I have a full size spare tire. Spare is a 33x12.5x15.
Could I put the tire on the original holder of an 83 cj7???
No prob. I had a 33" hanging on the original holder for more than 10 years! Only when I put a 35" & hilift on it started to come off...
But seriously you may want to consider a heavy duty aftermarket bumper & tire holder.