I agree with Va.FireTruck. 8.25 X 20, is a good size for your truck. It would have came standard from the factory 7.50 X 20 front, & 8.25 X 20 rear. I've got 8.25's, all the way around, on my '46 Chevy 2 ton, & '53 Chevy COE 2ton.
Spanky Hardy Collector Of Fine Old G.M. COE Trucks & Antique Holmes Wreckers
I just mounted two fronts tonight. You need to make sure you have the wider wheels to mount the 8.25's on. Most 7.50 wheels are an inch narrower than the 8.25 wheels, Scott