Engine Vibration at highway rpm/speed

High speed vibrations at 60 MPH and higher are usually caused by a bad tire, rim or a bad brake drum or rear disc rotor. Lower speed vibrations at 35 to 45 mph are usually driveline related and could be an out-of-balance drive shaft or improper u-joint alignment. If the vibration can be felt in the shifter, it is likely a front of the driveshaft balance problem or a bad u-joint. If you feel it in the back seat or in the floor at the rear, it could be a rear of the driveshaft balance problem or u-joint. However, a bad rear tire, drum or rotor (if you have them on the back) can cause the same vibration in the rear. Before pulling the suspected driveshaft, swap the front wheels for the back and back to front or borrow a known balanced set of wheels to test drive the car. If you haven’t balanced your wheels for a while, it wouldn’t hurt to do so to ensure they are indeed balanced.