I had an extremely bad vibration between 60-70 mph, and the dealer said it was the $1800 driveshaft. I had had the tires balanced twice, but it was still there. I went ahead and bought new tires anyway, and that nearly fixed it. The old tires had scalloped really bad on the front.

It is still there sometimes around 50 mph, but really only when it is cold. When they balanced them they noticed that one rim seemed a little bit bent, so that is my next step.

You could also have a small sandbag added to the culprit rim(s). Which will be pulled to the out-of-whack spot and fix the vibration.

Just what I have been through.