I would go either 35 or 40 at most on the profole, as I think 45's will look to thick, even when I had 235-40-18 on the rear with a small stretch it still made the tyre look thicker than it was!
A mate of mine sorted out my tryes! sadly they were only part worn with 7mm on then! still have them on today after 8 months or so running my pork rims!
with 235/35/18 on rear and 225/40/18 up front
and these where when she had 235/40/18 shoes! looks much thicker in the wall.

I personally i would stay well away from 45's as the profile will be too dam think!
Sorry for the pics not the best I know, but give some idea anyway! lol..
S-star