PCA. go to http://www.pcaocr.org/AX2009.htm, use the registration button. Register as a non-PCA member with your car, print the tech form , fill out the form, show up at 6:45am on Sunday, go to registration, then tech, You're in. It is a high speed autocross, what the SCCA would define as a Time Trial or Solo Trial. I have recorded speeds close to 100 mph with very high G's transitions, neck breaking indeed.
Ideally, we should use the R888 265/305 on 9"/11" wheels using the stock offsets. For the stock wheels (8"/10") the 235/295 are a better match. The 305 is a lot wider than the 295 R888, and not a good fit for a 10" wheel.
Although the R888 295/30-19 is exactly the same width as the stock Corsa 285/35-19, it is 0.8" smaller in diameter.
Measured the R888 and tested them on the weekend. All electronics work well in the Scuderia with the 235/295 Toyo R888. Grip level way better than stock, they were 3 seconds slower than fresh Hoosier A6 on a 56 secs course. Stock Corsas were in between 5.0-6.5 secs slower in similar testing conditions. The understeer is reduced. The 295 R888 is 0.5" wider than the 285 Pirelli Corsa. The 285 Corsa is 26.125" tall, the 295 R888 is 25.5" tall and 2 lbs heavier. The front 235 R888 is 0.5" wider than the stock 235 Corsa, but there is more contact patch on the R888 hence the reduced understeer.