When did you notice the tire vibration? If it was after you had the tires swapped out it could be a broken tire pressure sensor. It happened to me when I got my tire repaired for a nail at Sears. It likely happened when the tire got put back on and the person wasn't paying attention to details. When I would go above 70 MPH my steering wheel would vibrate and wouldn't stop until I slowed down to under 60 MPH. I took it back to Sears and they checked the suspension and it checked ok. Then the tire that was repaired was checked on the balance machine at a slow speed to listen for anything loose inside the tire and was broken down. Next thing I'm being handed my tire pressure sensor and the valve stem is still on the wheel
. Since the sensor was broken during their repair of the tire the covered buying the new one and put it on. But here's the kicker, the car has to be taken to the dealer so the ECU recognizes the new sensor. I got hit with an $80 bill for them to break down the tire again to get the serial off the sensor and to reprogram the ECU. I was was not happy about that and made a trip back to sears after that to get reimbursed but only got half back though(when I went it was like a week later and talked to a different manager and tried to tell me different about how the TPMS system works, lol), I also only had 2 hrs of sleep so I lost out some money. So now your informed, of it is a broken sensor have them take the car to the dealer to make sure they take all charges.