I just picked up a 90 f350 with a 6.9 and a banks turbo I was told tire size wont mess with yer gas mileage and was wondering if that was true on this engine setup.. I know it does on gas engines this is my first diesel. I was also wondering whats the largest tire size I could get on a stock f350 suspension setup.. Also what 8 lug patterns does my truck share with other vehicles??