JP2018099925A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire that can effectively improve braking performance on snow by maintaining a snow column in a closed groove in a compressed state.SOLUTION: The pneumatic tire, which comprises a tread part 1 and whose rotation direction R is specified, has: two circumferential grooves 11 and 12 which extend in a tire circumferential direction in a one-side area bordered by a tire equator CL of the tread part; a plurality of inclined grooves 31 extending in a tire width direction to communicate with the circumferential grooves and inclined toward the opposite direction of a rotation direction, toward outside in the tire width direction; a plurality of blocks 32 partitioned by the circumferential grooves and the inclined grooves; a closed groove 33, extending along the inclined groove in each block, one end of which is opened to a main groove 11 close to the tire equator and the other end of which is closed in each block. The block has a protruding part 32A protruding into the inclined groove at a site close to a grounding front end side and the tire equator, where protrusion amounts B of the protruding part relative to the maximum value Gmax of a groove width of the inclined groove satisfies the following relational expression: B/Gmax≥0.2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire suitable for icy and snowy roads, and more specifically, compresses a snow column in a closed groove by deforming the block so that the closed groove formed in the block is closed when braking on snow. It is related with the pneumatic tire which made it possible to hold and improve the braking performance on snow effectively.

  In pneumatic tires for icy and snowy roads typified by studless tires, generally, a plurality of main grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction are formed in the tread portion. A large number of blocks are defined by these main grooves and lug grooves. Moreover, a plurality of sipes are formed on each rib and each block, and the performance on ice and the performance on snow are enhanced by the edge effect of these sipes (for example, see Patent Documents 1 to 5).

  The pneumatic tire for an icy and snowy road constructed in this way generates driving force and braking force during running on snow based on the shearing force of the snow column formed in the groove when the snow is stepped and hardened. . Therefore, in order to improve the performance on snow, it is effective to increase the snow column shear force generated when traveling on snow. Generally, increasing the groove depth, groove width, and groove area in the tread portion increases the snow column shear force.

  However, in view of tire performance other than on-snow performance, the groove depth, groove width, and groove area are naturally limited, so there is a limit to improving snow performance based on these factors.

Japanese Patent No. 5770834 Japanese Patent No. 5102711 Japanese Patent No. 5276104 Japanese Patent No. 5981957 Japanese Patent No. 5629286

  The purpose of the present invention is to deform the block so that the closing groove formed in the block is closed when braking on snow, compressing and holding the snow column in the closing groove, and effectively improving the braking performance on snow It is an object of the present invention to provide a pneumatic tire that can be improved.

In order to achieve the above object, a pneumatic tire according to the present invention includes a tread portion that extends in the tire circumferential direction to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and the sidewall portions. In a pneumatic tire provided with a pair of bead portions arranged on the inner side in the tire outer diameter direction, and the rotation direction is designated,
Two circumferential grooves extending in the tire circumferential direction in a region on one side of the tire equator of the tread portion, and extending in the tire width direction so as to communicate with these circumferential grooves, the tire width A plurality of inclined grooves inclined outwardly in the direction opposite to the rotation direction, a plurality of blocks defined by the circumferential grooves and the inclined grooves, and extending along the inclined grooves in each block. One end is open to the main groove near the tire equator, and the other end is closed in each block, and the block protrudes into the inclined groove at the front end of the ground and on the tire equator side. The projecting amount B of the projecting portion satisfies the relationship of B / Gmax ≧ 0.2 with respect to the maximum value Gmax of the groove width of the inclined groove.

  In the present invention, in a pneumatic tire in which the rotation direction is specified, two circumferential grooves extending in the tire circumferential direction in a region on one side of the tire equator of the tread, and the circumferential grooves A plurality of inclined grooves extending in the tire width direction so as to communicate with each other and inclined toward the opposite side of the rotation direction toward the outer side in the tire width direction, and a plurality of blocks defined by the circumferential grooves and the inclined grooves; The block is provided with a closed groove extending along an inclined groove in each block, one end opening in the main groove near the tire equator, and the other end closed in each block, and the ground contact front end side of the block and the tire equator side A projecting portion that projects into the inclined groove is formed at a portion of the projecting portion, and the projecting amount B of the projecting portion satisfies a relationship of B / Gmax ≧ 0.2 with respect to the maximum value Gmax of the groove width of the inclined groove. In the tread when braking on snow Relative resulting snow flows block to close the pressing to closed grooves is to deform the protrusions. Such a behavior of the block at the time of braking makes it possible to compress and hold the snow column in the closed groove and effectively improve the braking performance on snow. In addition, since a similar behavior occurs when a pneumatic tire tries to flow laterally when running on snow, an effect of improving steering stability on snow can be expected.

  In the present invention, the groove width of the inclined groove is preferably narrowed from the outer side in the tire width direction toward the inner side. As a result, the groove width of the inclined groove becomes narrower in the direction in which snow flows during braking, and the force that pushes the protrusion and deforms the block increases, so that the braking performance on snow can be further improved.

  The inclined groove is bent with the protruding portion as a boundary, and the inclination angle of the inclined groove with respect to the tire circumferential direction of the inner portion in the tire width direction is smaller than the inclination angle of the inclined groove with respect to the tire circumferential direction of the outer portion in the tire width direction. The angle difference is preferably 10 ° or more. Since the inclined groove is bent as described above, the force for pushing the protrusion and deforming the block is increased, so that the braking performance on snow can be further improved.

  The projection length in the tire circumferential direction of the closing groove is 30% or more and 80% or less of the tire circumferential projection length of the block, and the tire circumferential projection length of the protrusion is 30% or more of the tire circumferential projection length of the block. It is preferable that it is 80% or less. In this way, by defining the projection length in the tire circumferential direction of the closing groove and the protruding portion, it is possible to secure a sufficient volume of snow held in the closing groove while maintaining good block rigidity, and deformation of the block. Can be promoted.

  The distance d from the center position in the tire circumferential direction of the tire equator side wall surface of the block to the center position of the groove width at the opening end of the closing groove is from the front contact end position or the rear contact end position of the block tire equator side wall surface to the center position. It is preferable to satisfy the relationship of d / D ≦ 0.2 with respect to the distance D. Thus, by arranging the position of the opening end of the closing groove in the vicinity of the center position of the tire equator side wall surface of the block, the closing groove is easily closed during braking.

  The groove width of the closing groove is preferably narrower toward the main groove closer to the tire equator. Thus, since the groove width of the closing groove becomes narrower toward the opening end, it becomes easier to hold snow in the closing groove during braking on snow.

  In the present invention, in order to satisfy the required characteristics as a pneumatic tire for icy and snowy roads, the JIS hardness of the tread rubber constituting the tread portion is in the range of 40 to 60, and each block formed in the tread portion has It is preferable to have a plurality of sipes.

In order to satisfy the required characteristics as a pneumatic tire for icy and snowy roads, it is preferable that the snow traction index STI represented by the following formula (1) is 180 or more.
STI = −6.8 + 2202ρg + 672ρs + 7.6Dg (1)
However, ρg: groove density (mm / mm ² ) = gross length of the extended component in the tire width direction of the groove (mm)
/ Total area of ground contact area (mm ² )
ρs: sipe density (mm / mm ² ) = total length of sipe extension components in the tire width direction
(Mm) / Total area of ground contact area (mm ² )
Dg: Average groove depth (mm)

  In the present invention, JIS hardness is durometer hardness measured at a temperature of 20 ° C. using an A type durometer in accordance with JIS K-6253. In addition, the contact area of the tread is based on the contact width in the tire axial direction measured when a normal load is applied by placing the tire on a normal rim and filling it with normal internal pressure, and placing it vertically on a flat surface. This area is specified by The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based, for example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO. Then, “Measuring Rim” is set. “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum air pressure is JATMA, and the table “TIRE ROAD LIMITS AT VARIOUS” is TRA. The maximum value described in “COLD INFRATION PRESURES”, “INFLATION PRESURE” for ETRTO, but 180 kPa when the tire is a passenger car. “Regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. The maximum load capacity is JATMA, and the table “TIRE ROAD LIMITS AT VARIOUS” is TRA. The maximum value described in “COLD INFORATION PRESSURES” is “LOAD CAPACITY” if it is ETRTO, but if the tire is a passenger car, the load is equivalent to 88% of the load.

It is meridian sectional drawing which shows the pneumatic tire which consists of embodiment of this invention. FIG. 2 is a development view showing a main part of a tread pattern of the pneumatic tire of FIG. 1. FIG. 6 is another development view showing the main part of the tread pattern of the pneumatic tire of FIG. 1. FIG. 5 is still another development view showing the main part of the tread pattern of the pneumatic tire of FIG. 1. FIG. 5 is still another development view showing the main part of the tread pattern of the pneumatic tire of FIG. 1.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 to 5 show a pneumatic tire according to an embodiment of the present invention. The pneumatic tire of this embodiment is a tire in which the rotation direction R is designated. 2 to 5, Tc is the tire circumferential direction, Tw is the tire width direction, and CL is the tire equator.

  As shown in FIG. 1, the pneumatic tire of the present embodiment includes a tread portion 1 that extends in the tire circumferential direction and has an annular shape, and a pair of sidewall portions 2, 2 disposed on both sides of the tread portion 1. And a pair of bead portions 3 and 3 disposed inside the sidewall portion 2 in the tire radial direction.

  A carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded from the inside of the tire to the outside around the bead core 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross-section is disposed on the outer periphery of the bead core 5.

  On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in a range of, for example, 10 ° to 40 °. A steel cord is preferably used as the reinforcing cord of the belt layer 7. For the purpose of improving high-speed durability, at least one belt cover layer 8 in which reinforcing cords are arranged at an angle of, for example, 5 ° or less with respect to the tire circumferential direction is disposed on the outer peripheral side of the belt layer 7. Yes. As the reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or aramid is preferably used.

  In addition, although the tire internal structure mentioned above shows the typical example in a pneumatic tire, it is not limited to this.

  As shown in FIG. 2, two circumferential grooves 11 and 12 extending along the tire circumferential direction Tc are formed in at least one region of the tread portion 1 with the tire equator CL as a boundary. By these circumferential grooves 11, 12, the center land portion 20 located on the tire equator CL, the intermediate land portion 30 located on the outer side in the tire width direction from the center land portion 20, and the tire than the intermediate land portion 30 A shoulder land portion 40 located outside in the width direction is partitioned.

  The center land portion 20 is formed with a plurality of sipes 24 extending along the tire width direction Tw. In addition to the sipe 24, the center land portion 20 may be provided with a lug groove, a notch groove, or the like as necessary.

  A plurality of intermediate land portions 30 that extend along the tire width direction Tw so as to communicate with the circumferential grooves 11 and 12 and incline toward the opposite side of the rotation direction R toward the outer side in the tire width direction. Are formed at predetermined intervals in the tire circumferential direction. The inclined land 31 and the circumferential grooves 11 and 12 define a plurality of blocks 32 in the intermediate land portion 30. Each block 32 is formed with one closing groove 33 extending along the inclined groove 31, one end opening in the main groove 11 near the tire equator CL, and the other end closed in each block 32. Yes. Each block 32 is formed with a plurality of sipes 34 extending along the inclined grooves 31. Further, each block 32 has a protruding portion 32A that protrudes into the inclined groove 31 at a portion on the front end side of the contact (that is, the front side in the rotational direction) and the tire equator CL side, and the protruding amount B of the protruding portion 32A is inclined. The relationship of B / Gmax ≧ 0.2 is satisfied with respect to the maximum value Gmax of the groove width of the groove 31.

  A plurality of lug grooves 41 extending along the tire width direction Tw so as to communicate with the circumferential groove 12 are formed in the shoulder land portion 40 at predetermined intervals in the tire circumferential direction. The lug groove 41 is preferably arranged on an extension line of the inclined groove 31. A plurality of blocks 42 are defined in the shoulder land portion 40 by the lug grooves 41 and the circumferential grooves 12. Each block 42 is formed with a plurality of sipes 44 extending along the lug grooves 41.

  In the pneumatic tire in which the rotation direction R is specified as described above, the two circumferential grooves 11 and 12 extending in the tire circumferential direction Tc in at least one region bordered by the tire equator CL of the tread portion 1 and A plurality of inclined grooves 31 extending in the tire width direction Tw so as to communicate with the circumferential grooves 11 and 12 and inclined in the opposite direction to the rotational direction R toward the outer side in the tire width direction, and A plurality of blocks 32 defined by the circumferential grooves 11 and 12 and the inclined grooves 31, extending along the inclined grooves 31 in each block 32, one end opening into the main groove 11 near the tire equator CL, and the like A closing groove 33 whose end is closed in each block 32 is provided, and a protruding portion 32A protruding into the inclined groove 31 is formed at a position on the front end side of the block 32 and on the tire equator CL side, and the protruding portion 32A protrudes. Amount B leans When the structure satisfying the relationship of B / Gmax ≧ 0.2 with respect to the maximum value Gmax of the groove width of the groove 31 is adopted, snow flow relatively occurs with respect to the tread portion 1 during braking on snow ( Arrow X1), the block 32 is deformed so that the snow flow presses the protrusion 32A and the closing groove 33 closes (arrow X2). Due to the behavior of the block 32 during braking, the snow column in the closing groove 33 can be compressed and held, and the braking performance on snow can be effectively improved. In addition, when the pneumatic tire is about to flow laterally when running on snow, the snow flows as described above, and the block 32 is deformed so that the snow flows press the protrusion 32A and the closing groove 33 is closed. In addition, it can be expected to improve the driving stability on snow.

  Here, the protrusion amount B of the protrusion 32A needs to satisfy the relationship of B / Gmax ≧ 0.2 with respect to the maximum value Gmax of the groove width of the inclined groove 31, but if the value of B / Gmax is too small, The action of compressing and holding the snow column in the closing groove 33 becomes insufficient. The upper limit value of B / Gmax is desirably 0.5. If the value of B / Gmax is too large, the drainage performance is reduced. Note that the protrusion amount B of the protruding portion 32A is measured in a direction orthogonal to the groove width center line of the inclined groove 31 at the portion where the protruding portion 32A is formed.

  In the pneumatic tire, as shown in FIG. 3, the groove width of the inclined groove 31 is preferably gradually narrowed from the outer side in the tire width direction toward the inner side. That is, it is preferable that the groove width GW1 at the inner end in the tire width direction of the inclined groove 31 and the groove width GW2 at the outer end in the tire width direction satisfy the relationship of GW1 <GW2. As a result, the groove width of the inclined groove 31 becomes narrower in the direction in which snow flows during braking, and the force that pushes the protrusion 32A and deforms the block 32 becomes stronger, so that the braking performance on snow can be further improved. .

  In the pneumatic tire, as shown in FIG. 4, the inclined groove 31 is bent with the protruding portion 32 </ b> A as a boundary, and the inclination angle ANG <b> 1 with respect to the tire circumferential direction Tc of the inner portion in the tire width direction of the inclined groove 31 is the inclined groove. It is preferable that the inclination angle ANG2 with respect to the tire circumferential direction Tc of the 31 outer portion in the tire width direction is smaller than that and the angle difference (ANG2-ANG1) is 10 ° or more. Since the inclined groove 31 is bent in this manner, the force for pushing the protrusion 32A and deforming the block 32 becomes stronger, so that the braking performance on snow can be further improved. Here, if the angle difference (ANG2-ANG1) is too small, the effect of increasing the force for deforming the block 32 becomes insufficient. For example, the inclination angle ANG1 of the inner portion of the inclined groove 31 in the tire width direction with respect to the tire circumferential direction Tc is set in a range of 45 ° to 75 °, and the inclination angle ANG2 of the outer portion of the inclined groove 31 in the tire width direction with respect to the tire circumferential direction Tc. Is preferably set in the range of 55 ° to 85 °. The inclination angles ANG1 and ANG2 are angles formed by the groove width center lines of the inclined grooves 31 in the corresponding portions with respect to the tire circumferential direction Tc.

  In the pneumatic tire, as shown in FIG. 4, the tire circumferential projection length GW3 of the closing groove 33 is 30% or more and 80% or less of the tire circumferential projection length BW of the block 32, and the tire of the protruding portion 32A. The circumferential projection length W is preferably 30% or more and 80% or less of the tire circumferential projection length BW of the block 32. By defining the tire circumferential direction projection lengths GW3 and W of the closing groove 33 and the protrusion 32A in this way, the volume of snow retained in the closing groove 33 is sufficiently maintained while maintaining the rigidity of the block 32 satisfactorily. And the deformation of the block 32 can be promoted. Here, if the projection length GW3 in the tire circumferential direction of the closing groove 33 is too small, the volume of snow held in the closing groove 33 is reduced, and the block 32 is hardly deformed. Conversely, the tire circumference of the closing groove 33 is reduced. If the direction projection length GW3 is too large, the rigidity of the block 32 decreases. Further, if the projected length W in the tire circumferential direction of the protruding portion 32A is out of the above range, the block 32 is difficult to deform. The tire circumferential direction projection lengths BW, GW3, and W are the lengths when each object is projected in the tire circumferential direction, in other words, the tire width direction length measured along the tire width direction Tw. .

  In the pneumatic tire, as shown in FIG. 5, the distance d from the center position in the tire circumferential direction of the tire equator side wall surface of the block 32 to the center position of the groove width at the opening end of the closing groove 33 is the tire equator side of the block 32. With respect to the distance D from the front end position of the wall surface (that is, the end position on the front side in the rotation direction R) or the rear end position (that is, the end position on the rear side in the rotation direction R) to the center position, d / It is preferable to satisfy the relationship of D ≦ 0.2. Thus, by arranging the position of the opening end of the closing groove 33 in the vicinity of the center position of the tire equator side wall surface of the block 32, the closing groove 33 is easily closed during braking. If the value of d / D is too large, the position of the opening end of the closing groove 33 is separated from the center position of the tire equator side wall surface of the block 32, so that it is difficult to cause the closing groove 33 to be closed as intended during braking. Become. It is desirable that the position of the opening end of the closing groove 33 is set as described above, and the closing groove 33 extends substantially parallel to the inclined groove 31.

  In the pneumatic tire, as shown in FIG. 5, the groove width of the closing groove 33 is preferably gradually narrowed toward the main groove 11 closer to the tire equator. That is, it is preferable that the groove width GW4 at the inner end portion in the tire width direction of the closing groove 33 and the groove width GW5 at the outer end portion in the tire width direction satisfy the relationship of GW4 <GW5. Thus, since the groove width of the closing groove 33 becomes narrower toward the opening end, it becomes easier to hold snow in the closing groove 33 during braking on snow.

  In the pneumatic tire, the JIS hardness of the tread rubber constituting the tread portion 1 is set in the range of 40 to 60, more preferably in the range of 45 to 55. When the JIS hardness of the tread rubber constituting the tread portion 1 is set in the above range, the tread portion 1 flexibly follows the road surface, which is suitable for icy and snowy roads (studless tires). Further, in the pneumatic tire, the snow traction index STI is set to 180 or more, more preferably in the range of 180 to 240.

  In the above-described embodiment, the description has been given of the one-side region with the tire equator CL as a boundary, but the groove arrangement in the remaining one-side region is not particularly limited. However, it is effective to employ a mirror-symmetrical groove arrangement on both sides of the tire equator CL, or a groove arrangement in which the mirror-symmetrical groove arrangement is shifted in the tire circumferential direction on both sides of the tire equator CL.

  Further, in the above-described embodiment, the case where two circumferential grooves are arranged in one region with the tire equator as a boundary has been described. However, in the present invention, two or more regions are disposed in one region with the tire equator as a boundary. It is possible to arrange a circumferential groove, and if an inclined groove is formed in a land portion defined between two of the circumferential grooves, a protruding portion is provided at a predetermined position of each block. good.

  The tire size is 225 / 65R17 102Q, and includes a tread portion, a pair of sidewall portions, and a pair of bead portions. The tread rubber constituting the tread portion has a JIS hardness of 50, a snow traction index STI of 200, In the pneumatic tire in which the rotation direction is specified, as shown in FIGS. 1 to 5, two circumferential grooves extending in the tire circumferential direction in a region on one side with the tire equator of the tread as a boundary, and these A plurality of inclined grooves extending in the tire width direction so as to communicate with the circumferential groove and inclined toward the outer side in the tire width direction and opposite to the rotational direction, and are partitioned by the circumferential groove and the inclined grooves. A plurality of blocks, and a closed groove that extends along the inclined groove in each block, opens at one end to the main groove near the tire equator, and closes at the other end within each block. It was fabricated ground front side and the tire of Comparative Example 1 and Examples 1-7 were formed protrusion which projects into the inclined groove in a portion of the tire equator side of the block.

  In Comparative Example 1 and Examples 1 to 7, the ratio B / Gmax of the protrusion amount B of the protrusion to the maximum value Gmax of the groove width of the inclined groove, the groove width GW1 at the inner end of the inclined groove in the tire width direction, and the tire width direction Magnitude relationship with the groove width GW2 at the outer end, Magnitude relationship between the inclination angle ANG1 of the inner portion in the tire width direction of the inclined groove and the inclination angle ANG2 at the outer portion in the tire width direction, the angle difference between the inclination angles ANG1 and ANG2, The ratio GW3 / BW of the tire circumferential projection length GW3 of the closing groove to the tire circumferential projection length BW, the ratio W / BW of the tire circumferential projection length W of the protrusion to the tire circumferential projection length BW of the block, The ratio d / D regarding the opening end position of the closing groove, and the size relationship between the groove width GW4 at the inner end portion in the tire width direction of the closing groove and the groove width GW5 at the outer end portion in the tire width direction are set as shown in Table 1.

  For comparison, a conventional tire having the same structure as that of Example 1 was prepared except that no protrusion was provided on the block.

  For these test tires, braking performance on snow was evaluated by the following test method, and the results are also shown in Table 1.

Snow braking performance:
The test tire is mounted on a wheel with a rim size of 17 x 7 J and mounted on a four-wheel drive vehicle (RV) with a displacement of 2400 cc. ABS braking was performed from the state, and the braking distance was measured. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. The larger the index value, the better the braking performance on snow.

  As can be seen from Table 1, the tires of Examples 1 to 7 were able to significantly improve the braking performance on snow in comparison with the conventional example. On the other hand, in Comparative Example 1, since the ratio B / Gmax of the protruding amount B of the protruding portion with respect to the maximum value Gmax of the groove width of the inclined groove was too small, the effect of improving the braking performance on snow was insufficient.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 20 Center land part 24,34,44 Sipe 30 Middle land part 31 Inclined groove 32,42 Block 33 Closure groove 41 Lug groove CL Tire equator

Claims (8)

An annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the tire radially outer side of the sidewall portions; In a pneumatic tire with a specified rotation direction,
Two circumferential grooves extending in the tire circumferential direction in a region on one side of the tire equator of the tread portion, and extending in the tire width direction so as to communicate with these circumferential grooves, the tire width A plurality of inclined grooves inclined outwardly in the direction opposite to the rotation direction, a plurality of blocks defined by the circumferential grooves and the inclined grooves, and extending along the inclined grooves in each block. One end is open to the main groove near the tire equator, and the other end is closed in each block, and the block protrudes into the inclined groove at the front end of the ground and on the tire equator side. A pneumatic tire, characterized in that a protrusion amount B of the protrusion satisfies a relationship of B / Gmax ≧ 0.2 with respect to a maximum value Gmax of the groove width of the inclined groove.   The pneumatic tire according to claim 1, wherein a groove width of the inclined groove is narrowed from an outer side in a tire width direction toward an inner side.   The inclined groove is bent with the protrusion as a boundary, and the inclination angle of the inclined groove with respect to the tire circumferential direction of the inner portion in the tire width direction is greater than the inclination angle of the inclined groove with respect to the tire circumferential direction of the outer portion in the tire width direction. The pneumatic tire according to claim 1 or 2, wherein the angle difference is 10 ° or more.   The projected length in the tire circumferential direction of the closing groove is not less than 30% and not more than 80% of the projected length in the tire circumferential direction of the block, and the projected length in the tire circumferential direction of the protrusion is the projected length in the tire circumferential direction of the block. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is 30% or more and 80% or less.   The distance d from the center position in the tire circumferential direction of the tire equator side wall surface of the block to the center position of the groove width at the opening end of the closing groove is the center from the front contact end position or rear contact end position of the block tire equator side wall surface. The pneumatic tire according to claim 1, wherein a relationship of d / D ≦ 0.2 is satisfied with respect to the distance D to the position.   The pneumatic tire according to any one of claims 1 to 5, wherein a groove width of the closing groove is narrowed toward a main groove closer to the tire equator.   The tread rubber constituting the tread portion has a JIS hardness in a range of 40 to 60, and each block formed in the tread portion has a plurality of sipes. The described pneumatic tire. The pneumatic tire according to any one of claims 1 to 7, wherein a snow traction index STI represented by the following formula (1) is 180 or more.
STI = −6.8 + 2202ρg + 672ρs + 7.6Dg (1)
However, ρg: groove density (mm / mm ² ) = gross length of the extended component in the tire width direction of the groove (mm)
/ Total area of ground contact area (mm ² )
ρs: sipe density (mm / mm ² ) = total length of sipe extension components in the tire width direction
(Mm) / Total area of ground contact area (mm ² )
Dg: Average groove depth (mm)

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