R888R in 235/40 and either 265/35 or 275/35 will do you just fine. 285 rear is really excessive unless you're running massive power, especially on track rubber where you've got masses of extra grip anyway.
Tbh, if you're running track rubber then you'll likely want to be running with the TCS off anyway, which makes the debate redundant. FWIW, I used to run 225/40 and 245/40 R888 on my old car and never had issues, nor a lack of grip