My '63 GMC 4000 came with 8.25x20s when I bought it. I found a '65 Chevy C60 with 9.00x22.5's on it, and bought it for the wheels and tires. When I picked it up the previous owner had thrown the original 8.25x20 wheels and tires in the bed. So, both '63 GMC and '65Chevy both had them on them. They were the 10 lug , 8.75 bolt circle. JP