Acoustical performance of winter tyres on in-service road surfaces

Exposure to excessively high noise levels is a relevant health problem in Europe and road traffic noise is the most widespread noise source. When considering cold climate countries, the available scientific literature on noise emission properties of winter tyres is still very limited. In order to contribute into filling this knowledge gap, this paper investigates the acoustical performance of different types of tyres, with focus on winter tyres, on different road surfaces, at different speeds, and with different states of wear. The results indicate that studded winter tyres have, indeed, an increased noise level at frequencies between 315 Hz and 10 kHz, having a significantly different response especially at frequencies higher than 4 kHz. The acoustical response also depends on the tyre type when comparing different road surfaces, as a result of conflicting vibrational and aerodynamic noise generation mechanisms. Additionally, the relationship between labelled and measured values was explored, however, no statistically significant relationship was found between them (and labelling is not applied for studded tyres). A frequency spectrum correction was attempted based on previous measurements on an ISO track, which reduced the difference between measured and labelled values, however, further investigation is still required to properly understand differences between label and road measurements, where the label is determined on a test track with a special, smooth surface.QC 20190618