Took the car today to have tires balanced and rotated. Have not had a chance to drive it on the interstate yet but it sure handles and drives a whole lot better. The guy who balanced it - same place I bought the tires over a year ago - said whoever installed them did not balance them to begin with! I stood over him while he did the work (just for my own piece of mind) and there were no wheel weights until he added them. He also torqued all the wheel bolts by hand without even having me suggest it. I could tell then he had worked on MBs before! I will make sure he does the next set of tires I purchase!
I will try to get out to the interstate this evening to see how it does.