High speed heavy duty tire including bead part with side packing rubber

Abstract

A high speed heavy duty tire with improved bead durability, which includes: a bead core disposed in each of the bead portions; a radial carcass extending between the bead portions and turned up around the bead cores to form two turned up portions and one main portion therebetween; a belt disposed radially outside the carcass; a tapered bead apex disposed between the main portion and each turned up portion of the carcass and extending radially outwardly; and a sidewall disposed on each side of the carcass and extending from the bead base to the tread edge, wherein the sidewall comprises a lower sidewall and an upper sidewall, the lower sidewall extending radially outwardly from the bead base over a height corresponding to the radially outermost edge of a flange of the tire's regular rim, and the upper sidewall extending radially outwardly from the radially outer edge of the lower sidewall. Each bead portion is provided between the carcass and the lower sidewall with a side packing of small thickness, the side packing is made of rubber having a 100% modulus MP of 53 to 95 kg/sq.cm., the bead apex is made of rubber having a 100% modulus MA of 78 to 120 kg/sq.cm., the lower sidewall is made of rubber having a 100% modulus MC of 40 to 70 kg/sq.cm., the upper sidewall is made of rubber having a 100% modulus MS of 10 to 45 kgf/sq.cm., and these 100% modulus values MP, MA, MC and MS are in the relation of MS<MC<MP<MA.