Gap Analysis and Future Needs of Tyre Wear Particles

Non-exhaust and exhaust particles from traffic were evaluated to account for nearly equal proportions in traffic-related emissions. Among non-exhaust emissions, tyre wear has been a crucial contributor to Particulate matter (PM), with its mass contribution as high as 30% to non-exhaust emissions from traffic. As exhaust emissions control regulation becomes stricter, which leads to a substantial reduction in exhaust emissions from road traffic, currently relative contributions of non-exhaust particles generated from tyre wear to PM is becoming more important. Accordingly, possible regulatory requirement and effectively control strategy of tyre wear particles needs to be developed. This review paper covers the physical properties, chemical composition, emission rates, and mathematic model development of tyre wear particles. Three main methods, including the road simulation in the laboratory, the source analysis, and the on-road direct measurement under real driving conditions, were used to analyse the tyre wear particles in the existing literature. The particle number concentration presented primarily a unimodal distribution, while there was no consensus regarding the peak position of the distribution. The most important chemical components of tyre wear were within coarse and fine particles.