Camber play's a huge role on proper offset & fitment.
Camber is negative on front & rear of car from the factory (wheels lean inward) the rear has twice as much neg-camber as the front (from the factory)
Example F-0.8* R-1.6* (* is for degrees)
on a 26.5" diameter tire/the wheel will lean inward 7mm for every degree of negative camber....3.5for 0.5*,10.5mm for 1.5*etc....
easiest way i found to properly space,is to ensure your alignment is to your suit & then tape a small plumb weight to a string on fender's -directly over center of wheel & measure your gaps (rim lip or tire sidewall) Be sure to park on level surface w/no wind.