| 摘要 |
<p>Safety of a side-reinforced run-flat tire running at an inside pressure of 50 to 100 kPa is increased. A belt reinforcement layer (8a) is made from a composite cord produced by twisting high elasticity fibers and low elasticity fibers. The point of inflection from low elasticity region characteristics to high elasticity region characteristics in a stress-strain curve is preferably set in a range of 2 to 7 % of strain. In a range where strain of the composite cord is small, greater deformation is allowed for a tread section than when a low elasticity cord is used and deflection of a sidewall section is suppressed more than when a high elasticity cord is used. When strain of the composite cord reaches a high elasticity region, the cord exhibits a higher elasticity modulus than the low elasticity cord, so that the tread section does not deforms excessively as a case where the low elasticity cord is used. As a result, a center ground contact length and endurance at a tire inner pressure of 50 to 100 kPa are improved, increasing safety of the tire running at an inside pressure of 50 to 100 kPa.</p> |
