A pneumatic radial tire includes three or less steel belt layers, wherein a first block and a second block extending in an outer side than the first block are alternately provided in a tire circumferential direction on a ground edge region of a tread part. An annular region extending in a circumferential direction is provided on the outer surface of an outer side than a maximum width position in a side wall part, and plural projections are provided side by side on the annular region. An outer thin wall part continuing along an outer circumferential edge of the annular region and an inner thin wall part continuing along an inner circumferential edge of the annular region are provided, and the outer thin wall part is arranged adjacent to an inner radius height and inside of the inner radius height.