| 摘要 |
<p>A pneumatic radial tire comprising a pair of bead portions (1), a pair of sidewall portions (2), a tread portion (3) toroidally extending between both sidewall portions, a radial carcass (4) reinforcing said portions, and a belt (6) reinforcing the tread portion at the outer circumferential side of the radial carcass, in which a high-hardness rubber layer (15) having a JIS A-hardness higher by 3 degrees or more than the rubber hardness of a tread rubber is arranged in a region (14) at the meridional section of the tire including an outermost position (12) of a ground contact end at the meridional section of the tire under a normal loading in the case of truck and bus tires and under a loading corresponding to 70% of normal loading in the case of tires having a size smaller than that of truck and bus tires at an inflation state under a normal air pressure in accordance with the maximum loading capacity and a position (13) measured from a bead core (5) to 1/2 point of the carcass height (HO) from the bead core under inflation of the said normal air pressure. <IMAGE></p> |
