I think you should have enough room for chains. There is a little bit of play in the wheel well even with the OE 18'' option so you should be able to do it. May not be easy to get on and off though.
Refer to 'Miles/FocusFanatics' as your previous contact when you order online. You can also credit the forum by ordering through any [URL="http://www.tirerack.com/?affiliate=AD4"]Tire Rack[/URL] link.