Pneumatic radial tires for passenger cars having a low rolling resistance

A pneumatic radial tire for passenger cars having a low rolling resistance, comprising;

• a toroidal carcass composed of one ply of radially arranged polyester cords, each end portion of said ply being turned around a bead core to form a turnup portion;
• a belt superimposed about said carcass and comprising plural rubberized plies each containing cords arranged at an inclination angle of 60.degree.-80.degree. with respect to a radial plane of the tire, the cords of said plies being crossed with each other;
• a bead filler rubber having a dynamic modulus of 700 kg/cm.sup.2 -1500 kg/cm.sup.2 and a Shore A hardness 80.degree.-95.degree. arranged between said carcass and said turnup portion at a region extending from said beaad core to a substantially middle part of a side portion;
• a tread rubber composed of major parts of styrene-butadiene copolymer rubber and minor parts of polybutadiene rubber and containing a predetermined amount of carbon black ISAF and a base rubber composed of major parts of natural rubber and minor parts of polybutadiene rubber and containing a predetermined amount of carbon black HAF and having a loss modulus of 2 kg/cm.sup.2 -12 kg/cm.sup.2 and a resilience of 60%-85%;
• said base rubber arranged between said belt and said tread rubber on a volume ratio in said tread rubber of 0.1-0.5 so that said base rubber wraps said belt from one end to the other end over an upper portion thereof.