I have unbolted adjusted the bedroom slide on mine in the past, which is smaller and easier. You will be able to loosen it so it drops, but not sure it will be enough to get a look underneath,depends on where it currently sits on the mounting plates, you'd just have to try it. Of course you'll need a jack to adjust and hold it in the proper location before you tighten it back up. If you were to completely unbolt it from the rails, with a jack on either end I would think you could tilt it enough to change out the wheel.
2001 National Tradewinds 7372