I have an 07 4x4 SuperCrew with a leveling kit and an 18" aftermarket wheel with. Whats the largest tire you can fit under there without a significant amount of rubbing. Could you please send me pics of any similiar set-ups. Thank you

 

33s or 35s would be the largest you could put.

 

As a general rule, with a leveling kit on the new 4x4's you can run 35's using the OEM wheels or 33's with aftermarket wheels. I'd suggest a 325/60-18 (33x13.00). How wide are your wheels and what is the backspacing?

 

8.5" wide with 6'' of backspacing. Will the 325/60 fill up the fender well and would that sit flush with the fender

 

That should look fine. That wheel will stick out 1/2 inch farther than your OEM wheels so it should be close to flush or slightly tucked.