"It started as a mild wobble, but has progressed (over about 3-5 thousand miles) to the point where the car is essentially undriveable. The wobble hits around 50-55 MPH, then doesn't go away again until I slow down to about 30-35 MPH."


I had those exact symptoms in my 1990 300SE. I had new Michelins mounted and balanced and the problem disappeared.