My '97 E420 has horrible steering vibrations. It used to be at speeds above 60 and on the highway, but it recently does it all the time, especially on highway curves. I would call it a steering "shimmey." My dealer has balanced my wheels, replaced both front shocks, performed alignment, and replaced the control arms including all bushings. I took it to a tire retailer and they inspected my car telling me the tire/steering Extention rods need to be replaced. Also could it be that I have an aftermarket rim on the drivers side. Please give me some advice.