When I bought my 65, it had a set of the early Lightning rims. The front tires were P255/50R17; the backs were 60 series tires. These tires have very little sidewall and you may not like their appearance. I didn't. I would strongly suggest that you work with a tire shop that will mount and let you see what they look like before buying. The only place were clearances were tight were the rears up against the outside of the fender; this is on a styleside box. There was no signs of rubbing but I don't think that owner evere carried anything but a 12 pack.

Lee
1965 F100 short box styleside