A pneumatic radial tire having a thin groove continuous in a tire circumferential direction at a buttress formed between a shoulder of a tread and a sidewall includes a tire contour portion that is formed between an end portion of the shoulder and a groove floor of the thin groove. A tire transverse direction outermost portion at a shoulder side curved portion is disposed further toward a tire radial direction inner side than a sidewall side end portion of a sidewall side groove wall surface of the thin groove.