Spencer Cameron wrote on Thursday, February 10, 2011 - 06:30 pm:Track oriented tyres like the Ad08's have reinforced sidewalls that don't respond well to being run undersized. There a completely different kettle of fish to the relatively soft sidewalls found in regular road tyres. That said, I enquired about a set of Neova's for my track rims a couple of months ago with this guy:
http://www.gordonleven.com/motorsport/index.php
And he suggested the 245's for a 9.5 inch rim which would be about as undersized as the 235 I have on my road 9's. Considering his reputation, I'm inclined to take his word for it.