A pneumatic radial tire having a reduced rolling resistance and particularly suitable for a passenger car, comprising a toroidal carcass, a belt layer, a bead core, a side rubber, a tread rubber, a relatively thin base rubber, and a rubber filler, wherein provision is made of a stress relieving groove composed of a depression facing toward the bead rubber at a position near the joint portion between the side rubber and the tread rubber, the base rubber having a resilience which is higher than those of the tread rubber and the bead rubber.