But rubber will degrade and fail at higher temperatures. There were also clear differences between tires made at the Decatur, Illinois plant which failed at a rate higher than tires made at other Firestone plants. However, Van Ooij emphasizes that there was no evidence of poor workmanship, poor quality control, or poor management in Decatur. These are absolutely untrue. Finally, Van Ooij explained that all tires will fail eventually.
Rubber degrades naturally under exposure to heat and oxygen.
However, the tread normally wears down well before the belts would separate or the tread would peel off. The aging process was somehow accelerated.