I'm running 15's, 7&8's, right now.
I just ordered some tires for some wheels my brother gave me some time ago which are 17's.
I'm really looking forward to changing the look, although I'm a little apprehensive about how the ride will change. The 17's weigh a ton compared to the Fuchs and with the thinner sidewall I'm not sure about the ride quality. I guess it's a good thing I have comfortable seats.