I had a severe shuddering when braking from speed on my 1987 300E when I
first bought it in 1999. It assumed it was warped brake discs as that
was exactly what it felt like.
I replaced the worn our tires with new Michelins and it has never
shuddered when braking since. It rode smoothly so I don't suspect tire
balance, separation bulge, or flat spot was the cause.