www.safetechnology.com/downloads.asp?fid=35652
Here is a nice article of how and why synthetic rubber components on tracks (and road wheels) fatigue over time and use. It has nothing to do with different coefficients of thermal expansion. This article explains the failure mechanism and how cracks form. Rubber is selected for a good engineering reason and if substitution with plastic (such as polyurethane) were a viable option it would be in common use, and it is not.
As the plastic is stressed beyond its design parameters it will shear. We tried many different rubber compounds on the Leopard to try and extend the life of these components and polyurethanes were deemed not suitable. Proceed with caution.
