| 摘要 |
<p>The heat resistance of carcass cords is enhanced, whereby the runflat durability is enhanced. A pneumatic tire has a carcass 6 and a tread-reinforcing cord layer 7 disposed radially outward of the carcass, the carcass 6 comprising a carcass ply 6A in which carcass cords 20 of aramid fiber are arranged at an angle of 45 to 90° with respect to the tire circumferential direction and are covered with a topping rubber, preferable carcass cords 20 have a two-bundle twisted structure that two bundles of first-twisted filaments are subjected to final twist, and preferable carcass cords 20 have a twist factor T of 0.5 to 0.7 represented by the equation (1): T = N × 0.125 × D / 2 / Á × 10 - 3
in which N is the number of final twists per 10 cm, D is a total nominal dtex (fineness) of a cord, and is a specific gravity of a cord material.</p> |
