Run-flat tire

Abstract

A run-flat tire comprises a carcass composed of an inner ply and an outer ply each made of organic fiber cords, a belt disposed radially outside the carcass in the tread portion, and three sidewall reinforcing rubber layers disposed in each sidewall portion. The inner and outer carcass plies are turned up around the bead cores from the inside to the outside of the tire, and the turnup portions of the inner carcass ply extends into between the belt and the carcass so that the radially outer end thereof is secured therebetween. The sidewall reinforcing layers include: an inside layer disposed axially inside the main portion of the inner ply; a middle layer disposed between the main portion of the inner ply and the main portion of the outer ply; and an outside layer disposed axially outside the main portion of the outer ply. At least one of the sidewall reinforcing rubber layers has a radially outer end located beneath the belt. At least one of the sidewall reinforcing rubber layers has a radially inner end located radially outward of the bead core but radially inward of a maximum tire section width point. At the maximum tire section width point, the total of the thicknesses of the inside layer, middle layer and outside layer is not less than 50% of the total thickness of the sidewall portion.