Don, I can't help you with the actual lug nut size, but 1-1/8 socket seems to stick in my mind. As for an air impact, better try getting a 3/4" drive. The lug nut torques are 450 ft./lbs and many 1/2" drives won't get there. Try doing an "advanced search" (under the Find tab above) for keyword "lugnut torque" in the Winnebago Coach Owners Forum... You may find some reference to the size of the nuts.