| 摘要 |
PURPOSE:To reduce pattern noise by forming one round of a tread by plural pitch lengths, starting with the shortest pitch and specifying the half period length of a period including at least one longest pitch/the whole period length and the average value of the short half-period length/the whole period length of one round. CONSTITUTION:In case of forming one round of a tread by plural pitches with different lengths, the period starts with the shortest pitch to make one period using pitches by the shortest pitch of the next period, in which at least one longest pitch is included. The length from the center of the first shortest pitch group of each period to the center of the first longest pitch group in the period is set to the former half period length, the rest is set to the latter half period length, and the percentage of the former or latter half period length to the whole period length is let be 15-40%. The average of percentage of the shorter half period length to the whole period length in one round of a tread is set to 15-35%. By this arrangement, pattern noise can be reduced. |
