| 摘要 |
<p>The bead portion durability of a pneumatic radial tire for large-size vehicles is improved by disposing a combination of a first protection rubber layer (A) having a 100% modulus of 25-40 kgf/cm<2> and a second protection rubber layer (B) having a 100% modulus of 30-50 kgf/cm<2> in given places of the bead portion (5) so as to locate an inner end (AE) of the first protection rubber layer (A) in the radial direction of the tire between an outer end (P) of a curved face of the bead heel (8) in the radial direction and an end (Q) of a curved face of a rim flange (7), and to locate an outer end (BS) of the second protection rubber layer (B) in the radial direction of the tire at such a position outward in the radial direction of the tire that an inclination angle ( PROPORTIONAL ) defined between a line segment (L) connecting said end (BS) to a curvature center (O) of the curved face of the rim flange (7) and a phantom line (BL) passing through the curvature center (O) and in parallel to a rotating axis of the tire is not less than 20 DEG . <IMAGE></p> |
