19.5 is what a F450 comes with, and it did wander before I changed tires. It may be a tire tread problem they are highway treads. The truck is a crewcab and the truck looks like it is front end light, I have not had it weighed. The center of gravity sticker on the camper is directly center of the rear wheels, but I have a long hitch stinger out past the end of camper with a spare tire mounted on it. a lot of weight back there. and just looking at the rig from the side it looks high in the front and low in the rear. I don't know how I could move more weight forward.