Easy way to make sure the hubs are good is to mic them.
I believe that the number is 4.750 with a 0.005 tolerance. If they are good, replace the wheels. Yes that is a big deal, but the problem is only going to get worse.
With no centering, the wheels will loosen quickly. And when they do, not only are they moving up and down relative to the hubs, but they are rotating back and forth every time you step on the gas or brake. Essentially the wheels are slamming back and forth into the fasteners. They can wear or sheer off studs/bolts. This also ovals the holes in the wheels so they move more and slam harder and wear more.........
Very Not Safe.
Check the fronts as well, they could be fine, or wheels could have been moved around so all are suspect.
Last edited by Jim Sears; 04/23/2017 5:30 AM.