Investigation of ultra fine particulate matter emission of rubber tires

In this study, we focus on the ultra fine particulate matter emission of rubber tires and investigate it with the inner drum tire test bench of the Karlsruhe Institute of Technology. We examine if a tire emits particulate matter and explore under which running conditions it emits most significantly. We concentrate on the emission of ultra fine particulate matter with an aerodynamic diameter between 5.6 nm and 560 nm of common friction winter tires, exemplary chosen, under multiple driving conditions. To investigate the tire's particulate matter emission we vary the speed during straight and curved driving as well as the wheel load and the longitudinal forces during straight driving at our test bench. At the same time we measure the particle size distribution behind the tire's tread with a particle size analyzer and evaluate the measurements in respect to the driving conditions. Further, mathematical regression models are used and presented to gain a correlation between the concentration of ultra fine particulate matter emission and the varied driving parameters for an estimation of their influences. The results indicate that the tested tire emits ultra fine particulate matter significantly at driving conditions with increased slip angles and increased longitudinal forces. Additionally, the results show that moderate driving reduces the tire's emission of ultra fine particulate matter. Therefore, one can use the presented results to initiate further, adapted measurements and to initiate an optimization of the tread's compound to reduce its particulate matter emission.