Urban roads stand as a major aspect of human activity. Understanding their contribution to microplastic pollution through the abrasion of macrolitter and the generation of tyre and road wear particles is crucial to better assess the sources and fate of microplastics in terrestrial environments. In particular, the microplastic infiltration into roadside soil and soils of sustainable urban drainage systems via urban runoff remains to be assessed. This study focuses on microplastic infiltration in the soil of a biofiltration swale alongside a high-traffic highway in the north of Paris, France. Ten soil cores were collected manually at a depth of 35 cm and were each subdivided by depth into four samples ([0-5[, [5–15[, [15–25[, [25–35[ cm). Each sample represented a mass of 10g, that was separated into 2 subsamples for separate quantification of microplastics and tyre wear particles. After specific treatment processes, the microplastic content of the samples was characterized and quantified using an automated micro-FTIR imaging analysis. The tyre wear particles content of the samples was indirectly assessed by quantifying the styrene-butadiene rubber (SBR) and butadiene rubber (BR) content of the samples by Pyr-GC/MS analysis. Results revealed a median concentration of 5.4 µg MP g-1, for a median abundance of 4MP/g. Surface samples presented a significantly higher microplastic abundance than deeper layers, with a median abundance of 47 MP g-1 against 1.8 MP g-1. SBR concentrations were significantly higher than microplastics for all samples, with a median concentration of 150 µg SBR g-1, suggesting a much higher tyre wear particles concentration in the roadside soils. Interestingly, SBR concentrations presented a similar vertical profile as microplastics, with a decrease in concentration in the deeper samples. These findings advocate for an increased attention to tyre wear particles in microplastic studies, particularly within urban contexts, as they likely represent high concentrations and follow similar transport pathways as other microplastics.