looking at the American Racing wheels web site they show wheels as large as 17x7 for a 64 Catalina. Measure your width clearance in inches and multiply by 25.4 to get a tire cross section such as 245. The original tire I believe has a 28" diameter. (28" - 17")/2=5.5" sidewall height. 5.5"*25.4=139.7mm sidewall height. (139,7/245)*100=57 roughly a 60 series tire. So the tire size if you can fit a 245 is 245/60x17. I know, too much math.