Road traffic noise accounts for the majority of perceived urban environmental noise and has important health consequences. The rolling noise of vehicle tires is a major contributor to perceived road noise. The tread pattern of light vehicle tires is already designed to minimize the amplitude of the noise emitted, but this is not the case for heavy vehicles. The European LEON-T project aims to minimize the nuisance of heavy vehicle tires, especially noise. Prior to a study of the effects of tire noise on sleep, an experiment was conducted to determine the timbre parameters of such noise. The data set used was obtained by a series of recordings on a standardized track using tires of various sizes. These stimuli were presented to headphones in a free sorting task. The presentation will show the results of this experiment, including the correlations between acoustic parameters and perceptual space structure determined from the groups formed by the participants.