Definitely keep 18's on the front. (I went a 1/2" wider)
18's on the back DO fit, but they look super tiny. It looks like 20's will clear.
Try and stay away from 19's if you can. that tire size is going the way of the Dodo.
Just find some rims you like with 18's in the front with 5x112 bolt pattern
and make super sure they have 20's with a 5x112 bolt pattern

, that's the real trick.