Bridgestone Corporation

Hiroyuki Mori

Takeshi Yano

Masaaki Nakamura

Seiji Itai

A run-flat tire is provided with a reinforcing cord layer adjoining the radial carcass at least from the belt end to the maximum width portion of the tire side portion; the cord constituting the reinforcing cord layer is nylon 66 cord, cellulose fiber cord, PET cord, PEN cord or aramid/nylon 66 hybrid cord, and has a cord angle of less than 10&#xb0; with respect to the tire radius direction; and the elastic modulus of the cord pulled out from the tire at a temperature of 25&#xb0; C. under the conditions of a load of 3 N is not higher than 40 cN/dtex, and the thermal shrinkage stress &#x3c3; (cN/dtex) at a temperature of 177&#xb0; C. and the elastic modulus E (cN/dtex) at a temperature of 177&#xb0; C. under the conditions of a load of 10 N satisfy the following conditions: &#x3c3;+0.025E&#x2267;0.36, 40&#x2267;E&#x2267;8, and &#x3c3;&#x2267;0.05.

Run-flat tire

In the pneumatic radial tire of the present invention, a total strength Kof a belt layerin a circumferential direction of the tire per unit of width at a tire equator surface position Pis set greater than a total strength of the belt layerin the circumferential direction of the tire per unit of width at a width position Pcorresponding to &#x2154; of a maximum width of the belt layer having the tire equator surface CL as a center.

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Kodaira, Japan

Hiroyuki Mori