JP6287276B2 - Rehabilitation tire - Google Patents

Description

  The present invention relates to a retreaded tire, and more particularly to a retreaded tire that can improve uneven wear resistance in a retreaded tire for a light truck.

  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

  In addition, since a small truck tire may travel in an empty state, for example, it is rarely used at the tire standard maximum load. For this reason, the tread part center region tends to be easily worn under the use condition in which the retread tire is mounted on the rear wheel and the double wheel of the vehicle.

  Therefore, the present invention has been made in view of the above, and it is an object of the present invention to provide a retread tire that can improve uneven wear resistance performance particularly in a small truck tire.

To achieve the above object, a retread tire according to the present invention is a retread tire for a small truck including a tread and a base tire, and the base tire includes a carcass layer and an outer side in the tire radial direction of the carcass layer. The tread profile sagging angle θ at a position of 35% of the tread width TW from the tire equator plane is 1.0 [deg] ≦ θ ≦ 6.0 [deg]. in the range, the tread width TW and total tire width SW is, 0.73 ≦ TW / SW ≦ 0.80 range near the is, in the tire radial direction from the measurement point of the rim diameter to the tire maximum width position distance SDH When the tire section height SH is 0.52 Ri range near the ≦ SDH / SH ≦ 0.60, and a tread gauge Dcc at the tire equatorial plane, 35 [%] of the tread width from the tire equatorial plane In position The tread gauge Dt has a relationship of 0.70 ≦ Dcc / Dt ≦ 1.30 .

  In the retread tire according to the present invention, the tread profile depression angle θ in the tread shoulder region is set to be small, so that the land portion in the tread shoulder region is appropriate even under use conditions where the load factor is low such as when the vehicle is empty. Can be grounded. Thereby, there is an advantage that the ground contact state of the tread portion shoulder region is appropriately secured and uneven wear of the tread portion center region is suppressed.

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 an enlarged view showing the retread tire described in FIG. 1. FIG. 4 is an enlarged view showing the retread tire described in FIG. 1. FIG. 5 is an explanatory view showing a modified example of the retread tire described in FIG. 1. FIG. 6 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.

  In the configuration of FIG. 1, the retread tire 10 includes a plurality of circumferential main grooves 21 and 22 that extend in the tire circumferential direction, and a plurality of land portions 31 that are partitioned by the circumferential main grooves 21 and 22. , 32 are provided on the tread surface. Further, the circumferential main grooves 21 and 22 and the land portions 31 and 32 are arranged symmetrically with respect to the tire equatorial plane CL.

  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 groove width on the tread surface, and is measured excluding notches and chamfers formed in the groove openings. Further, the groove depth is measured as the maximum value from the tread surface to the groove bottom, and is measured by excluding partial uneven portions formed on the groove bottom.

[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.

  It is recommended that a general retread tire is mounted on one of the rear wheel and the double wheel of the vehicle in order to ensure the driving safety of the vehicle. Such tire mounting methods are usually described in tire catalogs.

  In addition, since a small truck tire may travel in an empty state, for example, it is rarely used at the tire standard maximum load. For this reason, the tread part center region tends to be easily worn under the use condition in which the retread tire is mounted on the rear wheel and the double wheel of the vehicle.

  Therefore, the retreaded tire 10 employs the following configuration in order to suppress uneven wear (so-called center wear) in the center region of the tread portion in a light truck tire.

  In this retread tire 10, in FIG. 1, the tread width TW and the total tire width SW have a relationship of 0.70 ≦ TW / SW ≦ 0.80. The ratio TW / SW is 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.

  In FIG. 1, 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 0.50 ≦ SDH / SH ≦ 0.60. Have. The ratio SDH / SH is 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.

  In addition, the tread profile drop angle θ (see FIG. 3 described later) at a position 35% of the tread width TW from the tire equatorial plane CL is in the range of 1.0 [deg] ≦ θ ≦ 6.0 [deg]. Preferably, it is in the range of 1.5 [deg] ≦ θ ≦ 4.5 [deg].

  The sagging angle θ is measured as follows in a cross-sectional view in the tire meridian direction in which a tire is mounted on a specified rim to apply a specified internal pressure and a no-load state. First, a point on the tread profile at a position of 35% of the tread width TW from the tire equatorial plane CL is taken. Next, a straight line is drawn that passes through the point at the position 35% of the tread width TW and the intersection of the tire equatorial plane CL and the tread profile. Then, an angle formed by this straight line and a straight line passing through the intersection of the tire equatorial plane CL and the tread profile and parallel to the tire width direction is measured as a depression angle.

  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.

  In FIG. 2, the actual ground contact width was measured as follows. First, a tire is mounted on a prescribed rim and a prescribed internal pressure is applied. Next, a predetermined ratio of load based on the specified load is applied to the tire. The tire is placed perpendicularly to the flat plate in a stationary state, and a predetermined ratio of load is applied to the tire based on the specified load. And the maximum linear distance of the tire axial direction in the contact surface of the tire and flat plate in each load is measured as an actual contact width.

  In this retreaded tire 10, the ratio TW / SW and the ratio SDH / SH are optimized, and the tread profile drop angle θ in the tread shoulder region is set to be small, so that the tire equatorial plane CL reaches the shoulder. The profile becomes flat. Then, the land portion of the tread shoulder region can be properly grounded even under use conditions where the load factor (load) is low. Thereby, the ground contact state of the tread portion shoulder region is appropriately ensured, and uneven wear of the tread portion center region is suppressed.

  In this retread tire 10, all the circumferential main grooves 21 and 22 are arranged at positions away from the region at a distance of 32 [%] to 38 [%] of the tread width TW from the tire equatorial plane CL. (See FIG. 1). In such a configuration, since all the circumferential main grooves 21 and 22 are disposed at positions away from the vicinity of the tire ground contact end, rigidity near the tire ground contact end is ensured during cornering. As a result, the steering performance is improved, and a cornering force can be obtained at a lower steering angle.

[Carcass layer and belt layer]
As described above, the retread tire 10 includes the carcass layer 13 and the belt layer 14 disposed on the outer side in the tire radial direction of the carcass layer 13 (see FIGS. 1 and 3).

  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 Wb 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 ≦ Wb / Wa ≦ 0.90. It is more preferable to have a relationship of .68 ≦ Wb / Wa ≦ 0.80. Thereby, ratio Wb / Wa is optimized and the riding comfort of a tire improves.

  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.

  The belt width Wb is the distance in the tire width direction of the belt cord on the outermost side in the tire width direction in a cross-sectional view in the tire meridian direction. The belt width Wb is measured as an unloaded state while attaching the tire to a specified rim and applying a specified internal pressure. Is done.

  Further, it is preferable that the belt width Wb of the wide cross belt 141 and the tread width TW are in a range of 0.70 ≦ Wb / TW ≦ 1.00.

[Tread Profile]
FIG. 3 is an enlarged view showing the retread tire described in FIG. 1. FIG. 1 shows an enlarged cross-sectional view of the tread portion of the retread tire 10.

  In FIG. 3, the amount of depression t1 of the tread profile at the measurement point (tread end) T of the tread width TW and the amount of depression d2 of the tread profile at the position of 35% of the tread width TW from the tire equatorial plane CL are 0. It is preferable to have a relationship of 2 ≦ d2 / d1 ≦ 0.8, and it is more preferable to have a relationship of 0.3 ≦ d2 / d1 ≦ 0.6. As a result, the ratio d2 / d1 is optimized, and the contact width of the tread portion is ensured appropriately under use conditions where the load factor is low such as when the vehicle is empty.

  The sagging amounts d1 and d2 are measured as a no-load state while attaching a tire to a prescribed rim and applying a prescribed internal pressure in a cross-sectional view in the tire meridian direction. The amount of depression d1 at the measurement point T of the tread width TW is measured as the distance between the measurement point T of the tread width TW and a straight line passing through the tire equatorial plane CL and parallel to the tire width direction. Further, the sagging amount d2 at the position of 35 [%] of the tread width TW is determined by the point on the tread profile at the position of 35 [%] of the tread width TW from the tire equatorial plane CL, and the tire equatorial plane CL and the tread profile. It is measured as the distance from a straight line passing through the intersection and parallel to the tire width direction.

[Belt cover]
Further, in this retreaded tire 10, a single or a plurality of belt covers 143 are disposed so as to cover at least a position crossing the tire equator plane CL and ends of the pair of cross belts 141 and 142 on the outer side in the tire width direction. It is preferable.

  In such a configuration, the belt cover 143 covers the position intersecting the tire equatorial plane CL, so that the diameter growth of the tread portion center region is suppressed, and the profile from the tire equatorial plane CL to the shoulder portion becomes flat. Thereby, the ground contact state of the tread portion shoulder region is appropriately ensured, and uneven wear of the tread portion center region is suppressed.

  In FIG. 3, the belt cover 143 is preferably disposed so as to continuously cover at least a region from the tire equatorial plane CL to a position of 25 [%] of the tread width TW. It is more preferable that the region up to the position of 35% of TW is continuously covered. In such a configuration, since the radial growth in the tread portion center region is suppressed, there is an advantage that the ground contact state of the tread portion shoulder region is appropriately secured and uneven wear in the tread portion center region is suppressed.

  In FIG. 3, the plurality of stacked belt covers 143 and 144 are preferably disposed in a region outside the tire width direction from the position of 25 [%] of the tread width TW from the tire equatorial plane CL. Thereby, the rigidity of the tread portion shoulder region is reinforced, and uneven wear of the tread portion shoulder region is suppressed. It should be noted that, under use conditions where tires are mounted on the vehicle's multiple wheels, due to the characteristics of the vehicle, uneven wear tends to occur in the left and right shoulder regions of the tire mounted on the wheels on the inner side in the vehicle width direction. is there.

  Further, in FIG. 1, it is preferable that 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 have a relationship of 0.75 ≦ Wc / TW ≦ 1.00. 0.80 ≦ Wc / TW ≦ 0.90 is more preferable. Thereby, the displacement amount of the edge part of the cross belts 141 and 142 accompanying a raise of a belt share rate can be reduced effectively.

  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] or more and 1500 [dtex] 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. 3, 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.

  In addition, a plurality of belt covers may be partially disposed at positions that intersect the tire equatorial plane CL and positions that cover the ends of the pair of intersecting belts 141 and 142 on the outer side in the tire width direction (not shown). ). At this time, the belt covers arranged at the respective positions may be arranged so as to wrap around each other or may be arranged apart from each other. Further, it is preferable that the belt cover disposed on the tire equatorial plane CL has a belt width that covers an area of 5% or more of the belt width Wb (see FIG. 1) of the wide cross belt 141. Moreover, it is preferable that the belt cover arrange | positioned at the edge part of a pair of cross belts 141 and 142 has a belt width which covers the area | region 10% or more of the belt width Wb of the wide cross belt 141. FIG.

[Tread rubber gauge]
In FIG. 3, the tread gauge Dcc at the tire equator plane CL and the tread gauge Dt at a position 35% of the tread width TW from the tire equator plane CL satisfy 0.70 ≦ Dcc / Dt ≦ 1.30. It is preferable to have a relationship. Thereby, the tread gauge Dcc in the tread center region and the tread gauge Dt in the tread shoulder region are made uniform.

  The tread gauge Dcc is a belt of a belt ply (belt cover 143 in FIG. 3) that is the outermost point in the tire radial direction of the belt layer 14 and the intersection of the tire equatorial plane CL and the tread profile in a 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 Dt is a point at a position of 35% of the tread width from the tire equatorial plane CL in a cross-sectional view in the tire meridian direction, and a belt ply (in FIG. , And measured as a distance from the belt cord surface of the belt cover 143).

  In FIG. 3, 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 and the riding comfort and durability of the tire are ensured.

  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.

  FIG. 4 is an enlarged view showing the retread tire described in FIG. 1. The figure shows an enlarged cross-sectional view of the circumferential main grooves 21 and 22 of the retread tire 10.

  4, it is preferable that 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]. More preferably, it is in the range of 0 [mm] ≦ Ga1 ≦ 3.0 [mm]. As a result, the new under-groove gauge Ga1 of the circumferential main groove 21 in the center region of the tread portion is optimized, and the belt durability is improved.

  The circumferential main groove 21 closest to the tire equatorial plane CL corresponds to the circumferential main groove 21 in the configuration having the circumferential main groove 21 on the tire equatorial plane CL (see FIG. 1). In the configuration having a land portion on the top (not shown), the circumferential main groove 21 closest to the tire equatorial plane CL is applicable.

  In FIG. 4, the new rubber sub-groove gauge Ga2 of the circumferential main groove 22 located on the outermost side in the tire width direction is in contrast to the new rubber sub-groove gauge Ga1 of the circumferential main groove 21 closest to the tire equatorial plane CL. , Ga2 <Ga1 is preferable. As described above, the new rubber groove gauge Ga2 of the circumferential main groove 22 in the circumferential main groove 22 of the tread portion shoulder region is made smaller than the new rubber groove gauge Ga1 of the circumferential main groove 21 of the tread portion center region. Heat generation in the shoulder region at the time can be suppressed. Thereby, belt durability improves.

  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. As a result, the new under-groove gauge Ga2 of the circumferential main groove 22 in the shoulder region of the tread portion is optimized, and belt durability is improved.

  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. 4, 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 and the uneven wear resistance of the tire is improved.

[Modification]
FIG. 5 is an explanatory view showing a modified example of the retread tire described in FIG. 1. This figure shows the profile of the shoulder portion.

  In the configuration of FIG. 1, as shown in FIG. 3, 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.

  However, the present invention is not limited to this, and the retread tire 10 may include a shoulder portion having a round shape (see FIG. 5) 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 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 buttress portion (non-ground region of the shoulder portion) in a sectional view in the tire meridian direction. Defined by '.

  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 base tire 30 has a carcass layer 13 and a belt layer 14 disposed on the outer side in the tire radial direction of the carcass layer 13. In addition, the drop angle θ of the tread profile at a position of 35 [%] of the tread width TW from the tire equatorial plane CL is in the range of 1.0 [deg] ≦ θ ≦ 6.0 [deg] (see FIG. 3). .

  In such a configuration, since the depression angle θ of the tread profile in the tread portion shoulder region is set to be small, the land portion of the tread portion shoulder region can be properly grounded even under use conditions where the load factor is low such as when the vehicle is empty. . Thereby, there is an advantage that the ground contact state of the tread portion shoulder region is appropriately secured and uneven wear of the tread portion center region is suppressed.

  Further, in this retreaded tire 10, the amount of depression t1 of the tread profile at the measurement point T of the tread width TW and the amount of depression d2 of the tread profile at the position of 35% of the tread width TW from the tire equatorial plane CL are 0. 2 ≦ d2 / d1 ≦ 0.8 (see FIG. 3). Thereby, there exists an advantage by which ratio d2 / d1 is optimized. That is, by satisfying 0.2 ≦ d2 / d1, the contact width of the tread portion is appropriately ensured by properly grounding the shoulder region of the tread portion under use conditions where the load factor is low such as when the vehicle is empty. Thus, uneven wear in the center area of the tread portion is suppressed. Further, since d2 / d1 ≦ 0.8, the straightness of the tire and the ease of slipping out of the heel are improved.

  In the retread tire 10, the belt layer 14 includes a pair of cross belts 141 and 142, and a belt cover 143 disposed on the outer side in the tire radial direction of the pair of cross belts 141 and 142. Further, the belt cover 143 is disposed so as to cover at least a region from the tire equatorial plane CL to a position of 25 [%] of the tread width TW (see FIG. 1). In such a configuration, since radial growth in the tread portion center region is suppressed, there is an advantage that the ground contact shape of the tire is optimized and uneven wear in the tread portion center region is suppressed.

  Further, in this retreaded tire 10, a plurality of stacked belt covers 143 and 144 are disposed in a region outside the tire width direction from the position of 25 [%] of the tread width TW from the tire equatorial plane CL (FIG. 3). reference). In such a configuration, since the rigidity of the tread shoulder region is reinforced, there is an advantage that uneven wear of the tread shoulder region is suppressed.

  In this retreaded tire 10, the tread gauge Dcc on the tire equatorial plane CL and the tread gauge Dt at a position 35% of the tread width from the tire equatorial plane CL are 0.70 ≦ Dcc / Dt ≦ 1.30. (See FIG. 3). Thereby, the tread gauge Dcc in the tread portion center region and the tread gauge Dt in the tread portion shoulder region are made uniform, and there is an advantage that uneven wear of the tire is effectively suppressed.

  Moreover, in this retreaded tire 10, all the circumferential main grooves 21, 22 are arranged at positions deviated from the region at a distance of 32 [%] to 38 [%] of the tread width TW from the tire equatorial plane CL. (See FIG. 1). In such a configuration, since all the circumferential main grooves 21 and 22 are disposed at positions away from the vicinity of the tire ground contact end, rigidity near the tire ground contact end is ensured during cornering. Then, the steering performance is improved, and the cornering force can be obtained at a lower steering angle. Thereby, there exists an advantage by which the partial wear of a tire is suppressed.

  In the retread tire 10, the belt layer 14 includes a pair of cross belts 141 and 142 and a belt cover 143 disposed on the outer side in the tire radial direction of the pair of cross belts 141 and 142. Further, the tread width TW and the tire total width SW have a relationship of 0.70 ≦ TW / SW ≦ 0.80. 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 0.50 ≦ SDH / SH ≦ 0.60. In such a configuration, the ratio TW / SW and the ratio SDH / SH that define the profile are optimized, so that the ground contact state of the tread shoulder region is appropriately secured, and the uneven wear of the tread center region is suppressed. (See Fig. 2).

  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. Further, 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. 4). 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 ensure tire durability. Further, since Ga1 ≦ 5.0 [mm], it is possible to prevent the new rubber groove gauge Ga1 of the circumferential main groove 21 from becoming excessive. Then, heat generation due to excessive volume of the tread rubber is suppressed, and the durability of the tire is improved.

  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]. Is in range (see FIG. 4) 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, there is an advantage that distortion of the peripheral rubber at the end portion of the belt layer 14 is reduced and belt durability is ensured. 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 ensure tire durability. Further, since Ga2 ≦ 4.0 [mm], the new sub-groove gauge Ga2 of the circumferential main groove 22 is prevented from becoming excessive. Then, heat generation due to excessive volume of the tread rubber is suppressed, and the durability of the tire is improved.

  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, the difference in diameter growth between the tread center region and the shoulder region is increased, and the tread center region tends to be unevenly worn. is there. Therefore, there is an advantage that the effect of suppressing uneven wear in the center region of the tread portion can be remarkably obtained by applying the configuration including the carcass layer 13 made of such an organic fiber material.

  In this retreaded tire 10, the belt cover 143 is made of an organic fiber material and includes a plurality of cords arranged at an angle of ± 5 [deg] or less with respect to the tire circumferential direction. In the retreaded tire 10, the tire life is generally extended by the retreading and the traveling distance is increased. For this reason, when the belt cover is made of an organic fiber material, the strength of the belt cover decreases, the difference in diameter growth between the tread portion center region and the shoulder region increases, and the tread portion center region tends to be unevenly worn. is there. Therefore, there is an advantage that the effect of suppressing the uneven wear in the center region of the tread portion can be remarkably obtained by using the configuration including the belt cover 143 made of such an organic fiber material.

  Further, in this retread tire 10, the groove depth D1 (see FIG. 4) of the circumferential main groove 21 closest to the tire equatorial plane CL and the tread gauge Dcc (see FIG. 3) on the tire equatorial plane CL are 1. 30 ≦ Dcc / D1 ≦ 1.55. Thereby, there exists an advantage by which ratio Dcc / D1 is optimized. That is, by satisfying 1.30 ≦ Dcc / D1, the volume of the tread rubber in the tread portion center region is secured, and the uneven wear resistance of the tire is improved. Further, when Dcc / D1 ≦ 1.55, excessive volume of the tread rubber is suppressed, and uneven wear resistance of the tire is improved.

  Further, in this retreaded tire 10, the belt width Wb of the wide cross belt 141 and the carcass cross-sectional width Wa of the carcass layer 13 have a relationship of 0.65 ≦ Wb / Wa ≦ 0.90 (see FIG. 1). . Thereby, there exists an advantage by which ratio Wb / Wa is optimized. That is, by satisfying 0.65 ≦ Wb / Wa, there is an advantage that the belt width Wb 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. Further, since the distance between the end portion of the belt ply and the sidewall portion is ensured by satisfying Wb / Wa ≦ 0.90, the movement of the end portion of the belt ply during tire rolling is suppressed, and the tire Improves durability.

  In this retread tire 10, the number of ends of the belt cover 143 is in the range of 40 [lines / 50 mm] to 60 [lines / 50 mm]. Thereby, there exists an advantage by which the number of ends of the belt cover 143 is optimized.

  Moreover, in this retreaded tire 10, the thickness of the thread | yarn which comprises the belt cover 143 exists in the range of 1100 [dtex] or more and 1500 [dtex] or less. Thereby, there exists an advantage by which the thickness of the thread | yarn of the belt cover 143 is optimized.

[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. For this reason, the tread portion center region is easily worn and uneven wear is likely to occur. Therefore, there is an advantage that the effect of suppressing uneven wear in the center region of the tread portion can be remarkably obtained by using such a low flat tire for a small truck.

  6 and 7 are charts showing the results of performance tests of the retreaded tire according to the embodiment of the present invention.

  In this performance test, evaluations on (1) outer diameter growth rate, (2) center wear resistance, (3) shoulder wear resistance, and (4) straight running performance were performed for a plurality of types of test tires. Further, a test tire having a tire size of 205 / 70R16 111/109 LT is assembled to an applicable rim defined by JATMA, and the highest air pressure defined by JATMA is applied to the test tire. A small truck having a maximum loading capacity of 2.0 [ton] is used as a test vehicle.

  (1) The outer diameter growth rate is determined by measuring the maximum value of the outer diameter of the tire when the test tire is mounted on an applicable rim specified by JATMA to be in an unloaded state and the highest air pressure specified by JATMA is applied to the test tire. Then, the tire outer diameter growth rate is calculated using the tire outer diameter under atmospheric pressure as a reference (100).

  (2) In the evaluation regarding the center wear resistance, a load of 80% based on the maximum load specified by JATMA is applied to the test tire. Then, the test vehicle travels 50,000 [km] on the paved road, and then the partial wear generated in the land portion of the tread portion center region is observed and evaluated. This evaluation is performed by index evaluation, and the larger the value, the better.

  (3) In the evaluation on the shoulder wear resistance, the test tire is mounted on the rear and inner wheels of the test vehicle, and a load of 40 [%] or 80 [%] based on the maximum load specified by JATMA is given to the test tire. Is done. Then, the test vehicle travels 50,000 [km] on the paved road, and then the uneven wear generated in the land portion of the tread shoulder region is observed and evaluated. This evaluation is performed by index evaluation, and the larger the value, the better.

  (4) In the evaluation of straight running performance, a load of 80% based on the maximum load specified by JATMA is applied to the test tire, the test vehicle runs on the straight course, and a specialized test driver performs sensory evaluation. . This evaluation is performed by index evaluation, and the larger the value, the better.

  The test tires of Examples 1 to 8 have the structure shown in FIG. 1, and the belt cover 143 has a full cover structure that covers the tread part center region and the ends of the cross belts 141 and 142. The tire total width SW is SW = 204 [mm], and the tire cross-section height SH is SH = 143.7 [mm]. Further, the tread gauge Dcc on the tire equatorial plane CL is Dcc = 13.7 [mm]. Further, the belt width Wb of the wide cross belt 141 is Wb = 150 [mm].

  The test tire of the conventional example has the same configuration as the test tire of Example 1.

  As the test results show, in the test tires of Examples 1 to 8, it is understood that the uneven wear resistance performance of the tire is improved.

  10: retread tire, 20: tread, 30: tire, 301: residual tread, 11: bead core, 12: bead filler, 13: carcass layer, 14: belt layer, 141, 142: cross belt, 143, 144: belt Cover, 15: tread rubber, 16: side wall rubber, 17: rim cushion rubber, 21, 22: circumferential main groove, 31, 32: land portion

Claims (11)

A retread tire for a light truck with a tread and a base tire,
The base tire has a carcass layer and a belt layer disposed on the outer side in the tire radial direction of the carcass layer,
The tread profile sagging angle θ at a position of 35 [%] of the tread width TW from the tire equator plane is in the range of 1.0 [deg] ≦ θ ≦ 6.0 [deg],
A tread width TW and total tire width SW is Ri range near the 0.73 ≦ TW / SW ≦ 0.80,
The distance SDH in the tire radial direction from the measurement point of the rim diameter to the tire maximum width position, the tire section height SH is Ri range near the 0.52 ≦ SDH / SH ≦ 0.60, and,
Rehabilitation characterized in that a tread gauge Dcc on the tire equator plane and a tread gauge Dt at a position 35% of the tread width from the tire equator plane have a relationship of 0.70 ≦ Dcc / Dt ≦ 1.30. tire.   The relationship between the tread profile depression amount d1 at the tread width measurement point and the tread profile depression amount d2 at a position of 35% of the tread width from the tire equator plane is 0.2 ≦ d2 / d1 ≦ 0.8. The retread tire of Claim 1 which has these. The belt layer includes a pair of cross belts and a belt cover disposed on the outer side in the tire radial direction of the pair of cross belts; and
The retread tire according to claim 1 or 2, wherein the belt cover is disposed so as to cover at least a region from the tire equatorial plane to a position of 25% of the tread width. The belt layer includes a pair of cross belts and a belt cover disposed on the outer side in the tire radial direction of the pair of cross belts; and
The retreaded tire according to any one of claims 1 to 3, wherein the plurality of stacked belt covers are arranged in a region outside the tread width in the tire width direction from a position of 25 [%] of the tread width from the tire equatorial plane. . A tread surface includes a plurality of circumferential main grooves extending in the tire circumferential direction, and a plurality of land portions defined by the circumferential main grooves, and
All of the circumferential main grooves, 32 [%] of the tread width from the tire equatorial plane than 38 [%] to claim 1-4 which is disposed at a position deviated from a region in the following distance The rehabilitated tire described. The retread tire according to any one of claims 1 to 5 , wherein the carcass layer is configured by arranging a plurality of carcass cords made of an organic fiber material. The belt layer includes a pair of cross belts and a belt cover disposed on the outer side in the tire radial direction of the pair of cross belts; and
The rehabilitation according to any one of claims 1 to 6 , wherein the belt cover is made of an organic fiber material and includes a plurality of cords arranged at an angle of ± 5 [deg] or less with respect to the tire circumferential direction. tire. A tread surface includes a plurality of circumferential main grooves extending in the tire circumferential direction, and a plurality of land portions defined by the circumferential main grooves, and
The groove depth D1 of the closest the circumferential main groove in the tire equatorial plane, one and the tread gauge Dcc at the tire equatorial plane, according to claim 1 to 7 having a relationship of 1.30 ≦ Dcc / D1 ≦ 1.55 Rehabilitation tire as described in one. The retreaded tire according to any one of claims 1 to 8 , wherein the number of ends of the belt cover is in a range of 40 [lines / 50mm] to 60 [lines / 50mm]. The retread tire according to any one of claims 1 to 9 , wherein a thickness of a thread constituting the belt cover is in a range of 1100 [dtex] to 1500 [dtex]. The retreaded tire according to any one of claims 1 to 10 , which has a flatness ratio of 70% or less.

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