worse case scenario, they can dry fit them on...my dealer said the 15s would fit my car, but i'm not 100% sure they were right, because they didn't seem overly confident in saying they would.
i ordered my steelies today, so when they come in (likely a week or so), i will drop by and have them pull a wheel off and see if it fits...if it does, i'll get my wheels switched out and put the winter rubber on...if they don't, i will have to return everything and buy 16" stuff (which sucks, because it would be quite a bit more money).