You will be surprised on how much ET and MPH your car will pick up going from the old bias ply tires to the new smaller radials
I use to race NHRA stock back a long time ago when the radial slicks first came out for stockers, every one I know that bought them complained about the circumferences until they made the first pass with them on, all of the their cars picked up ET and mph with no other changes
I ran Firestone 9x30 on ten inch wide rims and always ask for the biggest circumference tires they, Parnelli Jones Firestone race tire division in Torance, CA, had in stock. They where all above 95.0 in circumference I sold my stocker before the radials came out, I use to help several other Division 7 racers after that and learned form them about the radials being better
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