225's on the front should fit fine, wouldn't try to go much smaller, at roughly 8.75" depending on tire model that should be a good fit on an 8.5" wheel. 255s on the rear though would be too small, its only about 10" wide. Is it physically possible to put those on the wheels without the beads tearing, probably, airing it up would be pretty difficult, let alone driving on them.
265's would probably be the smallest I would try, 275's would fit more ideal, but would probably touch your fenders. Since you are planning on rolling them, I think you will be safe, it'll be close, but its one of those things where you won't know for sure until you try it.