Question for some of the experienced autocross/track day members. Should you use the 305's for track days, or up-size to 315's? Is the added contact patch worth the loss in turn-in? Inquiring mind wants to know...
I've had good results with 285/35 Continental Extreme Contact Sport Plus on all fours with my 9.5" OE wheels. Good quality rubber pays off more than just wider. If you are trying to stuff a wide tire on an undersized wheel, you're not gaining much anyway since the contact patch is still similar to a narrower tire designed to fit. When I lowered my car and went from OE Pirelli summer tires to the Conti's, I took 5 seconds off my personal best time.
If you're looking for a good autocross tire the top 2 are the Bridgestone RE71 and BFG Rival SI was considering the purchase of the Toyo888, but honestly, I'm open to recommendations. Texas heat... so no consideration needed for cold weather.