1997 C280. The car shakes a bit when I get up to 65mph. Seems to be coming from left front. Tire air pressure ok. Supposed to be balanced, but that could the the problem. Thoughts? Thank you.
Normally, the first thing to investigate is wheel balance. That covers most unbalance cases. Other causes could be unbalanced rotor, too much play in the suspension, and, if you bought the cheaper Chinese or Korean tires, an unevenness in the hardness of the rubber in the tread.
I would go to a good tire shop with a dynamic balancing machine. Some tires, like the ones with the varying rubber hardnes cannot be balanced, as they wear unevenly. Check the balance on both tires.