have an 2009 , 2500hd. have had an issue similar to rear wheel not balanced , took to dealer and went for ride . head mechanic told me it was frame beaming , and then check rear mounts , they are the newer one suppose to fix the problem. what else can be done. i put new rims (stock chevy chrome rims ) and new firestone mt tires... can somebody help me , this is a real problem and is driving me nuts. tires have been balanced and rotated front to back and no issue with tires being unbalanced.