Stock width, stock "feel" bigger rim?
 

I would very much like to increase the size of the rims(height), and bump up to an 18 just for the aesthetics. I don't want to get rid of the lose back end or the slide-ability. Ideally, i'd like to keep the 215's, but i'd be willing to go 225's. Unfortunately, there aren't many aftermarket wheels available in an 18x7.5.

So my question: what would be the widest wheel that i could put a 215/225 onto without stretching it too far? I'm sure a 18x8 would work with a 225, but what about 215? I think and 8.5 might be too wide for the little 215's, but i want to get a confirmed yes or no.

Thoughts?

half of the loose back end and "slide-ability" are the crappy tires that come with the car, just put crappy tires on your new rims too.