Where the rubber meets the road

The wear of rubber tires produces microplastic particles that release harmful chemicals as they degrade. However, researchers don’t fully understand how pressure, speed, and environmental conditions affect the wear-rate of tires.

Persson et al. investigated rubber wear with experiment and theory. Experimentally, they studied the wear-rate of tire tread rubber sliding on concrete paver surfaces at different contact pressures and sliding speeds. They found the wear-rate is proportional to the contact pressure and independent of the sliding speed. Wet conditions produced lower wear-rates than dry conditions.

The authors analyzed this data using an innovative theoretical approach. In previous theories, the wear rate is often assumed to be proportional to the friction work. In contrast, wear in this theory depends on stored-up elastic energy, which forms due to stress in contact regions between tire and road surface. Once large enough, this elastic energy breaks the necessary bonds to form a rubber wear particle.

The theory can be used to predict the wear-rates and wear particle sizes of rubber due to material properties and contact conditions.

“This is the first study of wear where the full range of surface roughness, which could extend from nanometers to centimeters, is taken into account to predict the probability distribution of wear particle sizes and the wear rate,” said author Bo Persson.

But this theory is not complete: Next, the authors will extend it to include plastic flow, a deformation process involved in the wear of non-rubber materials.

“Our study is not the final theory of wear, but presents a new approach to this problem,” Persson said.

Source: “Rubber wear: Experiment and theory,” by B.N.J. Persson, R. Xu, and N. Miyashita, Journal of Chemical Physics (2025). The article can be accessed at https://doi.org/10.1063/5.0248199 .