About fifteen years ago tire noise that sounded like bad wheel bearings began being more and more common. Before you continue chasing your tool over this, borrow a few tires and wheels off a friends car and bolt them on the front and go around the block.

If you have no friends with a similar Benz, rotate front to rear and go around the block.

LarryBible you were correct. One of the front tires was the source of the noise. I used the spare to find it. I would not have ever thought that a tire could sound like that. The only sounds I have ever heard from bad bearings are a rhytmic sort of cross between a rumbling and grinding sound that was loudest about 30 mph. Thanks for the info.

I'll see how long my adjusted by feel wheel bearings last because I don't see how american car bearings can be adjusted OK by feel but not MB. How do the bearings know what car they're in? I used Timkin, made in the US on the box. Maybe the box is what's made in the US.

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85 300 SD ~ 115K
82 500 SEC Euro ??K
78 450SL 164K

The country of origin (where it was machined) is stamped on the side of the bearing itself.
That's no guarantee where the steel came from though.