Have your wheels been DYNAMICALLY balanced? This means weights inboard AND outboard on every wheel.

The most common thing I've seen is the fact that many tire stores will balance alloy wheels with weights being applied ONLY on the inboard lip of the wheels. They do this because people complain about their wheels being scratched.

If the weights are only used inboard, the wheel is statically balanced and will not hop up and down, but this aggrevates the DYNAMIC balance which causes the wheel to wobble. I have gotten so discouraged with the people at the tire stores that I bought my own used computer balancer. On MB wheels I either use the two piece MB weight on the outboard lip, or a tape weight just behind the web of the wheel where it is not seen, this gives an outboard plane in order to gain a dynamic balance. The newer balancers are actually set up to tell you how much tape weight and where to put it.

If I were you, I would go out and look at your wheels. If there are no weights on the outboard rim, I fully expect that this is the problem.

Good luck,