Rear wheel backspacing

[BigBHolt]

I am wanting to put a 18" x 10" wheel on the rear of my 96 Mark VIII. Does anyone know what the backspacing has to be to keep them under the car? I can't seem to find anyone at a wheel shop that is willing to help me.

 

[mecaple1]

depends on tire size. 38 offset 255 tire,roll the fenders 275 tire,50 offset probably 275 without rolling can go to 295 if you roll them.careful on front wheel offset and size u can create a nitemare,i did. get me the tire sizes front wheel width and offset same for rear i might can answer questions