I concur...15's are prime. You need some sidewall. When you are hard cornering and pushing to the brink, something will give. Either traction (on a larger wheel that has no sidewall) or the sidewall will flex and keep you pushing through the corner (with a smaller wheel and sidewall). I HIGHLY recommend, at minimum, a V speed rated tire.
...Just for reference and smiles............I am currently running '89 crx si wheels (13) with 205/60/13 Yokohama AVS intermediates, no longer available :cry: (I knew you would smile!). When I autocross, I drop pressure to 24psi/f and 26psi/r without rolling past the roll ring :rockon: