When variable pitches are classified into a plurality of groups (S, M, and L) depending on lengths thereof in the tire circumferential direction, all the differences of the average pitch lengths of one of the groups and the average pitch lengths of the other groups are 3 to 30 mm and in at least one group of the groups, any one of the pitch of the group differs from the average pitch length (PM) and among the differences of the average pitch lengths, when the minimum difference is defined to be Xmin, the pitch lengths of all the pitches of each group (M group) are modified to have the values of ±10% of the minimum difference is defined to be Xmin based on the average pitch length of the group.