its not even just the wheels to fit the tires, you need to lift the whole thing to fit 33" tires on there...
Backspace is basically how far it will set the tire from outside of the wheel well...you need backspacing in order to turn larger tires and not rub. Backspace is from where the wheel mounts to the inside of the rim.
If you put a wide tire on a stock rim and turn, you'll rub.
you need to space the tires out further in order to turn them
but like i mentioned, you cant fit a 33x12.5 tire on your stock tj even with new wheels. You need a 2" lift minimum to run them and even then you'll rub if you go offroad.