Patent ID: 6196289
Filing Date: 2001-03-06
Classification: B60C

Abstract:
A run-flat tire comprisinga tread portion,a pair of sidewall portions,a pair of bead portions with a bead core therein,a carcass comprising an inner ply and an outer ply each made of organic fiber cords,a belt disposed radially outside the carcass in the tread portion,sidewall reinforcing rubber layers disposed in each said sidewall portion,each of the inner ply and outer ply extending between the bead portions through the tread portion and sidewall portions and turned up around the bead core in each said bead portion from the inside to the outside of the tire to form a pair of turnip portions and a main portion therebetween,the turnip portions of the inner ply extended into between the belt and the carcass and each having a radially outer end secured therebetween,said sidewall reinforcing rubber layers including: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; andan outside layer disposed axially outside the main portion of the outer ply,at least one of the sidewall reinforcing rubber layers having a radially outer end located beneath the belt,at least one of the sidewall reinforcing rubber layers having a radially inner end located radially outward of the bead core but radially inward of a maximum tire section width point measured when the tire is mounted on a standard rim and inflated to a standard inner pressure but loaded with no tire load,at the maximum tire section width point, the total (a1+b1+c1) of the thickness a1 of the inside layer, the thickness b1 of the middle layer, and the thickness c1 of the outside layer being not less than 0.5 times the thickness S1 of the sidewall portion.