a little off topic....but FYI the tire compound is different on certain sizes like 235/40/17. Most people won't know unless they go to their site cuz venders don't really mention it on their web sites.
I sent an email asking why the treadwear was 200/A/A instead of 200/AA/A on certain sizes....and got this response
" Our RS-2 Z212 tire is made in different rubber compounds in select sizes and those tires have a lower handling rating which is a lower wet handling rating. If you have further questions please contact me at the number listed below."
anyway back on topic....if you're worried about rubbing there are people running 235 and more w/o problems. You might need to roll the fenders a bit though. There is a pretty long thread on that topic around somewhere. The 235/40 has a shorter sidewall which helps with clearance as well.