Tyre/road noise modelling: Measurement of passenger car tyres on an ISO track and frequency analysis of results.

-22 passenger car tyres have been measured on the ISO surface at the Kloosterzande test track in the Netherlands. All measurements have been done with the Norwegian CPX-trailer.The results are compared to similar measurements on different road surfaces in Norway, including normally used SMA surfaces.The analysis show that the ranking on the ISO surface differs significantly from the ranking on SMA surfaces exposed to winter conditions and studded tyres. The correlation is improved if the ISO-levels are compared to surfaces not exposed to winter conditions. A 1/3rd octave band frequency analysis have been performed on all CPX-measurements, and compared with SPERoN modelling results. The analysis shows that there is some correlation at the low frequency (315 Hz), but zero or negative correlation at higher frequencies. The lack of correlation can be related to comparing levels within the uncertainty range of the SPERoN model and uncertainty in the relationship between near field measurements (CPX) and far field (CPB) modelling. Oppdragsgiver: Vegdirektoratet;SFT;Norges forskningssrå