Characterisation of low-noise tyres for the roads of Hong Kong

This study on low noise tyres started with a survey on commonly used tyres on 941 light duty vehicles. Subsequently, most common brands of tyre with a carefully selected size and tread block patterns were selected for testing on one commonly laid road surface, namely wearing course (WC), and one low noise road surface, namely polymer modified friction course (PMFC). Over 30 new and old tyres with varying properties of rubber hardness, depth and sizes were tested; tyre/road noise, air and road surface temperature, tyre pressure and vibration data were recorded. In order to identify the tyre properties on tyre/road noise, over 500 runs on the roads were made. It was found that the bi-directional & asynchronous (Michelin) was the quietest and the symmetrical tyre pattern (SRTT) was the noisiest on WC. The asymmetric pattern (Yokohama C.drive) became noisiest on PMFC. The change of driving speed from 50 to 70 km/h changed the noise order of bi-directional tyre (Yokohama A.drive) and the directional tyre (Dunlop Direzza). Tyre/road noise increased as the tyre rubber hardness increased owing to aging. The effects of the tyre tread depth and the tyre size on the level of noise are uncertain and minor.