Unless the car has been lowered, 315s Absolutely WILL fit, but not perfectly...the beads are pinched about 1" too close, 'crowning' the tire a bit. [Back in the "old Days' dean Word and Bob Woodhouse and I were probably the 1st to try 315s up front, and we pledged to keep the 'secret' as long as we could. It lasted about 2 Viper days events!]
Downside is that the tire will sandblast your sills and rear door bulges with road debris, esp if you are using sticky tires.
Also pull your "sport shims" for autocross, handling is dramatically improved.
Call for more, and have fun!