JP2014019198A - Precure retreaded tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a necessary groove width.SOLUTION: A precure retreaded tire is formed by arranging a tread part 1, having land parts 13 formed with a plurality of main grooves 12 extended in a tire peripheral direction. A tread surface 11 is characterized in that the tread part 1 includes hard rubber members 4 which are arranged at least inside a periphery of at least one main groove 12 in a tire diameter direction along a tire peripheral direction, and consists of a rubber harder than a tread rubber on a surface of the land part 13 on the tread part 1.

Description

  The present invention relates to a precure retreaded tire.

  It is generally known to reuse as a pre-cured retread tire by attaching a new vulcanized tread part to a base tire that has been buffed by removing the tread rubber of a pneumatic tire whose remaining groove has reached the end of its life. Yes.

  Conventionally, for example, Patent Document 1 discloses that a precure retreaded tire is manufactured by attaching a belt-shaped tread portion to the surface of a base tire and then vulcanizing.

  Conventionally, for example, Patent Document 2 discloses that a precure retreaded tire is manufactured by attaching an annular tread portion to the surface of a base tire and then vulcanizing.

JP 2007-62248 A JP 2010-167672 A

  Precured retreaded tires have old rubber on the buffed surface from the belt of the base tire, and a tread part is newly provided on the outside, so the rubber thickness under the groove is thicker than the new tire, and the calorific value Increases the heat resistance. Therefore, in order to obtain heat resistance equivalent to that of a new tire, the rubber thickness under the groove of the tread portion attached to the base tire is reduced.

  However, the tread part of the precure retreaded tire is vulcanized and has grooves formed on the tread surface. After being attached to the base tire, it is vulcanized by applying pressure from the surroundings without using a mold that forms the grooves. For this reason, if the rubber thickness under the groove is formed thin, the groove part may be pressurized from the surroundings and the required groove width may not be ensured.

  This invention is made in view of the above, Comprising: It aims at providing the precure retreaded tire which can ensure the required groove width.

  In order to solve the above-described problems and achieve the object, the precure retread tire according to the first invention includes a tread portion in which a land portion is formed on a tread surface by a plurality of main grooves extending in a tire circumferential direction. In the precured retread tire configured to be disposed on the base tire, the tread portion is disposed at least on the inner side in the tire radial direction around the at least one main groove and along the tire circumferential direction. Compared with the tread rubber on the surface of the land portion in the portion, a hard rubber member made of hard rubber is provided.

  According to this pre-cured retread tire, when the tread part is attached to the base tire and then vulcanized by applying pressure from the periphery, the hard rubber member has the shape of the main groove even if the main groove is pressurized from the periphery. Acts to maintain. For this reason, the groove width required for the main groove can be ensured. In addition, since the hard rubber member maintains the shape of the groove bottom of the main groove, in order to reduce the amount of heat generation, when the rubber thickness under the groove, which is the inner side of the main groove in the tire radial direction, is formed thin, The effect of ensuring the required groove width can be remarkably obtained. In addition, if the rubber thickness under the groove, which is the inner side of the main groove in the tire radial direction, is thin, there is a risk that the groove bottom of the main groove may tear when the tread part is taken out from the press vulcanization mold during manufacturing of the tread part. However, since the hard rubber member maintains the shape of the bottom of the main groove, such a situation can be prevented.

  Further, in the precured retread tire according to the second invention, in the first invention, the hard rubber member has a width W in the tire width direction of 0.3 ≦ W / G with respect to the opening width G of the main groove. ≦ 4.0 is satisfied, and at least a part of the main groove is disposed on the inner side in the tire radial direction of the groove bottom.

  According to this precure retreaded tire, by disposing at least a part of the hard rubber member on the inner side in the tire radial direction of the groove bottom in the main groove, the situation where the groove bottom of the main groove is bent so as to narrow the groove width is prevented, Since the shape of the groove bottom of the main groove is maintained, the effect of ensuring the groove width required by the main groove can be remarkably obtained. Moreover, the width of the hard rubber member is set to 0.3 ≦ W / G ≦ 4.0 with respect to the opening width of the main groove, and at least a part of the hard rubber member is on the inner side in the tire radial direction of the groove bottom in the main groove. By disposing, the amount of use of the hard rubber member on the inner side in the tire radial direction of the land portion can be reduced, and the wear resistance and ride comfort by the tread rubber which is softer than the hard rubber member can be maintained.

  Further, in the precured retread tire according to the third invention, in the first invention, the hard rubber member is continuous in the tire width direction between the adjacent main grooves, and the tire radial direction of the groove bottom in the main groove It is arrange | positioned inside, It is characterized by the above-mentioned.

  According to this precure retreaded tire, the hard rubber member is arranged on the inner side in the tire radial direction of the groove bottom in the main groove, so that the groove bottom of the main groove is prevented from being bent so as to narrow the groove width. Since the shape of the bottom is maintained, the effect of ensuring the groove width required for the main groove can be remarkably obtained. Moreover, since the hard rubber member is continuously arranged in the tire width direction between the adjacent main grooves in the tire width direction, the hard rubber member is also arranged on the inner side of the land portion in the tire radial direction. After attaching, when the pressure is applied from the surroundings and vulcanized, the shape of the entire tread portion can be maintained.

  Further, in the precured retread tire according to the fourth invention, in any one of the first to third inventions, the hard rubber member is 1.6 [mm] outward from the groove bottom of the main groove in the tire radial direction. It is characterized by being arranged on the inner side in the tire radial direction than the position.

  A position 1.6 [mm] from the bottom of the main groove to the outer side in the tire radial direction is the wear limit of the land portion, and a wear indicator is provided at this position to notify the wear limit. That is, by disposing the hard rubber member on the inner side in the tire radial direction from the above position, the hard rubber member does not appear on the tread surface until the wear limit of the land portion is reached. It is possible to maintain the wear resistance and ride comfort of the tread rubber that is softer than the hard rubber member.

  Further, in the precured retread tire according to the fifth invention, in any one of the first to fourth inventions, the hard rubber member has a difference in rubber hardness of 2 points or more as compared with the tread rubber. It is characterized by.

  According to this pre-cured retreaded tire, the hard rubber member is made to have a rubber hardness difference of 2 points or more with respect to the tread rubber, and the tread portion is attached to the base tire and then vulcanized by applying pressure from the surroundings. In this case, it becomes easy to maintain the shape of the groove bottom of the main groove, and the effect of ensuring the groove width required for the main groove can be remarkably obtained.

  Moreover, the precure retread tire according to a sixth aspect of the invention is characterized in that, in any one of the first to fifth aspects, the hard rubber member has a rubber hardness Hs satisfying a range of 62 ≦ Hs ≦ 82. To do.

  According to this precure retreaded tire, when the rubber hardness Hs of the hard rubber member is in the range of 62 ≦ Hs ≦ 82, the tread portion is attached to the base tire and then vulcanized by applying pressure from the surroundings. In addition, it is easy to maintain the shape of the groove bottom of the main groove, and the effect of ensuring the required groove width of the main groove can be remarkably obtained. In addition, by setting the rubber hardness Hs of the hard rubber member in the range of 62 ≦ Hs ≦ 82, it is possible to prevent the main groove from being cracked due to the hard rubber member being too hard when the precured retreaded tire is used.

  Further, in the precured retread tire according to the seventh invention, in any one of the first to sixth inventions, the tread rubber is arranged in such a manner that at least the hard rubber member is not exposed at the groove bottom of the main groove. It is characterized by that.

  According to this pre-cured retread tire, the configuration of the tread rubber is arranged so that the hard rubber member is not exposed to the main groove, so that the shape of the groove bottom of the main groove is maintained by the hardness of the hard rubber member via the tread rubber. And the effect which ensures the groove width which a main groove requires can be acquired. Moreover, since the tread rubber is disposed at least on the groove bottom of the main groove, it is possible to prevent the main groove from being cracked due to the hard rubber member being too hard when the precure retread tire is used.

  In addition, the precure retread tire according to an eighth aspect of the present invention is the tire according to any one of the first to seventh aspects, wherein the hard rubber member has a thickness D in the tire radial direction on the inner side in the tire radial direction of the groove bottom in the main groove. Satisfies the range of 1 [mm] ≦ D ≦ 4 [mm].

  According to this precure retreaded tire, by setting the thickness D of the hard rubber member in the above range, the rubber thickness under the groove, which is the inner side in the tire radial direction of the main groove, is formed relatively thin, and the tread portion is made into the base tire. After being attached to, when the pressure is applied from the surroundings and vulcanized, the shape of the groove bottom of the main groove can be maintained and the required groove width of the main groove can be secured.

  The retreaded tire according to the present invention can ensure the required groove width.

FIG. 1 is a partial meridional cross-sectional schematic view of a precure retreaded tire according to an embodiment of the present invention. FIG. 2 is an enlarged schematic meridian cross-sectional view of a precure retread tire according to an embodiment of the present invention. FIG. 3 is an enlarged meridian cross-sectional schematic diagram of another example of a precure retreaded tire according to an embodiment of the present invention. FIG. 4 is an enlarged schematic meridian cross-sectional view of another example of the precure retread tire according to the embodiment of the present invention. FIG. 5 is an enlarged schematic meridian cross-sectional view of another example of the precure retread tire according to the embodiment of the present invention. FIG. 6 is a partial meridional cross-sectional schematic view of another example of a precure retread tire according to an embodiment of the present invention. FIG. 7 is an enlarged schematic meridian cross-sectional view of another example of the precure retread tire according to the embodiment of the present invention. FIG. 8 is an enlarged schematic meridian cross-sectional view of another example of the precure retread tire according to the embodiment of the present invention. FIG. 9 is an enlarged schematic meridian cross-sectional view of another example of the precure retread tire according to the embodiment of the present invention. FIG. 10 is an enlarged schematic meridian cross-sectional view of another example of the precure retread tire according to the embodiment of the present invention. FIG. 11 is an enlarged meridian cross-sectional schematic diagram of another example of the precure retreaded tire according to the embodiment of the present invention. FIG. 12 is an enlarged meridian cross-sectional schematic diagram of another example of a precure retreaded tire according to an embodiment of the present invention. FIG. 13 is a chart showing the results of a performance test of a precure retread tire according to an example of the present invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  In the following description, the tire radial direction refers to a direction orthogonal to the rotational axis (not shown) of the precure retreaded tire, and the tire radial inner side refers to the side toward the rotational axis in the tire radial direction, the tire radial outer side, and Means the side away from the rotation axis in the tire radial direction. Further, the tire circumferential direction refers to a direction around the rotation axis as a central axis. Further, the tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction means the side toward the tire equator plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction means the tire width direction. Is the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane that is orthogonal to the rotational axis of the precured retreaded tire and passes through the center of the tire width of the precure retreaded tire. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equator line is a line along the tire circumferential direction of the retread tire on the tire equator plane CL. In the present embodiment, the same sign “CL” as that of the tire equator plane is attached to the tire equator line.

  As shown in FIG. 1, the precure retread tire according to this embodiment has a tread portion 1. The tread portion 1 is made of a rubber material, exposed at the outermost side in the tire radial direction of the retread tire, and the surface thereof becomes the contour of the retread tire. A tread surface 11 is formed on the outer peripheral surface of the tread portion 1, that is, the tread surface that comes into contact with the road surface during traveling. The tread surface 11 is provided with a plurality of (four in this embodiment) main grooves 12 extending in the tire circumferential direction. The main groove 12 may be formed in a linear shape extending in the tire circumferential direction and parallel to the tire equatorial plane CL, or may be formed in a zigzag shape extending in the tire circumferential direction. And the tread surface 11 is formed with a plurality of (in this embodiment, five) rib-like land portions 13 extending in the tire circumferential direction by a plurality of main grooves 12. In the rib-shaped land portion 13, block-shaped land portions that are divided into a plurality of pieces in the tire circumferential direction may be formed by a plurality of lug grooves that communicate with the main groove 12 and are arranged in the tire circumferential direction.

  The tread portion 1 is disposed between the base tire 2 and the cushion rubber 3 to constitute a precure retread tire. The base tire 2 is obtained by cutting out and buffing the tread rubber of a pneumatic tire whose remaining groove has reached the end of its life. The tire has a main configuration such as a bead portion, a carcass layer, and a belt layer. The cushion rubber 3 is used for bonding the tread portion 1 and the base tire 2. The tread portion 1 may be formed in a belt shape or an annular shape when being attached to the base tire 2.

  In this embodiment, the precure retread tire is made of hard rubber in the tread portion 1 around the main groove 12 as compared with the tread rubber constituting the tread surface 11 which is the surface of the land portion 13 in the tread portion 1. A hard rubber member 4 is provided. The hard rubber member 4 is disposed along the tire circumferential direction together with the main groove 12. The hard rubber member 4 may be arranged to reach the tread surface 11 so as to surround the main groove 12 as shown in FIGS. 1, 6, 10, and 11. As shown in FIGS. 7 to 9 and FIG. 12, it does not reach the tread surface 11 and may be disposed at least inside the main groove 12 in the tire radial direction. Further, as shown in FIGS. 1 and 3, the hard rubber member 4 may be provided in all the main grooves 12, but may be provided in at least one main groove 12.

  As described above, the precure retreaded tire according to the present embodiment is disposed in the tread portion 1 at least inside the tire radial direction around the at least one main groove 12 and along the tire circumferential direction. Compared with the tread rubber on the surface of the land portion 13, a hard rubber member 4 made of hard rubber is provided.

  According to this pre-cured retread tire, when the tread portion 1 is attached to the base tire 2 and vulcanized by applying pressure from the periphery, even if the main groove 12 is pressurized from the periphery, the hard rubber member 4 is It acts to maintain the shape of the main groove 12. For this reason, it becomes possible to ensure the groove width which the main groove 12 requires. Moreover, since the hard rubber member 4 maintains the shape of the groove bottom of the main groove 12, in order to reduce the amount of heat generation, when the rubber thickness below the groove that is the inner side in the tire radial direction of the main groove 12 is formed, The effect of ensuring the groove width required for the main groove 12 can be remarkably obtained. Furthermore, when the rubber thickness under the groove, which is the inner side in the tire radial direction of the main groove 12, is formed, the groove bottom of the main groove 12 is taken out when the tread part 1 is taken out from the press vulcanization mold during the production of the tread part 1. However, since the hard rubber member 4 maintains the shape of the groove bottom of the main groove 12, such a situation can be prevented.

  The base tire 2 is formed such that the buffed surface to which the tread portion 1 is attached is curved inward in the tire radial direction toward the outer side in the tire width direction. In contrast, the tread portion 1 has a flat surface to be attached to the buffed surface of the base tire 2. For this reason, the tread portion 1 is subjected to great pressure on the outer side in the tire radial direction and the outer side in the tire width direction on the outer side in the tire width direction, and the groove width of the main groove 12 on the outer side in the tire width direction tends to be narrow. Therefore, it is preferable that the hard rubber member 4 that secures the groove width of the main groove 12 is provided at least in the main groove 12 on the outermost side in the tire width direction.

  Moreover, in the precure retreaded tire of this embodiment, as shown in FIGS. 1-5, 8, 10, and 12, the hard rubber member 4 has a width W in the tire width direction and the opening of the main groove 12. It is preferable that the range of 0.3 ≦ W / G ≦ 4.0 is satisfied with respect to the width G. Further, it is preferable that at least a part of the hard rubber member 4 is disposed on the inner side in the tire radial direction of the groove bottom in the main groove 12.

  The width W in the tire width direction of the hard rubber member 4 refers to the maximum dimension of the hard rubber member 4 continuous in the tire width direction, as shown in FIGS. 1 to 5, 8, 10, and 12. Further, the groove bottom of the main groove 12 refers to a portion where the depth of the main groove 12 is the deepest. Therefore, depending on the opening width G of the main groove 12 and the distance between the adjacent main grooves 12 in the tire width direction, the range of 0.3 ≦ W / G ≦ 4.0 is mainly the tire of the adjacent main groove 12. It shows that the hard rubber member 4 is divided and arranged in the tire width direction between the width directions. 1 and 10 show a form in which the hard rubber member 4 is arranged to reach the tread surface 11 so as to surround the main groove 12, and in FIGS. 2 to 5, 8 and 12, the hard rubber member is shown. 4 shows a form that does not reach the tread surface 11 and is arranged inside the main groove 12 in the tire radial direction.

  According to this precure retreaded tire, by arranging at least a part of the hard rubber member 4 on the inner side in the tire radial direction of the groove bottom in the main groove 12, the groove bottom of the main groove 12 is bent so as to narrow the groove width. Is prevented and the shape of the groove bottom of the main groove 12 is maintained, so that the effect of ensuring the groove width required by the main groove 12 can be remarkably obtained. Moreover, the width W of the hard rubber member 4 is set to 0.3 ≦ W / G ≦ 4.0 with respect to the opening width G of the main groove 12, and at least a part of the hard rubber member 4 is a groove bottom in the main groove 12. The amount of the hard rubber member 4 used in the tire radial direction inner side of the land portion 13 is reduced, and the wear resistance and ride comfort by the tread rubber that is softer than the hard rubber member 4 are disposed. Can be maintained.

  Further, in the precure retreaded tire of the present embodiment, as shown in FIGS. 6, 7, 9, and 11, the hard rubber member 4 is continuous in the tire width direction between the adjacent main grooves 12, and is main. The groove 12 is preferably disposed on the inner side in the tire radial direction of the groove bottom.

  6 and 11 show a form in which the hard rubber member 4 is arranged to reach the tread surface 11 so as to surround the main groove 12, and in FIGS. 7 and 9, the hard rubber member 4 is placed on the tread surface 11. The form arrange | positioned in the tire radial direction inner side of the main groove 12 without reaching is shown.

  According to this pre-cured retread tire, the hard rubber member 4 is arranged on the inner side in the tire radial direction of the groove bottom in the main groove 12 to prevent the groove bottom of the main groove 12 from bending so as to narrow the groove width, Since the shape of the groove bottom of the groove 12 is maintained, the effect of ensuring the groove width required by the main groove 12 can be obtained remarkably. And since the hard rubber member 4 is arrange | positioned also in the tire radial direction inner side of the land part 13 by arrange | positioning the hard rubber member 4 continuously in the tire width direction between the adjacent main grooves 12, the tread part 1 After affixing to the base tire 2, when the pressure is applied from the surroundings and vulcanized, the shape of the entire tread portion 1 can be maintained.

  Moreover, in the precure retreaded tire of this embodiment, as shown in FIGS. 2-5, 7-9, and 12, the hard rubber member 4 is f = from the groove bottom of the main groove 12 to the tire radial direction outer side. It is preferable to be arranged on the inner side in the tire radial direction than the position F of 1.6 [mm].

  From the groove bottom of the main groove 12 to the outer side in the tire radial direction, f = 1.6 [mm] is a wear limit of the land portion 13, and a wear indicator that notifies the wear limit is provided at a position F. That is, by arranging the hard rubber member 4 on the inner side in the tire radial direction from the position F, the hard rubber member 4 does not appear on the tread surface 11 until the wear limit of the land portion 13 is reached. It is possible to prevent the situation from affecting the running of the vehicle and to maintain the wear resistance and ride comfort of the tread rubber which is softer than the hard rubber member 4.

  Moreover, in the precure retreaded tire of this embodiment, it is preferable that the hard rubber member 4 has a rubber hardness difference of 2 points or more as compared with the tread rubber.

  According to this precure retread tire, the hard rubber member 4 is made to have a difference in rubber hardness of 2 points or more with respect to the tread rubber, so that the tread portion 1 is attached to the base tire 2 and then pressure is applied from the surroundings. When vulcanized, the shape of the groove bottom of the main groove 12 can be easily maintained, and the effect of ensuring the groove width required by the main groove 12 can be obtained remarkably.

  Moreover, in the precure retread tire of this embodiment, it is preferable that the rubber hardness Hs of the hard rubber member 4 satisfies the range of 62 ≦ Hs ≦ 82.

  In addition, rubber hardness means JIS-A hardness based on JIS-K6263, and shall be based on the measurement of the sample extract | collected from the precure retreaded tire.

  According to this precure retreaded tire, by setting the rubber hardness Hs of the hard rubber member 4 in the range of 62 ≦ Hs ≦ 82, the tread portion 1 is attached to the base tire 2 and then pressure is applied from the periphery. When vulcanized, the shape of the groove bottom of the main groove 12 can be easily maintained, and the effect of ensuring the groove width required by the main groove 12 can be remarkably obtained. In addition, by setting the rubber hardness Hs of the hard rubber member 4 in the range of 62 ≦ Hs ≦ 82, it is possible to prevent the main groove 12 from cracking due to the hard rubber member 4 being too hard when the precured retreaded tire is used. become. In addition, it is preferable that the rubber hardness Hs of the hard rubber member 4 is in a range of 66 ≦ Hs ≦ 74 because the above effect can be obtained more remarkably.

  Moreover, in the precure retread tire of this embodiment, as shown in FIGS. 8-12, it is preferable that a tread rubber is arrange | positioned in the aspect which does not expose the hard rubber member 4 to the groove bottom of the main groove 12 at least.

  8, FIG. 9 and FIG. 12 show a form in which the tread rubber is arranged in such a manner that the hard rubber member 4 is not exposed at the groove bottom of the main groove 12. FIGS. 10 and 11 show a form in which the tread rubber is arranged in such a manner that the hard rubber member 4 is not exposed in the entire main groove 12.

  According to this precure retreaded tire, the hard rubber member 4 is configured not to be exposed to the main groove 12 by the arrangement of the tread rubber, so that the groove bottom of the main groove 12 is formed by the hardness of the hard rubber member 4 via the tread rubber. Thus, it is possible to obtain the effect of ensuring the groove width required by the main groove 12. In addition, since the tread rubber is disposed at least on the groove bottom of the main groove 12, it is possible to prevent the main groove 12 from being cracked due to the hard rubber member 4 being too hard when the precure retread tire is used.

  Moreover, in the precure retreaded tire of this embodiment, as shown to FIGS. 2-5 and FIGS. 7-12, the hard rubber member 4 is a tire radial direction inner side of the tire radial direction of the groove bottom in the main groove 12. FIG. It is preferable that the thickness D satisfies a range of 1 [mm] ≦ D ≦ 4 [mm].

  According to this precure retread tire, by setting the thickness D of the hard rubber member 4 within the above range, the rubber thickness under the groove, which is the inner side of the main groove 12 in the tire radial direction, is formed relatively thin, and the tread portion 1 After attaching the tire to the base tire 2, it is possible to maintain the shape of the groove bottom of the main groove 12 and secure the required groove width of the main groove 12 when vulcanized by applying pressure from the surroundings. Become.

  Incidentally, in the precure retread tire shown in FIGS. 1 to 11, the hard rubber member 4 is provided so as to contact the cushion rubber 3, but the hard rubber member 4 is separated from the cushion rubber 3 as shown in FIG. 12. As described above, a tread rubber may be provided between the hard rubber member 4 and the cushion rubber 3. With such a configuration, the tread rubber comes into contact with the entire cushion rubber 3, so that the adhesive force of the tread portion 1 to the base tire 2 by the cushion rubber 3 can be more evenly applied. In addition, in FIG. 12, although the example which comprised the hard rubber member 4 of the form shown in FIG. 8 so that it may leave | separate from the cushion rubber 3, the structure shown to FIGS. 1-7 and FIGS. 9-11 is shown. The same effect can be obtained by applying to the above.

  In this example, performance tests on narrow groove width, groove crack resistance (cracking at the groove bottom of the main groove), durability and wear resistance were conducted for multiple types of pre-cured retread tires with different conditions. (See FIG. 13).

  In the performance test of the narrow width resistance of the groove width, a pre-cured retread tire having a tire size of 11R22.5 was applied. The groove width of the main groove when the tread part, which is in the middle of the manufacturing process of the precure retreaded tire, is affixed to the base tire, and the main groove in the precure retreaded tire that is not rim assembled by vulcanizing by applying pressure from the surroundings The groove width was measured, and the narrowing ratio of the groove width was calculated. Based on this calculation result, index evaluation is performed with the conventional (80) standard. This evaluation shows that as the index is larger, the narrowing ratio is lower and the groove width is maintained.

In the performance test of the groove crack resistance, a prepure retread tire having a tire size of 11R22.5 is assembled to a normal rim, filled with a normal internal pressure, and a normal load is applied. And
With an indoor drum tester, the load was increased by 5 [%] every 24 hours from the above load while running at a speed of 45 [km / h], and the cracks at the bottom of the main groove when the tire broke down Presence / absence and number were determined visually. Based on this determination result, index evaluation with the conventional value as the standard (100) is performed. This evaluation shows that the smaller the index, the fewer (or no) cracking at the groove bottom of the main groove, and the better the groove crack resistance.

  The regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “maximum air pressure” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The normal load is “maximum load capacity” defined by JATMA, a maximum value described in “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.

  The durability performance test is performed by a low-pressure durability test using an indoor drum tester. Then, the running speed is increased by 1 [km / h] every 12 hours from the initial speed of 5 [km / h], and the running time until the tire breaks down is measured. Then, based on this measurement result, index evaluation using the conventional example as a reference (100) is performed. This evaluation shows that the numerical value is excellent in durability.

  In the wear resistance performance test, retreaded tires with a tire size of 11R22.5 are assembled on a regular rim, filled with regular internal pressure, and applied to the rear wheel of a test vehicle of 2-D4 (front 2-rear 4-drive). Four were installed, and after traveling 50,000 [km], the groove depth of the main groove was measured, and the reduction rate from before traveling was calculated. Based on this calculation result, index evaluation with the conventional value as the standard (100) is performed. This evaluation shows that the greater the index, the lower the groove reduction rate and the better the wear resistance.

  In FIG. 13, the precure retread tire of the conventional example does not have a hard rubber member.

  On the other hand, in FIG. 13, the precure retread tires of Examples 1 to 14 have hard rubber members. In addition, in the precured retread tires of Example 2, Example 3, and Examples 5 to 14, W / G satisfies the specified range. In the retreaded tire of Example 4, the hard rubber member is continuous between the main grooves. Further, in the precured retread tires of Example 2 and Examples 5 to 14, the hard rubber member is disposed on the inner side in the tire radial direction than the position of 1.6 mm on the outer side in the tire radial direction of the groove bottom of the main groove. Has been. Further, in the precure retread tires of Examples 6 to 14, the hard rubber member has an altitude difference of 2 points or more from the tread rubber. In the precure retread tires of Examples 7 to 14, the rubber hardness Hs of the hard rubber member is in the range of 62 ≦ Hs ≦ 82. Further, in the precure retread tires of Examples 11 to 14, the hard rubber eve material is not exposed in the main groove. In addition, in the precure retreaded tires of Examples 12 to 14, the hard rubber member has a thickness in the tire radial direction inside of the groove bottom of the main groove within a specified range.

  And as shown to the test result of FIG. 13, the precure retreaded tire of Example 1- Example 14 has narrow width resistance, groove crack resistance (crack at the groove bottom of the main groove), and durability. It can be seen that the wear resistance is maintained.

1 tread portion 11 tread surface 12 main groove 13 land portion 2 tires 3 cushion rubber 4 hard rubber member CL tire equatorial surface

Claims (8)

In the precure retreaded tire constituted by arranging the tread part in which the land part is formed by the plurality of main grooves extending in the tire circumferential direction on the tread surface on the base tire,
The tread portion is disposed at least inside the tire radial direction around the at least one main groove and along the tire circumferential direction, and is harder than the tread rubber on the surface of the land portion in the tread portion. A precured retreaded tire comprising a hard rubber member made of a rubber.   The hard rubber member has a width W in the tire width direction that satisfies a range of 0.3 ≦ W / G ≦ 4.0 with respect to the opening width G of the main groove, and at least a part of the hard rubber member in the main groove. The pre-cured retread tire according to claim 1, wherein the precure retread tire is arranged on the inner side in the tire radial direction of the groove bottom.   2. The precure retreading according to claim 1, wherein the hard rubber member is continuous in the tire width direction between the adjacent main grooves, and is disposed on the inner side in the tire radial direction of the groove bottom in the main groove. tire.   The said hard rubber member is arrange | positioned in the tire radial direction inner side rather than the position of 1.6 [mm] from the groove bottom of the said main groove to the tire radial direction outer side. Precured retreaded tire according to one.   The precured retreaded tire according to any one of claims 1 to 4, wherein the hard rubber member has a difference in rubber hardness of 2 points or more as compared with the tread rubber.   The precure retreaded tire according to any one of claims 1 to 5, wherein the hard rubber member has a rubber hardness Hs satisfying a range of 62≤Hs≤82.   The pre-cured retreaded tire according to any one of claims 1 to 6, wherein the tread rubber is disposed in such a manner that at least the hard rubber member is not exposed at the groove bottom of the main groove.   2. The hard rubber member according to claim 1, wherein a thickness D in a tire radial direction on a tire radial direction inner side of a groove bottom of the main groove satisfies a range of 1 [mm] ≦ D ≦ 4 [mm]. Precure retreaded tire as described in any one of -7.

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