I was hoping someone else would have answered by now. Here's my guess: Have the tires balanced. When a passive wheel (like the rear tires) makes a sound (vibrates) at a certain speed, it usually happens because it is not perfectly balanced.
It could also be that some part of the frame of the car is acting like a tuning fork, amplifying normal road noise that occurs at a given speed, but if this were the case, I'd expect more people to have reported it. You might also go for the 4-wheel alignment while you are at it, but that's less likely to be the problem.
It could also be that some part of the frame of the car is acting like a tuning fork, amplifying normal road noise that occurs at a given speed, but if this were the case, I'd expect more people to have reported it. You might also go for the 4-wheel alignment while you are at it, but that's less likely to be the problem.
