PURPOSE: To increase rigidity and concurrently reduce the weight by forming at least one layer of belt layers and bead reinforcing layers of radial tire, which are locked in right and left bead cores, extend in a toroidal shape, and which possess a reinforcing layer for the belt etc., by means of an aromatic polyamide cord, whose twist coefficient and denier number remain within certain prescribed range.
CONSTITUTION: A pneumatic radial tire 10 is provided with a pair of bead cores 12 and a carcass layer 14, which is located between the cores 12 and consists of carcass plies 16, 18, the end-parts of which are folded back toward the outside in the radial direction of the tire 10. A belt layer 22 having two belt plies 24, 26 is arranged between the carcass layer 14 and a tread rubber layer 20, while a reinforcing layer is arranged outside the belt layer 22 in such a manner that the end part of the belt layer 22 is covered with the reinforcing layer. In addition, a bead reinforcing layer 19 is arranged inside the fold-back part 18B of the carcass ply 18. At least one of the belt layer 22 and the bead reinforcing layer 19 includes at least one layer of an aromatic polyamide cord layer, whose twist coefbicient and total denier number, which are computed by a formula, should be 0.08 to 0.43 and 400 to 3500, respectively.
HAMAMURA KAZUYUKI
UBUKATA TORU
KODAMA SUNAO
