A reminder that a few of the members here that autocross go with 18's on the rear. More than once have I read Crossfire reviews where the car being 'over tired' was pointed out. Case in point, there are quite a few other sports cars that have similar, if not better performance specs with smaller tires.
Asthetics played a large role in sizing of the Crossfires tire/rim size.

As for 'performance tires', get what suits your needs. The all season Conti's that came on mine from the factory are hardly what I would call 'performance tires'. I would more correctly call them...'non performance tires', which is why they were the first things I changed on my car.