| 摘要 |
PURPOSE:To reduce travelling noise by making ziazag grooves in the peripheral direction and lag grooves in a shoulder part corresponding to the zigzag grooves. CONSTITUTION:A groove in the peripheral direction consists of a central groove 1 in the peripheral direction and outer grooves 2 in the peripheral direction. These grooves are in shape of zigzag consisting of two straight line parts d1, d2 parallel with an equatorial plane and transition parts (e). Lag grooves 3 of shoulder parts are set to be within areas D in the peripheral direction of shoulder side straight line parts d1 of outer grooves 2 in the peripheral direction. Such a structure may reduce noise in travelling and also improve residential environment. |
