JP5768364B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of improving heel and toe wear resistance.

  In a pneumatic tire for trucks and buses, since the traction performance of the tire is important, a tread pattern based on a deep groove block row is generally adopted.

  Here, in such a pneumatic tire, there is a problem that heel and toe wear easily occurs in the block. As a conventional pneumatic tire related to such a problem, a technique described in Patent Document 1 is known.

Japanese Patent Laying-Open No. 2005-255097

  An object of the present invention is to provide a pneumatic tire capable of improving heel and toe wear resistance.

In order to achieve the above object, a pneumatic tire according to the present invention is divided into a plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction. a pneumatic tire provided with a block, said block comprises a first recess which is open to at least one of the walls of the both wall surfaces of the circumferential main groove side while being positioned on the wall surface of at least one of the lug groove side A second recess disposed on the wall surface on the other lug groove side, the total volume of the first recess is larger than the total volume of the second recess, and the one lug groove side is The rotation direction is designated with the block kick-out side and the other lug groove side as the stepping-in side of the block .

In this pneumatic tire, when the tire rolls, when the one lug groove side is the block kicking side and the other lug groove side is the block stepping side, the rigidity of the end on the kicking side is the stepping side Therefore, the increase in the contact pressure at the end on the kick-out side is suppressed. Thereby, there is an advantage that the wear at the kick-out side and the step-on side is made uniform, and the heel and toe wear resistance of the tire is improved.
Also, when the tire is rolling, when one lug groove side is the block kicking side and the other lug groove side is the block stepping side, the rigidity of the kicking side end is less than the stepping side end. It becomes smaller than rigidity. Thereby, an increase in the contact pressure at the end portion on the kick-out side is suppressed, and there is an advantage that the wear on the end portion on the kick-out side and the end portion on the step-on side is made uniform.

  In the pneumatic tire according to the present invention, the concave portion extends from the end portion on the one side lug groove side toward the end portion on the other lug groove side on the wall surface on the circumferential main groove side. The length l in the tire circumferential direction of the recess in the wall surface on the circumferential main groove side and the length L in the tire circumferential direction of the block have a relationship of 0.30 ≦ l / L ≦ 0.70.

  In this pneumatic tire, since the ratio 1 / L between the length l of the concave portion and the length L of the block 1 is optimized, there is an advantage that the heel and toe wear resistance performance of the tire is further improved.

  In the pneumatic tire according to the present invention, the recess extends from the end on the one lug groove side toward the other lug groove side on the wall surface on the circumferential main groove side, and the recess The depth d or the width w of the slab decreases as it goes toward the other lug groove.

  In this pneumatic tire, since the degree of wear of the block can be made uniform, there is an advantage that heel and toe wear can be further reduced.

  In the pneumatic tire according to the present invention, the volume v of the recess and the volume V of the block have a relationship of 0.005 ≦ v / V ≦ 0.05.

  This pneumatic tire has an advantage that the concave portion can be easily processed and formed while improving the heel and toe wear resistance of the tire.

  Further, the pneumatic tire according to the present invention has a width of the recess in the region of the wall surface on the one lug groove side and the region from the end portion on the one lug groove side to 0.30 × L in the tire circumferential direction. w and depth d are in the range of 1.0 [mm] ≦ w ≦ 3.0 [mm] and 1.0 [mm] ≦ d ≦ 3.0 [mm].

  In this pneumatic tire, since the width w and depth d of the recess are optimized within a necessary and sufficient range, there is an advantage that the heel and toe wear resistance performance of the tire is improved.

  In the pneumatic tire according to the present invention, the depth direction of the concave portion is inclined toward the groove bottom side with respect to the tread surface of the block.

  This pneumatic tire has an advantage that the mold for forming the concave portion can be easily removed.

A pneumatic tire according to the present invention includes a plurality of blocks that are divided into a plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction. The tire has a recess disposed on at least one of the wall surfaces on the side of the lug groove , and has no recess on the wall surface on the other side of the lug groove. a trailing side of the block, the other lug groove side have a specified rotation direction leading side of the block, the recess is open on at least one of the walls of the both wall surfaces of the circumferential main groove side And extending in the tire circumferential direction of the recess in the wall surface on the circumferential main groove side and extending from the kick-out side end portion to the stepping side end portion on the wall surface on the circumferential main groove side Length l and the bro A pneumatic tire and the tire circumferential direction length L of the click, characterized in that it has a relationship of 0.30 ≦ l / L ≦ 0.70.

  The pneumatic tire according to the present invention has an advantage of improving the heel and toe wear resistance.

FIG. 1 is a perspective view showing a block of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a plan view showing the block shown in FIG. FIG. 3 is a front view showing the block shown in FIG. 1. FIG. 4 is an explanatory diagram showing the operation of the block shown in FIG. FIG. 5 is an explanatory view showing a modification of the block shown in FIG. FIG. 6 is an explanatory view showing a modification of the block shown in FIG. FIG. 7 is an explanatory view showing a modification of the block shown in FIG. FIG. 8 is an explanatory view showing a modification of the block shown in FIG. FIG. 9 is an explanatory view showing a modification of the block shown in FIG. FIG. 10 is an explanatory diagram showing a modification of the block shown in FIG. FIG. 11 is a table showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Pneumatic tire block]
FIG. 1 is a perspective view showing a block of a pneumatic tire according to an embodiment of the present invention. 2 and 3 are a plan view (FIG. 2) and a front view (FIG. 3) showing the block shown in FIG.

  The pneumatic tire includes a block 1 that is divided into a plurality of circumferential main grooves 10 extending in the tire circumferential direction and a plurality of lug grooves 20 and 20 ′ extending in the tire width direction (FIG. 1). reference). For example, in this embodiment, a plurality of blocks 1 are defined by adjacent circumferential main grooves 10 and 10 and a plurality of open lug grooves 20 and 20 ′ connecting these circumferential main grooves 10 and 10. (Not shown). A block pattern based on these blocks 1 (block rows) is formed on the tread surface.

  In addition, the block pattern of a well-known pneumatic tire can be employ | adopted for this block pattern suitably. Moreover, the pneumatic tire does not need to have a block in all the land parts, and it is sufficient if it has at least one block row on the tread surface.

  Moreover, this pneumatic tire has designation | designated of a rotation direction. For example, in the vehicle mounted state, the rotation direction is designated with reference to the forward direction of the vehicle (the rotation direction with high usage frequency). The designation of the rotation direction is displayed by, for example, a mark or uneven display on the sidewall portion of the tire. In this embodiment, on the basis of the designation of the rotation direction, the stepping side of the block 1 (the side that contacts the ground first when the tire rolls in the designated rotation direction) and the kicking side (the opposite side to the stepping side) ) Is defined (see FIG. 1).

  This pneumatic tire is applied to a tire for trucks and buses, and is mounted on a drive shaft of a regional operation for Europe, for example. In such an application object, since the traction performance of the tire is important, a tread pattern based on a deep groove block row is generally employed.

[Block recess]
In this pneumatic tire, the block 1 has a recess 4 on the wall surface 21 of the lug groove 20 on the kick-out side when the designation of the rotation direction is used as a reference (see FIG. 1). The recess 4 forms a difference in rigidity between the end portion on the kicking side (the portion of the block 1 including the wall surface 21 on the kicking side) and the end portion on the stepping side. Specifically, since the wall surface 21 has the recess 4, when the contact pressure is applied to the block 1, the recess 4 is crushed so that the end of the block 1 on the kicking side is in the plane direction of the wall 21 or the recess 4. It becomes easy to deform in the width direction. The rigidity of the end portion on the kick-out side having the concave portion 4 is smaller than the rigidity of the end portion on the stepping side not having the concave portion 4.

  For example, in this embodiment, a single-stage recess 4 is formed on the wall surface 21 on the kick-out side of the block 1 (see FIGS. 1 to 3). Moreover, this recessed part 4 is arrange | positioned in the wall surface 21 on the kicking side near the tread surface 3 rather than the middle. Further, the recess 4 has a narrow groove shape having a predetermined width w and depth d. Moreover, the recessed part 4 is opened to the wall surface 23 by the side of the circumferential direction main groove 10 across the wall surface 21 by the side of a kick in the tire width direction. Further, the concave portion 4 extends from the end portion on the kick-out side of the block 1 toward the end portion on the stepping side on the wall surface 23 on the circumferential main groove 10 side, and reaches the center portion of the block 1. Thereby, the recessed part 4 is arrange | positioned so that the edge part by the side of kicking out of the block 1 may be enclosed in U shape. Therefore, the recess 4 extends in the horizontal direction with respect to the ground contact surface, so that when the ground pressure is applied to the block 1, the recess 4 can be crushed in the height direction of the block 1. Thereby, the kicking side end of the block 1 is easily deformed with respect to the ground pressure. In addition, the recessed part is not formed in the wall surface 22 of the step-on side of the block 1.

  When the tire rolls, a shearing force due to braking acts on the block 1, and the contact pressure at the end of the block 1 on the kicking side increases (see FIG. 4). At this time, since the rigidity of the end portion on the kicking side is smaller than the rigidity of the end portion on the stepping side, an increase in the contact pressure at the end portion on the kicking side is suppressed. As a result, the wear at the kick-out end and the step-on end is made uniform, and the heel and toe wear resistance of the tire is improved.

  In this embodiment, the recess 4 has a narrow groove shape or a slit shape (see FIGS. 1 to 3). Such a configuration is preferable because the mold portion for processing the recess 4 can be easily pulled out in the vulcanization molding step of the tire. However, the present invention is not limited to this, and the recess 4 may be composed of a plurality of holes (see FIG. 5). Even with this configuration, the recess 4 can be formed in the block 1.

  Moreover, in this embodiment, the single recessed part 4 is formed (refer FIGS. 1-3). However, the present invention is not limited to this, and a plurality of recesses 4 may be arranged stepwise (aligned in the block height direction) on the wall surface 21 on the kicking side of the block 1 (see FIG. 6). Thereby, the rigidity of the edge part by the side of kick-out can be reduced efficiently.

  In such a configuration, a sipe-shaped recess 4 may be employed instead of the narrow groove-shaped recess 4 (see FIG. 7). For example, in the example shown in FIG. 7, three open sipes having an opening width of less than 1.0 [mm] are arranged in a step shape. In such a configuration, a large number of recesses 4 can be arranged in a step shape, so that the rigidity of the end portion on the kick-out side can be easily adjusted.

  Moreover, in this embodiment, the recessed part 4 is arrange | positioned in the area | region including the both edge parts of the kicking side of the block 1 at least (refer FIGS. 1-3). In other words, the recess 4 is disposed at the intersection (both edges on the kicking side of the block 1) of the wall surface 21 on the kicking side of the block 1 and the wall surfaces 23, 23 on the left and right circumferential main grooves 10 side. . In such a configuration, the block 4 reduces the block rigidity at both edges on the kick-out side of the block 1. This suppresses an increase in contact pressure at both edges on the kick-out side when the tire rolls, so that compared to a configuration in which no recess is provided on both edges on the kick-out side, the tire resistance is reduced. The heel and toe wear performance is effectively improved.

  Moreover, in this embodiment, the recessed part 4 is arrange | positioned over the whole region of the tire width direction of the wall surface 21 by the side of kicking out of the block 1 (refer FIGS. 1-3). In other words, the recess 4 opens across the kick-out side wall 21 in the tire width direction (both side walls 23, 23 on the circumferential main groove 10 side) of the block 1. Yes. With this configuration, the rigidity of the end portion on the kick-out side of the block 1 is reduced over the entire region in the tire width direction. As a result, an increase in the contact pressure over the entire area on the kick-out side is suppressed during rolling of the tire, so that the heel and toe wear resistance performance of the tire is further improved. However, the present invention is not limited thereto, and the recess 4 may be opened from the kick-out side wall surface 21 to only one of the kick-out side edges of the block 1 (not shown).

  Further, in this embodiment, the concave portion 4 extends from the end portion on the kicking side toward the end portion on the stepping side on the wall surface 23 on the circumferential main groove 10 side (see FIGS. 1 and 2). ). At this time, the length l in the tire circumferential direction of the recess 4 on the wall surface on the circumferential main groove 10 side and the length L in the tire circumferential direction of the block 1 have a relationship of 0.30 ≦ l / L ≦ 0.70. It is preferable. For example, depending on the tire specifications, heel and toe wear may occur up to 70% of the length L of the block 1. In this case, the length l of the recess 4 is set so that 1 / L = 0.70.

  Moreover, in this embodiment, the recessed part 4 has the fixed depth d and the width | variety w (refer FIGS. 1-3). However, the present invention is not limited to this, and in the configuration in which the recess 4 extends from the end on the kick-out side toward the end on the step-in side on the wall surface on the circumferential main groove 10 side, the depth d or width w of the recess 4 May decrease as it goes toward the stepped side end (see FIG. 8). For example, in the example shown in FIG. 8, both the depth d and the width w of the recess 4 monotonously decrease from the end on the kicking side toward the end on the stepping side. For this reason, the cross-sectional area of the recessed part 4 is monotonously decreasing toward the end part on the stepping side. Here, the contact pressure distribution of the block at the time of rolling of the tire is greatest at the end portion on the kicking side of the block, and becomes smaller toward the stepping side (see FIG. 4). Therefore, the depth d or the width w of the recess 4 decreases as it goes toward the stepped side end, so that the degree of wear of the block can be made uniform and heel and toe wear can be further reduced.

  In this embodiment, the volume v of the recess 4 and the volume V of the block 1 have a relationship of 0.005 ≦ v / V ≦ 0.05. For example, in a general pneumatic tire for trucks and buses, the length L, width W and height H of the block 1 are set to L = W = 40 [mm] and H = 20 [mm]. Here, the height H is the maximum groove depth of the circumferential main groove 10. At this time, when the length l, width w, and depth d of the recess 4 are l = 12 [mm], w = 2 [mm], and d = 2 [mm], v / V = 0.005. When v = 28 [mm], w = 5 [mm] and d = 3.5 [mm], v / V = 0.05.

  In this embodiment, the width w and the depth d of the recess 4 are set to 1. in the region of the wall surface 21 on the kicking side and the region from the end on the kicking side to 0.03 × L in the tire circumferential direction. It is in the range of 0 [mm] ≦ w ≦ 3.0 [mm] and 1.0 [mm] ≦ d ≦ 3.0 [mm] (see FIGS. 1 to 3). That is, the width w and the depth d of the recess 4 are set in the above range in a predetermined region at the end portion on the kicking side of the block 1. As a result, the width w and the depth d of the recess 4 are optimized, particularly in a region where heel and toe wear is likely to occur.

  Further, in this embodiment, the recess 4 is disposed closer to the tread surface 3 than the middle on the wall surface 21 on the kick-out side (see FIG. 3). However, the recess 4 is not open to the tread surface 3. Specifically, the height position h of the concave portion 4 with respect to the groove bottom and the height H of the block 1 are set to 0.50 ≦ h / H ≦ 0.80. In such a configuration, since the recess 4 is disposed in a region near the tread surface 3 that is easily deformed when the tire rolls, the block rigidity by the recess 4 can be adjusted appropriately. In the configuration in which the plurality of recesses 4 are arranged in a step shape (see FIGS. 6 and 7), it is preferable that more than half of the recesses 4 are arranged in the above h / H range.

  In this embodiment, the direction of the depth d of the recess 4 is set parallel to the tread surface 3 of the block 1 (see FIG. 3). However, the present invention is not limited to this, and the direction of the depth d of the recess 4 may be inclined at a predetermined inclination angle θ toward the groove bottom side with respect to the wall surface 23 on the lug groove side of the block 1 (see FIG. 9). This facilitates removal of the mold part for forming the recess 4.

  The depth d, width w, length l and position h of the recess 4 and the length L, width W and height H of the block 1 are applied to the tire by a prescribed rim and given a prescribed internal pressure. In addition, it is measured with reference to the time when no load is applied.

  Here, the prescribed rim refers to “applied rim” prescribed in JATMA, “Design Rim” prescribed in TRA, or “Measuring Rim” prescribed in ETRTO. The specified internal pressure means “maximum air pressure” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The specified load means the “maximum load capacity” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO. However, in JATMA, in the case of tires for passenger cars, the specified internal pressure is air pressure 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

[effect]
As described above, in this pneumatic tire, the block 1 is disposed on the wall surface on the one lug groove 20 side, and has a recess 4 that opens on at least one wall surface of both wall surfaces on the circumferential main groove 10 side. By having this, there is a difference in rigidity between the end portion on the one lug groove 20 side and the end portion on the other lug groove 20 ′ side (see FIGS. 1 to 3). In such a configuration, when the tire rolls, when the one lug groove 20 side becomes the kicking side of the block 1 and the other lug groove 20 'side becomes the stepping side of the block 1, the rigidity of the end portion on the kicking side Is smaller than the rigidity of the end portion on the step-in side, so that an increase in the contact pressure at the end portion on the kick-out side is suppressed. Thereby, there is an advantage that the wear at the kick-out side and the step-on side is made uniform, and the heel and toe wear resistance of the tire is improved.

  Moreover, in said structure, it is preferable that the recessed part 4 is arrange | positioned at least in the edge part (connection part with the wall surface 23 by the side of the circumferential direction main groove 10) of the wall surface 21 by the side of one lug groove 20 (FIG. 1-FIG. (See FIG. 3). Thereby, there exists an advantage which the heel-and-toe wear-resistant performance of a tire improves further.

  For example, it is preferable that (a) the recess 4 crosses the wall surface 21 on the one lug groove 20 side and opens to the edge of the wall surface 21 (the wall surface 23 on the circumferential main groove 10 side) (FIGS. 1 to 3). reference). Thereby, there exists an advantage which the heel-and-toe wear-resistant performance of a tire improves further. Also, for example, (b) the block 1 has a plurality of recesses 4, and some of the recesses 4 are arranged at the center of the wall surface 21 on the one lug groove 20 side and open at the edge of the wall surface 21. The other recessed part 4 is separately arrange | positioned at the edge part of the wall surface 21 by the side of one lug groove 20, (c) The recessed part 4 is arrange | positioned only at the edge part of the wall surface 21 by the side of one lug groove 20 In addition, a configuration that is not arranged in the center may be employed (not shown).

  Further, in this pneumatic tire, the recess 4 may extend from the end on one lug groove 20 side toward the end on the other lug groove 20 'side on the wall surface 23 on the circumferential main groove 10 side. Preferred (see FIGS. 1 and 2). At this time, the length l in the tire circumferential direction of the recess 4 in the wall surface 23 on the circumferential main groove 10 side and the length L in the tire circumferential direction of the block 1 are in a relationship of 0.30 ≦ l / L ≦ 0.70. It is preferable to have. In such a configuration, since the ratio 1 / L between the length 1 of the recess 4 and the length L of the block 1 is optimized, there is an advantage that the heel and toe wear resistance of the tire is further improved. For example, when l / L <0.30 or 0.70 <l / L, the difference in rigidity between the kick-out end and the step-on end is reduced, and an effect of improving the heel and toe wear resistance is obtained. It is not preferable.

  In this pneumatic tire, the concave portion 4 extends from the end portion on the one lug groove 20 side toward the other lug groove 20 ′ side on the wall surface 23 on the circumferential main groove 10 side. It is preferable that the depth d or the width w decreases as it goes toward the other lug groove 20 ′ (see FIG. 8). Thereby, since the degree of wear of the block can be made uniform, there is an advantage that heel and toe wear can be further reduced.

  In this pneumatic tire, the volume v of the recess 4 and the volume V of the block 1 preferably have a relationship of 0.005 ≦ v / V ≦ 0.05. Such a configuration has an advantage of facilitating the processing and forming of the recess 4 while improving the heel and toe wear resistance of the tire. For example, when v / V <0.005, the concave portion 4 is small, and the effect of improving the heel and toe wear resistance is not obtained, which is not preferable. On the other hand, when 0.05 <v / V, it is difficult to pull out the mold, which is not preferable.

  Further, in this pneumatic tire, in the region of the wall surface 21 on the one lug groove 20 side and the region from the end on the one lug groove 20 side to 0.03 × L in the tire circumferential direction, the width w of the recess 4 and The depth d is in the range of 1.0 [mm] ≦ w ≦ 3.0 [mm] and 1.0 [mm] ≦ d ≦ 3.0 [mm] (see FIGS. 1 to 3). As a result, the width w and depth d of the recess 4 are optimized within a necessary and sufficient range, and there is an advantage that the heel and toe wear resistance performance of the tire is improved.

  Moreover, in this pneumatic tire, it is preferable that the depth direction of the recessed part 4 inclines to the groove bottom side with respect to the tread surface 3 of the block 1 (refer FIG. 9). Thereby, there exists an advantage from which the metal mold | die for shape | molding the recessed part 4 becomes easy.

  Moreover, in this pneumatic tire 1, the block 1 has the recessed part 4 only in the wall surface 21 by the side of one lug groove 20, and does not have the recessed part in the wall surface 22 by the side of the other lug groove 20 '(FIG. 1). And FIG. 2).

  However, the present invention is not limited to this, and the block 1 may have recesses 4 and 4 ′ on both the wall surface 21 on the one lug groove 20 side and the wall surface 22 on the other lug groove 20 ′ side (see FIG. 10). ). For example, in the modification shown in FIG. 1, a closed structure and slit-shaped recess 4 ′ that does not open to the tread surface and the edge of the block 1 is formed at the center of the wall surface 22 on the other lug groove 20 ′ side. Here, the concave portion 4 of the wall surface 21 on one lug groove 20 side is referred to as a first concave portion, and the concave portion 4 ′ of the wall surface 22 on the other lug groove 20 ′ side is referred to as a second concave portion. At this time, the total volume of the first recess 4 needs to be larger than the total volume of the second recess 4 '. Thereby, a required rigidity difference is formed between the end portion on the one lug groove 20 side and the end portion on the other lug groove 20 'side.

  In such a configuration, when the tire rolls, when the one lug groove 20 side is the kicking side of the block 1 and the other lug groove 20 'side is the stepping side of the block 1, the rigidity of the end part on the kicking side is Becomes smaller than the rigidity of the end portion on the stepping side. Thereby, an increase in the contact pressure at the end portion on the kick-out side is suppressed, and there is an advantage that the wear on the end portion on the kick-out side and the end portion on the step-on side is made uniform.

  When a plurality of recesses are provided, the sum of the volumes of these recesses becomes the “total volume of the recesses”. Further, the total volume of the recesses can be changed not only by the number of recesses installed but also by the size and shape of the recesses.

[performance test]
FIG. 11 is a table showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention. Here, a performance test on heel and toe wear resistance performance was performed on a plurality of pneumatic tires having different conditions.

  In this performance test, a pneumatic tire having a tire size of 295 / 80R22.5 is assembled to an applicable rim defined by JATMA, and the maximum air pressure and maximum load capacity specified by JATMA are given to the pneumatic tire. A pneumatic tire is mounted on all wheels of a test vehicle of 2-D4 (front 2-rear 4-drive). Then, the heel and toe wear amount of the block after the test vehicle travels 30,000 [km] is measured. Then, based on this measurement result, index evaluation using the conventional example as a reference (100) is performed. This index evaluation is preferable as the numerical value increases. In addition, it can be said that index evaluation has an advantage if the numerical value is 103 or more.

  Conventional Example 1 is a pneumatic tire in which a block does not have a recess. Conventional examples 2 and 3 are pneumatic tires in which the block has recesses on both the kick-out wall surface and the step-in wall surface. For this reason, in Conventional Examples 1 to 3, the block does not have a rigidity difference between the kick-out side end portion and the stepping-side end portion.

  In the first to ninth embodiments, the block 1 has the depression 4 on the stepping side wall surface 21, thereby having a difference in rigidity between the stepping side end and the stepping side end. Moreover, although Examples 1-5 are the pneumatic tires described in FIGS. 1 to 3, the ratio between the length l of the recess 4 and the length L of the block 1 in the wall surface 23 on the circumferential main groove 10 side. l / L are different from each other. Example 6 is the pneumatic tire illustrated in FIG. 5, in which the concave portion 4 is configured by a plurality of round holes. Examples 7 and 8 are the pneumatic tires described in FIG. 8, and the width w and the depth d of the recesses 4 are reduced toward the stepping side on the wall surface 23 on the circumferential main groove 10 side. Yes. Example 9 is the pneumatic tire illustrated in FIG. 6, and the two concave portions 4 are arranged in a step shape.

  As shown in the test results, it can be seen that the pneumatic tires of Examples 1 to 9 have improved heel and toe wear resistance as compared with Conventional Examples 1 to 4 (see FIG. 11). Further, when Examples 1 to 3 are compared with Conventional Example 4, the recess 4 extends over the entire area of the stepping side wall surface 21 (the wall surface on the circumferential main groove 10 side across the stepping side wall surface 21). It can be seen that the heel and toe wear resistance is further improved. Further, comparing Examples 1 to 3 with Examples 4 and 5, it can be seen that the heel and toe wear resistance is further improved by optimizing the ratio 1 / L. Moreover, when Example 4 is seen, even if the recessed part 4 is a structure which consists of a some hole, it turns out that a heel and toe wear-proof performance improves appropriately. In addition, when Example 3 and Example 7 are compared, the width w and depth d of the concave portion 4 decrease on the wall surface 23 on the circumferential main groove 10 side as the distance toward the stepped-side end portion increases. It can be seen that the heel and toe wear performance is further improved. Further, when Example 7 and Example 8 are compared, it can be seen that the heel and toe wear resistance is further improved by optimizing the width w and depth d of the recess 4. Moreover, when Example 9 is seen, it turns out that the heel and toe wear-proof performance improves further by the recessed part 4 having a two-stage structure.

  As described above, the pneumatic tire according to the present invention is useful in that the heel and toe wear resistance can be improved.

1 block, 3 tread surface, 4 recess, 10 circumferential main groove, 20, 20 'lug groove, 21 kicking side wall surface, 22 stepping side wall surface, 23 circumferential groove side wall surface

Claims (7)

A pneumatic tire comprising a plurality of blocks divided into a plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction,
Said block comprises a first recess which is open to at least one of the walls of the both wall surfaces of the circumferential main groove side while being positioned on the wall surface of at least one of the lug groove side, the wall surface of the other of the lug groove side A second recess disposed,
The total volume of the first recess is larger than the total volume of the second recess, and
A pneumatic tire having a designation of a rotational direction in which the one lug groove side is a kicking side of the block and the other lug groove side is a stepping side of the block . The first recess extends from the end on the one lug groove side toward the end on the other lug groove side on the wall surface on the circumferential main groove side, and the wall surface on the circumferential main groove side 2. The pneumatic tire according to claim 1, wherein a length l in the tire circumferential direction of the first recess and a length L in the tire circumferential direction of the block have a relationship of 0.30 ≦ l / L ≦ 0.70. . The first recess extends from the end on the one lug groove side toward the other lug groove side on the wall surface on the circumferential main groove side, and the depth d or width w of the first recess The pneumatic tire according to claim 1 or 2, wherein the tire decreases as it goes toward the other lug groove. The pneumatic tire according to claim 1, wherein the volume v of the first recess and the volume V of the block have a relationship of 0.005 ≦ v / V ≦ 0.05. In the region of the wall surface on the one lug groove side and the region from the end on the one lug groove side to 0.30 × L in the tire circumferential direction, the width w and depth d of the first recess are 1.0. The pneumatic tire according to claim 1, which is in a range of [mm] ≦ w ≦ 3.0 [mm] and 1.0 [mm] ≦ d ≦ 3.0 [mm]. The pneumatic tire according to any one of claims 1 to 5, wherein a depth direction of the first concave portion is inclined toward a groove bottom side with respect to a tread surface of the block. A pneumatic tire comprising a plurality of blocks divided into a plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction,
The block has a recess disposed on at least one of the lug groove side walls, and does not have a recess on the other lug groove side wall ,
A trailing side of the block lug groove side of the one, have a designated rotational direction of the other of the lug groove side and leading side of the block,
The concave portion opens on at least one of the wall surfaces on the circumferential main groove side, and from the end on the kicking side toward the end on the stepping side on the wall surface on the circumferential main groove side. Extended, and
The length l in the tire circumferential direction of the recess on the wall surface on the circumferential main groove side and the length L in the tire circumferential direction of the block have a relationship of 0.30 ≦ l / L ≦ 0.70. A featured pneumatic tire.

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