I use, and highly recommend, a Yakima Hold-up Two.
Yakima HoldUp Bike Hitch Rack at REI.com
I use mine to haul a 6"-travel mountain bike with 2.5" wide tires and road bikes with equal aplomb. It's so tough it totaled a Volvo that rear-ended me, with no significant damage to the rack. I've been very satisfied with it, but of course, YMMV. Good luck!
Jason