Have the balance rechecked. Sometimes the machines are out of calibration. Very often new wheel weights fly off. There could have been a spot of impacted mud on the back of a wheel that wasn't removed prior to balancing, and it's gone now. Could have a broken tire belt although that would be quite the coincidence to happen at the same time, plus you would see the steering wheel oscillate at low speeds.
Any reputable shop will recheck the balance for free provided you don't wait too long.
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Sunday, May 29th, 2011 AT 8:13 PM