JP5987099B2 - Vulcanized tread and tire manufacturing method - Google Patents

Description

  The present invention relates to a vulcanized tread formed with a tread pattern and vulcanized in advance, and a tire manufacturing method in which a vulcanized tread and a base tire are bonded with unvulcanized rubber and then vulcanized.

  Conventionally, a pre-vulcanized tread portion (referred to as a vulcanized tread) and a tire basic structure portion excluding the tread portion (referred to as a base tire) are manufactured separately and then vulcanized via an unvulcanized rubber for bonding. There is a tire manufacturing method (referred to as a precure method) in which a vulcanized tread and a base tire are bonded together by bonding a vulcanized tread and a base tire and vulcanizing an unvulcanized rubber (refer to Patent Document 1). A tire manufacturing method using a precure method has been attracting attention in recent years because it can be applied to rehabilitation of used tires. In particular, it is used for rehabilitation processing of large vehicle tires such as buses and trucks that have a relatively high frequency of tire replacement.

  A rib pattern is frequently applied to large vehicle tires from the viewpoint of wear resistance and the like. However, in rib-pattern tires, uneven wear tends to occur at the circumferential edge of the circumferential groove formed in the shoulder region on the outer side in the tire width direction, and the tread portion is difficult to come off when stones are clogged in the circumferential groove. It becomes a problem to speed up.

  Thus, tires having a structure that suppresses uneven wear and tires in which a protrusion is formed at the bottom of the circumferential groove have been proposed as a structure that prevents clogging of the circumferential groove (Patent Documents 2 and 3). reference). In recent years, tires having a characteristic structure such as the protrusions in the grooves described above have also been manufactured by the precure method.

JP-A-8-104108 JP 2001-206015 A JP 2009-61886 A

  However, since the pre-cure type tire manufacturing method has a specific process, tire molding defects may occur. That is, in the precure method, the vulcanization treatment is performed inside the vulcanization chamber in a state where the base tire to which the vulcanized tread is adhered is wrapped in a rubber bag.

  In the vulcanization treatment, the rubber bag is brought into close contact with the surface of the vulcanized tread. Therefore, as in Patent Documents 2 and 3, the protrusion is formed at the bottom of the circumferential groove, and the length in the groove width direction in the groove of the protrusion is larger than the length in the groove depth direction. If the shape is short, the protruding portion may be deformed by a rubber bag that is in close contact with the tread portion, or the base portion of the protruding portion may be separated from the unvulcanized rubber due to the deformation of the protruding portion. There was a thing.

  Therefore, the present invention relates to a vulcanized tread that can prevent the occurrence of molding defects in the manufacturing process in the tire manufacturing method in which the vulcanized tread is joined to the base tire, and the vulcanized tread that can prevent the occurrence of molding defects in the manufacturing process. It aims at providing the tire manufacturing method using this.

  In order to solve the above-described problems, the present invention is characterized by having a sticking surface (sticking surface 11B) attached to a base tire (base tire 12) and a grounding surface (surface 11A) that contacts the road surface. A vulcanized tread (vulcanized tread 11) that has been vulcanized in advance, and is recessed in the grounding surface from at least the grounding surface toward the sticking surface, and the longitudinal direction of the vulcanized tread. (Circumferential grooves 31, 32) extending from the bottom of the groove to the grounding surface side, and a protrusion (protrusion 51) extending in the longitudinal direction is formed, and the groove is formed by the protrusion. The first groove and the second groove are partitioned, and the groove width (Wa) of the first groove in the tire width direction is wider than the groove width (Wb) of the second groove in the tire width direction. In the state of being attached to the tire, the protrusion on the outer side in the tire radial direction of the protrusion The length (Lcu) of the protruding portion in the tire width direction is shorter than the length (Lcb) of the protruding portion in the tire width direction of the bottom portion, and the surface of the protruding portion on the grounding surface side and the first of the protruding portions are arranged. Of the first portion where the side wall on the first groove side is continuous and the second portion (edge R) where the surface on the ground surface side of the protruding portion and the side wall on the second groove side of the protruding portion are continuous. The gist is that only the second part is chamfered.

  In the vulcanized tread according to the present invention, the chamfering process is performed on a portion where the surface on the ground contact surface side of the projecting portion and the side wall of the second groove are continuous. Therefore, in the process of manufacturing the vulcanized tread, A part of them easily enters the second groove formed with a relatively small interval.

  Therefore, when the vulcanized tread according to the present invention is applied to a tire manufacturing method in which a vulcanized tread and a base tire are bonded with unvulcanized rubber and then vulcanized, the second groove having a narrow groove width is used. The rubber bag can easily enter the groove, and deformation due to the protrusion being pressed against the rubber bag and a problem of separation between the portion where the protrusion is formed and the unvulcanized rubber can be prevented. Thereby, generation | occurrence | production of a molding defect can be prevented in the manufacturing process of a tire.

  ADVANTAGE OF THE INVENTION According to this invention, the tire manufacturing method using the vulcanized tread which can prevent generation | occurrence | production of a molding defect in the manufacturing process of a tire, and the vulcanized tread which can prevent generation | occurrence | production of a molding defect in a manufacturing process can be provided.

FIG. 1 is a cross-sectional view in the tread width direction and the tire radial direction of a tire manufactured using the vulcanized tread according to the embodiment. FIG. 2 is an enlarged view of a part of the vulcanized tread according to the embodiment. 3 is a cross-sectional view taken along line AA in FIG. FIG. 4 is a flowchart for explaining a tire manufacturing method using the vulcanized tread according to the embodiment. Fig.5 (a) is a schematic diagram explaining the state of the vulcanized tread in the sealing process of the tire manufacturing method using the conventional vulcanized tread. FIG. 5B is a schematic diagram for explaining the state of the vulcanized tread in the sealing process packed in the rubber bag 100 in the tire manufacturing method according to the embodiment. FIG. 6 is a cross-sectional view of a modified example of the vulcanized tread. FIG. 7 is a cross-sectional view of a modified example of the vulcanized tread.

  An embodiment of a vulcanized tread according to the present invention will be described with reference to the drawings. Specifically, (1) description of schematic configuration of tire, (2) configuration of circumferential groove, (3) description of tire manufacturing method, (4) action and effect, (5) modification, (6) other The embodiment will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

(1) Explanation of schematic structure of tire The structure of the tire 1 manufactured using the vulcanized tread which concerns on embodiment is demonstrated, referring drawings. FIG. 1 is a cross-sectional view of the tire 1 in the tread width direction and the tire radial direction. FIG. 2 is an enlarged view of a part of the vulcanized tread constituting the tire 1.

  The tire 1 includes a tread portion 11, a base tire 12, and a cushion rubber 13 that bonds the tread portion 11 and the base tire 12. The tire 1 is formed by adhering a vulcanized tread and a base tire formed in advance through an unvulcanized rubber, and joining the vulcanized tread and the base tire by vulcanizing the unvulcanized rubber. It is manufactured by a so-called precure method.

  The tread portion 11 is formed of a rubber material used for a normal tire, and has a surface 11A on which a tread pattern is formed and an attaching surface 11B attached to the base tire 12. The tread portion 11 is hereinafter referred to as a vulcanized tread 11 because a tread pattern is formed on the surface 11A and vulcanization is performed. The surface 11A constitutes a contact surface that contacts the road surface.

  Grooves 31 and 32 extending in a predetermined direction are formed on the surface 11A of the vulcanized tread 11. The grooves 31 and 32 have bottom portions 31B and 32B that are recessed from at least the surface 11A toward the sticking surface 11B. Here, the predetermined direction is a tire circumferential direction in a state where the vulcanized tread 11 is adhered to the base tire 12. That is, the vulcanized tread 11 is bonded to the crown portion 12 </ b> A of the base tire 12 so that the extending direction of the grooves 31 and 32 coincides with the tire circumferential direction of the base tire 12. The grooves 31 and 32 are referred to as circumferential grooves 31 and 32.

  Further, the vulcanized tread 11 is formed with grooves 41 and 42 along an orthogonal direction orthogonal to the direction in which the grooves 31 and 32 extend. The orthogonal direction is a tread width direction in a state where the vulcanized tread 11 is stuck to the base tire 12.

  The base tire 12 includes a crown portion 12A, a sidewall portion 12B that constitutes a side surface of the tire, and a bead portion 12C that comes into contact with the rim wheel. The base tire 12 includes a pair of bead cores 21 and a carcass layer 22 that is a skeleton of the base tire 12. An inner liner 23 that is a highly airtight rubber layer corresponding to a tube is provided inside the carcass layer 22 in the tire radial direction. Both ends of the carcass layer 22 are supported by a pair of bead cores 21. A belt layer 24 is disposed outside the carcass layer 22 in the tire radial direction. The belt layer 24 includes a first belt layer 24a and a second belt layer 24b in which a steel cord is covered with rubber.

(2) Configuration of circumferential groove Next, the configuration of the circumferential groove will be described. 3 is a cross-sectional view taken along line AA in FIG. The circumferential groove 32 formed on the surface 11A of the vulcanized tread 11 is recessed at least from the surface 11A toward the sticking surface 11B, and from the bottom 32B on the sticking surface 11B side than the surface 11A, and the bottom 32B. It has the 1st groove | channel side part 32a and the 2nd groove | channel side part 32b which continue to the surface 11A. The circumferential groove 32 is formed with a protruding portion 51 that protrudes from the bottom 32B toward the surface 11A and continues in the tire circumferential direction. The circumferential groove 32 includes a first groove 321 and a second groove 322 defined by the protruding portion 51.

  The protrusion 51 is connected to the first side 51a along the tire circumferential direction, the second side 51b opposite to the first side 51a, the first side 51a and the second side 51b, and has a surface 11A. It has upper part 51s located in the sticking surface 11B side rather than.

  The bottom portion 32B of the circumferential groove 32 is divided into a first bottom portion 32c and a second bottom portion 32d by the protruding portion 51. The first bottom portion 32c is continuous with the first side portion 51a and a groove side portion 32a that is one side portion of the circumferential groove 32 facing the first side portion 51a. The second bottom portion 32d is continuous with the second side portion 51b and a groove side portion 32b that is the other side portion of the circumferential groove 32 facing the second side portion 51b.

  The interval Wa between the first side portion 51a and the groove side portion 32a (that is, the groove width in the tire width direction of the first groove 321) is the interval Wb between the second side portion 51b and the groove side portion 32b (that is, the second width). It is wider than the groove width 322 in the tire width direction. That is, Wa> Wb.

  In the embodiment, the interval Wa can be set to 4.0 to 10.0 mm. Further, the interval Wb can be set to 1.5 to 6.0 mm.

  Further, a depth Da (groove depth of the first groove 321) from the surface 11A to the first bottom portion 32c can be set to a depth Da = 10.0 mm to 20.0 mm. The depth Db from the surface 11A to the second bottom portion 32d (the groove depth of the second groove 322) can be set to the depth Db = 8.0 to 18.0 mm.

  In the embodiment, the first groove 321 having a relatively wide groove width and a deep groove depth is formed outside the second groove 322 in the tire width direction.

  In the embodiment, the length Lcu in the intersecting direction (tread width direction) C intersecting the longitudinal direction of the upper portion 51s in the protrusion 51 is shorter than the length Lcb in the intersecting direction C on the bottom 32B side of the protrusion 51. Chamfering is applied to the edge R where the 51s and the second side 51b are connected. Here, the crossing direction C corresponds to the tire width direction W in a state where the crossing direction C is bonded to the base tire bonded via the cushion rubber 13 in the embodiment.

(3) Description of Tire Manufacturing Method FIG. 4 is a flowchart illustrating a tire manufacturing method using the vulcanized tread 11 according to the embodiment. The tire manufacturing method according to the embodiment is a tire manufacturing method using a so-called precure method. There are a step (S1) for manufacturing the base tire 12, and a step (S2) for manufacturing the vulcanized tread 11 by forming a tread pattern on the rubber material constituting the tread portion and vulcanizing.

  Next, the vulcanized tread 11 and the base tire 12 manufactured by separate processes are bonded together. First, a cushion rubber arrangement step (S3) is performed. In the cushion rubber placement step, unvulcanized rubber (cushion rubber 13) is placed on the crown portion 12A of the base tire 12. Subsequently, the vulcanized tread 11 is attached to the base tire 12 via the cushion rubber 13 (S4).

  Subsequently, an enclosing step of enclosing the base tire 12 to which the vulcanized tread 11 is attached in a rubber bag is performed. In the enclosing step, the base tire 12 is encapsulated and packed in a rubber bag (S5). In the sealing step, a rubber bag (see FIG. 5 described later) is formed between the first side portion 51a and the first groove side portion 32a, and at the edge portion R where the chamfered upper portion 51s and the second side portion 51b are continuous. The base tire 12 to which the vulcanized tread 11 is adhered is covered with a rubber bag so that a part of the rubber bag 100 shown in FIG. Next, a vulcanization process is performed. In the vulcanization step, the base tire 12 to which the vulcanized tread 11 packed in a rubber bag is attached is vulcanized under a predetermined temperature / pressure condition (S6). By vulcanizing the cushion rubber 13 by the vulcanization process, the vulcanized tread 11 and the base tire 12 are joined, and the tire 1 is manufactured.

  In the final inspection step (S7), the presence or absence of defects such as scratches on the tire 1 after vulcanization, pressure resistance, and the like are inspected. In the final inspection process, tires that meet certain standards become products.

  This tire manufacturing method can be applied to renewal treatment of used tires. In this case, instead of the step (S1) of manufacturing the base tire, a step of inspecting whether the collected used tire can be renewed, a step of scraping the tread portion from the used tire, and the like are executed. A retread tire can be manufactured by performing the process after a cushion rubber arrangement | positioning process (S3) to the base tire from which the tread part was scraped off from the used tire.

(4) Action / Effect FIG. 5A is a schematic diagram for explaining a state of a vulcanized tread in an encapsulation process of a tire manufacturing method using a conventional vulcanized tread. FIG. 5B is a schematic diagram for explaining the state of the vulcanized tread in the sealing process packed in the rubber bag 100 in the tire manufacturing method according to the embodiment.

  As shown in FIG. 5B, in the vulcanized tread 11, the upper portion 51s is located closer to the sticking surface 11B than the surface 11A. Due to a dimensional difference between the surface 11A and the upper portion 51s in the tire radial direction, a braking force is generated in the upper portion 51s when the tire 1 rolls while being loaded. Further, in the vulcanized tread 11, the interval Wa between the first side portion 51a and the groove side portion 32a is wider than the interval Wb between the second side portion 51b and the groove side portion 32b.

  Thereby, the protrusion part 51 receives wear preferentially and the partial wear of the groove edge part of the circumferential groove | channel 31 can be suppressed. In particular, when the interval between the groove side portions on the outer side in the tire width direction of the grooves 32 divided by the protrusions 51 is widened, the uneven wear of the groove edge portion of the groove side portion 32a located on the outer side in the tread width direction of the tire 1 is suppressed. The effect can be improved.

  However, when a tire having the protruding portion 51 formed on the bottom of the circumferential groove 32 aiming at the above-described effect is manufactured by the precure method, a rubber bag is formed in the second groove 322 having a groove width narrower than the first groove 321. A part of 100 becomes difficult to enter. In this case, in the conventional vulcanized tread, as shown in FIG. 5A, in the step of being enclosed in the rubber bag 100 (S5), the protruding portion is pressed against a part of the rubber bag 100, Upon receiving a force in the direction of the arrow shown in FIG. 5A, the vulcanized tread 11 at the base portion of the protrusion and the cushion rubber 13 are separated (boundary region N shown in FIG. 5A) and lifted. There was a concern that problems such as (air entering) would occur.

  On the other hand, in the vulcanized tread 11, the length Lcu of the upper portion 51s of the protruding portion 51 is shorter than the length Lcb of the bottom portion 32B of the protruding portion 51, and the edge where the upper portion 51s and the second side portion 51b are continuous. The portion R is chamfered. For this reason, a part of the rubber bag 100 is likely to enter between the second side portion 51b and the second groove side portion 32b. Thereby, the deformation of the protrusion 51 itself and the fall of the protrusion 51 due to the protrusion 51 being pressed against the rubber bag 100 can be prevented, and the vulcanized tread 11 and the cushion rubber 13 at the base of the protrusion 51 can be prevented. It is possible to prevent problems such as separation of the boundary region N between the two. Therefore, according to the vulcanized tread 11, it is possible to prevent the occurrence of molding defects in the tire manufacturing process.

(5) Modification (5.1) Modification 1
FIG. 6 is a cross-sectional view of a vulcanized tread 111 shown as a modification. The vulcanized tread 111 has a protrusion 151 formed in the circumferential groove 132. The length Lcu in the intersecting direction C (tire width direction W) intersecting the predetermined direction of the protrusion 151 increases from the surface 111A toward the sticking surface 111B, and the length Lcu is equal to the length of the protrusion 151. It is shorter than the length Lcb of the bottom portion 132B. Chamfering is applied to an edge portion R1 where the upper portion 151s and the second side portion 151b are continuous, and an edge portion R2 where the upper portion 151s and the first side portion 151a are continuous.

  For this reason, a part of the rubber bag 100 easily enters between the second side portion 151b and the second groove side portion 132b. Moreover, a part of the rubber bag 100 is likely to enter between the first side portion 151a and the first groove side portion 132a. Therefore, the deformation of the protrusion 151 itself in the vulcanization process and the collapse of the protrusion 151 can be prevented, and problems such as separation between the vulcanized tread 111 and the cushion rubber 113 at the base of the protrusion 151 are prevented. it can. Therefore, according to the vulcanized tread 111, generation | occurrence | production of a molding defect can be prevented in the manufacture process of a tire.

(5.2) Modification 2
FIG. 7 is a cross-sectional view of a vulcanized tread 211 shown as a modification. The vulcanized tread 211 has a protrusion 251 formed in the circumferential groove 232. The length Lcu in the crossing direction (tire width direction W) intersecting the predetermined direction of the protrusion 251 increases from the surface 211A toward the sticking surface 211B, and the length Lcu is the bottom of the protrusion 251. It is shorter than the length Lcb on the 132B side. The depth Db from the surface 211A to the second bottom 232d is shallower than the depth Da from the surface 211A to the first bottom 232c. That is, Da> Db. Here, it is preferable that | Da−Db | <2 mm.

  Thereby, the strength at the base of the protruding portion 251, that is, the connecting portion with the bottom portion 232 </ b> B is increased. In particular, the second bottom portion 232d, in which the distance between the second side portion 251b and the second groove side portion 232b is relatively narrow, is formed shallower than the first bottom portion 232c. The strength against the movement in the direction in which the distance between the side portion 251b and the second groove side portion 232b is narrowed is further increased.

(6) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments and examples will be apparent to those skilled in the art. For example, the embodiment of the present invention can be modified as follows.

  For example, in the embodiment, it has been described that the interval Wa between the first side portion 51a and the groove side portion 32a is wider than the interval Wb between the second side portion 51b and the groove side portion 32b (Wa> Wb). However, it may be equally spaced (Wa = Wb).

  Further, in the embodiment, it has been described that the protruding portion 51 is formed in the circumferential groove 32. However, it may be formed in the circumferential groove 31. The protruding portion may be formed in the lateral groove 41.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is determined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  Twenty tires were manufactured using the vulcanized tread according to the embodiment and the conventional vulcanized tread, and the shape of the protruding portion and the entry of air into the boundary region N were inspected.

(Comparative tire)
・ Tire size: 275 / 70R22.5
The dimensions of each part of the tire shown in FIG. 3 are as follows.
Wa = 5.0mm, Wb = 1.5mm
Da = Db = 16.0 mm
No chamfer (Example tire)
・ Tire size: 275 / 70R22.5
-The dimensions of each part of the tire shown in FIG.
Wa = 5.0mm, Wb = 1.5mm
Da = Db = 16.0 mm
With chamfering Wa variation ΔWa was measured before and after attaching the vulcanized tread to the base tire. In addition, the number of occurrences of air per cross section generated after the vulcanized tread was attached to the base tire was counted. In Table 1, the cereal side is the side on which a stamp such as a serial number is formed, and the anti-cereal side is the opposite side of the cereal side. Twenty samples of Examples and Comparative Examples were produced, and the result was an average value of 20 samples. Table 1 shows.

  From the results shown in Table 1, it was found that in the tire manufactured using the vulcanized tread of the embodiment, the amount of change in the interval Wa was improved by 18%. It has also been found that the number of air in the tire after joining the vulcanized tread to the base tire is greatly improved.

  DESCRIPTION OF SYMBOLS 1 ... Tire, 11 ... Vulcanized tread (tread part), 11A ... Surface, 11B ... Adhering surface, 12 ... Base tire, 12A ... Crown part, 12B ... Side wall part, 12C ... Bead part, 13 ... Cushion rubber 21 ... Bead core, 22 ... Carcass layer, 23 ... Inner liner, 24 ... Belt layer, 24a ... First belt layer, 24b ... Second belt layer, 31, 32 ... Circumferential groove, 31B, 32B ... Bottom, 32a ... Groove side, 32b ... groove side, 32c ... first bottom, 32d ... second bottom, 41 ... lateral groove, 51 ... projection, 51a ... first side, 51b ... second side, 51s ... top, 100 ... rubber bag, 111 ... vulcanized tread, 111A ... surface, 111B ... sticking surface, 132 ... circumferential groove, 151 ... protrusion, 211 ... vulcanized tread, 11A ... surface, 211B ... sticking surface, 232 ... circumferential groove, 232b ... groove side, 251 ... projection, 251a ... first side, 251b ... second side, 311 ... vulcanized tread, 332 ... Circumferential groove, 332b ... groove side part, 351 ... projecting part, 351b ... second side part, 351s ... upper part, N ... boundary region, R ... edge part, W ... tire width direction, Wa ... interval, Wb ... interval

Claims (4)

A vulcanized tread having a bonding surface to be bonded to the base tire and a grounding surface to be grounded to a road surface,
In the ground contact surface, at least a recess from the ground contact surface toward the sticking surface, and a groove extending in a longitudinal direction of the vulcanized tread,
Projecting from the bottom of the groove to the grounding surface side, and a projecting portion continuous in the longitudinal direction is formed,
The groove includes a first groove and a second groove defined by the protrusion,
In the state of being attached to the base tire, the groove width in the tire width direction of the first groove is wider than the groove width in the tire width direction of the second groove,
The length of the protrusion in the tire width direction on the outer side in the tire radial direction of the protrusion is shorter than the length of the protrusion in the tire width direction of the bottom, and the surface on the grounding surface side of the protrusion and the protrusion A first portion that is continuous with the side wall on the first groove side, and a second portion where the surface on the grounding surface side of the protrusion and the side wall on the second groove side of the protrusion are continuous, A vulcanized tread with chamfering applied only to the second part.   The vulcanized tread according to claim 1, wherein a depth from the ground contact surface to a bottom portion of the first groove is deeper than a depth from the ground contact surface to a bottom portion of the second groove.   The vulcanized tread according to claim 1 or 2, wherein the first groove is formed on the outer side in the tire width direction than the second groove. A step of adhering a pre-vulcanized vulcanized tread having a tread pattern formed on a ground contact surface to be in contact with a road surface via an unvulcanized rubber, and the vulcanized tread was adhered A tire manufacturing method including an encapsulation step of encapsulating the base tire in a rubber bag, and a vulcanization step of vulcanizing the unvulcanized rubber,
As the vulcanized tread,
A groove extending in the longitudinal direction of the vulcanized tread, at least recessed from the ground contact surface toward the attachment surface with the base tire, on the ground contact surface;
Projecting from the bottom of the groove to the grounding surface side, and a projecting portion continuous in the longitudinal direction is formed,
The groove comprises a first groove and a second groove defined by the protrusion,
The groove width in the tire width direction of the first groove in the state adhered to the base tire is wider than the groove width in the tire width direction of the second groove,
The length of the protrusion in the tire width direction on the outer side in the tire radial direction of the protrusion is shorter than the length of the protrusion in the tire width direction of the bottom, and the surface on the grounding surface side of the protrusion and the protrusion A first portion that is continuous with the side wall on the first groove side, and a second portion where the surface on the grounding surface side of the protrusion and the side wall on the second groove side of the protrusion are continuous, Only the second part is chamfered,
The depth from the grounding surface to the bottom of the first groove is deeper than the depth from the grounding surface to the bottom of the second groove,
The first groove uses a vulcanized tread formed on the outer side in the tire width direction than the second groove,
In the encapsulation step,
A tire characterized in that the base tire is covered with a rubber bag so that a part of the rubber bag is in contact with at least the groove of the first groove and the second portion subjected to the chamfering process. Production method.