[Alex van de Wetering]

Hanno,

I think the obvious answer is that there is no such thing as "the original" tyre manufacturer for CMP's. Both Chevrolet and Ford factory pictures show a varierty of tyre threads and brands. The Good year (Chevron thread, Sure grip) and Firestone ground grip seem plentiful, but you also see the Dunlop Track grip tyres, and also road and sand tyres made by Dunlop, Firestone, Good year and India.
Even when looking at rows of finished vehicles at the Ford and Chev plant, you'll note a variety of tyres in a line of the same type of CMP.

Alex