| 摘要 |
<p>A heavy duty pneumatic radial tire (100) comprises a pair of bead portions (1), a pair of sidewall portions (2), a tread portion, a radial carcass ply (4) and a belt, in which at least three rubber layers having different hardnesses are existent in a zone (Ro) ranging from cord in a turnup portion (4t) of the carcass ply to an outer portion of the bead portion at a region (R) of the bead portion (1) corresponding to a vertical line drawn in a contact area increased portion of the bead portion located between two contact alienating positions (A,B) of a flange (10f) of a design rim (10) from an outside surface of the bead portion as measured under particular conditions, and are comprised of a coating rubber of the carcass ply and a softest rubber layer and a hardest rubber layer, and the softest rubber layer has a 100% modulus of not more than 20kgf/cm<2> and a 100% modulus of the hardest rubber layer is not less than 3 times that of the softest rubber layer. <IMAGE></p> |
