I was just about to purchase a set of 235/40r17 Nankang NS-2Rs, but have just read that the contact patch is 13% larger than average! That's fairly substantial (Approximately 15mm extra width on each side of the tyre), so I wondered if it really is that much?!
I'm currently running 215/45r17s on 8" rims and they're spot on. 235's of the equivalent tyre (RainSport 3's) would be pushing it, but should fit.
I think I've already talked myself out of getting them just by writing this

I guess they're track tyres, they're going to run out fairly quickly anyway. I'll gauge the 215's this time round and then go from there. 215's are cheaper anyway
Thanks for your help boys, it's good to talk these things through
Cheers!