you could run a 235/45 if you just want it to be a slightly skinnier, shorter tire. however, it's going to increase wheel gap.
I'll just stick with 245/45s... Every thread I have read talking about suggested tire sizes points to 245/45-18s as being perfect. Not ready for them yet, but hopefully by June-ish.
2014 Chevy Impala LTZ Limited -- Silver/Black, Grand Prix replacement
2004 Pontiac GTO -- my garage queen
2004 GMC Yukon SLT -- wife's daily driver