To be honest I have never seen tires do this before on any vehicle I have ever owned. My brother has a 2009 Toyota Tundra 4-door and his rear tires are actually having the tread torn/ripped off the surface? I have done some research on this and what I'm seeing is worn shocks can cause this. Are there any other parts to look at that would cause tire chunking? Really would appreciate any experience/insight to this problem...thanks guys!