Tire Wear Particle Emissions: A Review of Measurement Approaches and Impact on Reported Results

Tire-related emissions account for a significant proportion of traffic-related emissions. However, unlike brakes, the measurement of tire wear and airborne tire wear particle emissions is not yet standardized. On the contrary, there are numerous research approaches. This paper provides an overview on test procedures to measure tire wear and airborne particle emissions from tires that are described in literature. These methods include laboratory tests such as inner and outer drums, as well as measurements on road simulators, test tracks or public roads. Since wear mechanisms may differ depending on the test setup, a short overview on wear mechanisms is given. The measurement equipment used to evaluate the particle number (PN) and the particle mass (PM 2.5 , PM 10 ) is described in detail, as well as the specific test setups. Finally, a comparison is shown of values for PN and PM presented in the literature. The results show clear differences in the measurement results for PM 10 and PM 2.5 , even when subdivided into indoor and outdoor measurements. The same applies to PN. This highlights substantial differences in controllability, representativeness, and measurement uncertainty among methods shown in literature.