WO2015174413A1 - Retreaded tire - Google Patents

Abstract

In this retreaded tire (10), a tread (20) has, provided in a tread surface, at least three circumferential main grooves (21, 22) extending in a tire-circumference direction, and a plurality of land parts (31, 32) formed by subdividing these circumferential main grooves (21, 22). The tread width (TW) and the tire total width (SW) satisfy the relationship 0.65 ≤ TW/SW ≤ 0.85. The distance (SDH) in the tire-diameter direction from a rim diameter measurement point (P) to a tire maximum width position (Q), and the tire cross-sectional height (SH), satisfy the relationship 0.45 ≤ SDH/SH ≤ 0.65. The land parts (31) adjacent on the tire-widthwise inner side to the outermost circumferential main grooves (22) are each provided with one circumferential thin groove (311) extending continuously throughout the entire tire circumference.

Description

Rehabilitation tire

The present invention relates to a retreaded tire, and more particularly to a retreaded tire that can improve wet 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 small truck tires. As such a retread tire for a small truck, a technique described in Patent Document 1 is known.

JP 2009-0410179 A

On the other hand, retreaded tires also have problems to improve the wet performance of the tires.

Therefore, the present invention has been made in view of the above, and an object thereof is to provide a retread tire that can improve wet 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 plurality of land portions divided into a tread surface, and the base tire includes a carcass layer and a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and the belt layer A retread tire having 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, wherein the outer circumferential main groove is the outermost circumferential main When referred to as a groove, the tread width TW and the tire total width SW have a relationship of 0.65 ≦ TW / SW ≦ 0.85, and the tire radial direction from the rim diameter measurement point to the tire maximum width position Distance SD And the tire cross-section height SH has a relationship of 0.45 ≦ SDH / SH ≦ 0.65, and the land portion on the inner side in the tire width direction adjacent to the outermost circumferential direction main groove is One circumferential narrow groove extending continuously over the circumference is provided.

In the retreaded tire according to the present invention, since the ratio TW / SW and the ratio SDH / SH that define the profile are optimized, there is an advantage that the ground contact shape of the tire is optimized and the wet performance of the tire is improved. Further, the land portion on the inner side in the tire width direction adjacent to the outermost circumferential main groove is provided with one circumferential narrow groove and a plurality of lug grooves, thereby ensuring the land area of the land portion. Drainage is improved. Thereby, there exists an advantage which the wet performance of a tire improves further.

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 the 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 rehabilitated 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, it is used for a heavy load tire, a light 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 this embodiment, the circumferential main groove 22 on the outermost side in the tire width direction is referred to as the outermost circumferential main groove. The land portion 32 on the outer side in the tire width direction adjacent to the outermost circumferential main groove is referred to as a shoulder land portion.

[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.

Such remolded retread tire 10 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 retread tire 10 by the precure 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, cushion rubber (not shown) is pasted 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.

Also, retreaded tires use tires whose remaining grooves have reached the end of their life as stand tires, so the tire profile tends to be rounded as a whole and the tread radius tends to be small. For this reason, there is a problem that the contact area of the shoulder region of the tread portion is insufficient and the wet performance of the tire is deteriorated.

Therefore, the retreaded tire 10 employs the following configuration in order to improve wet performance particularly in a small truck tire.

In this retread tire 10, in FIG. 1, the tread width TW and the total tire width SW have a relationship of 0.65 ≦ TW / SW ≦ 0.85. 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 the tread pattern portion of the tire when the tire is mounted on a specified rim to apply a specified internal pressure and is in an unloaded 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.

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 is 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 by attaching the tire to the specified rim and applying the specified internal pressure, as well as no load.

FIG. 2 is an explanatory view showing the operation of the retreaded tire shown in FIG. 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, the ratio TW / SW and the ratio SDH / SH are optimized, the profile from the tire equatorial plane CL to the shoulder becomes flat, and the ground contact shape of the tire approaches a rectangle. Then, the contact area of the tread shoulder region at the time of tire contact is secured, and the wet 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).

Here, 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.

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 specified rim and filled with the specified 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.

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

The 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.

Also, it is preferable that the groove width W1 of the circumferential main groove 21 closest to the tire equatorial plane CL and the tread width TW have a relationship of 0.05 ≦ W1 / TW ≦ 0.09. Moreover, it is preferable that the groove width W2 of the outermost circumferential main groove 22 and the tread width TW have a relationship of 0.06 ≦ W2 / TW ≦ 0.10. As a result, the groove widths W1 and W2 of the circumferential main grooves 21 and 22 are optimized.

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. 3). In the configuration having a land portion on the top (not shown), the circumferential main groove 21 closer to the tire equatorial plane CL among the left and right circumferential main grooves defining the land portion corresponds.

In the configuration of FIG. 3, the three circumferential main grooves 21 and 22 are arranged symmetrically about the tire equatorial plane CL. Thus, in the configuration in which the plurality of circumferential main grooves 21 and 22 are arranged symmetrically with respect to the tire equatorial plane CL as a boundary, the wear forms in the left and right regions with the tire equatorial plane CL as a boundary are uniformed, This is preferable in that the wear life of the tire is improved.

However, the present invention is not limited to this, and 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).

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

However, the present invention is not limited to this, and four or more circumferential main grooves may be arranged (not shown). For this reason, the land part 31 may be arrange | positioned on the tire equator surface CL.

[Circular narrow groove and lug groove in the center land]
4 to 6 are enlarged views showing a main part of the retreaded tire shown in FIG. In these drawings, FIG. 4 shows an enlarged plan view of the land portion 31 on the inner side in the tire width direction adjacent to the outermost circumferential main groove 22. FIG. 5 shows a cross-sectional view in the tire meridian direction of one side region as the tire equatorial plane CL. FIG. 6 shows an enlarged cross-sectional view of the circumferential main grooves 21 and 22.

As shown in FIGS. 3 and 4, in this retreaded tire 10, the land portion 31 on the inner side in the tire width direction adjacent to the outermost circumferential main groove 22 has one circumferential narrow groove 311 and a plurality of lug grooves 312. With. For example, in the configuration of FIG. 3, the retread tire 10 has a point-symmetric tread pattern, so the left and right outermost circumferential main grooves 22, 22 each have one circumferential narrow groove 311 and a plurality of lug grooves 312. ing. Thereby, the groove area of the land part 31 increases and the drainage property is improved.

The circumferential narrow groove 311 is a narrow groove extending continuously over the entire circumference of the tire. The circumferential narrow groove 311 may have a straight shape, or may have a zigzag shape or a wavy shape. 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. Further, the circumferential narrow groove 311 has a wide structure in which the groove width is widened at the short portion.

Moreover, the circumferential direction narrow groove 311 is arrange | positioned in the approximate center area | region of the land part 31, and divides the land part 31 in a tire width direction. Specifically, the width Wr of the land portion 31 and the distance Da in the tire width direction from the edge portion of the land portion 31 to the circumferential narrow groove 311 have a relationship of 0.40 ≦ Da / Wr ≦ 0.60. Have.

The width Wr of the land portion 31 is measured as the distance in the tire width direction of the left and right edge portions on the tread surface of the land portion in a no-load state in which the tire is mounted on the specified rim and filled with the specified internal pressure. Moreover, in the structure which a land part has a notch part and a chamfering part in an edge part, a land part width | variety is measured on the basis of the intersection of the tread of a land part and the extended line of a groove wall.

The distance Da of the circumferential narrow groove 311 is from the measurement point of the width Wr of the land portion 31 to the groove center line of the circumferential narrow groove 311 in a no-load state in which the tire is mounted on the defined rim and filled with the defined internal pressure. Measured as distance.

Moreover, in FIG. 4, it is preferable that the groove width W3 of the circumferential narrow groove 311 is in the range of 1.5 [mm] ≦ W3 ≦ 4.3 [mm]. Thereby, the groove area of the circumferential narrow groove 311 is ensured, and the rigidity of the land portion 31 is ensured.

In FIG. 6, the groove depth D3 of the circumferential narrow groove 311 and the groove depth D2 of the outermost circumferential main groove 22 preferably have a relationship of 0.10 ≦ D3 / D2 ≦ 0.40. More preferably, the relationship is 0.20 ≦ D3 / D2 ≦ 0.30. In other words, the circumferential narrow groove 311 is preferably a shallow groove. Thereby, the rigidity of the land portion 31 is ensured, and the steering stability performance of the tire is ensured.

In the configuration of FIG. 3, the retread tire 10 includes the three circumferential main grooves 21 and 22 and the four rows of land portions 31 and 32 as described above. For this reason, the land portion 31 on the inner side in the tire width direction adjacent to the outermost circumferential main groove 22 is also adjacent to the tire equatorial plane CL, and the circumferential narrow groove 311 and the lug groove 312 are arranged on the land portion 31. ing.

On the other hand, in a configuration including five or more rows of land portions (not shown), at least a land portion (so-called second land portion) on the inner side in the tire width direction adjacent to the outermost circumferential main groove 22 is a circumferential narrow groove 311 and a lug. A groove 312 may be provided.

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 are each provided with a plurality of lug grooves 312. A plurality of lug grooves 312 are arranged at a predetermined interval L1 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. Moreover, short and a plurality of sipes (so-called multi-sipe, not shown) are disposed at predetermined intervals in the tire circumferential direction at the left and right edge portions of the land portion 31 facing the circumferential main grooves 21 and 22.

Moreover, in FIG. 4, it is preferable that the groove width W4 of the lug groove 312 is in the range of 1.0 [mm] ≦ W4 ≦ 4.0 [mm]. Thereby, the groove area of the lug groove 312 is ensured, and the rigidity of the land portion 31 is ensured.

In FIG. 6, the groove depth D4 of the lug groove 312 and the groove depth D2 of the outermost circumferential main groove 22 preferably have a relationship of 0.10 ≦ D4 / D2 ≦ 0.40. It is more preferable to have a relationship of 20 ≦ D4 / D2 ≦ 0.30. That is, the lug groove 312 is preferably a shallow groove. Thereby, the rigidity of the land portion 31 is ensured, and the steering stability performance of the tire is ensured.

In the configuration of FIG. 6, the groove depth D4 of the lug groove 312 increases from the circumferential narrow groove 311 side toward the outermost circumferential main groove 22 side, and at the opening with respect to the outermost circumferential main groove 22. It has become the maximum. Thereby, the drainage of the lug groove 312 is improved.

3 and 4, the lug groove 312 communicates with the circumferential narrow groove 311 at the inner end in the tire width direction. For this reason, a portion of the land portion 31 that is divided into the circumferential narrow groove 311 and the outermost circumferential main groove 22 is divided in the tire circumferential direction by the plurality of lug grooves 31 to form a block row composed of a plurality of blocks 313. ing. Such a configuration is preferable in that the drainage of the land portion 31 is improved and the wet performance of the tire is improved.

However, the present invention is not limited to this, and may be terminated in a region between the circumferential narrow groove 311 and the outermost circumferential main groove 22 without intersecting the circumferential narrow groove 311 (not shown). In this case, a portion of the land portion 31 that is partitioned into the circumferential narrow groove 311 and the outermost circumferential main groove 22 is a rib that is continuous in the tire circumferential direction. With this configuration, the rigidity of the land portion 31 in the region between the circumferential narrow groove 311 and the outermost circumferential main groove 22 is increased, and uneven wear at the edge portion on the outermost circumferential main groove 22 side of the land portion 31 is reduced. It is preferable in terms of being suppressed.

3 and 4, the lug groove 312 terminates at the connecting portion with the circumferential narrow groove 311 without penetrating the circumferential narrow groove 311 in the tire width direction. For this reason, the area | region inside the tire width direction of the circumferential direction narrow groove 311 in the land part 31 is a rib which continues in a tire circumferential direction. Such a configuration is preferable in that the rigidity of the land portion 31 on the tire equatorial plane CL side is ensured and the steering stability performance of the tire is improved.

However, the present invention is not limited thereto, and the lug groove 312 may extend through the circumferential narrow groove 311 in the tire width direction and extend to the inner region in the tire width direction of the circumferential narrow groove 311 (not shown). At this time, the lug groove 312 does not open to the circumferential main groove 21 and terminates inside the land portion 31, whereby the rigidity of the land portion 31 on the tire equatorial plane CL side is appropriately ensured.

3 and 4, the circumferential narrow groove 311 has a zigzag shape, and the lug groove 312 is connected to the zigzag bent portion of the circumferential narrow groove 311. Further, the lug groove 312 widens the groove width at the connection portion with the circumferential narrow groove 311, so that the groove width of the circumferential narrow groove 311 is widened at the zigzag bent portion. Such a configuration is preferable in that the drainability of the land portion 31 is improved and the wet performance of the tire is improved.

[Notch of shoulder land]
In the configuration of FIG. 3, the shoulder land portion 32 includes a plurality of notches 321 at the edge portion on the outermost circumferential main groove 22 side. Thereby, the groove area of the outermost circumferential main groove 22 is increased, and drainage is improved.

For example, in the configuration of FIG. 3, the cutout portion 321 has a trapezoidal shape in a plan view of the tread and is arranged at a ratio of one to one pitch of the tread pattern. In addition, a plurality of sets of cutout portions 321 and lug grooves 312 of the center land portion 31 are alternately arranged in one outermost circumferential main groove 22 while being offset in the tire circumferential direction. Thereby, the notch part 321 and the opening part of the lug groove 312 are disperse | distributed and arrange | positioned in the tire circumferential direction, and the groove area of the outermost periphery direction main groove 22 is equalized in the tire circumferential direction.

In FIG. 4, the length L2 of the notch 321 in the tire circumferential direction and the arrangement interval L1 of the lug groove 312 in the tire circumferential direction have a relationship of 0.20 ≦ L2 / L1 ≦ 0.60. Preferably, it has a relationship of 0.35 ≦ L2 / L1 ≦ 0.45. Thereby, the length L2 of the notch 321 is optimized.

The length L2 of the notch 321 is measured as the opening length in the tire circumferential direction of the notch 321 with respect to the outermost circumferential main groove 22 on the tread surface.

The arrangement interval L1 of the lug grooves 312 is equal to the pitch length of the tread pattern.

In FIG. 4, the width W5 of the notch 321 and the groove width W2 of the outermost circumferential main groove 22 preferably have a relationship of 0.20 ≦ W5 / W2 ≦ 0.40, and 0.25 ≦ It is more preferable to have a relationship of W5 / W2 ≦ 0.35. Thereby, the width W5 of the notch 321 is optimized.

The width W5 of the notch 321 is measured as the opening width in the tire width direction of the notch 321 on the tread surface.

In FIG. 6, it is preferable that the depth D5 of the notch 321 and the groove depth D2 of the outermost circumferential main groove 22 have a relationship of 0.60 ≦ D5 / D2 ≦ 1.00. The depth D5 of the notch 321 is optimized.

[Groove area ratio]
In the configuration of FIG. 3, the groove area ratio A of the entire tread pattern is preferably in the range of 0.20 ≦ A ≦ 0.35. Thereby, the groove area ratio A is optimized and the contact pressure at the time of tire contact is optimized.

The groove area ratio A of the entire tread pattern is defined by groove area / (groove area + ground area). The groove area refers to the opening area of the groove on the ground contact surface. Further, the groove refers to a circumferential groove and a lug groove in the tread portion, and does not include sipes, kerfs, and notches. The ground contact area is the contact area between the tire and the road surface. In addition, the groove area and the contact area are determined when the tire is mounted on the specified rim and applied with the specified internal pressure, and is placed perpendicular to the flat plate in a stationary state and applied with a load corresponding to the specified load. Measured at the contact surface between the plate and the flat plate.

3, the groove area ratio Ac of the land portion 31 on the inner side in the tire width direction adjacent to the outermost circumferential main groove 22 and the groove area ratio As of the land portion 32 on the outer side in the tire width direction are 1.5 ≦. It is preferable to be in the range of Ac / As. The ratio Ac / As is more preferably in the range of 2.5 ≦ Ac / As ≦ 4.5. Thereby, ratio Ac / As is optimized and the rigidity of the shoulder land part 32 is ensured.

The groove area ratios Ac and As of the land portions 31 and 32 are defined in the same manner as the groove area ratio A of the entire tread pattern described above. However, the groove area of the land portion is measured as the sum of the areas of grooves formed in the land portion itself (for example, lug grooves, narrow grooves, etc.). Areas such as formed sipes, kerfs, and notches are excluded from the land area.

[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 small 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, 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).

Further, the belt cover 143 is configured 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, ratio Wb1 / 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.

Further, 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.

Further, 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 and is disposed so as to cover the entire 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 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 144 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 with reference 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.

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. This figure shows the profile of the shoulder portion.

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.

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. 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 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 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 belt layer 14 disposed on the outer side in the tire radial direction of the carcass layer 13. Further, 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 0.65 ≦ TW / SW ≦ 0.85 (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 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 extending continuously over the entire tire circumference.

In such a configuration, since the ratio TW / SW and the ratio SDH / SH that define the profile are optimized, there is an advantage that the contact shape of the tire is optimized and the wet performance of the tire is improved. Further, 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, thereby securing the groove area of the land portion 32. Thus, the drainage of the land portion 32 is improved. Thereby, there exists an advantage which the wet performance of a tire improves further.

Further, in this retreaded tire 10, the land portion 31 on the inner side in the tire width direction adjacent to the outermost circumferential main groove 22 extends in the tire width direction and communicates with the outermost circumferential main groove 22, and the circumferential narrow groove 311. Are provided with a plurality of lug grooves 312 (see FIG. 3). In such a configuration, the plurality of lug grooves 312 connect the circumferential narrow groove 311 and the outermost circumferential main groove 22, thereby improving the drainage of the land portion 32. Thereby, there exists an advantage which the wet performance of a tire improves further.

Further, in this retreaded tire 10, the groove depth D3 of the circumferential narrow groove 311 and the groove depth D2 of the outermost circumferential main groove 22 have a relationship of 0.10 ≦ D3 / D2 ≦ 0.40 ( (See FIG. 6). Thereby, there exists an advantage by which the groove depth D3 of the circumferential direction fine groove 311 is optimized. That is, by satisfying 0.10 ≦ D3 / D2, the groove depth D3 of the circumferential narrow groove 311 is secured, and the drainage of the land portion 31 is secured. Moreover, the rigidity of the land part 31 is ensured by being D3 / D2 <= 0.40, and the partial wear of the land part 31 is suppressed.

Further, in this retreaded tire 10, the groove depth D4 of the lug groove 312 and the groove depth D2 of the outermost circumferential main groove 22 have a relationship of 0.10 ≦ D4 / D2 ≦ 0.40 (FIG. 5). reference). Thereby, there exists an advantage by which the groove depth D4 of the lug groove 312 is optimized. That is, by satisfying 0.10 ≦ D4 / D2, the groove depth D4 of the lug groove 312 is ensured, and the drainage of the land portion 31 is ensured. Moreover, by being D4 / D2 <= 0.40, the rigidity of the land part 31 is ensured and the partial wear of the land part 31 is suppressed.

In this retreaded tire 10, the groove width W1 of the circumferential main groove 21 closest to the tire equatorial plane CL and the tread width TW have a relationship of 0.05 ≦ W1 / TW ≦ 0.09 (FIG. 3). reference). Thereby, the groove width W1 of the circumferential direction main groove 21 is ensured, and there exists an advantage by which drainage property is ensured.

Further, in this retreaded tire 10, the groove width W2 of the outermost circumferential main groove 22 and the tread width TW have a relationship of 0.06 ≦ W2 / TW ≦ 0.10 (see FIG. 3). Thereby, the groove width W2 of the outermost circumferential main groove 22 is ensured, and there is an advantage that drainage is ensured.

Further, in this retread tire 10, the circumferential narrow groove 311 extends in a zigzag shape or a wave shape in the tire circumferential direction (see FIG. 3). Thereby, there exists an advantage by which the edge component of the land part 31 is ensured.

Further, in this retreaded tire 10, the circumferential main groove 21 closest to the tire equatorial plane CL has a zigzag shape or a wave shape substantially parallel to the circumferential narrow groove 311 and extends in the tire circumferential direction (see FIG. 3). In such a configuration, the rigidity in the tire circumferential direction of the portion of the land portion 31 partitioned into the circumferential main groove 21 and the circumferential narrow groove 311 is made uniform. Thereby, there exists an advantage by which the partial wear of the land part 31 is suppressed.

In the retread tire 10, the outermost land portion 32 in the tire width direction has a plurality of notches 321 at the edge portion on the outermost circumferential main groove 22 side (see FIG. 3). Thereby, the groove area (groove volume) of the outermost circumferential main groove 22 is increased, and there is an advantage that the wet performance of the tire is improved.

Moreover, in this retreaded tire 10, the length L2 of the notch 321 in the tire circumferential direction and the arrangement interval L1 of the lug groove 312 in the tire circumferential direction have a relationship of 0.2 ≦ L2 / L1 ≦ 0.6. (See FIG. 4). Thereby, there exists an advantage by which the length L2 of the notch part 321 is optimized. That is, by satisfying 0.2 ≦ L2 / L1, the length L2 of the notch 321 is secured, and an increase in the groove area (groove volume) of the outermost circumferential main groove 22 is secured. Moreover, by L2 / L1 <= 0.6, the rigidity reduction of the land part 32 by the notch part 321 becoming excessive is suppressed, and the uneven wear of the land part 32 is suppressed.

Further, in the retread tire 10, the width W5 of the notch 321 and the groove width W2 of the outermost circumferential main groove 22 have a relationship of 0.2 ≦ W5 / W2 ≦ 0.4 (see FIG. 4). Thereby, there exists an advantage by which the width W5 of the notch part 321 is optimized. That is, by satisfying 0.2 ≦ W5 / W2, the width W5 of the notch 321 is secured, and an increase in the groove area (groove volume) of the outermost circumferential main groove 22 is secured. Moreover, by being W5 / W2 <= 0.4, the rigidity fall of the land part 32 by the notch part 321 becoming excessive is suppressed, and the uneven wear of the land part 32 is suppressed.

In this retread tire 10, the depth D5 of the notch 321 and the groove depth D2 of the outermost circumferential main groove 22 have a relationship of 0.60 ≦ D5 / D2 ≦ 1.00 (see FIG. 6). ). Thereby, the depth D5 of the notch 321 is ensured, and an increase in the groove area (groove volume) of the outermost circumferential main groove 22 is ensured. Moreover, by being D5 / D2 <= 1.00, the rigidity fall of the land part 32 by the notch part 321 becoming excessive is suppressed, and the partial wear of the land part 32 is suppressed.

Moreover, in this retread tire 10, the groove area ratio A of the entire tread pattern is in the range of 0.20 ≦ A ≦ 0.35 (see FIG. 3). Thereby, there exists an advantage by which the groove area ratio A of the whole tread pattern is optimized. That is, by satisfying 0.20 ≦ A, the groove area A is secured and the wet performance of the tire is secured. Further, when A ≦ 0.35, the contact pressure of the entire contact surface is optimized, and the uneven wear resistance performance of the tire is ensured.

Further, in this retreaded tire 10, the groove area ratio Ac of the land portion 31 on the inner side in the tire width direction adjacent to the outermost circumferential main groove 22 and the groove area ratio As of the land portion 32 on the outer side in the tire width direction are 1.5 ≦. It is in the range of Ac / As. Thereby, there is an advantage that the rigidity of the shoulder land portion 32 is secured and the tire uneven wear performance of the tire is secured.

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 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]. 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, 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.

Further, in this retread tire 10, the carcass layer 13 is configured by arranging a plurality of carcass cords made of organic fiber materials. 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 tire ground contact shape becomes inappropriate, and the wet performance of the tire tends to be lowered. Therefore, there is an advantage that the effect of improving the wet performance 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 belt cover 143 is formed of a plurality of cords made of an organic fiber material and 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, in the structure which a belt cover consists of organic fiber materials, the intensity | strength of a belt cover falls, the tire ground contact shape becomes inadequate, and there exists a tendency for the wet performance of a tire to fall easily. Therefore, there is an advantage that the effect of improving the wet performance can be remarkably obtained by applying the configuration including the belt cover 143 made of such an organic fiber material.

Further, in this retread tire 10, the single or plural belt covers 143 and 144 cover at least the position intersecting the tire equatorial plane CL and the ends of the pair of intersecting belts 141 and 142 on the outer side in the tire width direction. (See FIGS. 1 and 5). In such a configuration, the belt cover 143 covers the position intersecting the tire equator plane CL, thereby suppressing the diameter growth of the tread portion center region. Thereby, the profile from the tire equatorial plane CL to the shoulder portion becomes flat, and the ground contact shape of the tire is optimized. Further, the belt cover 143 covers the ends of the pair of cross belts 141 and 142 on the outer side in the tire width direction, so that the displacement amount of the ends of the cross belts 141 and 142 is reduced, and the ground contact shape of the tire is optimized. Is done. These have the advantage of improving the wet performance of the tire.

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 disposed horizontally with respect to the tire contact surface, the tension acting on the belt ply at the time of tire contact is made uniform, and the belt durability is improved. In addition, since Dcc / De ≦ 1.20 prevents the tread gauge Dcc in the center region from becoming excessive, the profile from the tire equatorial plane CL to the shoulder becomes flat, and the ground contact shape of the tire is It is optimized. These have the advantage of improving the wet performance of the tire.

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, there is an advantage that the belt width Wb is secured and the distortion of the peripheral rubber at the outer end of the belt layer 14 in the tire width direction is reduced. Further, since the distance between the end portion of the belt ply and the sidewall portion is secured by Wb1 / Wa ≦ 0.90, the movement of the end portion of the belt ply during tire rolling is suppressed, and the tire Improves durability.

Further, 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.

Further, in this retread tire 10, the thickness of the thread constituting the belt cover 143 is in the range of 1100 [dtex / 2] to 1500 [dtex / 2]. 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. Then, the ground contact shape of the tire becomes inappropriate, and the wet performance of the tire tends to decrease. Therefore, there is an advantage that the effect of improving the wet performance can be remarkably obtained by using such a low flat tire for a small truck.

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

In this performance test, the wet performance was evaluated for multiple types of test tires. In addition, 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 and maximum load specified by JATMA are applied to the test tire.

Also, a test vehicle equipped with a test tire travels on a wet road surface (a flooded asphalt road surface), and a braking distance from an initial speed of 60 [km / h] is measured. Then, based on this measurement result, index evaluation using the conventional example as a reference (100) is performed. An evaluation result is so preferable that the numerical value is large.

The test tires of Examples 1 to 16 have the structures described in FIGS. However, in Examples 1 to 4, the land portion 31 does not include a lug groove. 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 W2 (FIG. 3) of the outermost circumferential main groove 22 is 13.0 [mm], and the groove depth D2 (FIG. 6) is 10.0 [mm]. The arrangement interval (pitch) L1 of the lug grooves 312 is in the range of 30.0 [mm] ≦ L1 ≦ 50.0 [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 conventional test tire does not include the circumferential narrow groove 311 and the lug groove 312 in the configuration of FIGS.

As shown in the test results, it can be seen that in the test tires of Examples 1 to 16, the wet 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, 30: tire, 301: residual tread, 21, 22: circumferential main groove, 31, 32: land portion, 311: circumferential narrow groove, 312: lug groove, 321: notch Part

Claims (15)

1. 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 base tire includes a carcass layer and a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and the belt layer is disposed on the outer side in the tire radial direction of the pair of cross belts and the pair of cross belts. A retread tire having a belt cover disposed thereon,
   When the circumferential main groove on the outermost side in the tire width direction is called the outermost circumferential main groove,
   The tread width TW and the tire total width SW have a relationship of 0.65 ≦ TW / SW ≦ 0.85,
   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, and
   The retread tire, wherein the land portion on the inner side in the tire width direction adjacent to the outermost circumferential main groove includes one circumferential narrow groove extending continuously over the entire circumference of the tire.
2. A plurality of lug grooves that extend in the tire width direction and communicate with the outermost circumferential direction main groove and communicate with the circumferential direction narrow groove while the land portion adjacent to the outermost circumferential direction main groove extends in the tire width direction. The retread tire according to claim 1 provided.
3. The rehabilitation according to claim 1 or 2, wherein a groove depth D3 of the circumferential narrow groove and a groove depth D2 of the outermost circumferential main groove have a relationship of 0.10 ≦ D3 / D2 ≦ 0.40. tire.
4. The retreaded tire according to claim 2, wherein a groove depth D4 of the lug groove and a groove depth D2 of the outermost circumferential main groove have a relationship of 0.10 ≦ D4 / D2 ≦ 0.40.
5. The groove width W1 of the circumferential main groove closest to the tire equatorial plane and the tread width TW have a relationship of 0.05 ≦ W1 / TW ≦ 0.09. Rehabilitation tire.
6. The rehabilitated tire according to any one of claims 1 to 5, wherein a groove width W2 of the outermost circumferential main groove and a tread width TW have a relationship of 0.06 ≦ W2 / TW ≦ 0.10.
7. The retread tire according to any one of claims 1 to 6, wherein the circumferential narrow groove extends in a zigzag shape or a wave shape in the tire circumferential direction.
8. The retread tire according to claim 7, wherein the circumferential main groove closest to the tire equatorial plane has a zigzag shape or a wave shape substantially parallel to the circumferential narrow groove and extends in the tire circumferential direction.
9. The retread tire according to any one of claims 1 to 8, wherein the land portion on the outermost side in the tire width direction has a plurality of notches at an edge portion on the outermost circumferential main groove side.
10. The rehabilitated tire according to claim 9, wherein a length L2 of the notch in the tire circumferential direction and an arrangement interval L1 of the lug grooves in the tire circumferential direction have a relationship of 0.2 ≦ L2 / L1 ≦ 0.6. .
11. The rehabilitated tire according to claim 9 or 10, wherein a width W5 of the notch portion and a groove width W2 of the outermost circumferential main groove have a relationship of 0.2≤W5 / W2≤0.4.
12. The depth D5 of the notch and the groove depth D2 of the outermost circumferential main groove have a relationship of 0.60 ≦ D5 / D2 ≦ 1.00. Rehabilitation tire.
13. The retread tire according to any one of claims 1 to 12, wherein a groove area ratio A of the entire tread pattern is in a range of 0.20 ≦ A ≦ 0.35.
14. The groove area ratio Ac of the land portion inside the tire width direction adjacent to the outermost circumferential main groove and the groove area ratio As of the land portion outside the tire width direction are in a range of 1.5 ≦ Ac / As. Item 14. The retread tire according to any one of Items 1 to 13.
15. The retread tire according to any one of claims 1 to 14, which has a flatness ratio of 70% or less.

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