JP5833424B2 - Precure tread and tire - Google Patents

Description

  The present invention relates to a precure tread, and more particularly to a precure tread that can effectively suppress the progress of tire wear and a tire including the precure tread.

Conventionally, as a tread pattern of a tire employed particularly in heavy-duty vehicles, a rib pattern that is partitioned by a plurality of circumferential grooves (main grooves) extending in the tire circumferential direction and forms a plurality of land portions that come into contact with the road surface In addition, a block pattern or the like in which a land portion is divided in a circumferential direction by a plurality of lateral grooves intersecting with the main groove to form a block shape is known.
In these tires, generally near the edge of the rib located on the outer side in the tire width direction due to the braking force and lateral force received by the tire due to the difference (diameter difference) between the radius on the tire center side and the radius on the tire shoulder side It is known that wear (abrasion nuclei) is likely to occur on the shoulder side, and the wear generated on the shoulder side gradually progresses to the tire center side.

  In Patent Document 1, in order to prevent the wear generated in the shoulder rib from progressing toward the tire center side, a groove for preventing wear progression called Defense Groove is provided in the shoulder rib, and the width of the groove is determined. A tire having a configuration in which wear is concentrated as a discard rib called a defense rib or a wear sacrifice rib on the outer side in the direction is disclosed, and the wear is tired until the discard rib partitioned by a groove for preventing progress of wear disappears. Progress toward the center side is suppressed.

However, as described above, the wear of the tire is fundamentally progressed from the shoulder side to the center side. Therefore, when the groove for preventing the progress of wear formed in the shoulder rib disappears, the other groove is Naturally, after the groove for preventing the progress of wear disappears, the wear progresses again toward the tire center, so the shoulder rib tends to be unevenly worn. It will be necessary to change the tire before it is fully worn.
In order to make up for this drawback, it is conceivable to form a similar groove on the inner side in the width direction of the groove for preventing the progress of wear. However, the formation of the groove reduces the block rigidity of the shoulder rib. There is a concern that the uneven wear resistance of the steel deteriorates.

JP 2003-200713 A

  In order to solve the above-mentioned problem, the present invention is a precure tread capable of preventing the wear generated on the shoulder side from progressing to the tire center side even when the groove for preventing wear progress disappears, And the tire provided with the said precure tread is provided.

As a configuration of the precure tread for solving the above-described problem, among the plurality of circumferential grooves extending in the circumferential direction and the plurality of ribs partitioned by the plurality of circumferential grooves, the precure tread is positioned at the outermost side in the width direction. About the precure tread having a wear progress suppressing groove extending in the circumferential direction in the shoulder rib on the ground surface side, the ground surface is worn by the wear of the shoulder rib in the shoulder rib on the inner side in the width direction from the wear progress suppressing groove. The back surface groove is exposed to the side, and the position of the back surface groove is set to be within 1/3 L from the uneven wear progress suppressing groove when the width direction distance between the circumferential groove and the uneven wear progress suppressing groove is L. .
According to this configuration, the back surface groove located in the width direction inner side than the wear progress suppressing groove is exposed to the grounding surface side by the wear of the shoulder rib, so that a new groove is obtained when the wear of the shoulder rib has progressed to a certain degree. Appears on the ground contact surface side, and it is possible to suppress the progress of wear toward the tire center side while ensuring the rigidity of the shoulder rib in the initial stage of wear. Further, since the position of the back groove is set within 1/3 L from the uneven wear progress suppressing groove when the width direction distance between the main groove and the uneven wear progress suppressing groove is L, the back groove in the shoulder rib is set. Since the groove wall on the outer side in the width direction properly contacts the groove wall on the inner side in the width direction, it is possible to prevent the wear from progressing to the tire center side.
Further, the depth of the back groove was set to 50% or more of the precure tread thickness, and 50% or more of the depth overlapped with the depth of the wear progress suppressing groove.
According to this configuration, the depth of the back groove is 50% or more of the thickness of the precure tread, and 50% or more of the depth overlaps with the depth of the wear progress suppressing groove. Since the rear groove appears immediately before or after disappearing, it is possible to suppress the progress of wear toward the tire center after the disappearance of the wear progress suppressing groove. Moreover, it is preferable to set the width | variety of a back surface groove | channel to 0.3 mm-3 mm, Furthermore, it is preferable to make the width | variety of a back surface groove | channel narrower than the width | variety of an abrasion suppression groove | channel.
Moreover, according to the tire provided with each pre-cured tread, it is possible to suppress the possibility that the tire needs to be replaced before the complete wear as a tire use limit, and it is possible to obtain a tire that realizes a long life. .
The summary of the invention does not enumerate all necessary features of the present invention, and individual configurations constituting the feature group can also be the invention.

It is a top view of a precure tread. It is width direction sectional drawing of a precure tread. It is an expanded sectional view of a precure tread. It is a section perspective view of a tire provided with precure tread. It is an expanded sectional view of a precure tread. It is a table | surface which shows the result of an actual vehicle abrasion test.

  Hereinafter, the present invention will be described in detail through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included in the invention. It is not always essential to the solution.

FIG. 1 is a plan view of a precure tread 1 according to the present embodiment, and FIG. 2 is a cross-sectional view in the width direction of the precure tread 1. The details of the precure tread 1 will be described with reference to the drawings.
As shown in each figure, the precure tread 1 is composed of a plurality of circumferential grooves 2A to 2C formed on the ground contact surface 15; 16 side that contacts the road surface, and a center rib partitioned by the circumferential grooves 2A to 2C. 3A; 3B and shoulder ribs 4A; 4B. The precure tread 1 is, for example, a plate-like body that is vulcanized and molded by a press mold (not shown), and the length in the longitudinal direction is substantially equal to the circumferential length of a base tire 50 described later. Is set.
In addition, the vulcanization degree of the precure tread 1 may be in a semi-vulcanized state lower than the vulcanization degree required as a product.

The circumferential groove 2A extending across the tire width direction center (tire center Tc) is a groove formed continuously along the longitudinal direction of the precure tread 1 (circumferential direction of the base tire 50), As shown in FIG. 2, the cross-sectional shape is set to a substantially U shape, for example. Note that the cross-sectional shape is not limited to this, and various cross-sectional shapes such as a V shape, a trapezoidal shape, and a rectangular shape are possible.
The circumferential groove 2B; 2C is a groove located on the outer side in the tire width direction (hereinafter simply referred to as the width direction) than the circumferential groove 2A, and extends in the longitudinal direction of the precure tread 1 in parallel with the circumferential groove 2A. It is formed continuously along. Further, the cross-sectional shape of the circumferential grooves 2B; 2C is set to be substantially U-shaped, for example, like the circumferential groove 2A. Note that the shape of the circumferential grooves 2A to 2C is not limited to a linear shape, and may be a curved shape or a zigzag shape, for example.

  The center rib 3A is located between the circumferential groove 2A and the circumferential groove 2B, and is partitioned by the circumferential groove 2A and the circumferential groove 2B, thereby continuously along the longitudinal direction of the precure tread 1. It extends and functions as a land portion having a ground contact surface 15 (tread surface). The center rib 3B is located between the circumferential groove 2A and the circumferential groove 2C, and extends continuously along the longitudinal direction of the precure tread 1 by being partitioned by the circumferential groove 2A and the circumferential groove 2C. And functions as a land portion having a ground contact surface 15. Although not shown, a narrow groove called a sipe extending in the width direction may be provided on the ground contact surface 15 of the center rib 3A; 3B.

The shoulder rib 4A is a region located on the outer side in the width direction with respect to the circumferential groove 2B. By being partitioned by the circumferential groove 2B, the shoulder rib 4A continuously extends along the longitudinal direction of the precure tread 1, It functions as a land portion having the ground 16. The shoulder rib 4B is an area located on the outer side in the width direction than the circumferential groove 2C, and is continuously extended along the longitudinal direction of the precure tread 1 by being partitioned by the circumferential groove 2C. It functions as a land portion having the ground 16. That is, the shoulder ribs 4 </ b> A and 4 </ b> B are ribs located on the outermost side in the width direction of the precure tread 1. Similar to the center ribs 3A; 3B, a narrow groove called a sipe extending in the width direction may be provided on the grounding surface 16 of the shoulder ribs 4A; 4B.
Thus, the precure tread 1 according to the present embodiment is molded as a tread having a total of four ribs 3A; 3B, 4A; 4B by a total of three circumferential grooves 2A to 2B.
The number of circumferential grooves and the number of ribs partitioned by the circumferential grooves are not limited to the above example, and the number can be changed as appropriate according to the use of the tire. Further, for example, the shape and width of the ribs 3A; 3B, 4A; 4B can be asymmetrical.

  As shown in FIG. 2, for example, a flat back surface 11 is formed along the width direction on the opposite side of the ground contact surface 15; 16 in the precure tread 1. The back surface 11 is a surface that faces the circumferential surface 50 </ b> A of the base tire 50 when being attached to the base tire 50 described later. The back surface 11 may be slightly curved in advance along the surface shape (buff line) of the circumferential surface 50 </ b> A of the base tire 50.

Next, a specific structure of the shoulder ribs 4A; 4B will be described.
Both shoulder ribs 4 </ b>A; 4 </ b> B located at the outermost side in the width direction in the precure tread 1 are partitioned into a shoulder main body portion 30 and a wear sacrifice portion 35 by the wear progress suppressing groove 20.
The wear progress suppressing groove 20 is a narrow groove extending from the ground contact surface 16 in the thickness direction of the precure tread 1 (back surface 11 side). The wear progress suppressing groove 20 extends continuously along the longitudinal direction of the precure tread 1 in the same manner as the circumferential grooves 2A to 2C described above, and the shoulder ribs 4A and 4B are connected to the shoulder main body 30 and the shoulder. A partition is formed with the wear sacrificial part 35 located on the outer side in the width direction than the main body part 30.

  As shown in FIG. 2, the wear progress suppressing groove 20 includes a straight portion 20 </ b> A linearly extending in the thickness direction of the precure tread 1 and a bulging portion 20 </ b> B whose outer shape bulges toward the groove bottom 21. Therefore, the groove walls 22; 23 mainly constituting the straight portion 20A are brought into contact with each other due to the fall of the wear sacrifice portion 35 located on the outer side in the width direction of the shoulder main body portion 30, and the wear is prevented from progressing toward the tire center Tc. To do. The operation of the wear progress suppressing groove 20 will be described later.

Moreover, as shown in FIG. 2, the back surface groove | channel 40 is formed in shoulder rib 4A; 4B. The back groove 40 is a narrow groove extending from the back surface 11 in the thickness direction of the precure tread 1 (on the grounding surface 16 side). The back surface groove 40 is formed in the shoulder main body 30 on the inner side in the width direction than the wear progress suppressing groove 20 in the shoulder ribs 4A; 4B. The back surface groove 40 extends intermittently along the longitudinal direction of the precure tread 1 or continuously like the circumferential grooves 2A to 2C described above.
Further, the back groove 40 extends, for example, linearly toward the grounding surface 16 side, and the groove bottom 41 located on the grounding surface 16 side is not exposed to the grounding surface 16 when not in use or at the initial stage of wear. It stays inside the shoulder body 30. The angle of the back groove 40 with respect to the back surface 11 is set so as to be substantially perpendicular to the back surface 11 in a state where the precure tread 1 is affixed to an inner peripheral surface 50A described later curved along the width direction. It is desirable to do. More desirably, the angles of the back surface groove 40 and the wear progress suppressing groove 20 with respect to the back surface 11 are parallel to each other.

  Next, with reference to an enlarged cross-sectional view shown in FIG. 3, the positional relationship between the wear progress suppressing groove 20 and the back groove 40 formed in the shoulder ribs 4A; 4B will be described. In addition, since shoulder rib 4A and shoulder rib 4B in this embodiment are provided as substantially the same shape, in the following description, shoulder rib 4A will be described as a representative.

First, the distance in the width direction (separation distance) between the wear progression suppressing groove 20 and the back groove 40 will be described. The back surface groove 40 is formed on the inner side in the width direction than the wear progress suppressing groove 20. The distance L1 from the wear progress suppressing groove 20 is the distance L2 between the wear progress suppressing groove 20 and the circumferential groove 2B. It is set within a distance multiplied by one third (L1 = L2 / 3).
More specifically, the distance L2 is the width direction outer side forming the circumferential groove 2B from the edge portion E1 where the groove wall 22 on the inner side in the width direction forming the linear portion 20A of the wear progress suppressing groove 20 and the grounding surface 16 intersect. This is the distance to the edge E2 where the groove wall 33 and the ground contact surface 16 intersect.
The distance L1 is a distance from the edge portion E1 to the edge portion E3 where the groove wall 43 on the outer side in the width direction forming the back surface groove 40 and the groove bottom 41 intersect.
Then, by setting the relationship between the distances L1 and L2 defined in this way to L1 = L2 / 3, it is possible to obtain an effect that the groove wall 43 appropriately contacts the groove wall 42. The operation of the back groove 40 will be described later.

Next, the groove depth between the wear progress suppressing groove 20 and the back groove 40 will be described.
The groove depth H1 of the back groove 40 is set to 50% or more of the thickness of the precure tread 1, more specifically, the thickness H2 of the shoulder rib 4A; 4B through which the center in the width direction of the back groove 40 passes. The groove depth H <b> 1 is a distance from the back surface 11 to the groove bottom 41. The thickness H2 is a distance from the back surface 11 to the ground plane 16. Then, by setting the groove depth H1 defined in this way according to the relationship with the thickness H2 (H1 ≧ 0.5 × H2), before the wear progresses in the second shoulder main body 30A described later. Since the back surface groove | channel 40 is exposed on the grounding surface 16, progress of wear can be suppressed appropriately.
That is, if the groove depth H1 of the back surface groove 40 is 50% or less of the thickness H2, the wear of the second shoulder main body 30A can be considerably advanced before the back surface groove 40 is exposed on the ground surface 16. Therefore, it is desirable that the groove depth H1 is 50% or more of the thickness H2, and the back groove 40 appears before the wear of the second shoulder main body 30A progresses. The second shoulder main body 30A will be described later.

  Further, the range (overlap distance H4) where the groove depth H1 of the back groove 40 and the groove depth H3 of the wear progress suppressing groove 20 overlap in the thickness direction of the precure tread is the groove depth of the wear progress suppressing groove 20. It is desirable that it is 50% or more with respect to H3. Here, the groove depth H3 of the wear progress suppressing groove 20 is a distance between the groove bottom 21 of the wear progress suppressing groove 20 and the edge portion E1. The overlap distance H4 is a distance from the groove bottom 21 of the wear progress suppressing groove 20 to the groove bottom 41 of the back surface groove 40. By setting the overlap distance H4 defined in this way according to the relationship with the groove depth H3 (H4 ≧ 0.5H3), the ground contact surface 16 does not cause a time lag during or after the wear progress suppression groove 20 disappears. It becomes possible to expose the back surface groove | channel 40 appropriately on the top. Further, as shown in the figure, the groove width W1 of the back surface groove 40 is set to be narrower than the groove width W2 of the wear progress suppressing groove 20.

FIG. 4 is a partial cross-sectional view of the tire T showing a state in which the precure tread 1 having the above structure is attached to the base tire 50.
As shown in the figure, the base tire 50 includes an inner liner 55 positioned at the innermost position in the tire radial direction, and a carcass 57 laminated on the inner liner 55. The carcass 57 is composed of one or more carcass plies made of a cord extending in the radial direction of the tire.
Both end portions 57A; 57B of the carcass 57 are folded around a pair of bead cores 56 disposed on both sides in the tire width direction, and extend in a toroidal shape across the pair of bead cores 56; Further, a belt layer 58 made of, for example, a plurality of steel belts 58A is disposed on the crown portion 57C of the carcass 57.

  On the circumferential surface 50 </ b> A of the base tire 50 having the above-described configuration, the above-mentioned precure tread 1 molded as a long member along the circumferential direction is stuck via a cushion rubber 52. The circumferential surface 50A is a buff surface formed by cutting a tread portion of a used tire with a device called a buffing machine, for example. The circumferential surface 50A is formed as a surface that gently curves inward in the radial direction from the tire center Tc to both sides in the width direction. And the above-mentioned precure tread 1 is arrange | positioned on the circumferential surface 50A in the state which the back surface 11 of the said precure tread 1 faced.

  The cushion rubber 52 is an unvulcanized rubber interposed between the circumferential surface 50A of the base tire 50 and the back surface 11 of the precure tread 1, and the base tire 50 in a state where the precure tread 1 is adhered is illustrated. By being vulcanized by an external vulcanizer, the base tire 50 and the precure tread 1 are firmly integrated.

Next, with reference to an enlarged cross-sectional view shown in FIG. 5, the operation of the shoulder ribs 4A and 4B in the tire T provided with the precure tread 1 will be described.
FIGS. 5A to 5D are enlarged cross-sectional views showing the state of the shoulder rib 4A when the tire T is mounted on a vehicle or the like and a prescribed internal pressure is applied.

As shown in FIG. 5A, in the state in which the vehicle load is applied to the tire T to which the prescribed internal pressure is applied, the wear sacrifice located on the outermost side in the shoulder rib 4A located on the outermost side in the width direction of the tire T. The portion 35 is bent inward in the width direction and is in a state of being collapsed with respect to the shoulder main body portion 30.
As a result of this falling, the groove wall 23 constituting the straight portion 20A of the wear progress suppressing groove 20 comes into contact with the groove wall 22 located on the inner side in the width direction starting from the bulging portion 20B. When the groove wall 23 comes into contact with the groove wall 22 positioned on the inner side in the width direction, the edge portion E1 (edge component) on the outer side in the width direction of the shoulder main body 30 facing the road surface R is pseudo-eliminated and is added to the tire T. The braking force (the force applied in the direction opposite to the vehicle traveling direction) and the lateral force applied mainly when the vehicle is turning suppresses the edge E1 of the shoulder body 30 from becoming a wear nucleus. It is possible to suppress uneven wear from occurring in the shoulder main body 30 itself due to the progress of wear from the edge E1 toward the tire center Tc.

  On the other hand, the edge portion E4 on the outer side in the width direction of the wear sacrificial portion 35 is a portion that receives a strong pressure from the road surface R at the time of braking force or lateral force input, so the wear of the tire T is exaggerated by the chain line P1. As shown, it gradually advances toward the tire center Tc with the edge E4 as a core. As is clear from the above description, the wear sacrificial portion 35 formed on the shoulder ribs 4A; 4B has wear nuclei generated at the edge E1 located on the outer side in the width direction of the shoulder main body 30 in the initial stage of wear, and the shoulder main body. It is a sacrificial part to prevent the partial wear from occurring in the portion 30, and suppresses the edge portion E1 of the shoulder body portion 30 from becoming a wear nucleus until the wear progress suppression groove 20 disappears, The wear is prevented from progressing toward the tire center Tc.

  FIG. 5B shows a state in which the wear indicated by the broken line P1 has progressed, and the wear progress suppressing groove 20 (straight portion 20A) that partitions the wear sacrificial portion 35 and the shoulder body portion 30 is disappearing. When the wear progression suppression groove 20 that partitions the wear sacrificial portion 35 and the shoulder main body 30 gradually disappears due to wear of the wear sacrificial portion 35, the wear suppression action by the wear sacrificial portion 35 is gradually lost, and the shoulder main body portion 30. The edge portion E1 gradually wears, and the wear tends to progress from the edge portion E1 toward the tire center Tc.

  On the other hand, when wear centering on the edge portion E1 of the shoulder body portion 30 progresses due to the disappearance of the wear progress suppressing groove 20, it is formed on the inner side in the width direction than the edge portion E1, as exaggerated by the broken line P2. The rubber Tr below the groove bottom 41 of the back groove 40 is worn.

  Then, as shown in FIG. 5C, when the wear of the rubber Tr below the groove bottom 41 further progresses and the groove bottom 41 of the back groove disappears, both edge portions of the groove walls 42; 43 of the back groove 40 simultaneously. E3; E5 appears on the ground surface 16. That is, the back surface groove 40 remaining in the shoulder main body 30 in the initial stage of wear is exposed to the ground contact surface 16 due to the progress of wear.

  In this case, the back surface groove 40 that appears on the ground contact surface 16 partitions the shoulder main body portion 30 defined by the wear progress suppressing groove 20 as the second wear sacrificial portion 35A and the second shoulder main body portion 30A. That is, the shoulder main body 30 is further partitioned into the second wear sacrificial portion 35A and the second shoulder main body 30A by the rear groove 40 newly appearing with the disappearance of the wear progress suppressing groove 20.

  As shown in FIG. 5D, in the case where the rear groove 40 appears on the ground surface 16, and the shoulder main body 30 is partitioned into the second wear sacrificial portion 35A and the second shoulder main body 30A. When a vehicle load is applied to the tire T to which the specified internal pressure is applied, the second wear sacrificial portion 35A bends in the same manner as the above-mentioned wear sacrificial portion 35, and the second shoulder main body 30A on the inner side in the width direction is bent. It will be in a collapsed state. And the groove wall 43 which comprises the back surface groove | channel 40 will be in the state which contacted the groove wall 42 located in the width direction inner side by the fall of 2nd wear sacrifice part 35A. When the groove wall 43 comes into contact with the groove wall 42 located on the inner side in the width direction, the edge portion E5 (edge component) on the outer side in the width direction of the second shoulder main body 30A facing the road surface R is the same as the edge portion E1 described above. Therefore, the braking force applied to the tire T and the lateral force applied during turning of the vehicle suppresses the edge E5 of the second shoulder body 30A from becoming a wear nucleus, and wear is reduced to the edge. It can suppress progressing from E5 to the tire center Tc side.

That is, the back surface groove 40 according to the present embodiment is a groove that is exposed on the ground surface 16 after the disappearance process or disappearance of the wear progress suppressing groove 20, and is a wear sacrificial portion 35 provided on the ground surface side by the progress of wear. Disappears and the function of quasi-eliminating the edge part (edge component) E1 of the shoulder body part 30 is lowered or the function is not fulfilled, the shoulder body part 30 is replaced with the second wear sacrifice part 35A and the second wear sacrifice part 35A. It is a groove which divides into the shoulder main-body part 30A.
And the 2nd wear sacrifice part 35A divided by the appearance of the back surface groove | channel 40 is the edge part (edge component) of the 2nd shoulder main-body part 30A similarly to the wear sacrifice part 35 as a 1st wear sacrifice part. Since it functions so as to eliminate E5 in a pseudo manner, it is ensured that the wear progresses rapidly from the edge portion E1 of the original shoulder body portion 30 toward the tire center Tc even after the wear progress suppressing groove 20 disappears. It becomes possible to prevent.
Further, since the back surface groove 40 is formed as a groove extending from the back surface 11 toward the ground surface 16, in other words, as a groove remaining in the shoulder body 30 at the initial stage of wear, the back surface groove 40 extends from the ground surface 16 toward the back surface 11. Compared with the case where the groove is made, the rigidity of the shoulder ribs 4A and 4B at the initial stage of wear is not lowered.

Further, the back surface groove 40 according to the present embodiment has a relationship within the above-described L1 = L2 / 3 in the positional relationship with the wear progress suppressing groove 20, and therefore the back surface groove 40 appears on the grounding surface 16. In this case, the groove wall 43 can be appropriately brought into contact with the groove wall 42.
That is, when the distance L1 between the back surface groove 40 and the wear progress suppressing groove 20 is set to L2 / 3 or more, in other words, when the separation distance between the back surface groove 40 and the wear progress suppressing groove 20 is excessive, The rigidity of the second wear sacrificial portion 35A defined by the appearance of 40 becomes excessive, the second wear sacrificial portion 35A does not fall down sufficiently inward in the width direction, and the groove wall 43 does not contact the groove wall 42. However, if the distance L1 is set within L2 / 3, the groove wall 43 can be appropriately brought into contact with the groove wall 42.
Moreover, since the depth of the back surface groove | channel 40 which concerns on this embodiment has the relationship of the above-mentioned H4> = 0.5H3 in relation with the depth (overlap distance) of the wear progress suppression groove | channel 20, it is worn out. The back groove 40 can appear on the ground contact surface 16 immediately after the disappearance process of the progress suppression groove 20 or after the disappearance, and the wear progresses rapidly in the tire center Tc direction due to the disappearance of the wear progress suppression groove 20. It can be surely prevented.
Moreover, since the groove width of the back surface groove | channel 40 which concerns on this embodiment has the relationship of the above-mentioned W1 <W2 in relation with the groove width of the wear progress suppression groove | channel 20, shoulder rib 4A in the wear initial stage; The rigidity of 4B does not fall, and the partial wear resulting from a rigidity fall can be prevented appropriately.

Hereinafter, with reference to the table shown in FIG. 6, the result of the actual vehicle abrasion test of the tire provided with the precure tread 1 having the back groove 40 will be described.
As shown in the table, the size of the tire used in the actual vehicle wear test is 295 / 75R22.5. In addition, the tires according to the comparative example and the example are mounted on the steer (S) and trailer (T) side of the 6 × 4 trailer, and the tire internal pressure is set to 7.0 KPA.
Further, in the actual vehicle wear test, the life (S / T) when the trailer equipped with the above-described tire is driven for 200,000 miles is evaluated as an index with respect to the comparative example (100).
Further, the main groove depth (circumferential groove depth) of the tires according to the comparative example and the example are both 15 mm, and the Sh defense groove depth (wear progress suppressing groove) is also 15 mm. Further, the tire according to the example is provided with a rear groove, the depth is 14 mm, the width direction distance L1 from the Sh defense groove, and the distance L2 between the main groove and the defense groove is equally divided into four (L1 = L2). / 4). Moreover, the width | variety of a back surface groove | channel is 1.0 mm, and it extends continuously along the circumferential direction of a tire. The angle of the back groove was set as an angle of 90 ° with respect to the back of the precure tread affixed on the base tire.

As is clear from the table, in the tire according to the example, it is clear that both the tire mounted on the steer side and the trailer side have improved life compared to the tire according to the comparative example, It can be seen that the occurrence of uneven wear that can occur at the center side is suppressed.
That is, according to the precure tread 1 according to the present embodiment and the tire T provided with the precure tread 1, the occurrence of uneven wear on the shoulder side is suppressed, so that the tire has a longer life. Thus, the possibility that the tire needs to be replaced before the tire is completely worn is suppressed, and the economic efficiency is greatly improved.

  The present invention has been described based on the embodiments. However, the technical scope of the present invention is not limited to the above embodiments, and various modifications and improvements can be made by combining the embodiments. Obviously in the trader. Further, it is apparent from the scope of the claims that the embodiments added with such various changes and improvements can be included in the technical scope of the present invention.

1 Precured tread, 2A to 2C Circumferential groove (main groove), 3A; 3B Center rib,
4A; 4B shoulder rib, 11 back surface, 15; 16 ground surface,
20 Abrasion progress suppressing groove, 30 shoulder main body, 30A second shoulder main body,
35 wear sacrificial part, 35A second wear sacrificial part, 40 back groove, 41 groove bottom,
50 tires, 50A circumferential surface (buff surface), E1-E5 edge, T tire

Claims (5)

Of the plurality of circumferential grooves extending in the circumferential direction on the ground contact surface side and the plurality of ribs partitioned by the plurality of circumferential grooves, the shoulder ribs that extend in the circumferential direction extend in the circumferential direction. It is a precure tread equipped with a wear progress suppressing groove on the ground surface side,
In the shoulder rib on the inner side in the width direction than the wear progress suppressing groove, the back surface groove exposed to the grounding surface side by wear of the shoulder rib ,
The pre-cured tread is characterized in that the position of the back groove is within L / 3 of the wear progress suppressing groove when the distance in the width direction between the circumferential groove and the wear progress suppressing groove is L. And wherein the depth of the previous SL back grooves have a more than 50% of the depth of the precured tread thickness, and more than 50 percent of the depth to depth and overlap the wear progress suppression groove claim 1 Symbol placement precured tread to. The precure tread according to claim 1 or 2 , wherein the back groove has a width of 0.3 mm to 3 mm. The precure tread according to any one of claims 1 to 3, wherein a width of the back groove is narrower than a width of the wear progress suppressing groove. A tire comprising the precure tread according to any one of claims 1 to 4 .

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