Allen - The rear tire width (from outside of wheel to outside of wheel) should be 6 3/4". The best way to make sure its spaced properly is make a mark directly in the center of the lower rear pod plate (some plates like the L4 one have a hole in the center which you can use) and measure to the outside of either wheel and make sure its 3 3/8" evenly. My car always feels much more stable than having the rear end narrower so I never change it.