I described the problem to my local independent shop. He asked what style rim the spare had that I installed on the right rear. The car has MB alloys with a steel spare. When I told him it was a steel rim, he said the alloy rims use a longer bolt and when used with a steel rim they can catch on the emergency brake mechanism, preventing the wheel from turning. When the tow truck arrived, I had probably broke something loose which allowed the wheel to turn but still make noise.

I checked out his theory and he was right on. The wheel bolts were scarred on the ends and the cable end/bracket of the emergency brake was gouged on one side. I will carry a set of shorter bolts in case I flat.

I am glad it wasn't anything more serious. At least my differential fluid got changed out and I can rest easy knowing the rear end is in fairly good shape.

Thanks for the responses I received from this list.

Paul Jones
'84 300TD, '80 240D