my tire size is 235/55R20
what other tire sizes will work with my 20'rims on my cadillac? if any?
There are calculators on the internet to get the same diameter of tire, so it all fits . But rimwidth ideal for 235 is 7.5 inch, you have to look that up, what yours is. 6.5 to 8.5 inch is allowed. If for instance 255( I dont suppose you want to go less then 235) , it has to be 255/50 to get same diameter. For that rimmwidth 7- 8-9 inch is allowed.