www.tirerack.com has a nifty little thing that will show you what size wheels will look like what on your car. 17 or 18 is about best for me.... around here we have tons of potholes... it's been suggested by a couple people here to not get 18's... cause they are more suseptable to pothole damage than 17's. I don't know how true this is... but I can probably only afford 17's anyway.

Where are you located, roughly?