Originally Posted by teachutofly
#1 supsect for vibration that comes on at 55 is tire balance.
If you feel the vibration in the steering wheel, this would support the balance theory. If you feel it though the car body (i.e. through your seat) and NOT through the wheel, it may be something else.
technically if you feel it in the seat it could still be one of the REAR tires being out of balance, id recommend rotating the tires IF its not in the wheel.
If its in the wheel already then prolly one of the fronts has a bad tire and they need to be checked/balanced
If its not, rotate them in an X pattern and if the problem THEN comes from the fronts then one of the *NOW* front tires has a bad tire and they need to be checked/balanced.
During the rotation visually inspect all the tires by rotating them around to see if you see any bad spots in the tires, ie bubbles, warps, bad cracks in the treads, nails, screws, etc...
If you do this and nothing changes, let us know