Radial tires provided with improved sidewall-stiffening structure

Claim 1

In a pneumatic tire for vehicle wheels comprising a radial carcass, a tread, a bead containing a bead cord and a breaker arranged between the carcass and the tread, the improvement wherein the carcass has at least one ply of cords lying in substantially radial planes, said cords extending from one bead to the other and being turned up about the bead core contained in each bead from the inner side towards the outer side of the tire, each bead comprising a filling of high rigidity rubber arranged on the core, the lower zone of each sidewall comprising at least one strip of metal cords arranged with said cords inclined at 90° with respect to the circumferential lines of the tire, in an axially outer position with respect to the turn-up of said carcass and extending radially from the core zone to at least a height equal to 45% of the section height of the tire, and said breaker comprises at least two superimposed layers of cords of threads or wires of a material selected between textile or metallic material having a width corresponding at least to that of the tread, said breaker cords being parallel to one another in each layer and crossed with respect to those of the adjacent layer, and being inclined at an angle ranging between 10° and 35° with respect to the equatorial plane of the tire and, in a radially outer position with respect to said two layers, at least one strip of textile cords arranged in a direction parallel to the equatorial plane of the tire, having a width greater than that of said two layers, said textile cords being made of a material which reduces in length under the action of heat, characterized in that the tire also comprises, in each sidewall, a reinforcement made of a fabric of cords of threads or wires of a material selected between textile or metallic material, arranged in an axially outer position with respect to the carcass and to its turn-up in such a way that said cords, parallel to one another, are inclined, with respect to the circumferential lines of the tire, at an angle ranging between 20° and 30°, said reinforcement being so folded as to have a greater skirting extending from the bead core zone as far as the tire shoulders and a smaller skirting extending from the shoulder zone as far as one half of the section height of said tire, the folding edge of said reinforcement lying substantially adjacent to the layers of cords of threads or wires of a material selected between textile or metallic material of said breaker and underlying said strip of textile cords of the breaker itself.