cArNiVaLwOrKeR:
You can run the Ribs or Tractions on your 4X4. The Tractions, as I'm sure you've realized are an aggressive tread. The Ribs are more like a steer tire (no aggressive tread). Unless you run solely on pavement "I" wouldn't recommend the Ribs for the rear. Some have combined the tires by running the Ribs on the front and the Tractions on the rear. With 6 tires this is not the greatest setup regarding rotation. Just FYI, I've been running Tractions on all 6 and expect to get about 65K out of them. Hope this has helped.
David