JP6369183B2 - Rehabilitation tire - Google Patents

Description

  The present invention relates to a retread tire, and more particularly to a retread tire that can improve noise performance.

  Conventionally, rehabilitation has been performed on heavy-duty tires mounted on trucks and buses, but in recent years, rehabilitation is also being performed on light truck tires. As such a retread tire for a small truck, a technique described in Patent Document 1 is known.

JP 2009-0410179 A

  This invention is made | formed in view of the above, Comprising: It aims at providing the retreaded tire which can improve noise performance.

  In order to achieve the above object, a retread tire according to the present invention includes a tread and a base tire, and the tread has at least three circumferential main grooves extending in the tire circumferential direction, and the circumferential main groove. A retread tire comprising a plurality of land portions divided into a tread surface, and the base tire including a carcass layer and a pair of cross belts arranged on the outer side in the tire radial direction of the carcass layer. When the outer circumferential direction main groove on the outermost side in the tire width direction is referred to as an outermost circumferential direction main groove, and the land portion on the outer side in the tire width direction defined by the outermost circumferential direction main groove is referred to as a shoulder land portion. Further, the tread width TW and the tire total width SW have a relationship of 0.65 ≦ TW / SW ≦ 0.90, and the distance SDH in the tire radial direction from the rim diameter measurement point to the tire maximum width position , Tire cross section height SH Has a relationship of 0.45 ≦ SDH / SH ≦ 0.65, and the shoulder land portion is formed at a plurality of lug grooves extending in the tire width direction and an edge portion on the outermost circumferential main groove side. And a circumferential distance L between the lug groove and the notch portion is 0.20 ≦ L / Pk ≦ 0.80 with respect to a circumferential length Pk of the notch portion. It has the relationship of these.

  In the retreaded tire according to the present invention, the ratio TW / SW and the ratio SDH / SH that define the profile are optimized, so that the ground contact shape of the tire is optimized, and the deformation amount of the tread portion during rolling of the tire is small. Become. Thereby, there is an advantage that the sliding noise of the tread is suppressed and the noise performance of the tire is improved. Moreover, there exists an advantage by which the relationship (ratio L / Pk) of the circumferential direction distance L of a lug groove and a notch part, and the circumferential direction length Pk of a notch part is optimized.

FIG. 1 is a cross-sectional view in the tire meridian direction showing a retread tire according to an embodiment of the present invention. FIG. 2 is an explanatory view showing the operation of the retread tire described in FIG. 1. FIG. 3 is a plan view showing a tread surface of the retread tire described in FIG. 1. FIG. 4 is an enlarged view showing a main part of the retread tire described in FIG. 1. FIG. 5 is an enlarged view showing a main part of the retread tire described in FIG. 1. FIG. 6 is an enlarged view showing a main part of the retread tire described in FIG. 1. FIG. 7 is an explanatory view showing a modified example of the retread tire described in FIG. 1. FIG. 8 is a chart showing the results of the performance test of the retreaded tire according to the embodiment of the present invention. FIG. 9 is a chart showing the results of the performance test of the retreaded 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.

[Rehabilitated tire]
FIG. 1 is a cross-sectional view in the tire meridian direction showing a retread tire according to an embodiment of the present invention. The same figure has shown sectional drawing of the one-side area | region of a tire radial direction. Moreover, the figure has shown the retreaded tire for light trucks as an example.

  In the figure, the cross section in the tire meridian direction means a cross section when the tire is cut along a plane including a tire rotation axis (not shown). Reference sign CL denotes a tire equator plane, which is a plane that passes through the center point of the tire in the tire rotation axis direction and is perpendicular to the tire rotation axis. Moreover, the code | symbol T is a tread end. Further, the tire width direction means a direction parallel to the tire rotation axis, and the tire radial direction means a direction perpendicular to the tire rotation axis.

  The retread tire 10 is a tire that is reused by replacing the tread rubber of a tire whose remaining groove has reached the end of its life. For example, the retread tire 10 is used for a heavy load tire, a small truck tire, or the like.

  As shown in FIG. 1, the retread tire 10 includes a tread 20 and a base tire 30. The tread 20 is a rubber member that constitutes the tread portion, and is newly added when the retread tire 10 is manufactured. The base tire 30 is formed by cutting off part of the tread rubber and part of the sidewall rubber of the tire whose remaining grooves have reached the end of life, and buffing the outer peripheral surface thereof. The retread tire 10 is manufactured by a remolding method or a precure method, as will be described later.

  Further, the retread tire 10 includes a pair of bead cores 11 and 11, a pair of bead fillers 12 and 12, a carcass layer 13, and a plurality of belt plies 141 to 143 (in FIG. 1, a pair of bead cores 11 and 11). Belt layer 14 formed by laminating cross belts 141 and 142 and belt cover 143), tread rubber 15 constituting a tread portion, side wall rubbers 16 and 16 constituting left and right sidewall portions, and left and right bead portions. Rim cushion rubbers 17 and 17 are provided. Among these components, the tread rubber 15 includes a newly added tread 20 and a residual tread 301 of the base tire 30. Further, the sidewall rubber 16 and the rim cushion rubber 17 are included in the base tire 30.

[Rehabilitated tire by remolding method]
In the retread tire 10 manufactured by the remolding method, the tread 20 is unvulcanized rubber at the material stage, and constitutes the tread portion of the retread tire 10 at the product stage. Further, the tread 20 can be made of, for example, a strip-shaped unvulcanized rubber, a plate-shaped unvulcanized rubber, or the like.

  The remolded tire 10 by this remolding method is manufactured by the following process (not shown).

  First, the tread rubber of the tire whose remaining groove has reached the end of its life is cut out, and the outer peripheral surface thereof is buffed to obtain the base tire 30. This buffing process is performed in a state where an internal pressure is applied to the tire.

  Next, the tread 20 is disposed on the outer peripheral surface of the base tire 30. At this time, the tread 20 may be formed by (a) strip-shaped unvulcanized rubber being spirally wound around the outer peripheral surface of the base tire 30, or (b) a plate-shaped rubber member serving as a basis. The tread 20 may be formed by being wound around the outer peripheral surface of the base tire 30 and spirally winding a strip-like unvulcanized rubber around the outer periphery. In the case of the latter (b), the time required for the installation process of the tread 20 can be shortened compared to the case of the former (a).

  Next, a vulcanization process is performed. In this vulcanization step, the assembly of the tread 20 and the base tire 30 is filled into a tire vulcanization mold (not shown) having a tire molding die. Next, the assembly of the tread 20 and the base tire 30 is expanded radially outward by the pressurizing device, and the tread 20 is pressed against the tire molding die. Further, the assembly of the tread 20 and the base tire 30 is heated, so that the tread 20 is vulcanized and the shape of the tire molding die is transferred to the tread 20. Thereafter, the vulcanized tire is taken out from the tire vulcanization mold.

[Rehabilitated tire by precure method]
On the other hand, in the retreaded tire 10 manufactured by the precure method, the tread 20 is a tread rubber (precure tread) that has been vulcanized in the material stage, and constitutes a tread portion of the retreaded tire 10. Further, the tread 20 has a plate-like structure or an annular structure, and has a tread pattern when the retread tire 10 is new on its outer peripheral surface in advance.

  The retreaded tire 10 by this precure method is manufactured by the following processes (not shown).

  First, the tread rubber of the tire whose remaining groove has reached the end of its life is cut out, and the outer peripheral surface thereof is buffed to obtain the base tire 30. This buffing process is performed in a state where an internal pressure is applied to the tire.

  Next, cushion rubber (not shown) is affixed over the entire circumference of the outer peripheral surface of the base tire 30. The cushion rubber is a sheet-like unvulcanized rubber at the material stage. Thereafter, the tread 20 is disposed on the outer peripheral surface of the base tire 30 and bonded to the base tire 30 via cushion rubber.

  At this time, when the tread 20 has a plate-like structure, the tread 20 is wound around the base tire 30 and is fixed by temporarily fixing both ends by a fixing member (not shown). On the other hand, in the configuration in which the tread 20 has an annular structure, the tread 20 is expanded and contracted by a dedicated expansion / contraction diameter device (not shown) and is fitted to the outer periphery of the base tire 30.

  Next, a vulcanization process is performed. In this vulcanization process, the assembly of the tread 20 and the base tire 30 is housed in a vulcanization can (not shown), the air in the vulcanization can is sucked in vacuum, and then heated and pressurized. The cushion rubber is vulcanized. Thereafter, the vulcanized tire is taken out from the vulcanization can.

[Tire profile]
Conventionally, rehabilitation has been performed on heavy-duty tires mounted on trucks and buses, but in recent years, rehabilitation is also being performed on light truck tires.

  Further, since the retread tire uses a tire whose remaining groove has reached the end of its life as a stand tire, (1) the tire profile tends to be rounded as a whole, and the tread radius tends to be small. Then, the amount of deformation of the tread portion increases when the tire rolls, and slipping noise on the tread surface tends to occur. Also, (2) old rubber (residual tread) that has deteriorated and hardened is present in the lower layer of the new rubber, so that the tread rigidity is higher and the noise level is higher than that of a new tire. For this reason, in the retreaded tire, there is a specific problem that the noise performance of the tire is likely to deteriorate.

  Therefore, the retreaded tire 10 employs the following configuration in order to improve noise performance particularly in light truck tires.

  In this retread tire 10, in FIG. 1, the tread width TW and the total tire width SW have a relationship of 0.65 ≦ TW / SW ≦ 0.90. Further, the ratio TW / SW is preferably in the range of 0.70 ≦ TW / SW ≦ 0.80, and more preferably in the range of 0.73 ≦ TW / SW ≦ 0.78.

  The tread width TW is measured as a linear distance between both ends of a tread pattern portion of the tire when the tire is mounted on a specified rim to apply a specified internal pressure and is in a no-load state.

  The total tire width SW is measured as the linear distance between the sidewalls (including all parts such as the pattern on the tire side and characters) when the tire is mounted on the specified rim to provide the specified internal pressure and the load is not loaded. Is done.

  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.

  Further, in FIG. 1, the distance SDH in the tire radial direction from the measurement point P of the rim diameter to the tire maximum width position Q and the tire cross-section height SH have a relationship of 0.45 ≦ SDH / SH ≦ 0.65. Have. The ratio SDH / SH is preferably in the range of 0.50 ≦ SDH / SH ≦ 0.60, and more preferably in the range of 0.52 ≦ SDH / SH ≦ 0.58.

  The tire maximum width position Q refers to the maximum width position of the tire cross-sectional width specified by JATMA. Note that the tire cross-sectional width is measured as a no-load state while applying a specified internal pressure by mounting the tire on a specified rim.

  The tire cross-section height SH is a distance that is ½ of the difference between the tire outer diameter and the rim diameter. The tire cross-section height SH is measured as an unloaded condition while a tire is mounted on a prescribed rim and a prescribed internal pressure is applied.

  FIG. 2 is an explanatory view showing the operation of the retread tire described in FIG. 1. The figure shows the evaluation results of the test tires of the conventional example and Example A.

  The evaluation results in FIG. 2 were obtained as follows. First, the maximum principal strain [%] of the peripheral rubber at the end portions of the cross belts 141 and 142 is measured while a tire is mounted on a prescribed rim and a prescribed internal pressure is applied and no load is applied. In addition, the fluctuation range of the main strain is the main strain [%] of the peripheral rubber at the ends of the cross belts 141 and 142 when the tire is mounted on the specified rim and the specified internal pressure and the specified load are applied. Is measured at each position in the tire circumferential direction, and is calculated as the difference between the maximum value and the minimum value of these measured values. Then, based on the calculation result, index evaluation using the conventional example as a reference (100) is performed.

  In this retreaded tire 10, when the ratio TW / SW and the ratio SDH / SH are optimized, the profile from the tire equatorial plane CL to the shoulder portion becomes flat, and the ground contact shape of the tire approaches a rectangle. Then, the deformation amount of the tread portion at the time of rolling of the tire is reduced, slipping noise on the tread surface is suppressed, and the noise performance of the tire is improved.

[Tread pattern]
FIG. 3 is a plan view showing a tread surface of the retread tire described in FIG. 1. The figure shows a tread pattern of an all-season tire. In the figure, the tire circumferential direction refers to the direction around the tire rotation axis. Moreover, the code | symbol T is a tire grounding end.

  The retread tire 10 includes a plurality of circumferential main grooves 21 and 22 extending in the tire circumferential direction, and a plurality of land portions 31 and 32 partitioned by the circumferential main grooves 21 and 22 in a tread portion. (See FIG. 3).

  The circumferential main groove is a circumferential groove having a wear indicator indicating the end of wear, and generally has a groove width of 5.0 [mm] or more and a groove depth of 7.5 [mm] or more.

  The groove width is measured as the maximum value of the distance between the left and right groove walls at the groove opening in a no-load state in which the tire is mounted on the prescribed rim and filled with the prescribed internal pressure. In the configuration where the land part has a notch part or a chamfered part at the edge part, the groove width is based on the intersection of the tread surface and the extension line of the groove wall in a cross-sectional view in which the groove length direction is a normal direction. Measured. In the configuration in which the groove extends in a zigzag shape or a wave shape in the tire circumferential direction, the groove width is measured with reference to the center line of the amplitude of the groove wall.

  The groove depth is measured as the maximum value of the distance from the tread surface to the groove bottom in an unloaded state in which the tire is mounted on the specified rim and filled with the specified internal pressure. Moreover, in the structure which a groove | channel has a partial uneven | corrugated | grooved part and a sipe in a groove bottom, groove depth is measured except these.

  The circumferential main grooves 21 and 22 may have a straight shape, or may have a zigzag shape or a wavy shape. For example, in the configuration of FIG. 3, the circumferential main groove 21 on the tire equatorial plane CL has a zigzag shape formed by alternately connecting long portions and short portions having different inclination angles in the tire circumferential direction. Have. The left and right outermost circumferential main grooves 22, 22 have a straight shape.

  For example, in the configuration of FIG. 3, the three circumferential main grooves 21 and 22 are arranged symmetrically about the tire equatorial plane CL. Further, the circumferential main groove 21 is disposed on the tire equatorial plane CL. In addition, four rows of land portions 31 and 32 are partitioned by these circumferential main grooves 21 and 22.

  However, the present invention is not limited to this, and four or more circumferential main grooves may be arranged (not shown). Further, the circumferential main grooves 21 and 22 may be arranged asymmetrically about the tire equatorial plane CL (not shown). Further, the circumferential main groove 21 may be disposed at a position deviated from the tire equatorial plane CL (not shown). For this reason, the land portion 31 can be disposed on the tire equatorial plane CL.

  In the configuration of FIG. 3, the circumferential main groove 21 on the tire equatorial plane CL has a zigzag shape in which long portions and short portions having different inclination angles are alternately connected in the tire circumferential direction. Have. The left and right outermost circumferential main grooves 22, 22 have a straight shape.

  However, the present invention is not limited to this, and the circumferential main grooves 21 and 22 may have a straight shape, or may have a zigzag shape or a wavy shape that extends while being bent or curved in the tire circumferential direction ( (Not shown).

  In this embodiment, the left and right circumferential main grooves 22 and 22 on the outermost side in the tire width direction are referred to as outermost circumferential main grooves. Further, the tread portion center region and the tread portion shoulder region are defined with the left and right outermost circumferential main grooves 22 and 22 as boundaries.

  In addition, the land portion 31 on the inner side in the tire width direction defined by the outermost circumferential main groove is called a center land portion, and the land portion 32 on the outer side in the tire width direction is called a shoulder land portion.

[Shoulder land]
FIGS. 4-6 is an enlarged view which shows the principal part of the retreaded tire described in FIG. In these drawings, FIG. 4 shows an enlarged plan view of the shoulder land portion 32. FIG. 5 is a cross-sectional view in the tire meridian direction of one side region with the tire equatorial plane CL as a boundary. FIG. 6 shows an enlarged cross-sectional view of the circumferential main grooves 21 and 22.

  In this retreaded tire 10, as shown in FIGS. 3 and 4, the shoulder land portion 32 includes a plurality of lug grooves 321 and a plurality of notches 322.

  The plurality of lug grooves 321 extend in the tire width direction and are arranged at predetermined intervals in the tire circumferential direction.

  For example, in the configuration of FIG. 4, the lug groove 321 is formed at the outer edge portion of the shoulder land portion 32 in the tire width direction. Also, the lug groove 321 terminates in the ground contact surface of the shoulder land portion 32 at one end, extends in the tire width direction beyond the tire ground contact T, and becomes the tread end at the other end. It is open. The lug groove 321 has a linear shape and extends in the tire width direction while being inclined in the tire circumferential direction. A plurality of lug grooves 321 are arranged in the tire circumferential direction according to the pitch length P of the tread pattern. The lug groove 321 is not limited to the linear shape described above, and may have, for example, a bent shape, a zigzag shape, an arc shape, and the like (not shown).

  The plurality of notches 322 are formed at the edge portion of the shoulder land portion 32 on the outermost circumferential direction main groove 22 side, and are arranged at predetermined intervals in the tire circumferential direction.

  For example, in the configuration of FIG. 4, the cutout portion 322 has a trapezoidal shape with an opening width widened toward the outermost circumferential main groove 22 in a tread plan view. Moreover, the notch part 322 is arrange | positioned in the ratio of one to one pitch of a tread pattern. The notch 322 is not limited to the trapezoidal shape described above, and may have, for example, a triangular shape whose opening width is widened toward the outermost circumferential main groove 22 (not shown).

  At this time, the circumferential distance L (L1, L2 in FIG. 4) between the lug grooves 321 and 321 and the notch 322 is 0.20 ≦ L / Pk ≦ 0 with respect to the circumferential length Pk of the notch 322. .80 relationship. The ratio L / Pk preferably has a relationship of 0.30 ≦ L / Pk ≦ 0.50.

  The circumferential distance L (L1, L2) is the tire between the lug groove 321 and the notch 322 on the tread of the shoulder land portion 32 when the tire is mounted on the specified rim to apply the specified internal pressure and to be in an unloaded state. It is measured as a circumferential distance. Specifically, on the tread surface of the shoulder land portion 32, the circumferential distance L (L1, L2) is measured using the end portions in the tire circumferential direction of the lug groove 321 and the notch portion 322 as measurement points.

  The tread surface of the shoulder land portion 32 refers to a region from the edge portion on the inner side in the tire width direction of the shoulder land portion 32 to the tire ground contact end T.

  The tire ground contact edge T is the contact between the tire and the flat plate when a load corresponding to the predetermined load is applied by attaching the tire to the specified rim and applying the specified internal pressure and placing the tire perpendicularly to the flat plate in a stationary state. The maximum width position in the tire axial direction on the surface.

  The circumferential length Pk of the notch 322 is the extension of the notch 322 in the tire circumferential direction on the tread surface of the shoulder land portion 32 when the tire is mounted on the prescribed rim to apply the prescribed internal pressure and is in an unloaded state. Measured as length. In FIG. 4, the circumferential length of the notch 322 is maximum at the opening with respect to the outermost circumferential main groove 22, and the circumferential length Pk is measured at this position.

  For example, in the configuration of FIG. 4, the lug grooves 321 and the notch portions 322 are arranged with their positions shifted (shifted in phase or offset) in the tire circumferential direction. For this reason, the lug grooves 321 and the notches 322 are alternately arranged on the left and right edge portions of the shoulder land portion 32 in the tire circumferential direction. Moreover, the lug groove 321 and the notch part 322 are arrange | positioned so that it may not mutually wrap in the projection view to a tire width direction. Further, the circumferential distances L1 and L2 between one notch 322 and a pair of adjacent lug grooves 321 and 321 are 0.20 ≦ L1 / Pk ≦ 0. 80 and 0.20 ≦ L2 / Pk ≦ 0.80.

  In the above configuration, the lug groove 321 and the notch portion 322 are arranged with their positions shifted in the tire circumferential direction, so that the lug groove 321 and the notch portion 322 contact each other at different timings during tire rolling. Enter the ground. In addition, the relationship (ratio L / Pk) between the circumferential distance L between the lug groove 321 and the notch 322 and the circumferential length Pk of the notch 322 is optimized. Then, the fluctuation range of the ground reaction force at the time of tire rolling is narrowed, and the noise level due to pattern noise is reduced. Thereby, the noise performance of a tire improves.

  In FIG. 4, it is preferable that the circumferential length Pk of the notch 322 and the pitch length P of the tread pattern have a relationship of 0.10 ≦ Pk / P ≦ 0.50, and 0.35 ≦ Pk It is more preferable to have a relationship of /P≦0.45. As a result, the lug groove 321 and the notch 322 can be arranged without difficulty so as not to wrap each other in a projection view in the tire width direction.

  Further, in FIG. 4, the opening width Pr in the tire circumferential direction of the lug groove 321 on the tire contact surface and the circumferential length Pk of the notch 322 have a relationship of 0.25 ≦ Pr / Pk ≦ 0.75. It is preferable to have a relationship of 0.40 ≦ Pr / Pk ≦ 0.60. Thereby, the relationship between the opening width Pr of the lug groove 321 in the tire circumferential direction and the circumferential length Pk of the notch 322 is optimized.

  The opening width Pr in the tire circumferential direction of the lug groove 321 is the opening width in the tire circumferential direction of the lug groove 321 on the tire contact surface when the tire is mounted on the specified rim to apply the specified internal pressure and is in an unloaded state. Measured as the maximum value.

  The circumferential length Pr ′ of the lug groove 321 and the pitch length P of the tread pattern preferably have a relationship of 0.10 ≦ Pr ′ / P ≦ 0.60, and 0.20 ≦ Pr ′ / It is more preferable to have a relationship of P ≦ 0.35. As a result, the circumferential length Pr ′ of the lug groove 321 is optimized.

  The circumferential length Pr ′ of the lug groove 321 is the extension length of the lug groove 321 in the tire circumferential direction in the entire tread when the tire is mounted on the prescribed rim to apply the prescribed internal pressure and is in an unloaded state. As measured.

  In FIG. 4, the width Wk of the notch 322 and the ground contact width Ws of the shoulder land portion 32 preferably have a relationship of 0.05 ≦ Wk / Ws ≦ 0.20, and 0.07 ≦ Wk / It is more preferable to have a relationship of Ws ≦ 0.15. Thereby, the width Wk of the notch 322 is optimized.

  The width Wk of the notch portion 322 is measured as the maximum value of the opening width in the tire width direction of the notch portion 322 on the tire contact surface when the tire is mounted on the prescribed rim to apply the prescribed internal pressure and is in an unloaded state. The The width Wk of the notch 322 is measured with reference to the edge portion of the shoulder land portion 32 on the outermost circumferential direction main groove 22 side.

  The ground contact width Ws of the shoulder land portion 32 is such that when the tire is mounted on a specified rim to apply a specified internal pressure, the tire and the flat plate are placed perpendicular to the flat plate in a stationary state and a load corresponding to the specified load is applied. Is measured as the maximum linear distance in the tire axial direction on the contact surface.

  In the configuration of FIG. 4, the extension length Wr of the lug groove 321 in the tire width direction on the tire contact surface and the contact width Ws of the shoulder land portion 32 satisfy 0.03 ≦ Wr / Ws ≦ 0.10. It is set to have a relationship. Thereby, the drainage performance of the lug groove 321 is ensured, and the rigidity of the shoulder land portion 32 is ensured.

  In FIG. 6, it is preferable that the depth Dk of the notch 322 and the groove depth D2 of the outermost circumferential main groove 22 have a relationship of 0.80 ≦ Dk / D2 ≦ 1.00. Thereby, the notch 322 is formed deeper and remains until the end of wear.

[Center land]
As shown in FIGS. 3 and 4, the land portion 31 on the inner side in the tire width direction adjacent to the outermost circumferential main groove 22 includes one circumferential narrow groove 311 and a plurality of lug grooves 312. In the configuration of FIG. 3, the retread tire 10 has a point-symmetric tread pattern, so that the left and right outermost circumferential main grooves 22 and 22 each have one circumferential narrow groove 311 and a plurality of lug grooves 312. .

  The circumferential narrow groove 311 is a narrow groove extending continuously over the entire circumference of the tire.

  For example, in the configuration of FIG. 4, the circumferential narrow groove 311 has a zigzag shape formed by alternately connecting long portions and short portions having different inclination angles in the tire circumferential direction. Moreover, the circumferential direction narrow groove 311 is arrange | positioned in the center part of the land part 31, and has divided the land part 31 in the tire width direction. Further, the groove width of the circumferential narrow groove 311 is set in a range of 1.5 [mm] to 4.3 [mm]. Further, the groove depth of the circumferential narrow groove 311 is set in a range of 10% to 40% with respect to the groove depth of the outermost circumferential main groove 22. That is, the circumferential narrow groove 311 is a shallow groove. Thereby, the rigidity of the land portion 31 is ensured, and the steering stability performance of the tire is ensured.

  The plurality of lug grooves 312 are lateral grooves that extend in the tire width direction and communicate with the outermost circumferential main groove 22. That is, the lug groove 312 is disposed in the region between the circumferential narrow groove 311 and the outermost circumferential main groove 22 of the land portion 31 as shown in FIG. 3 and FIG. Opening in the outer circumferential main groove 22.

  For example, in the configuration of FIG. 3, the land portions 31, 31 on the inner side in the tire width direction adjacent to the left and right outermost circumferential main grooves 22, 22 each include a plurality of lug grooves 312. A plurality of lug grooves 312 are arranged at predetermined intervals in the tire circumferential direction. Further, the lug groove 312 extends while inclining at a predetermined angle in the tire width direction, and connects the circumferential narrow groove 311 and the outermost circumferential main groove 22. In addition, the lug groove 312 widens the groove width at both the connecting portion with the circumferential narrow groove 311 and the connecting portion with the outermost circumferential main groove 22. The groove width of the lug groove 312 is set in a range of 1.0 [mm] to 4.0 [mm]. Further, the groove depth of the lug groove 312 is set in the range of 10% to 40% with respect to the groove depth of the outermost circumferential main groove 22. That is, the lug groove 312 is a shallow groove. Thereby, the rigidity of the land portion 31 is ensured, and the steering stability performance of the tire is ensured.

  Moreover, short and a plurality of sipes (so-called multi-sipe, not shown) are arranged at predetermined intervals in the tire circumferential direction at the edge portions of the land portions 31 and 32 facing the circumferential main grooves 21 and 22. .

  In the configuration of FIG. 4, the opening position of the lug groove 312 of the center land portion 31 with respect to the outermost circumferential main groove 22 and the opening position of the notch portion 322 of the shoulder land portion 32 are mutually positioned in the tire circumferential direction. They are shifted (shifted in phase or offset). Further, in one outermost circumferential main groove 22, a plurality of sets of notch portions 322 and lug grooves 312 of the center land portion 31 are alternately arranged on the left and right sides in the tire circumferential direction. Thereby, the notch part 322 and the opening part of the lug groove 312 are disperse | distributed and arrange | positioned in the tire circumferential direction.

[Carcass layer and belt layer]
Moreover, the retread tire 10 is provided with the carcass layer 13 and the belt layer 14 arrange | positioned on the tire radial direction outer side of the carcass layer 13 as mentioned above (refer FIG. 1).

  For example, in the retread tire 10 for a light truck shown in FIG. 1, the carcass layer 13 and the belt layer 14 are included in the base tire 30. Further, the carcass layer 13 is bridged in a toroidal shape between the pair of left and right bead cores 11 and 11 to constitute a tire skeleton. Further, both end portions of the carcass layer 13 are wound and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12. The carcass layer 13 is formed by rolling a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coat rubber, and has an absolute value of 80 [deg]. A carcass angle of 95 [deg] or less (inclination angle in the fiber direction of the carcass cord with respect to the tire circumferential direction) is obtained.

  The belt layer 14 is formed by laminating a pair of cross belts 141 and 142 and a belt cover 143, and is arranged so as to be wound around the outer periphery of the carcass layer 13.

  The pair of cross belts 141 and 142 is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and is an absolute value of 10 [deg] or more and 55 [deg] or less. Have an angle. Further, the pair of cross belts 141 and 142 have belt angles of different signs (inclination angles in the fiber direction of the belt cord with respect to the tire circumferential direction) and are laminated so that the fiber directions of the belt cords cross each other. Yes (cross-ply structure). Note that three or more cross belts may be laminated (not shown).

  The belt cover 143 is formed by rolling a plurality of cords made of steel or organic fiber material covered with a coat rubber. The belt cover 143 preferably has an absolute value of a belt angle of 0 [deg] or more and 10 [deg] or less, and more preferably a belt angle of 0 [deg] or more and 5 [deg] or less. A belt cover 143 is disposed so as to be laminated on the outer side in the tire radial direction of the cross belts 141 and 142.

  1, the belt width Wb1 of the wide cross belt 141 and the carcass cross-sectional width Wa of the carcass layer 13 preferably have a relationship of 0.65 ≦ Wb1 / Wa ≦ 0.90. .68 ≦ Wb1 / Wa ≦ 0.80 is more preferable. Thereby, the ratio Wb1 / Wa is optimized.

  The carcass cross-sectional width Wa is a distance in the tire width direction at the left and right maximum width positions of the carcass layer 13, and is measured as a no-load state while attaching a tire to a specified rim and applying a specified internal pressure.

  Moreover, it is preferable that the belt width Wb1 of the wide cross belt 141 and the tread width TW have a range of 0.70 ≦ Wb1 / TW ≦ 1.00.

  Further, the belt width Wb2 of the narrow cross belt 142 and the tread width TW preferably have a range of 0.70 ≦ Wb2 / TW ≦ 0.95, and 0.80 ≦ Wb2 / TW ≦ 0.90. It is more preferable to have this range.

  The belt widths Wb1 and Wb2 are distances in the tire width direction of the belt cords on the outermost side in the tire width direction in a cross sectional view in the tire meridian direction. As measured.

[Belt cover]
Moreover, in this retreaded tire 10, in FIG. 1, the distance Wc between the left and right end portions on the outer side in the tire width direction of the belt cover 143 and the tread width TW satisfy 0.75 ≦ Wc / TW ≦ 1.00. It is preferable to have a relationship, and it is more preferable to have a relationship of 0.80 ≦ Wc / TW ≦ 0.90. Thereby, the ground contact shape of a tire is optimized and the wet performance of a tire is ensured.

  The distance Wc is the distance in the tire width direction of the outermost belt cord in the tire width direction in a cross-sectional view in the tire meridian direction, and is measured as an unloaded condition while attaching the tire to a specified rim and applying a specified internal pressure. The Further, in a configuration (not shown) in which the belt cover 143 is divided in the tire width direction, the distance Wc is measured with reference to the left and right end portions of the belt cover that is the outermost in the tire width direction.

  The number of ends of the belt cover 143 is preferably in the range of 40 [lines / 50 mm] to 60 [lines / 50 mm]. Moreover, it is preferable that the thickness of the thread | yarn which comprises the belt cover 143 exists in the range of 1100 [dtex / 2] or more and 1500 [dtex / 2] or less. As a result, the structure of the belt cover 143 is optimized.

  For example, in the configuration of FIG. 1, the single-layer belt cover 143 has a so-called full cover structure, and extends continuously in the tire width direction so as to cover the entire area of the belt layer 14. Further, the belt cover 143 extends to the end of the wide cross belt 141, thereby covering the ends of the pair of cross belts 141 and 142 at the same time. Further, as shown in FIG. 5, an additional belt cover 144 is laminated on the outer side in the tire radial direction of the belt cover 143. The additional belt cover 144 is partially disposed at a position covering the left and right ends of the pair of cross belts 141 and 142 and functions as a so-called edge cover. For this reason, a plurality of belt covers 143 and 144 are disposed at the left and right ends of the cross belts 141 and 142, respectively, and the number of stacked belt covers is greater than the position where the belt equatorial plane CL intersects. . Thereby, the restraining force with respect to the edge part of the cross belts 141 and 142 is heightened.

  However, the present invention is not limited to this, and a plurality of belt covers 143 having a full cover structure may be laminated so as to cover the entire belt layer 14 (not shown). Therefore, the belt cover 143 may have a multilayer structure. Further, a belt ply may be further arranged outside the belt cover 143 in the tire radial direction (not shown). Therefore, the belt cover 143 may not be disposed on the outermost layer of the belt layer 14.

[Tread rubber gauge]
In FIG. 5, the relationship between the tread gauge Dcc on the tire equatorial plane CL and the tread gauge De at the outer end in the tire width direction of the narrow cross belt 142 is 1.03 ≦ Dcc / De ≦ 1.20. It is preferable to have 1.05 ≦ Dcc / De ≦ 1.10. Thereby, the ratio Dcc / De is optimized.

  The tread gauge Dcc is a belt of a belt ply (the belt cover 143 in FIG. 5) that is the intersection of the tire equatorial plane CL and the tread profile and the outermost radial direction of the belt layer 14 in a cross-sectional view in the tire meridian direction. Measured as the distance to the code surface. The belt cord surface is defined as a surface including ends of the plurality of belt cords constituting the belt ply on the outer side in the tire radial direction.

  The tread gauge De is measured as the thickness of the tread rubber on the perpendicular drawn from the end of the narrow cross belt 142 to the tread surface in a cross-sectional view in the tire meridian direction. The end portion of the cross belt 142 refers to the end surface of the belt cord that is the outermost in the tire width direction among the belt cords constituting the cross belt 142.

  In FIG. 5, the tread gauge Dcc on the tire equatorial plane CL and the tread gauge Dsh from the outer end in the tire width direction of the belt cover 143 to the tread end T are 1.00 ≦ Dsh / Dcc ≦ 1.70. It is preferable to have a relationship of 1.20 ≦ Dsh / Dcc ≦ 1.40, and more preferable. Thereby, Dsh / Dcc is optimized.

  The tread gauge Dsh is measured on the basis of the end surface of the belt cord that is the outermost in the tire width direction among the belt cords constituting the belt cover 143 in a sectional view in the tire meridian direction.

  Moreover, in FIG. 6, it is preferable that the new rubber sub-groove gauge Ga1 of the circumferential main groove 21 closest to the tire equatorial plane CL is in the range of 1.0 [mm] ≦ Ga1 ≦ 5.0 [mm] More preferably, the range is 2.0 [mm] ≦ Ga1 ≦ 3.0 [mm]. Thereby, the new under-groove groove gauge Ga1 of the circumferential main groove 21 in the center region of the tread portion is optimized.

  In FIG. 6, the new rubber sub-groove gauge Ga2 of the outermost circumferential main groove 22 has a relationship of Ga2 <Ga1 with respect to the new rubber sub-groove gauge Ga1 of the circumferential main groove 21 closest to the tire equatorial plane CL. It is preferable to have. Therefore, the new under-groove groove gauge Ga2 of the circumferential main groove 22 in the tread portion shoulder region is smaller than the new under-groove gauge Ga1 of the circumferential main groove 21 in the tread portion center region.

  Further, the new sub-groove gauge Ga2 is preferably in the range of 1.0 [mm] ≦ Ga2 ≦ 4.0 [mm], and in the range of 1.3 [mm] ≦ Ga2 ≦ 3.0 [mm]. More preferably. Thereby, the new under-groove groove gauge Ga2 of the circumferential main groove 22 in the tread shoulder region is optimized.

  The new rubber sub-groove gauges Ga1 and Ga2 are sub-groove gauges in the tread 20 newly added by rehabilitation, and are treads from the maximum groove depth position of the circumferential main grooves 21 and 22 in the sectional view in the tire meridian direction. It is measured as the distance to the inner circumferential surface of 20 tire radial directions.

  In FIG. 6, the groove depth D1 of the circumferential main groove 21 closest to the tire equatorial plane CL and the tread gauge Dcc on the tire equatorial plane CL have a relationship of 1.30 ≦ Dcc / D1 ≦ 1.55. Preferably, it has a relationship of 1.40 ≦ Dcc / D1 ≦ 1.50. Thereby, the ratio Dcc / D1 is optimized.

[Modification]
FIG. 7 is an explanatory view showing a modified example of the retread tire described in FIG. 1. The figure shows an enlarged cross-sectional view of the tread shoulder region.

  In the configuration of FIG. 1, as shown in FIG. 5, the retread tire 10 includes a shoulder portion having a square shape in a sectional view in the tire meridian direction. In such a configuration, the measurement point of the tread width TW is the edge portion on the outer side in the tire width direction of the shoulder land portion 32. In FIG. 5, the tire ground contact edge T and the tread edge coincide with each other, and the tire ground contact edge T is a measurement point of the tread width TW.

  However, the present invention is not limited thereto, and the retreaded tire 10 may include a shoulder portion having a round shape (see FIG. 7) or a chamfered shape (not shown) in a sectional view in the tire meridian direction.

  In such a configuration, the measurement point of the tread width TW is defined by the intersection T ′ between the extension line of the ground contact surface of the shoulder land portion 32 and the extension line of the profile of the sidewall portion in a cross-sectional view in the tire meridian direction.

  Further, the tread gauge Dsh is a straight line drawn from the intersection T ′ to the end surface of the belt cord that is the outermost in the tire width direction among the belt cords that constitute the belt cover 143 in a sectional view in the tire meridian direction. Measured as the thickness of the tread rubber.

[effect]
As described above, the retread tire 10 includes the tread 20 and the base tire 30 (see FIG. 1). Further, the tread 20 includes at least three circumferential main grooves 21 and 22 extending in the tire circumferential direction and a plurality of land portions 31 and 32 that are partitioned by the circumferential main grooves 21 and 22. Prepare for the surface (see FIG. 3). Further, the base tire 30 includes a carcass layer 13 and a pair of cross belts 141 and 142 disposed on the outer side in the tire radial direction of the carcass layer 13. Further, the tread width TW and the total tire width SW have a relationship of 0.65 ≦ TW / SW ≦ 0.90 (see FIG. 1). Further, the distance SDH in the tire radial direction from the rim diameter measurement point P to the tire maximum width position Q and the tire cross-section height SH have a relationship of 0.45 ≦ SDH / SH ≦ 0.65. Further, the shoulder land portion 32 includes a plurality of lug grooves 321 extending in the tire width direction and a plurality of cutout portions 322 formed at the edge portion on the outermost circumferential main groove 22 side (see FIG. 4). Further, the circumferential distance L between the lug groove 321 and the notch 322 (distances L1 and L2 in FIG. 4) is 0.20 ≦ L / Pk ≦ 0.80 with respect to the circumferential length Pk of the notch 322. Have the relationship.

  In such a configuration, the ratio TW / SW and the ratio SDH / SH that define the profile are optimized, so that the ground contact shape of the tire is optimized and the deformation amount of the tread portion during tire rolling is reduced. Thereby, there is an advantage that the sliding noise of the tread is suppressed and the noise performance of the tire is improved.

  Further, an advantage that the relationship (ratio L / Pk) between the circumferential distance L (L1 and L2 in FIG. 4) between the lug groove 321 and the notch 322 and the circumferential length Pk of the notch 322 is optimized. There is. That is, by satisfying 0.20 ≦ L / Pk, the circumferential distance L is appropriately secured, the fluctuation range of the ground reaction force during tire rolling is narrowed, and the noise level due to pattern noise is reduced. . Further, by satisfying L / Pk ≦ 0.80, the function of the notch 322 is ensured, and slipping sound due to compression of the tread rubber 15 at the time of tire contact is suppressed. Thereby, there exists an advantage which the noise performance of a tire improves.

  In particular, the retread tire 10 is generally recommended to be mounted on the rear wheel of the vehicle in order to ensure safety. In such a use mode, the uneven wear in the center region of the tread portion is likely to proceed during the unloading travel, so that the shoulder land portion 32 remains until the end of wear. Therefore, there is an advantage that the noise performance of the tire is maintained until the end of wear by optimizing the ratio L / Pk and reducing the pattern noise of the shoulder land portion 32.

  In this retread tire 10, the circumferential length Pk of the notch 322 and the pitch length P of the tread pattern have a relationship of 0.10 ≦ Pk / P ≦ 0.50 (see FIG. 4). Thereby, there exists an advantage by which the circumferential direction length Pk of the notch part 322 is optimized. That is, by satisfying 0.10 ≦ Pk / P, the function of the notch 322 is ensured, and slipping noise caused by compression of the tread rubber 15 at the time of tire contact is suppressed. When Pk / P ≦ 0.50, a situation in which the groove volume of the circumferential main groove 22 becomes excessive is prevented, and an increase in noise level is suppressed.

  Further, in this retreaded tire 10, the relationship between the opening width Pr in the tire circumferential direction of the lug groove 321 on the tire contact surface and the circumferential length Pk of the notch 322 is 0.25 ≦ Pr / Pk ≦ 0.75. (See FIG. 4). Thereby, the opening width Pr of the lug groove 321 and the circumferential length Pk of the notch 322 are made uniform, and there is an advantage that fluctuation of the ground reaction force at the time of tire grounding is effectively suppressed.

  In this retread tire 10, the circumferential length Pr ′ of the lug groove 321 and the pitch length P of the tread pattern have a relationship of 0.10 ≦ Pr ′ / P ≦ 0.60 (see FIG. 4). . Thereby, there exists an advantage by which the circumferential direction length Pr 'of the lug groove 321 is optimized. That is, by satisfying 0.10 ≦ Pr ′ / P, the circumferential length Pr ′ of the lug groove 321 is ensured, the rigidity of the shoulder land portion 32 is reduced, and slipping sound and hitting sound at the time of tire contact are generated. There are advantages to be reduced. In addition, since Pr ′ / P ≦ 0.60, a phase difference between the notch 322 and the lug groove 321 after the progress of wear is ensured, and the fluctuation of the ground reaction force at the time of tire contact is effectively suppressed. The

  In the retreaded tire 10, the center land portion 31 includes a plurality of lug grooves 312 that open to the outermost circumferential main groove 22. Further, the opening position of the lug groove 312 of the center land portion 31 with respect to the outermost circumferential main groove 22 and the opening position of the notch portion 322 of the shoulder land portion 32 are arranged so as to be shifted from each other in the tire circumferential direction ( (See FIG. 4). In such a configuration, fluctuations in the ground reaction force in the center region of the tread portion under initial wear and low load conditions are suppressed. Thereby, the noise level at the time of tire contact is suppressed, and there is an advantage that the noise performance of the tire is improved.

  Further, in this retread tire 10, the depth Dk of the notch 322 and the groove depth D2 of the outermost circumferential main groove 22 have a relationship of 0.80 ≦ Dk / D2 ≦ 1.00 (see FIG. 6). ). In such a configuration, the notch 322 remains until the end of wear by setting the depth Dk of the notch 322 to be deeper (0.80 ≦ Dk / D2). Thereby, there exists an advantage which can reduce the sliding noise resulting from compression of the tread 20 at the time of tire contact in the last stage of wear with high tread rigidity.

  Moreover, in this retread tire 10, the width Wk of the notch part 322 and the ground contact width Ws of the shoulder land part 32 have the relationship of 0.05 <= Wk / Ws <= 0.20 (refer FIG. 4). Thereby, there exists an advantage by which the width Wk of the notch part 322 is optimized. That is, by satisfying 0.05 ≦ Wk / Ws, the width Wk of the notch portion 322 is ensured, and slipping sound due to compression of the tread rubber 15 at the time of tire contact is suppressed. Moreover, by being Wk / Ws <= 0.20, the rigidity reduction of the land part 32 by the notch part 322 becoming excessive is suppressed, and the partial wear of the land part 32 is suppressed.

  Further, the retread tire 10 has a plurality of circumferential main grooves 21 and 22 extending in the tire circumferential direction and a plurality of land portions 31 and 32 defined by the circumferential main grooves 21 and 22 on the tread surface. Prepare. In addition, the new sub-groove gauge Ga1 of the circumferential main groove 21 closest to the tire equatorial plane CL is in the range of 1.0 [mm] ≦ Ga1 ≦ 5.0 [mm] (see FIG. 6). In such a configuration, there is an advantage that the new under-groove gauge Ga1 of the circumferential main groove 21 in the center region of the tread portion is optimized. That is, by satisfying 1.0 [mm] ≦ Ga1, the new rubber sub-groove gauge Ga1 of the circumferential main groove 21 is secured. Then, since the new rubber of the tread 20 is softer than the old rubber (residual tread 301) of the base tire 30 (the residual tread 301 is deteriorated and hardened), the force acting on the interface between the new rubber and the old rubber is increased. Dispersed to optimize the ground pressure distribution. Thereby, the slip noise resulting from compression of the tread rubber 15 at the time of tire contact is suppressed. Further, since Ga1 ≦ 5.0 [mm], it is possible to prevent the land portion rigidity from being excessive, and to reduce slipping sound and hitting sound at the time of tire contact.

  Further, in this retreaded tire 10, the new rubber sub-groove gauge Ga2 of the circumferential main groove 22 at the outermost side in the tire width direction satisfies Ga2 <Ga1 and 1.0 [mm] ≦ Ga2 ≦ 4.0 [mm]. It is in range (see FIG. 6). In such a configuration, there is an advantage that the new under-groove gauge Ga2 of the circumferential main groove 22 in the tread shoulder region is optimized. That is, by Ga2 <Ga1, the distortion of the peripheral rubber at the end of the belt layer 14 is reduced, and the ground pressure distribution is optimized. Thereby, the slip noise resulting from compression of the tread rubber 15 at the time of tire contact is suppressed. Further, by satisfying 1.0 [mm] ≦ Ga2, the new rubber groove gauge Ga2 of the circumferential main groove 22 is secured. Then, since the new rubber of the tread 20 is softer than the old rubber (residual tread 301) of the base tire 30 (the residual tread 301 is deteriorated and hardened), the force acting on the interface between the new rubber and the old rubber is increased. Dispersed to optimize the ground pressure distribution. Thereby, the slip noise resulting from compression of the tread rubber 15 at the time of tire contact is suppressed. Further, since Ga2 ≦ 4.0 [mm], the new rubber groove gauge Ga2 of the circumferential main groove 22 is prevented from being excessive, and the land portion rigidity is prevented from being excessive. Sliding noise and hitting sound at the time of tire contact are reduced.

  Moreover, in this retreaded tire 10, the carcass layer 13 is configured by arranging a plurality of carcass cords made of an organic fiber material. In the retreaded tire 10, the tire life is generally extended by the retreading and the traveling distance is increased. For this reason, in the configuration in which the carcass layer is made of an organic fiber material, the strength of the carcass layer is lowered, and the distortion of the peripheral rubber at the end of the cross belt is increased. Then, the contact pressure distribution in the tire width direction becomes non-uniform, and the slipping sound of the tread surface at the time of tire contact tends to increase. Therefore, there is an advantage that the effect of improving the noise performance of the tire can be remarkably obtained by applying the configuration including the carcass layer 13 made of such an organic fiber material.

  Further, in this retreaded tire 10, the tread gauge Dcc on the tire equatorial plane CL and the tread gauge De at the outer end in the tire width direction of the narrow cross belt 142 are 1.03 ≦ Dcc / De ≦ 1.20. (See FIG. 5). Thereby, there exists an advantage by which ratio Dcc / De is optimized. That is, by satisfying 1.03 ≦ Dcc / De, the tread gauge Dcc in the tread portion center region is set larger than the tread gauge De in the shoulder region. Then, since the belt ply is arranged horizontally with respect to the tire ground contact surface, the tension acting on the belt ply is uniformized when the tire is grounded, and the ground pressure distribution is optimized. In addition, since Dcc / De ≦ 1.20 prevents the tread gauge Dcc in the center region from becoming excessive, the amount of displacement of the end portions of the cross belts 141 and 142 when the tire contacts the ground is reduced. The ground pressure distribution is optimized. Thereby, there exists an advantage which the noise performance of a tire improves effectively.

  Further, in this retreaded tire 10, the belt width Wb1 of the wide cross belt 141 and the carcass cross-sectional width Wa of the carcass layer 13 have a relationship of 0.65 ≦ Wb1 / Wa ≦ 0.90 (see FIG. 1). . Thereby, there exists an advantage by which ratio Wb1 / Wa is optimized. That is, by satisfying 0.65 ≦ Wb1 / Wa, the belt width Wb1 is secured, and the distortion of the peripheral rubber at the outer end in the tire width direction of the belt layer 14 is reduced. Thereby, there is an advantage that the ground pressure distribution is optimized and the noise performance of the tire is improved. Further, since Wb1 / Wa ≦ 0.90 ensures the distance between the end portion of the belt ply and the sidewall portion, movement of the end portion of the belt ply during tire rolling is suppressed. Thereby, there is an advantage that the ground pressure distribution is optimized and the noise performance of the tire is improved.

[Applicable to]
Further, the retread tire 10 is applied to a low flat tire having a flat rate of 70% or less, and particularly to a light truck tire defined by JATMA. In such a low-profile tire for a small truck, the ground contact state of the tread portion is likely to change between when the load is loaded and when the load is not loaded. That is, the center area and the shoulder area of the tread portion are uniformly grounded when the load is loaded, but the diameter growth of the tread center area becomes obvious and the contact area of the tread shoulder area tends to decrease when no load is loaded. It is in. Then, the repeated strain at the end of the belt layer becomes large, the contact pressure distribution becomes uneven, and the noise level tends to increase. Therefore, there is an advantage that the effect of improving the noise performance of the tire can be remarkably obtained by using such a low flat tire for a small truck.

  8 and 9 are charts showing the results of performance tests of the retread tire according to the embodiment of the present invention.

  In this performance test, evaluation regarding noise performance was performed for a plurality of types of test tires. A test tire having a tire size of 205 / 70R16 111/109 LT is assembled to a rim having a rim size of 16 × 6.0, and an air pressure of 600 [kPa] and a load of 9.0 [kN] are applied to the test tire. .

In the evaluation of noise performance, a test vehicle travels on an ISO (International Organization for Standardization) test road at a speed of 80 [km / h], and the sound pressure level of the passing noise is measured. And evaluation is performed by using a conventional pneumatic tire (conventional example) as a reference (0). In the evaluation, the larger the numerical value, the lower the sound pressure level, which is preferable.

  The test tires of Examples 1 to 17 have the structures described in FIGS. The tire total width SW is SW = 204 [mm], and the tire cross-section height SH is SH = 143.7 [mm]. Further, the groove width Wr (FIG. 4) of the outermost circumferential main groove 22 is 13.0 [mm], and the groove depth D2 (FIG. 6) is 10.0 [mm]. The pitch length P of the tread pattern is in the range of 30.0 [mm] ≦ P ≦ 50.0 [mm]. Further, the tread gauge Dcc on the tire equatorial plane CL is Dcc = 13.7 [mm]. Further, the belt width Wb1 of the wide cross belt 141 is Wb1 = 150 [mm].

  The test tire of the conventional example does not include the notch 322 in the configuration of the first embodiment. The lug groove 321 is a sipe having a groove width of 1 [mm] or less. The test tire of the comparative example has the same structure as that of Example 1.

  As shown in the test results, it can be seen that in the test tires of Examples 1 to 17, the noise performance of the tire is improved.

  10: retread tire, 11: bead core, 12: bead filler, 13: carcass layer, 14: belt layer, 141, 142: cross belt, 143, 144: belt cover, 15: tread rubber, 16: sidewall rubber, 17 Rim cushion rubber, 20: tread, 21, 22: circumferential main groove, 30: tire, 301: residual tread, 31: center land, 311: circumferential narrow groove, 312: lug groove, 32: shoulder land Part, 321: lug groove, 322: notch

Claims (13)

It has a tread and a base tire,
The tread includes, on the tread surface, at least three circumferential main grooves extending in the tire circumferential direction and a plurality of land portions defined by the circumferential main grooves, and
The said base tire is a retread tire provided with a carcass layer and a pair of cross belts arranged on the tire radial direction outside of the carcass layer,
When the outer circumferential direction main groove on the outermost side in the tire width direction is referred to as an outermost circumferential direction main groove, and the land portion on the outer side in the tire width direction defined by the outermost circumferential direction main groove is referred to as a shoulder land portion,
The tread width TW and the tire total width SW have a relationship of 0.65 ≦ TW / SW ≦ 0.90,
The distance SDH in the tire radial direction from the measurement point of the rim diameter to the tire maximum width position and the tire cross-section height SH have a relationship of 0.45 ≦ SDH / SH ≦ 0.65,
The shoulder land portion includes a plurality of lug grooves extending in the tire width direction, and a plurality of notches formed in an edge portion on the outermost circumferential direction main groove side; and
A retread tire characterized in that a circumferential distance L between the lug groove and the notch has a relationship of 0.20 ≦ L / Pk ≦ 0.80 with respect to a circumferential length Pk of the notch. The retreaded tire according to claim 1, wherein a circumferential length Pk of the notch and a pitch length P of the plurality of lug grooves have a relationship of 0.10 ≦ Pk / P ≦ 0.50.   The tire circumferential direction opening width Pr of the lug groove on the tire contact surface and the circumferential length Pk of the notch have a relationship of 0.25 ≦ Pr / Pk ≦ 0.75. The rehabilitated tire described. The circumferential length Pr ′ of the lug grooves and the pitch length P of the plurality of lug grooves have a relationship of 0.10 ≦ Pr ′ / P ≦ 0.60. Rehabilitation tire as described in. When calling the land portion on the inner side in the tire width direction defined in the outermost circumferential direction main groove as the center land portion,
The center land portion includes a plurality of lug grooves that open to the outermost circumferential main groove, and
The opening position of the lug groove of the center land portion with respect to the outermost circumferential main groove and the opening position of the notch portion of the shoulder land portion are arranged so as to be shifted from each other in the tire circumferential direction. The retreaded tire as described in any one of -4.   The depth Dk of the notch and the groove depth D2 of the outermost circumferential main groove have a relationship of 0.80 ≦ Dk / D2 ≦ 1.00. Rehabilitation tire.   The rehabilitated tire according to any one of claims 1 to 6, wherein a width Wk of the notch portion and a ground contact width Ws of the shoulder land portion have a relationship of 0.05 ≦ Wk / Ws ≦ 0.20.   The new rubber sub-groove gauge Ga1 of the circumferential main groove closest to the tire equatorial plane is in a range of 1.0 [mm] ≦ Ga1 ≦ 5.0 [mm]. The rehabilitated tire described.   The retreaded tire according to claim 8, wherein a new sub-groove gauge Ga2 of the outermost circumferential main groove is in a range of Ga2 <Ga1 and 1.0 [mm] ≦ Ga2 ≦ 4.0 [mm].   The retreaded tire according to any one of claims 1 to 9, wherein the carcass layer is configured by arranging a plurality of carcass cords made of an organic fiber material.   The tread gauge Dcc on the tire equator plane and the tread gauge De at the outer end in the tire width direction of the narrow cross belt have a relationship of 1.03 ≦ Dcc / De ≦ 1.20. The retreaded tire as described in any one of these.   The belt width Wb1 of the wide intersecting belt and the carcass cross-sectional width Wa of the carcass layer have a relationship of 0.65 ≦ Wb1 / Wa ≦ 0.90. Rehabilitated tire.   The retreaded tire according to any one of claims 1 to 12, which has a flatness ratio of 70% or less.

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