JP2010111337A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire enabling improvement of durability by effectively preventing oxidation deterioration of bead parts. <P>SOLUTION: In this pneumatic tire, a carcass layer 4 is stretched between the pair of bead parts, an inner liner layer 7 is arranged on a tire inner cavity side from the carcass layer 4, a tie-rubber layer 8 is interposed between the carcass layer 4 and the inner liner layer 7, and an end part on the tire inner cavity side of a chafer 9 for protecting the bead part is inserted between the carcass layer 4 and the inner liner layer 7. The inner liner layer 7 is made of a thermoplastic resin or a thermoplastic elastomer composition containing a blend of the thermoplastic resin and an elastomer. A lower end position 8e of the tie-rubber layer 8 is arranged at the same position as a lower end position 7e of the inner liner layer 7 or at the tire radial direction outside of the lower end position 7e. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire provided with an inner liner layer made of a thermoplastic elastomer composition containing a thermoplastic resin or a blend of a thermoplastic resin and an elastomer, and more specifically, effectively prevents oxidative deterioration of a bead portion. In addition, the present invention relates to a pneumatic tire that can improve its durability.

  In recent years, it has been proposed to arrange a film layer made of a thermoplastic elastomer composition containing a thermoplastic resin or a blend of a thermoplastic resin and an elastomer on the inner surface of the tire as an inner liner layer.

  In such a pneumatic tire, a carcass layer is mounted between a pair of bead portions, an inner liner layer is disposed closer to the tire lumen than the carcass layer, and both are disposed between the carcass layer and the inner liner layer. A tie rubber layer is interposed to improve the adhesion. Moreover, when providing the chafer for protecting a bead part, inserting the edge part of the tire lumen side of a chafer between a carcass layer and an inner liner layer is performed (for example, patent document 1). reference).

  FIG. 6 is a cross-sectional view schematically showing a bead portion in a conventional pneumatic tire. As shown in FIG. 6, the carcass layer 4 is wound up so as to wrap the bead core 5 and the bead filler 6, and the inner liner layer 7 is disposed closer to the tire lumen than the carcass layer 4. A tie rubber layer 8 is disposed between the two. The end portion on the tire lumen side of the chafer 9 that protects the bead portion is disposed between the inner liner layer 7 and the tie rubber layer 8.

  Here, the lower end position 7e of the inner liner layer 7 is arranged on the outer side in the tire radial direction than the bead toe T. This is because the inner liner layer 7 having a thermoplastic resin as a matrix has higher rigidity than that composed of butyl rubber, so that the inner liner layer 7 has dimensions that extend beyond the bead toe, This is because wrinkles are generated in the inner liner layer 7 when the carcass layer 4 is wound around the bead core 5 during tire molding. On the other hand, the lower end position 8 e of the tie rubber layer 8 is disposed on the inner side in the tire radial direction than the lower end position 7 e of the inner liner layer 7.

However, as described above, the lower end position 8e of the tie rubber layer 8 is located on the inner side in the tire radial direction from the lower end position 7e of the inner liner layer 7, and the tie rubber layer 8 that is generally not blended with an anti-aging agent is If it is present in the vicinity of the bead toe in an uncovered state, there is a problem that the elongation at break of the portion decreases due to oxidative deterioration or the like, and a separation failure starting from the edge of the tie rubber layer 8 tends to occur. In particular, such a separation failure is more likely to occur due to repeated operations of attaching and detaching the pneumatic tire and the rim.
Japanese Patent Laid-Open No. 10-81108

  The object of the present invention is to effectively prevent oxidative deterioration of the bead portion even when the inner liner layer is made of a thermoplastic elastomer composition containing a thermoplastic resin or a blend of a thermoplastic resin and an elastomer, An object of the present invention is to provide a pneumatic tire capable of improving its durability.

  In order to achieve the above object, the pneumatic tire of the present invention has a carcass layer mounted between a pair of bead portions, and an inner liner layer is disposed closer to the tire lumen than the carcass layer. In a pneumatic tire in which a tie rubber layer is interposed between the inner liner layer and an end portion on the tire lumen side of a chafer that protects the bead portion is inserted between the carcass layer and the inner liner layer, The inner liner layer is made of a thermoplastic elastomer composition containing a thermoplastic resin or a blend of a thermoplastic resin and an elastomer, and the lower end position of the tie rubber layer is the same position as or lower than the lower end position of the inner liner layer. It arrange | positions at the radial direction outer side.

  In the present invention, in a pneumatic tire in which an end portion on the tire lumen side of a chafer protecting a bead portion is inserted between a carcass layer and an inner liner layer, the inner liner layer is a thermoplastic resin or a thermoplastic elastomer composition. The tie rubber layer generally containing no anti-aging agent is disposed on the inner liner layer by disposing the lower end position of the tie rubber layer at the same position as the lower end position of the inner liner layer or on the outer side in the tire radial direction. Therefore, it is possible to effectively prevent oxidative degradation of the bead portion and improve the durability of the pneumatic tire.

  In the present invention, the lower end position of the inner liner layer is preferably disposed on the outer side in the tire radial direction than the bead toe. This is because the inner liner layer with a thermoplastic resin matrix is more rigid than the one made of butyl rubber, so if the inner liner layer has dimensions that extend beyond the bead toe, This is because when the carcass layer is sometimes rolled up around the bead core, wrinkles are generated in the inner liner layer. On the other hand, the lower end position of the inner liner layer is preferably disposed in a region of 35% or less of the tire cross-sectional height. Thereby, the air permeation prevention function can be sufficiently exhibited.

  The end portion on the tire lumen side of the chafer can be disposed at any position between the carcass layer and the inner liner layer. For example, the end portion on the tire lumen side of the chafer can be disposed between the tie rubber layer and the carcass layer. Further, the end portion of the chafer on the tire lumen side can be disposed between the tie rubber layer and the inner liner layer. Further, the tie rubber layer and the chafer may be arranged so as not to overlap each other. In this case, the distance in the tire radial direction between the tie rubber layer and the chafer is preferably 3 mm or more. If this separation distance is too small, an air pool is likely to occur in the gap, which causes a vulcanization failure.

  In order to prevent oxidative deterioration of the bead portion, it is also effective to add an anti-aging agent to the rubber composition constituting the chafer. In this case, it is possible to prevent the bead toe from being lost during the rim attaching / detaching operation.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire according to an embodiment of the present invention, and FIG. 2 schematically shows a bead portion in the pneumatic tire of FIG.

  In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. A carcass layer 4 is mounted between the pair of left and right bead portions 3, 3, and an end portion of the carcass layer 4 is folded around the bead core 5 from the inside of the tire to the outside. The bead filler 6 disposed on the bead core 5 is wrapped with the carcass layer 4 together with the bead core 5.

  An inner liner layer 7 made of a thermoplastic resin or a thermoplastic elastomer composition is disposed on the tire lumen side of the carcass layer 4 so as to substantially cover the inner surface of the tire. A tie rubber layer 8 is interposed between the carcass layer 4 and the inner liner layer 7. The chafer 9 for protecting the bead portion 3 includes a sheet material formed by rubber-coating an aligned reinforcing cord or reinforcing cloth, a sheet material formed from a rubber composition containing short fibers, or a peripheral rubber member. It is made of a sheet material made of a rubber composition that is more excellent in wear resistance. The chafer 9 is disposed so as to cover the inner peripheral side portion of the bead portion 3 that contacts the rim sheet, and the end portion of the chafer 9 on the tire lumen side is between the carcass layer 4 and the inner liner layer 7. Has been inserted. More specifically, as shown in FIG. 2, the chafer 9 has a laminated structure in which the end portion on the tire lumen side is disposed between the tie rubber layer 8 and the carcass layer 4. Further, the lower end position 8 e of the tie rubber layer 8 is disposed on the outer side in the tire radial direction than the lower end position 7 e of the inner liner layer 7.

  On the other hand, a plurality of belt layers 10 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 10 are disposed such that the reinforcing cords are inclined with respect to the tire circumferential direction, and the reinforcing cords cross each other between the layers. Further, a belt reinforcing layer formed by continuously winding a reinforcing cord in the tire circumferential direction may be disposed on the outer peripheral side of the belt layer 10.

  According to the pneumatic tire, the end portion of the chafer 9 that protects the bead portion 3 on the tire lumen side is inserted between the carcass layer 4 and the inner liner layer 7, and the inner liner layer 7 is made of the thermoplastic resin. Alternatively, when the thermoplastic elastomer composition is used, the lower end position 8e of the tie rubber layer 8 is arranged on the outer side in the tire radial direction from the lower end position 7e of the inner liner layer 7, so that the anti-aging agent is generally not blended. Since it is avoided that 8 exists in the vicinity of bead toe T in the state where it is not covered with inner liner layer 7, oxidation degradation of bead part 3 can be prevented effectively and durability of a pneumatic tire can be improved. it can.

  In the pneumatic tire, as shown in FIG. 2, the lower end position 7 e of the inner liner layer 7 is preferably disposed outside the bead toe T in the tire radial direction. When the inner liner layer 7 has such a dimension that the lower end position 7e of the inner liner layer 7 extends beyond the bead toe T, when the carcass layer 4 is rolled up around the bead core 5 at the time of tire molding, a thermoplastic resin is used. May cause wrinkles in the highly rigid inner liner layer 7 having a matrix. On the other hand, the lower end position 7e of the inner liner layer 7 is preferably disposed in a region of 35% or less of the tire cross-section height SH. That is, for the reasons described above, it is desirable to dispose the lower end position 7e of the inner liner layer 7 on the outer side in the tire radial direction from the bead toe T. However, the lower end position 7e is smaller than the position of 35% of the tire cross-section height SH. If it is located on the outer side in the direction, the air permeation preventing performance based on the inner liner layer 7 is lowered.

  As long as the end portion of the chafer 9 on the tire lumen side is between the carcass layer 4 and the inner liner layer 7, it can be arranged at an arbitrary position different from that in FIG. 2. In FIG. 3, the end portion of the chafer 9 on the tire lumen side is disposed between the tie rubber layer 8 and the inner liner layer 7, and the lower end position 8 e of the tie rubber layer 8 is more tire than the lower end position 7 e of the inner liner layer 7. Arranged radially outside. In FIG. 4, the end portion of the chafer 9 on the tire lumen side is disposed between the tie rubber layer 8 and the inner liner layer 7, and the lower end position 8e of the tie rubber layer 8 is equal to the lower end position 7e of the inner liner layer 7 and the tire diameter. Arranged at the same position in the direction. 2 to 4, the end portion of the chafer 9 on the tire lumen side is on the outer side in the tire radial direction from the lower end position 8 e of the tie rubber layer 8. The end portion is preferably disposed at a position 3 mm or more away from the lower end position 8e of the tie rubber layer 8 in the tire radial direction outer side. If the ends of the chafer 9 and the tie rubber layer 8 are close to each other, separation is likely to occur.

  In FIG. 5, the tie rubber layer 8 and the chafer 9 are arranged so as not to overlap each other. In this case, the distance t in the tire radial direction between the tie rubber layer 8 and the chafer 9 is preferably 3 mm or more. If the separation distance t is less than 3 mm, an air stagnation is likely to occur in the gap surrounded by the carcass layer 4, inner liner layer 7, tie rubber layer 8, and chafer 9, which causes a vulcanization failure.

  In the pneumatic tire, for example, a cylindrical inner liner layer is disposed around a molding drum, and a tire constituent member such as a tie rubber layer, a chafer, a carcass layer, a bead core, a bead filler, and a sidewall rubber is pasted thereon. The primary green tire is molded together, and the secondary green tire is molded by bonding the belt layer and the tread rubber while expanding the primary green tire in a toroidal shape, and then vulcanizing the secondary green tire. It is obtained by. Therefore, the lower end position 7e of the inner liner layer 7 and the lower end position 8e of the tie rubber layer 8 can be arbitrarily set based on the width (dimension in the drum axis direction) of each member.

  As another method for preventing the oxidative deterioration of the bead portion 3, it is also effective to add an anti-aging agent to the rubber composition constituting the chafer 9. As such an anti-aging agent, paraphenylenediamine-based [for example, N-phenyl-N′-isopropyl-p-phenylenediamine, N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine N, N'-diphenyl-p-phenylenediamine], diphenylamine type [for example, alkylated diphenylamine mixture], amine-ketone reaction product [for example, poly (1,2-dihydro-2,2,4-trimethylquinoline) ), 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline], imidazole [eg 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole], monophenol [eg mono (α -Methylbenzyl) phenol, 2,6-di-tert-butyl-4-methylphenol And bisphenol-based [for example, 2,2′-methylenebis (4-methyl-6-tert-butylphenol], special waxes (for example, paraffin wax), etc. In the rubber composition, the blending amount of the anti-aging agent with respect to 100 parts by weight of the rubber is preferably 0.5 to 5.0 parts by weight.

  Below, the inner liner layer in this invention is demonstrated. This inner liner layer can be composed of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer.

  Examples of the thermoplastic resin used in the present invention include polyamide resins [for example, nylon 6 (N6), nylon 66 (N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12), nylon 610 (N610), nylon 612 (N612), nylon 6/66 copolymer (N6 / 66), nylon 6/66/610 copolymer (N6 / 66/610), nylon MXD6, nylon 6T, nylon 6 / 6T copolymer, nylon 66 / PP copolymer, nylon 66 / PPS copolymer], polyester resin [for example, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), polybutylene terephthalate / Tetramethylene glycol copolymer, PET PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, aromatic polyester such as polyoxyalkylene diimide diacid / polybutylene terephthalate copolymer], polynitrile resin [for example, polyacrylonitrile ( PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / styrene copolymer, methacrylonitrile / styrene / butadiene copolymer], poly (meth) acrylate resin [eg polymethacryl Acid methyl (PMMA), polyethyl methacrylate, ethylene ethyl acrylate copolymer (EEA), ethylene acrylic acid copolymer (EAA), ethylene methyl acrylate resin (EMA)], polyvinyl resin [for example, vinyl acetate (EVA), polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate Copolymer], cellulose resin [eg, cellulose acetate, cellulose acetate butyrate], fluorine resin [eg, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene Copolymer (ETFE)], imide resin [for example, aromatic polyimide (PI)] and the like.

  Examples of the elastomer used in the present invention include diene rubbers and hydrogenated products thereof [for example, NR, IR, epoxidized natural rubber, SBR, BR (high cis BR and low cis BR), NBR, hydrogenated NBR, Hydrogenated SBR], olefin rubber [eg ethylene propylene rubber (EPDM, EPM), maleic acid modified ethylene propylene rubber (M-EPM)], butyl rubber (IIR), isobutylene and aromatic vinyl or diene monomer copolymer, Acrylic rubber (ACM), ionomer, halogen-containing rubber [for example, Br-IIR, Cl-IIR, brominated product of isobutylene paramethylstyrene copolymer (Br-IPMS), chloroprene rubber (CR), hydrin rubber (CHC, CHR), Chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM), maleic acid-modified chlorinated polyethylene (M-CM)], silicone rubber (eg, methyl vinyl silicone rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber), sulfur-containing rubber (eg, polysulfide rubber), fluoro rubber (eg, Vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicone rubber, fluorine-containing phosphazene rubber), thermoplastic elastomer (eg, styrene elastomer, olefin elastomer, polyester elastomer, And urethane elastomers and polyamide elastomers).

  In the thermoplastic elastomer composition used in the present invention, the composition ratio of the thermoplastic resin component (A) and the elastomer component (B) may be appropriately determined depending on the balance of the thickness and flexibility of the film layer, but is preferably within a preferable range. Is 10/90 to 90/10, more preferably 20/80 to 85/15 (weight ratio).

  In the thermoplastic elastomer composition according to the present invention, in addition to the essential components (A) and (B), as a third component, other polymers such as a compatibilizer and a compounding agent can be mixed. The purpose of mixing other polymers is to improve the compatibility between the thermoplastic resin component and the elastomer component, to improve the film molding processability of the material, to improve heat resistance, to reduce costs, etc. Examples of the material used for this include polyethylene, polypropylene, polystyrene, ABS, SBS, and polycarbonate.

The thermoplastic elastomer composition is prepared by melt-kneading a thermoplastic resin and an elastomer (unvulcanized material in the case of rubber) in advance using a twin-screw kneading extruder or the like, and adding an elastomer component in the thermoplastic resin forming a continuous phase. It is obtained by dispersing. When the elastomer component is vulcanized, a vulcanizing agent may be added under kneading to dynamically vulcanize the elastomer. Further, various compounding agents (excluding the vulcanizing agent) for the thermoplastic resin or the elastomer component may be added during the kneading, but it is preferable to mix them in advance before kneading. The kneading machine used for kneading the thermoplastic resin and the elastomer is not particularly limited, and examples thereof include a screw extruder, a kneader, a Banbury mixer, and a biaxial kneading extruder. Among these, it is preferable to use a twin-screw kneading extruder for kneading the resin component and the rubber component and for dynamic vulcanization of the rubber component. Further, two or more types of kneaders may be used and kneaded sequentially. As conditions for melt-kneading, the temperature may be higher than the temperature at which the thermoplastic resin melts. The shear rate during kneading is preferably 2500 to 7500 sec ⁻¹ . The entire kneading time is from 30 seconds to 10 minutes, and when a vulcanizing agent is added, the vulcanization time after addition is preferably from 15 seconds to 5 minutes. The thermoplastic elastomer composition produced by the above method is formed into a film by molding with a resin extruder or calender molding. The method for forming a film may be a method of forming a film of a normal thermoplastic resin or thermoplastic elastomer.

  The thin film of the thermoplastic elastomer composition thus obtained has a structure in which the elastomer is dispersed as a discontinuous phase in a thermoplastic resin matrix. By adopting the dispersion structure in such a state, it is possible to set the Young's modulus in the standard atmosphere as defined by JIS K7100 in the range of 1 to 500 MPa and to impart appropriate rigidity as a tire constituent member.

  The thermoplastic resin or thermoplastic elastomer composition can be molded into a sheet or film and embedded alone in the tire, but an adhesive layer may be laminated to improve the adhesion to the adjacent rubber. good. Specific examples of the adhesive polymer constituting the adhesive layer include ultrahigh molecular weight polyethylene (UHMWPE), ethylene ethyl acrylate copolymer (EEA), ethylene methyl acrylate resin (EMA) having a molecular weight of 1 million or more, preferably 3 million or more. ), Acrylate copolymers such as ethylene acrylic acid copolymer (EAA) and their maleic anhydride adducts, polypropylene (PP) and its maleic acid modification, ethylene propylene copolymer and its maleic acid modification, Polybutadiene resin and its modified maleic anhydride, styrene-butadiene-styrene copolymer (SBS), styrene-ethylene-butadiene-styrene copolymer (SEBS), fluorine thermoplastic resin, polyester thermoplastic resin, etc. Can be mentioned. These can be extruded into a sheet shape or a film shape by a conventional method, for example, by a resin extruder. The thickness of the adhesive layer is not particularly limited, but it is preferable that the thickness is small in order to reduce the weight of the tire, and 5 μm to 150 μm is preferable.

  The tire size is 225 / 40R18, a carcass layer is mounted between a pair of bead portions, an inner liner layer is disposed closer to the tire lumen than the carcass layer, and between the carcass layer and the inner liner layer. In a pneumatic tire in which a tie rubber layer is interposed and an end portion on the tire lumen side of a chafer that protects a bead portion is inserted between a carcass layer and an inner liner layer, the inner liner layer is made of a thermoplastic resin (nylon 6 66) and an elastomer (brominated butyl rubber), and tires of conventional examples and examples 1 to 5 were manufactured with various tie rubber layers and chafer arrangements. The inner liner layer had a thickness of 50 μm, and the tie rubber layer had a thickness of 500 μm.

  As shown in FIG. 6, in the tire of the conventional example, the end portion on the tire lumen side of the chafer is disposed between the tie rubber layer and the inner liner layer, and the lower end position of the tie rubber layer is set from the lower end position of the inner liner layer. Is also arranged on the inner side in the tire radial direction.

  In the tire of Example 1, as shown in FIG. 2, the end portion on the tire lumen side of the chafer is disposed between the tie rubber layer and the carcass layer, and the lower end position of the tie rubber layer is set lower than the lower end position of the inner liner layer. Is also arranged at a position of 2 mm outward in the tire radial direction.

  In the tire of Example 2, as shown in FIG. 3, the tire lumen end of the chafer is disposed between the tie rubber layer and the inner liner layer, and the lower end position of the tie rubber layer is the lower end position of the inner liner layer. It is arranged at a position of 2 mm outward in the tire radial direction.

  In the tire of Example 3, as shown in FIG. 4, the end portion of the chafer on the tire lumen side is disposed between the tie rubber layer and the inner liner layer, and the lower end position of the tie rubber layer is the lower end position of the inner liner layer. Are arranged at the same position.

  In the tire of Example 4, as shown in FIG. 5, the tie rubber layer and the chafer are arranged so as not to overlap each other between the inner liner layer and the carcass layer, and the separation distance between the tie rubber layer and the chafer is set. 3 mm.

  In the tire of Example 5, as shown in FIG. 2, the end portion on the tire lumen side of the chafer is disposed between the tie rubber layer and the carcass layer, and the lower end position of the tie rubber layer is set lower than the lower end position of the inner liner layer. Also, an anti-aging agent is blended in the rubber composition constituting the chafer while being arranged at a position of 2 mm outward in the tire radial direction.

  The durability of these test tires was evaluated by the following test method, and the results are shown in Table 1.

durability:
Each test tire is assembled on a wheel with a rim size of 18 × 8J, filled with air pressure of 230 kPa, left in an oven at a temperature of 50 ° C. for 2 weeks without load, and then again air pressure is set to 230 kP, which is 100% of the load capacity specified by JATMA. The vehicle was run at a speed of 80 km / h while being loaded, and when the damage that could be confirmed by visual appearance occurred in the bead portion, the run was terminated and the travel distance was measured. The evaluation results are shown as an index with the conventional example being 100. The larger the index value, the better the durability.

  As can be seen from Table 1, all of the tires of Examples 1 to 5 were excellent in durability of the bead portion in comparison with the conventional example.

It is a meridian half section view showing a pneumatic tire according to an embodiment of the present invention. It is sectional drawing which shows schematically the bead part in the pneumatic tire of FIG. It is sectional drawing which shows roughly the modification of the bead part in the pneumatic tire of this invention. It is sectional drawing which shows roughly the modification of the bead part in the pneumatic tire of this invention. It is sectional drawing which shows roughly the modification of the bead part in the pneumatic tire of this invention. It is sectional drawing which shows schematically the bead part in the conventional pneumatic tire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Inner liner layer 8 Tie rubber layer 9 Chafer 10 Belt layer

Claims (8)

  A carcass layer is mounted between a pair of bead portions, an inner liner layer is disposed closer to the tire lumen than the carcass layer, and a tie rubber layer is interposed between the carcass layer and the inner liner layer, and In a pneumatic tire in which an end portion on the tire lumen side of a chafer that protects a bead portion is inserted between the carcass layer and the inner liner layer, the inner liner layer is made of a thermoplastic resin or a thermoplastic resin and an elastomer. A pneumatic tire comprising a thermoplastic elastomer composition containing a blend of the above, wherein the lower end position of the tie rubber layer is disposed at the same position as the lower end position of the inner liner layer or on the outer side in the tire radial direction.   The pneumatic tire according to claim 1, wherein a lower end position of the inner liner layer is disposed on the outer side in the tire radial direction from the bead toe.   The pneumatic tire according to claim 2, wherein a lower end position of the inner liner layer is disposed in an area of 35% or less of a tire cross-sectional height.   The pneumatic tire according to any one of claims 1 to 3, wherein an end portion of the chafer on the tire lumen side is disposed between the tie rubber layer and the carcass layer.   The pneumatic tire according to any one of claims 1 to 3, wherein an end portion of the chafer on the tire lumen side is disposed between the tie rubber layer and the inner liner layer.   The pneumatic tire according to claim 1, wherein the tie rubber layer and the chafer are arranged so as not to overlap each other.   The pneumatic tire according to claim 6, wherein a separation distance in a tire radial direction between the tie rubber layer and the chafer is 3 mm or more.   The pneumatic tire according to any one of claims 1 to 7, wherein an anti-aging agent is blended in the rubber composition constituting the chafer.

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