I just traded in an '05 coupe for the '05 roadster. I drive exactly the same roads and highways so I know when the roadster switches to square wheels at about 30, it is not my imagination. I took it to the dealer and had all 4 wheels balanced. It made a slight improvement, but not enough. In the coupe, the steering wheel had no vibrations at any speed, but the roadster's starts to vibrate at 30 though it doesn't get any worse up to 80+. Any ideas?