug groove and has one end at the outer circumferential groove An intermediate notch is formed at the other end of the intermediate block, and the shoulder block is provided on an extension line of the intermediate lug groove and has one end at the outer circumferential side. Is connected to the groove, the other end it is preferable that shoulder notch for termination is formed in the shoulder block.

  In the pneumatic tire, it is preferable that the intermediate lug groove is formed with an inclination angle in a tire width direction with respect to a tire circumferential direction in a range of 75 ° to 105 °.

  Further, in the pneumatic tire, the intermediate lug groove and the shoulder lug groove include an inclination angle α1 of the intermediate lug groove in the tire width direction with respect to the tire circumferential direction, and the shoulder lug groove with respect to the tire circumferential direction. The relationship with the inclination angle α2 in the tire width direction is preferably 0 ° ≦ | α2−α1 | ≦ 10 °.

  In the pneumatic tire, the inner circumferential groove and the outer circumferential groove have a relationship between a groove width W1 of the inner circumferential groove and a groove width W2 of the outer circumferential groove of 0.5 ≦ ( It is preferable that W2 / W1) ≦ 0.9.

  In the pneumatic tire, the center block preferably has a width in the tire width direction of 20% or more and 40% or less of a tread developed width.

  In the pneumatic tire, the center block preferably has a ratio of a length L in the tire circumferential direction to a width W in the tire width direction of 0.9 ≦ (L / W) ≦ 1.1. .

  The pneumatic tire is preferably a heavy duty pneumatic tire.

  The pneumatic tire according to the present invention has an effect that both dry performance and snow performance can be improved.

FIG. 1 is a meridional cross-sectional view showing a main part of a pneumatic tire according to an embodiment. FIG. 2 is an AA arrow view of FIG. FIG. 3 is a detailed view of part B of FIG. FIG. 4 is an explanatory diagram of the bent space portion. FIG. 5 is a detailed view of part C of FIG. FIG. 6A is a chart showing the results of a performance test of a pneumatic tire. FIG. 6B is a chart showing the results of the performance test of the pneumatic tire. FIG. 6C is a chart showing the results of the performance test of the pneumatic tire. FIG. 6D is a chart showing the results of the performance test of the pneumatic tire.

  Hereinafter, an embodiment of a pneumatic tire according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be replaced by those skilled in the art and can be easily conceived, or those that are substantially the same.

  In the following description, the tire width direction refers to the direction parallel to the rotation axis of the pneumatic tire, the inner side in the tire width direction is the direction toward the tire equatorial plane in the tire width direction, and the outer side in the tire width direction is The direction opposite to the direction toward the tire equatorial plane in the tire width direction. The tire radial direction means a direction orthogonal to the tire rotation axis, the tire radial inner direction means the direction toward the tire rotation axis in the tire radial direction, and the tire radial direction outer direction means that the tire rotates in the tire radial direction. The direction away from the axis. Further, the tire circumferential direction refers to a direction rotating around the tire rotation axis.

  FIG. 1 is a meridional cross-sectional view showing a main part of a pneumatic tire according to an embodiment. The pneumatic tire 1 shown in FIG. 1 has a tread portion 2 disposed on the outermost side in the tire radial direction when viewed in a meridional section, and the surface of the tread portion 2, that is, the air A portion that comes into contact with the road surface when the vehicle (not shown) on which the entering tire 1 is mounted is formed as a tread surface 3. A plurality of circumferential grooves 20 extending in the tire circumferential direction are formed on the tread surface 3, and a plurality of lug grooves 30 (see FIG. 2) that intersect the circumferential grooves 20 are formed. A plurality of land portions 10 are defined on the tread surface 3 by the plurality of circumferential grooves 20 and lug grooves 30.

  Both ends of the tread portion 2 in the tire width direction are formed as shoulder portions 4, and sidewall portions 5 are disposed from the shoulder portion 4 to a predetermined position on the inner side in the tire radial direction. That is, the sidewall portions 5 are disposed at two places on both sides of the pneumatic tire 1 in the tire width direction.

  Further, bead portions 50 are located on the inner side in the tire radial direction of the respective sidewall portions 5, and the bead portions 50 are arranged at two locations on both sides of the tire equatorial plane CL, similarly to the sidewall portions 5. It is installed. That is, a pair of bead portions 50 is disposed on both sides of the tire equatorial plane CL in the tire width direction. Each of the pair of bead portions 50 is provided with a bead core 51, and a bead filler 55 is provided on the outer side of each bead core 51 in the tire radial direction. The bead core 51 is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler 55 is a rubber material disposed in a space formed by folding an end portion in the tire width direction of the carcass 6 to be described later outward in the tire width direction at the position of the bead core 51.

  A belt layer 7 is provided inside the tread portion 2 in the tire radial direction. The belt layer 7 has a multilayer structure in which, for example, four layers of belts 71, 72, 73, and 74 are laminated, and a plurality of belt cords made of steel or organic fiber materials such as polyester, rayon, and nylon are covered with a coat rubber. It is configured by rolling. Further, the belts 71, 72, 73, and 74 have different belt cords defined as inclination angles in the fiber direction of the belt cord with respect to the tire circumferential direction, and are laminated with the fiber directions of the belt cords intersecting each other. It is configured as a so-called cross ply structure.

  A carcass 6 including a radial ply cord is continuously provided on the inner side in the tire radial direction of the belt layer 7 and on the tire equatorial plane CL side of the sidewall portion 5. The carcass 6 has a single-layer structure composed of a single carcass ply or a multilayer structure formed by laminating a plurality of carcass plies, and is laid in a toroidal shape between bead cores 51 disposed on both sides in the tire width direction. Passed to form the tire skeleton. Specifically, the carcass 6 is disposed from one bead portion 50 to the other bead portion 50 of the pair of bead portions 50 located on both sides in the tire width direction, and wraps the bead core 51 and the bead filler 55. The bead portion 50 is wound back outward along the bead core 51 in the tire width direction. The carcass ply of the carcass 6 arranged in this way is a steel cord, which is a carcass cord made of a steel material, and is formed by rolling a plurality of steel cords with a coat rubber. That is, the carcass 6 is configured using a steel carcass material.

  An inner liner 8 is formed along the carcass 6 on the inner side of the carcass 6 or on the inner side of the carcass 6 in the pneumatic tire 1.

  FIG. 2 is an AA arrow view of FIG. The circumferential grooves 20 formed in the tread surface 3 are disposed on both sides of the tire equatorial plane CL in the tire width direction across the tire equatorial plane CL, and a pair of inner circumferential grooves 21 extending in the tire circumferential direction. A pair of outer circumferential grooves 25 are provided on the outer sides of the pair of inner circumferential grooves 21 in the tire width direction and extend in the tire circumferential direction. That is, the inner circumferential groove 21 has two inner circumferential grooves 21 disposed on both sides of the tire equatorial plane CL in the tire width direction, and the outer circumferential groove 25 has two outer circumferential grooves 25 that are tires. The two inner circumferential grooves 21 are disposed on both sides of the two inner circumferential grooves 21 in the tire width direction across the two inner circumferential grooves 21 in the width direction. The inner circumferential groove 21 and the outer circumferential groove 25 are formed to extend in the tire circumferential direction while oscillating in the tire width direction.

  The inner circumferential groove 21 has a groove width in the range of 6 mm to 15 mm and a groove depth in the range of 10 mm to 18 mm. The outer circumferential groove 25 has a groove width in the range of 4 mm to 12 mm, and a groove depth in the range of 6 mm to 18 mm. Further, the inner circumferential groove 21 and the outer circumferential groove 25 have a groove width W1 (see FIG. 5) of the inner circumferential groove 21 that is larger than a groove width W2 of the outer circumferential groove 25 (see FIG. 5). It is getting bigger. Specifically, in the inner circumferential groove 21 and the outer circumferential groove 25, the relationship between the groove width W1 of the inner circumferential groove 21 and the groove width W2 of the outer circumferential groove 25 is 0.5 ≦ (W2 / W1) ≦. 0.9, ie, (W2 / W1) has a relationship of 0.5 to 0.9. The relationship between the groove width W1 of the inner circumferential groove 21 and the groove width W2 of the outer circumferential groove 25 is preferably in the range of 0.6 ≦ (W2 / W1) ≦ 0.8.

  In addition to the circumferential groove 20, the tread surface 3 is provided with a plurality of lug grooves 30 extending in the tire width direction. As the lug groove 30, a center lug groove 31, an intermediate lug groove 35, and a shoulder lug groove 36 are provided. Among these, the center lug groove 31 is disposed between the pair of inner circumferential grooves 21 in the tire width direction, and is a lug groove 30 whose both ends are connected to the pair of inner circumferential grooves 21. The intermediate lug groove 35 is disposed between the inner circumferential groove 21 and the outer circumferential groove 25 adjacent in the tire width direction, and both ends thereof are connected to the inner circumferential groove 21 and the outer circumferential groove 25. Lug groove 30 is formed. Further, the shoulder lug groove 36 is disposed on the outer side in the tire width direction of the outer circumferential groove 25 and is a lug groove 30 having one end connected to the outer circumferential groove 25. A plurality of the center lug groove 31, the intermediate lug groove 35, and the shoulder lug groove 36 are provided side by side in the tire circumferential direction.

  The center lug groove 31 has a groove width in the range of 4 mm to 9 mm and a groove depth in the range of 9 mm to 18 mm. The intermediate lug groove 35 has a groove width in the range of 4 mm to 9 mm and a groove depth in the range of 2 mm to 16 mm. The shoulder lug groove 36 has a groove width in the range of 4 mm to 16 mm, and a groove depth in the range of 2 mm to 16 mm.

  The center lug groove 31 and the intermediate lug groove 35 are connected to the common inner circumferential groove 21, but the position of the portion connected to the inner circumferential groove 21 in the tire circumferential direction is the center lug groove 31 and the intermediate lug 21. It differs from the groove 35. Similarly, the intermediate lug groove 35 and the shoulder lug groove 36 are connected to the common outer circumferential groove 25, but the position in the tire circumferential direction of the portion connected to the outer circumferential groove 25 is the intermediate lug groove 35. And the shoulder lug groove 36 are different.

  In the land portion 10 formed on the tread surface 3, a center block 11, an intermediate block 12, and a shoulder block 13 are defined by the plurality of lug grooves 30 and the plurality of circumferential grooves 20. Among these, the center block 11 is the land portion 10 defined by the adjacent center lug groove 31 and the pair of inner circumferential grooves 21, whereby the center block 11 is on the tire equatorial plane CL. positioned. The intermediate block 12 is a land portion 10 defined by the adjacent inner circumferential groove 21 and outer circumferential groove 25 and the adjacent intermediate lug groove 35. Further, the shoulder block 13 is provided outside the outer circumferential groove 25 in the tire width direction, and is defined by the adjacent shoulder lug groove 36 and the inner portion in the tire width direction is defined by the outer circumferential groove 25. It is part 10. That is, the shoulder block 13 is defined by the outer circumferential groove 25 and the shoulder lug groove 36. A plurality of the center block 11, the intermediate block 12, and the shoulder block 13 are provided side by side in the tire circumferential direction.

  FIG. 3 is a detailed view of part B of FIG. Of the lug grooves 30 that divide the land portion 10, the center lug groove 31 is bent at a plurality of positions, whereby a circumferentially extending portion 33 extending in the tire circumferential direction and a widthwise extending portion extending in the tire width direction are provided. 34. Specifically, one center lug groove 31 has two bent portions 32 that are bent portions, and is formed in a crank shape by being bent at the two bent portions 32. The center lug groove 31 is formed as a circumferentially extending portion 33 at a position between the two bent portions 32. The circumferentially extending portion 33 is formed on the tire equatorial plane CL, and is inclined in the tire width direction within a predetermined range with respect to the tire circumferential direction. The inclination angle of the circumferentially extending portion 33 with respect to the tire circumferential direction is in the range of 0 ° to 15 °. Note that not all of the circumferentially extending portion 33 is located on the tire equator plane CL, some positions are located on the tire equator plane CL, and other portions are on the tire equator plane CL. It does not have to be located above.

  The width extending portion 34 extends from the end of the circumferential extending portion 33 in the tire width direction, so that the end of the circumferential extending portion 33 and the inner circumferential groove 21, that is, the bent portion 32, The inner circumferential groove 21 is connected. Specifically, the width direction extending portions 34 are provided at two locations of each center lug groove 31, and the two width direction extending portions 34 include different bent portions 32 and a pair of inner circumferential grooves 21. Are connected to different inner circumferential grooves 21. The two width direction extending portions 34 are inclined in the same direction in the tire circumferential direction while extending in the tire width direction. Specifically, the width direction extending portion 34 is on the same side as the side in which the circumferential direction extending portion 33 that forms the bent portion 32 together with the width direction extending portion 34 is inclined in the tire circumferential direction with respect to the tire width direction. The inclined portion 33 is inclined at an angle different from that of the circumferentially extending portion 33. Moreover, the inclination angle with respect to the tire width direction of the two width direction extending portions 34 of one center lug groove 31 is substantially the same angle.

  Further, a bent portion recess 40 formed by being recessed from the tread surface 3 is provided at a position on the minor angle side of the bent portion 32 of the center lug groove 31 in the center block 11. The bent portion recess 40 is connected to both the circumferentially extending portion 33 and the widthwise extending portion 34 constituting the bent portion 32, and is continuous from the circumferentially extending portion 33 and the widthwise extending portion 34. Then, it is formed to be recessed from the tread surface 3. The bent portion concave portion 40 is formed by chamfering applied to a portion of the center block 11 on the minor angle side of the bent portion 32. When viewed in the depth direction of the bent portion concave portion 40, the bent portion 32 is It is formed in a substantially triangular shape having a corner and a side connected to the circumferentially extending portion 33 and a portion connected to the widthwise extending portion 34.

  That is, the bent portion concave portion 40 is removed from the bent portion 32 between the circumferentially extending portion 33 and the widthwise extending portion 34 with a predetermined size from the bent portion 32 on the tread surface 3. Is configured. In the present embodiment, the bent portion recess 40 is formed such that the portion connected to the circumferentially extending portion 33 and the portion connected to the widthwise extending portion 34 have the same length. The bent portion recess 40 is formed with a depth from the tread surface 3 within a range of 1 mm to 8 mm and within a range of 10% to 50% of the depth of the center lug groove 31. Has been.

  Further, the center block 11 is provided with an extension line of the width direction extending portion 34, and a center notch portion 45 having one end connected to the bent portion 32 and the other end terminating in the center block 11 is formed. Yes. The center notch 45 is formed in a groove shape having a groove width that is the same as the groove width of the width direction extending portion 34 and a groove depth that is the same as the groove depth of the width direction extending portion 34. Has been. Therefore, in other words, the width direction extending portion 34, the center cutout portion 45, and the circumferential direction extension portion 33 are in the middle of one groove formed by the width direction extension portion 34 and the center cutout portion 45. It is comprised in the form where the edge part of the circumferential direction extension part 33 was connected.

  As described above, the center notch 45 connected to the bent portion 32 of the center lug groove 31 has a length EL in the direction along the forming direction of the width direction extending portion 34, and the center block 11 in the tire width direction. It is formed within the range of 10% or more and 20% or less of the width W. In this case, the length EL of the center notch 45 is determined by the center notch from the connection portion between the sides on the dominant angle side in the circumferentially extending portion 33 and the width extending portion 34 constituting the bent portion 32. It is the length in the extending direction of the portion 45.

  Further, the center notch 45 and the bent portion recess 40 have a relation of 3 ≦ (A2) between the opening area A1 of the bent portion recess 40 connected to the common bent portion 32 and the opening area A2 of the center notch 45. / A1) ≦ 6, that is, (A2 / A1) has a relationship of 3 or more and 6 or less.

  FIG. 4 is an explanatory diagram of the bent space portion. Further, the center cutout portion 45 includes an opening area A3 of a bent portion space portion 42 including a circumferentially extending portion 33 and a width extending portion 34, and a bent portion concave portion 40, and an opening area of the center cutout portion 45. It is formed so that the relationship with A2 is in the range of 0.03 ≦ (A2 / A3) ≦ 0.10. In this case, the bent space portion 42 has a side 41 facing the corner on the bent portion 32 side of the triangle, which is the shape of the bent portion concave portion 40, in the circumferentially extending portion 33 and the width extending portion 34. It is a space formed by extending to the groove walls 33a and 34a facing the groove wall on the side where the bent portion recess 40 is located.

  In other words, the bent portion space portion 42 is a groove facing the side 41 of the extended bent portion recess 40 and the groove wall on the side where the bent portion recess 40 is located in the circumferentially extending portion 33 and the width extending portion 34. Each of the walls 33a and 34a is a triangular space having sides. The center notch 45 has a relationship in which the ratio (A2 / A3) of the opening area A3 of the bent space portion 42 and the opening area A2 of the center notch 45 is 0.03 or more and 0.10 or less. It has become.

  In the pneumatic tire 1 according to the present embodiment, the contact area ratio in the center area CA, which is an area mainly including the center block 11 and the center lug groove 31 that are partitioned by the center lug groove 31 on both sides in the tire circumferential direction. However, it is formed within a range of 30% to 70%. In this case, the center area CA is an area of 10% of the width W of the center block 11 in the tire width direction with the center block center BC being the center of the center block 11 in the tire width direction as the center. That is, the center area CA is an area in a range of 5% of the width W of the center block 11 in the tire width direction on both sides in the tire width direction from the center block center BC.

  Further, the center block center BC in this case refers to the center position in the tire width direction of the portions located on the outermost side in the tire width direction on both sides of the center block 11 in the tire width direction. In the pneumatic tire according to the present embodiment, the center block center BC is located on the tire equatorial plane CL, and the center block center BC is located at the same position as the tire equatorial plane CL in the tire width direction. ing. Further, the width W of the center block 11 is a distance in the tire width direction between portions located on the outermost side in the tire width direction on both sides of the center block 11 in the tire width direction.

  The ground contact area ratio refers to the area of the tread surface 3 that is actually grounded with respect to the area of the center region CA. The circumferential extending portion 33 of the center lug groove 31 is located in the center area CA. When the pneumatic tire 1 is actually grounded, the pneumatic tire 1 is grounded at any position in the circumferential direction of the tire, and the ground area ratio varies depending on the portion to be grounded. In FIG. 5, the ratio of the contact surface in the center area CA is in the range of 30% to 70%. Further, the ratio of the ground contact surface in the center area CA is preferably in the range of 40% to 60%.

  Further, the center block 11 is formed such that the width W in the tire width direction is in the range of 20% to 40% of the tread development width TW. The tread deployment width TW in this case is such that the pneumatic tire 1 is assembled to a specified rim, the pneumatic tire 1 is filled with air at a specified internal pressure, and no load is applied to the tread portion 2 when no load is applied. The straight line distance between both ends in the tire width direction in the development view.

  The specified rim refers to “applied rim” defined in JATMA, “Design Rim” defined in TRA, or “Measuring Rim” defined in ETRTO. The specified internal pressure refers to the “maximum air pressure” specified in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified in TRA, or “INFLATION PRESSURES” specified in ETRTO. The width W of the center block 11 in the tire width direction is preferably in the range of 25% to 35% of the tread development width TW.

  The center block 11 is formed such that the ratio of the length L in the tire circumferential direction to the width W in the tire width direction is in a range of 0.9 ≦ (L / W) ≦ 1.1. That is, the center block 11 is formed in a shape in which the length L in the tire circumferential direction is 0.9 to 1.1 times the width W in the tire width direction. The length L of the center block 11 in this case is the distance in the tire circumferential direction between the portions of the center block 11 that are farthest apart in the tire circumferential direction.

  The center block 11 has an area larger than that of the intermediate block 12 and the shoulder block 13. In other words, the intermediate block 12 and the shoulder block 13 are smaller in area than the center block 11. For example, the shoulder block 13 has an area within a range of 40% to 60% of the area of the center block 11. It is formed. In addition, it is preferable that the area of the shoulder block 13 with respect to the area of the center block 11 is 45% or more and 55% or less.

  The center block 11 is formed such that the width W in the tire width direction is in the range of 25% to 45% of the maximum belt width BW that is the maximum width of the belt layer 7 in the tire width direction. Here, the maximum belt width BW is located at the outermost position in the tire width direction at the respective end portions on both sides in the tire width direction of the plurality of belts 71, 72, 73, 74 constituting the belt layer 7. It is the distance in the tire width direction between the ends. The width W in the tire width direction of the center block 11 with respect to the maximum belt width BW is preferably in the range of 30% to 40%.

  FIG. 5 is a detailed view of part C of FIG. The intermediate lug groove 35 and the shoulder lug groove 36 are both inclined in the tire circumferential direction with respect to the tire width direction. Specifically, the intermediate lug groove 35 is formed with an inclination angle in the tire circumferential direction with respect to the tire width direction within a range of 0 ° to 15 °. In other words, the intermediate lug groove 35 is formed with an inclination angle α1 in the tire width direction with respect to the tire circumferential direction within a range of 75 ° to 105 °, that is, the intermediate lug groove 35 is in the tire circumferential direction. The inclination angle α1 in the tire width direction is formed within a range of 90 ° ± 15 °. The inclination angle α1 of the intermediate lug groove 35 with respect to the tire circumferential direction is preferably in the range of 90 ° ± 10 °.

  The shoulder lug groove 36 is inclined in the tire circumferential direction with respect to the tire width direction in the same direction as the inclination direction of the intermediate lug groove 35 in the tire circumferential direction with respect to the tire width direction. The intermediate lug groove 35 and the shoulder lug groove 36 include an inclination angle α1 of the intermediate lug groove 35 in the tire width direction with respect to the tire circumferential direction, and an inclination of the shoulder lug groove 36 in the tire width direction with respect to the tire circumferential direction. The relationship with the angle α2 is in the range of 0 ° ≦ | α2−α1 | ≦ 10 °.

  Further, the intermediate block 12 is formed with an intermediate notch 46 connected to the outer circumferential groove 25, and the shoulder block 13 is formed with a shoulder notch 47 connected to the outer circumferential groove 25. Yes. Among these, the intermediate notch portion 46 is provided on an extension line of the shoulder lug groove 36 connected to the opposite side of the outer circumferential groove 25 to the side to which the intermediate notch portion 46 is connected, and one end of the outer notch portion 46 The other end is connected to the directional groove 25 and is terminated in the intermediate block 12. The intermediate notch 46 is formed such that the length ML in the extending direction of the shoulder lug groove 36 is in the range of 150% to 300% of the groove width W2 of the outer circumferential groove 25.

  Further, the shoulder notch 47 is provided on an extension line of the intermediate lug groove 35 connected to the opposite side of the outer circumferential groove 25 to the side to which the shoulder notch 47 is connected, and one end is in the outer circumferential direction. It is connected to the groove 25 and is formed with the other end terminating in the shoulder block 13. The shoulder notch 47 is formed such that the length SL in the extending direction of the intermediate lug groove 35 is in the range of 100% to 300% of the groove width W2 of the outer circumferential groove 25.

  The pneumatic tire 1 according to the present embodiment configured as described above is used for a heavy-duty pneumatic tire. When the pneumatic tire 1 is mounted on the vehicle, the pneumatic tire 1 is mounted on the vehicle in a rim-assembled and inflated state. The pneumatic tire 1 in a rim assembled state with a rim wheel is used by being mounted on a large vehicle such as a truck or a bus.

  When the vehicle equipped with the pneumatic tire 1 travels, the pneumatic tire 1 rotates while the tread surface 3 positioned below the tread surface 3 is in contact with the road surface. The vehicle travels by transmitting a driving force or a braking force to the road surface or generating a turning force by a frictional force between the tread surface 3 and the road surface. For this reason, the ground contact area in the ground contact region of the pneumatic tire 1 is an important factor with respect to steering stability during travel of the vehicle. On the other hand, when traveling on a snowy road, since the snow column shearing force and edge effect in the circumferential groove 20 and lug groove 30 are frequently used, the groove area in the ground contact region is also an important factor.

  Further, in a large vehicle such as a truck or a bus, the total weight of the vehicle greatly varies depending on the cargo loading state, and accordingly, the load acting on the pneumatic tire 1 also varies greatly. When the load acting on the pneumatic tire 1 changes greatly, the shape of the ground contact area of the pneumatic tire 1 changes, and the ground contact area increases as the load increases. That is, as the load acting on the pneumatic tire 1 increases, the contact area of the pneumatic tire 1 increases in both the tire width direction and the tire circumferential direction.

  However, the vicinity of the center of the tread surface 3 in the tire width direction, that is, the vicinity of the tire equatorial plane CL of the tread surface 3 is grounded when the vehicle travels regardless of the magnitude of the load acting on the pneumatic tire 1. In the pneumatic tire 1 according to the present embodiment, the inner circumferential grooves 21 are disposed on both sides of the tire equatorial plane CL, and the center block 11 is positioned on the tire equatorial plane CL. Area is secured. Thereby, irrespective of the magnitude of the load acting on the pneumatic tire 1, it is possible to ensure steering stability when traveling on a dry road surface.

  Further, the center lug groove 31 has a circumferentially extending portion 33 on the tire equator plane CL by being bent at a plurality of positions. Therefore, the center lug groove 31 is near the tire equator plane CL when traveling on a snowy road. Snow column shear force and edge effect are secured. Further, since the bent portion recess 40 is connected to the center lug groove 31 at a position on the inferior angle side of the bent portion 32, it is possible to improve the snow drainage property in the vicinity of the bent portion 32, which is a portion where snow is easily clogged. . As a result, regardless of the magnitude of the load acting on the pneumatic tire 1, it is possible to continuously ensure the resistance between the ground contact surface and the snow surface when traveling on a snowy road. Moreover, since the circumferentially extending portion 33 is formed in the center lug groove 31, an edge component in the tire width direction in the vicinity of the tire equatorial plane CL can be increased. Thereby, the side slip of the pneumatic tire 1 with respect to the slip at the time of acceleration can be reduced, and the steering stability at the time of drive | working on a snowy road can be improved.

  Further, the tread surface 3 has a ground contact area ratio in the center region CA of 30% or more and 70% or less, so that the ground contact when traveling on a dry road surface regardless of the magnitude of the load acting on the pneumatic tire 1. The area can be secured, and the resistance between the snow surface and the ground contact surface when traveling on a snowy road can be secured. That is, when the ground contact area ratio in the center area CA is less than 30%, the ground contact area becomes small when the load is small, so that it is difficult to ensure steering stability, and the ground contact area ratio in the center area CA is 70. If it exceeds%, the groove area when the load is small becomes small, and it becomes difficult to ensure the resistance between the ground contact surface and the snow surface. On the other hand, since the pneumatic tire 1 according to the present embodiment is formed in a range where the contact area ratio in the center area CA is 30% or more and 70% or less, the load acting on the pneumatic tire 1 is small. In this case, the resistance between the ground surface and the snow surface can be ensured while ensuring the ground contact area. As a result, it is possible to improve both dry performance and snow performance regardless of the cargo loading state, that is, regardless of whether the vehicle is empty or loaded, and in particular, improve the dry performance and snow performance when empty. be able to.

  Further, since the circumferentially extending portion 33 of the center lug groove 31 is located in the center area CA, the groove area in the center area CA is ensured when the center block 11 located on the tire equatorial plane CL is provided. can do. Thereby, when the dry performance at the time of empty vehicle is ensured by disposing the center block 11 on the tire equatorial plane CL, the resistance between the ground contact surface at the time of empty vehicle and the snow surface can be ensured. As a result, both dry performance and snow performance can be improved more reliably.

  Further, since the bent portion concave portion 40 is formed by chamfering, the bent portion is not reduced in the portion of the center lug groove 31 where the block rigidity tends to be lowered, on the inferior angle side of the bent portion 32 without lowering the rigidity of the center block 11. A recess 40 can be provided. Thereby, when providing the bending part recessed part 40 in order to improve snow drainage, the fall of the dry performance can be suppressed, and both dry performance and snow performance can be improved more reliably.

  Further, the bent portion recess 40 is formed with an equal length between the portion connected to the circumferentially extending portion 33 of the center lug groove 31 and the portion connected to the widthwise extending portion 34. The bent portion recess 40 can be provided without lowering the rigidity of the center block 11 due to the provision of 40. Thereby, when providing the bending part recessed part 40 in order to improve snow drainage, the fall of the dry performance can be suppressed, and both dry performance and snow performance can be improved more reliably.

  Moreover, since the depth from the tread surface 3 is formed within the range where the depth from the tread surface 3 is 10% or more and 50% or less of the groove depth of the center lug groove 31, the bent portion recess 40 has more reliable dry performance and snow performance. It can be compatible. That is, when the depth of the bent portion recess 40 is less than 10% of the groove depth of the center lug groove 31, the depth of the bent portion recess 40 is too shallow and the difference from the groove depth of the center lug groove 31 is too large. Therefore, it may be difficult to effectively remove the snow that has entered the center lug groove 31. Moreover, when the depth of the bent part recessed part 40 exceeds 50% of the groove depth of the center lug groove 31, the rigidity of the bent part recessed part 40 vicinity in the center block 11 may fall, and it may become difficult to ensure dry performance. There is. On the other hand, when the depth of the bent portion recess 40 is in the range of 10% or more and 50% or less of the groove depth of the center lug groove 31, the bent portion recess is not reduced without reducing the rigidity of the center block 11. Snow removal at 40 can be ensured. As a result, both dry performance and snow performance can be improved more reliably.

  Further, since the center block 11 is formed with a center notch 45 connected to the bent portion 32 of the center lug groove 31, the snow notch shear force and the edge effect can be ensured also by the center notch 45. Can do. As a result, the resistance between the ground contact surface and the snow surface in the vicinity of the center area CA can be more reliably increased, and the snow performance can be more reliably improved.

  Further, the center notch 45 has a length EL in a direction along the forming direction of the width extending portion 34 of the center lug groove 31 within a range of 10% to 20% of the width W of the center block 11. Since it is formed, it is possible to improve the traction performance on snow while sufficiently securing a ground contact area contributing to the dry grip. That is, when the length EL of the center notch 45 is less than 10% of the width W of the center block 11, the snow column shear force and the edge effect at the center notch 45 are not so high. It becomes difficult to effectively improve the resistance between the surfaces. Further, when the length EL of the center notch 45 exceeds 20% of the width W of the center block 11, the ground contact area of the center block 11 may be too small. On the other hand, when the length EL of the center notch 45 is in the range of 10% or more and 20% or less of the width W of the center block 11, a center notch that can be expected to have a snow column shear force and an edge effect. 45 can be provided without making the ground contact area of the center block 11 too small. As a result, both dry performance and snow performance can be improved more reliably.

  In addition, the bending portion recess 40 and the center notch portion 45 have a relationship between the opening area A1 of the bending portion recess 40 connected to the common bending portion 32 and the opening area A2 of the center notch portion 3 ≦ (A2). Since / A1) ≦ 6, the rigidity of the center block 11 can be made uniform. In other words, the bent portion recess 40 and the center cutout portion 45 are disposed on both sides of the circumferential extension portion 33 of the center lug groove 31 in the tire width direction, so (A2 / A1) is less than 3. Or (A2 / A1) exceeds 6, the difference in rigidity between the sides of the circumferentially extending portion 33 in the center block 11 becomes too large, which may cause uneven wear. On the other hand, when the relationship between the opening area A1 of the bent portion recess 40 and the opening area A2 of the center notch 45 is in the range of 3 ≦ (A2 / A1) ≦ 6, the circumferentially extending portion 33 The rigidity difference between both sides can be reduced. As a result, it is possible to suppress the occurrence of uneven wear when the bent portion concave portion 40 and the center cutout portion 45 are provided.

  Further, since the intermediate block 12 is formed with the intermediate notch 46 and the shoulder block 13 is formed with the shoulder notch 47, the snow column shear force between the intermediate notch 46 and the shoulder notch 47 is formed. Due to the edge effect, it is possible to increase the resistance between the contact surface and the snow surface in the vicinity of both ends in the tire width direction of the contact region. As a result, snow acceleration performance can be improved and snow performance can be improved more reliably.

  Further, the intermediate lug groove 35 is formed within a range of 75 ° or more and 105 ° or less in an inclination angle α1 in the tire width direction with respect to the tire circumferential direction. The edge component with respect to the tire circumferential direction can be improved. As a result, snow performance can be improved more reliably.

  The intermediate lug groove 35 and the shoulder lug groove 36 are such that the relationship between the inclination angle α1 of the intermediate lug groove 35 and the inclination angle α2 of the shoulder lug groove 36 is in the range of 0 ° ≦ | α2-α1 | ≦ 10 °. Therefore, the snow drainage can be ensured, and the snow column shear force and the edge effect in the intermediate lug groove 35 and the shoulder lug groove 36 can be effectively enhanced. As a result, snow performance can be improved more reliably.

  The inner circumferential groove 21 and the outer circumferential groove 25 have a relationship between the groove width W1 of the inner circumferential groove 21 and the groove width W2 of the outer circumferential groove 25 of 0.5 ≦ (W2 / W1) ≦ 0. .9, the groove area at the position near the center area CA can be secured, and the snow drainage can be sufficiently exhibited. As a result, it is possible to improve the snow performance when the vehicle is empty while improving the dry performance.

  Further, since the center block 11 is formed so that the width W in the tire width direction is 20% or more and 40% or less of the tread development width TW, the area of the center block 11 is ensured while ensuring the groove area of the center area CA. Can be taken big. As a result, it is possible to improve the dry performance while ensuring the snow performance.

  The center block 11 is formed so that the ratio of the length L in the tire circumferential direction to the width W in the tire width direction is within a range of 0.9 ≦ (L / W) ≦ 1.1. The rigidity of the block 11 can be ensured, and steering stability can be ensured. That is, if (L / W) is less than 0.9 or greater than 1.1, the rigidity of the center block 11 in the tire circumferential direction and the rigidity in the tire width direction may be too low. Since 11 becomes easy to fall down, there exists a possibility that the effective ground contact area of the center block 11 may fall. On the other hand, by setting the ratio of the length L in the tire circumferential direction of the center block 11 to the width W in the tire width direction within the range of 0.9 ≦ (L / W) ≦ 1.1, the center block 11 11 can be secured, so that the effective ground contact area of the center block 11 can be suppressed from decreasing. As a result, both dry performance and snow performance can be improved more reliably.

  Further, since the area of the shoulder block 13 is formed within the range of 40% or more and 60% or less of the area of the center block 11, the shoulder area 13 is less frequently grounded than the center area CA when empty. The groove area can be secured, and snow column shearing force and edge effect can be secured. Further, by increasing the area of the center block 11 relative to the area of the shoulder block 13, the rigidity of the center block 11 can be ensured. Thereby, it can suppress that the effective ground-contact area of the center block 11 falls resulting from the rigidity of the center block 11 being low. As a result, both dry performance and snow performance can be improved more reliably.

  Further, since the center block 11 is formed such that the width W in the tire width direction is in the range of 25% to 45% of the maximum belt width BW, the center block 11 is centered on the center area CA in the tire width direction. It is possible to optimize the width of the belt layer 7 in a region where the contact pressure is high. Thereby, the rigidity of the tread portion 2 in the tire width direction can be made uniform. As a result, the steering stability can be improved regardless of the running state of the vehicle.

  Moreover, since a steel carcass material is used for the carcass 6, the rigidity of the entire pneumatic tire 1 can be ensured. As a result, the steering stability can be improved regardless of the running state of the vehicle.

  In addition, by using the pneumatic tire 1 according to the present embodiment as a heavy duty pneumatic tire, even when the load acting on the pneumatic tire 1 varies greatly depending on the cargo loading state, regardless of the magnitude of the load, Both dry performance and snow performance can be improved. As a result, the running performance of the vehicle when the pneumatic tire 1 according to the present embodiment is mounted on a large vehicle such as a truck or a bus can be improved.

〔Example〕
6A to 6D are tables showing results of performance tests of pneumatic tires. Hereinafter, the performance evaluation test performed on the pneumatic tire 1 according to the related art and the pneumatic tire 1 according to the present invention will be described. In the performance evaluation test, a test for dry acceleration performance, which is acceleration performance on a dry road surface, and a test for snow acceleration performance, which is acceleration performance on snow, were performed.

  In these performance evaluation tests, a pneumatic tire 1 with a tire size specified by JATMA of 275 / 80R22.5 size and a road index of 151J is assembled on a rim wheel of a specified rim specified by JATMA, and the air pressure is increased. The test was carried out by adjusting the maximum air pressure specified by JATMA and mounting it on a 2-D test vehicle (tractor head).

  The evaluation method of each test item evaluated the dry acceleration performance by measuring the acceleration in the speed section of 5 to 40 km / h on the dry road surface and indexing the average acceleration. The larger the value, the better the dry acceleration performance. The snow acceleration performance was evaluated by measuring the acceleration in the speed section of 5 to 20 km / h on the snowy road surface and indexing the average acceleration. The larger the value, the better the snow acceleration performance. Further, it is assumed that the dry acceleration performance and the snow acceleration performance have effective performance when the index is 105 or more.

  The evaluation test is performed on the 24 types of pneumatic tires 1 of Examples 1 to 21 that are the pneumatic tires 1 of the conventional examples 1 to 3 that are examples of the conventional pneumatic tire 1 and the pneumatic tire 1 according to the present invention. went. In these pneumatic tires 1, whether or not the center lug groove 31 is bent, whether or not the circumferential groove 20 is oscillating in the tire width direction, the contact area ratio in the center region CA, The presence or absence is formed differently. Among these, the pneumatic tires 1 of the conventional examples 1 to 3 are not provided with the bent portion recess 40, and the center lug groove 31 is not bent, or the circumferential groove 20 is not oscillated, or the center. The ground contact area ratio in the area CA is not in the range of 30% to 70%.

  On the other hand, in Examples 1-21, which are examples of the pneumatic tire 1 according to the present invention, the center lug groove 31 is bent, the circumferential groove 20 is oscillating, and the contact area ratio in the center region CA is It is in the range of 30% or more and 70% or less, and has a bent portion recess 40. Furthermore, the pneumatic tire 1 according to Examples 1 to 21 has the opening of the center notch 45 with respect to the presence or absence of the center notch 45, the length EL of the center notch 45, and the opening area A1 of the bent recess 40. Ratio of area A2, presence / absence of intermediate notch 46 and shoulder notch 47, inclination angles α1, α2 of intermediate lug groove 35 and shoulder lug groove 36, groove width W1 of inner circumferential groove 21 and outer circumferential groove 25 , W2, the ratio of the width W of the center block 11 to the tread development width TW, the aspect ratio of the center block 11, the ratio of the area of the shoulder block 13 to the area of the center block 11, and the ratio of the center block 11 to the maximum belt width BW The ratio of the width W is different.

  As a result of performing an evaluation test using these pneumatic tires 1, as shown in FIGS. 6A to 6D, the pneumatic tires 1 of Examples 1 to 21 have a dry acceleration performance compared to the conventional examples 1 to 3. And snow acceleration performance are improved. That is, the pneumatic tire 1 according to Examples 1 to 21 can improve both dry performance and snow performance.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Tread surface 4 Shoulder part 5 Side wall part 6 Carcass 7 Belt layer 8 Inner liner 10 Land part 11 Center block 12 Intermediate block 13 Shoulder block 20 Circumferential groove 21 Inner circumferential groove 25 Outer circumferential direction Groove 30 Lug groove 31 Center lug groove 32 Bent part 33 Circumferentially extending part 34 Widthwise extending part 35 Intermediate lug groove 36 Shoulder lug groove 40 Bent part concave part 42 Bent part space part 45 Center notch part 46 Intermediate notch part 47 Shoulder notches 50 Beads CL Tire equator CA Center area

Claims (15)

A pair of inner circumferential grooves disposed on both sides of the tire equatorial plane in the tire width direction across the tire equatorial plane and extending in the tire circumferential direction;
A pair of outer circumferential grooves disposed on the outer sides of the pair of inner circumferential grooves in the tire width direction and extending in the tire circumferential direction;
A plurality of centers having both ends connected to the pair of inner circumferential grooves and having a circumferentially extending portion extending in the tire circumferential direction and a widthwise extending portion extending in the tire width direction by bending at a plurality of positions Lug grooves,
A center block which is a land portion defined by the center lug groove and the inner circumferential groove;
A bent portion recess formed by recessing from the tread surface at a position on the minor angle side of the bent portion of the center lug groove in the center block and connected to the circumferentially extending portion and the width extending portion. When,
With
Centering on the center of the center block in the tire width direction, the contact area ratio in the center region, which is a region of 10% of the width of the center block in the tire width direction, is 30% or more and 70% or less Pneumatic tire.   The pneumatic tire according to claim 1, wherein the circumferentially extending portion is located in the center region.   The pneumatic tire according to claim 1, wherein the bent portion recess is formed by chamfering.   The bent portion recess is formed with a length equal to a portion connected to the circumferentially extending portion and a portion connected to the widthwise extending portion. Pneumatic tires.   The air according to any one of claims 1 to 4, wherein the bent portion recess is formed such that a depth from the tread surface is within a range of 10% to 50% of a depth of the center lug groove. Enter tire.   The center block is formed with an extension line of the width direction extending portion, and one end is connected to the bent portion and the other end is terminated in the center block. The pneumatic tire according to any one of 5.   The center notch portion is formed such that a length in a direction along a forming direction of the width direction extending portion is within a range of 10% to 20% of a width of the center block in a tire width direction. 6. The pneumatic tire according to 6.   The relationship between the opening area A1 of the bending portion recess connected to the common bending portion and the opening area A2 of the center notch portion is 3 ≦ (A2 / A1). The pneumatic tire according to claim 6 or 7, wherein ≦ 6. A plurality of intermediate lug grooves whose both ends are connected to the adjacent inner circumferential groove and the outer circumferential groove;
A plurality of shoulder lug grooves disposed on the outer side in the tire width direction of the outer circumferential groove, one end of which is connected to the outer circumferential groove;
An intermediate block which is a land portion defined by the inner circumferential groove, the outer circumferential groove and the intermediate lug groove;
A shoulder block which is a land portion defined by the outer circumferential groove and the shoulder lug groove;
With
The intermediate block is formed on an extension line of the shoulder lug groove, and one end is connected to the outer circumferential groove, and the other end is formed with an intermediate notch that terminates in the intermediate block.
The shoulder block is formed on the extension line of the intermediate lug groove, and is formed with a shoulder notch portion having one end connected to the outer circumferential groove and the other end terminating in the shoulder block. The pneumatic tire according to any one of the above.   The pneumatic tire according to claim 9, wherein the intermediate lug groove is formed with an inclination angle in a tire width direction with respect to a tire circumferential direction within a range of 75 ° to 105 °. The intermediate lug groove and the shoulder lug groove are
An inclination angle α1 of the intermediate lug groove in the tire width direction with respect to the tire circumferential direction,
An inclination angle α2 of the shoulder lug groove in the tire width direction with respect to the tire circumferential direction;
The pneumatic tire according to claim 9 or 10, wherein the relationship is 0 ° ≦ | α2−α1 | ≦ 10 °.   In the inner circumferential groove and the outer circumferential groove, the relationship between the groove width W1 of the inner circumferential groove and the groove width W2 of the outer circumferential groove is 0.5 ≦ (W2 / W1) ≦ 0.9. The pneumatic tire according to any one of claims 1 to 11.   The pneumatic tire according to any one of claims 1 to 12, wherein the center block has a width in the tire width direction of 20% or more and 40% or less of a tread developed width.   The ratio of the length L in the tire circumferential direction to the width W in the tire width direction of the center block is 0.9 ≦ (L / W) ≦ 1.1. The described pneumatic tire.   The pneumatic tire according to any one of claims 1 to 14, wherein the pneumatic tire is used for heavy duty pneumatic tires.

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