I have a 96SL500 on which I have recently replaced tires. After many balances and rotations, I still have a vibration that comes on at 68 mph and stays to around 75. It may have been there on the old tires just not so pronounced. Since the speed limit on Interstate is 70, this is the range of most of my driving. I have been told that it may be the rubber bushings (front and rear) that Mercedes uses in place of universal joints on the drive shaft. I'm going for a second opinion this week. Anyone have any ideas as I don't want to just throw parts at this car.

 

the universal flex disc is a good place to look after taking the tires and wheels out of the equation

 

you could try trans mount or motor mounts. although there is a slight difference from tire vibration to driveline vibration. loose or worn suspension components or maybe a bad front strut or shock. i would check for a mild bend in a rim someplace.