A combined approach for correcting tyre hardness and temperature influence on tyre/road noise

For the determination of the road surface influences on tyre/road noise, the standard ISO 11819-2 (International Organization for Standardization, 2017), also called “CPX-method” is used. There, tyre/road noise is measured with a dedicated measurement trailer and tyre. As various parameters, such as temperature, trailer design, shore hardness of the tyre, etc. have significant influences on the CPX levels, correction procedures to address these are described in the standard. Where currently the air temperature and the shore A hardness, measured under laboratory conditions, are used, a different approach is presented in this paper. Here, the tyre temperature is measured during the measurement run, and subsequently calculated to the in-situ shore A hardness. As this is assumed to be the dominating influence on tyre/road noise emission, a direct correlation between the in situ shore A hardness and the CPX levels is performed. Extensive measurements are presented, and the different correction procedures are analysed with regard to their repeatability. It will be shown that, within the limitations of the measurement setup, the combined correction of temperature and shore A hardness is feasible and may support the further development of the CPX method.