What backspacing (mm) do I need to properly fit the 17 X 11" wheels on the rear of my 95 Formula ? Some say 56mm, others say 50mm. I also plan on running 315/35's on these wheels if that makes any difference. I would like them to tuck under the fender instead of hanging out a 1/2 inch or however much they do.

 

Get the 50mm offset.

 

They may be mixing up the 17x11's and the 17x9.5's. IMHO, for the best fit (tires under the fenders, not sticking out), you need:

Grand Sport offset:

17x9.5 56mm offset in the front
17x11 50mm offset in the back.

The alternatives, both of which move the wheels/tires toward the outside of the car are:

"True" ZR1 offset:

17x9.5 38mm offset
17x11 36.5mm offset

 

Yup they are correct!! the 50mm offset for the rear 11" wheels is what you want. Even though the wheels are still within the fender it gives the car a slight staggered look like a porsche because the rear wheels will flare out slightly more than the front. Looks awesome IMO.

 

Look at mine:

http://members.cardomain.com/n_ecstaz

17x9.5 with 56 in front
17x11 with 50mm in back

they fit and do not rub but when I lower it with the pro-kit I am going to roll the fender lip in to clear.

peace

 

Thanks guys for all your help!! Now I know what I need to get