have you autocrossed before?
the only reason i ask is because i feel a new autocrosser should run whatever he has on the car currently. especially if they are all seasons or a lower end summer tire. i feel this helps them get control of their car first. learn its limits. then once you put a sticky tire on, you'll feel like super man!
i was told by a DP national champ that sticky tires hide flaws in bad drivers.