Contours came with tires ranging from 24" OD to 25" OD. Anywhere in there should be fine. 205/50R15 is way too small, so is 215/50R15. Pick up some SVT wheels or stick with 205/55R16 as a minimum diameter size. You might find a 215 or 225 in 15", but they are pretty rare, so don't get your hopes up.