The ranking of rolling noise from passenger car tyres - a comparison between measurements and modelling results

Tyres are type approved with regard to rolling noise on an ISO-test track, according to the EU-directive 2001̸43̸EC. The test track is basically a rather smooth road surface with maximum chipping size of 8 mm. However, most surfaces normally used on roads, especially in the northern European countries, are rougher surfaces, typically Stone Mastic Asphalt (SMA) with 11 to 16 mm stones. A project has been initiated to compare the noise levels of a selection of highly used after market summer tyres (in Norway). Noise measurements of 12 tyres have been performed on a selection of new and old SMA-road surfaces. The 3D texture of the same road surfaces has been measured with laser profile equipment. In addition, the point mobility and other design features of the tyres have been measured to be used as input data to the SPERoN tyre̸road noise model. Then, comparison will be made between measurements and modelling results. Preliminary results from the noise measurements show a difference of 2.5-3 dB(A) on SMA-surfaces, between the tyres. The project is a co-operative between SINTEF (Norway), MüllerBBM (Germany), and Chalmers University (Sweden).