Hey Sham.......It's Jim (purchased rims). Finally getting around to have the rims installed by dealership today. They say the rims are all the same size and if they come off of an SS they should have been different sizes fronts from backs by 1". (8.8" front and 9.5" at back). Since they came directly off of your car they dealer must have switch something up on you while car was on lot to be sold. Only LT models have 8.5 on front and backs. They are telling me they will work with my current tires so not issue, just giving up the 1" width in the rear........FYI. Did you buy your new rims all same size or different front to backs? thanks!