Pneumatic tire

Abstract

A pneumatic tire capable of reducing rolling resistance and discharging static electricity generated during running, wherein each of a tread rubber, a breaker rubber, and a sidewall, respectively, has a volume specific resistivity of 1×10 8 Ω·cm or more, the pneumatic tire further including a conduction rubber embedded in the tread part so as to be at least partially exposed to a surface of the tread part, a coating rubber disposed on the upper part of the breaker part, a bead part rubber, and side part electroconductive rubber electrically connecting the conduction rubber to the beat part rubber, wherein each of the conduction rubber, the bead part rubber, the coating rubber and the side part electroconductive rubber has a volume specific resistivity of less than 10 8 Ω·cm.

What is claimed is: 
     
         1 . A pneumatic tire comprising a tread part, a sidewall part, a bead part, a carcass extending from said tread part to said bead part through said sidewall part, and a breaker part disposed at an outside of said carcass in a tire radial direction, wherein
 each of a tread rubber, a breaker rubber, and a sidewall rubber formed on said tread part, said breaker part, and said sidewall part, respectively, has a volume specific resistivity of 1×10 8  Ω·cm or more,   said pneumatic tire further comprising side part electroconductive rubber extending continuously in the tire circumferential direction from at least both edges of said breaker part to the bead part along the outside of said carcass wherein a part thereof is disposed between the carcass and the edges of the breaker part, a coating rubber having a region for contact with said side part electroconductive rubber and disposed so as to coat an upper part of the breaker part, a conduction rubber contacting the coating rubber and embedded in said tread part so as to be partially exposed to a surface of a tread, and a bead part rubber contacting a lower end of said side part electroconductive rubber and disposed at a region contacting a rim flange of said bead part, wherein   said conduction rubber is formed in the tire circumferential direction, and has a width from 0.2 to 10 mm in a tire width direction,   said coating rubber has a thickness from 0.2 mm or more and 3.0 mm or less, and has a contact part in a circumferential direction with the side part electroconductive rubber in width of 5 mm or more, and   said side part electroconductive rubber, said coating rubber, and said conduction rubber each have a volume specific resistivity of less than 1×10 8  Ω·cm, and one bead part is electrically connected with the other bead part through said side part electroconductive rubber and said coating rubber.   
     
     
         2 . The pneumatic tire according to  claim 1 , wherein said tire comprises carbon black and said carbon black is a ketjen black. 
     
     
         3 . The pneumatic tire according to  claim 1 , wherein said bead part rubber has a volume specific resistivity of less than 1×10 8  Ω·cm. 
     
     
         4 . The pneumatic tire according to  claim 1 , wherein said side part electroconductive rubber has a thickness in a range of from 0.2 to 2 mm. 
     
     
         5 . The pneumatic tire according to  claim 1 , wherein said side part electroconductive rubber, said coating rubber, and said conduction rubber contain carbon black having a nitrogen adsorption specific surface area of 600 m 2 /g or more in an amount of 5 parts by mass or more with respect to 100 parts by mass of a rubber component and a silica having a nitrogen adsorption specific surface area of 70 m 2 /g or more and 250 m 2 /g or less in an amount of 10 to 55 parts by mass with respect to 100 parts by mass of a rubber component.