To improve uniformity by vulcanizing a green tire molded by changing in a tire circumferential direction so that a thickness of a cap tread made of unvulcanized rubber is inversely proportional to a groove volume ratio, thereby suppressing a gage change of its tread.

A green tire molded by changing in a tire circumferential direction so that a thickness Ga of a cap tread made of unvulcanized rubber is inversely proportional to a groove volume ratio P is molded. That is, the thickness Ga of the tread is thinly molded at a pitch that the ratio P becomes large, and the thickness Ga of the tread is thickly molded at a pitch that the ratio P becomes small. The volume ratio is the ratio of a volume of the tread rubber disposed at a radially outside of the tire from a belt layer and belt cover layer embedded in the tread to the groove volume to a sum of the volume of the grooves provided on the tread. The green tire obtained in this manner is combined in a predetermined phase, and vulcanized and molded in the mold.