What size wheels? I run 315/75R16's which is the equivalent of a 35/12.50R16 on both our Excursion and F350. I may be switching to a 37" or 39" tire on the F350 this summer so I may have the 35"s available. I also might know where there is a set of 38-16.5" if you run 16.5"s and if 38" is not too tall. If you run 15" wheels I don't have any ideas..