Roadside soils are the environmental matrices most exposed to tire and road wear particles (TRWP) pollution. Runoff water and wind are the main vectors for the transfer of these particles to the surrounding environment. In order to assess the degree and extent of roadside impregnation, TRWP contents were measured up to a distance of 200 m in the surface soils adjacent to a major road in western France. The measurements revealed significant contamination in the first few meters from the roadside, around 4000 mg/kg. Furthermore, a power-law decrease in content with distance is observed until reaching a plateau beyond 20 m from the roadside. This evolution demonstrates the existence of a TRWP impregnation background in receiving soils distant from the roadside by more than a few tens of meters. This impregnation background averages 321 ± 104 mg of TRWP/kg of soil (n=15). The proportion of natural rubber (NR) in the TRWP of the samples is equal to 16%. If we assume that NR is predominant (approximately 80% by mass) in the TRWP emitted by heavy trucks (ca. 12% of the local road traffic), then the NR/TRWP ratio of the samples would accurately reflect the contribution of heavy truck emissions to the contamination of roadside soils with tire particles. This study provides an insight into the dispersion of TRWP at a small spatial scale from a known source, road traffic, and indicates the necessity of being outside the influence of these local sources to assess TRWP impregnation.