This one is most DEFINITELY a job for a Hunter GSP9700 wheel balancer. Go to www.gsp9700.com and search for the shop nearest you that has one of these great machines.

I fully expect that you have a defective tire. The 9700 will find the problem. Most likely your nearest MB dealership will have one of these machines.

Many tires are improperly balanced because the balancer operator didn't give a hoot about his job. These can be fixed by simply properly balancing on a decent balancer. When you get a description like you gave, it's definitely 9700 time.

Good luck,