Besides the temptation to make the obvious wise-*** response, I can't believe the OP states he has two rear tires that can't be balanced properly and one that is out of round...and is looking for other reasons why he has a vibration. Ummm, could it be because one of your tires has separated and is in the process of destroying itself?
Yeah, that's what I thought after reading the post also. But decided rather than hurt his feelings (because I'm not sure I can state the obvious without bringing CFS into the statement)I would go for the potty humor.