This is what I was getting at, also known as offset:
http://www.tirerack.com/wheels/tech/...jsp?techid=101
Basically, unless the wheel was designed for the car, it may fit, but not have the proper offset. This might leave the wheel sticking out from under the car and/or cause some clearance issues with the fender. The other side of the coin, if the offset was too much, could cause the tire to rub on the inner fender well.
I have 16 inch rims on my car that were designed to go on it and they clear, but only barely. I should point out my fenders have not been rolled or anything like that, I have read that by tweaking the fenders a 17 can be made to fit.
Ryan