Abstract: The present invention provides a pneumatic radial tire, in which rolling resistance is reduced and durability is improved without losing toe-chip resistance when assembling the rim. More specifically, the present invention relates to a pneumatic radial tire having a chafer comprising a rubber composition having complex modulus of 9 to 13 MPa measured under conditions of temperature of 70° C., frequency of 10 Hz and dynamic strain of ±2%, loss tangent of 0.08 to 0.11 and tensile elongation at break of at least 230% measured according to JIS-K6251.

Abstract: There is provided a rubber compound for a tire that can provide improved performance on ice, enhanced steering stability and prevent lost blocks without significantly reduced abrasion resistance, and a tire using the rubber compound. It relates to a rubber compound for a tire that contains pumice containing no less than 30% by mass of silicon oxide and has a JIS-A hardness of 55-75, and a tire using the rubber compound. The pumice preferably contains no less than 50% by mass of particles having a diameter of 45-250 &mgr;m. Furthermore, 2-20 parts by mass of the pumice is preferably blended relative to 100 parts by mass of rubber. To produce the present rubber compound, together with the pumice a silane coupling agent is preferably blended together.

Abstract: The present invention provides a rubber composition in which increase in elastic modulus due to thermal fatigue is small, change in properties is prevented and durability is significantly improved and a pneumatic tire having a strip comprising the rubber composition. More specifically, the present invention provides a rubber composition comprising 100 parts by weight of (A) a rubber component comprising natural rubber and/or isoprene rubber, 4 to 6 parts by weight of (B) sulfur, 0.5 to 2.0 parts by weight of (C) a resin containing resorcin or a derivative thereof, 0.5 to 2.0 parts by weight of (D) a compound capable of donating a methylene group, and (E) a cobalt metallic salt. The present invention also provides a pneumatic tire having a strip comprising the rubber composition, which is located on a breaker edge.