Hi eames88. Welcome to the forum. Alignment issues cause tire wear patterns, a crooked steering wheel, and / or pulling to one side when you let go of the steering wheel. Except for very rare and unusual circumstances, it will not cause a vibration and even then, worn parts are involved.
Out-of-balance tires, of course, are the most common causes of vibration, but a bent wheel, bent hub, and warped brake rotor can also cause this symptom. If the brake rotor is warped, you should also feel it in the steering wheel during braking if the caliper is sticking to its mount and is not able to slide back and forth freely. A tight universal joint on the front axle, between the upper and lower ball joints, will cause a vibration too although it shouldn't be so speed-specific.
To find out if this is tire / wheel-related, your mechanic should run the vehicle on a hoist, in gear, and in 4wd, then place a dial indicator against the lip of each wheel to check for sideways runout. Anything over around.040" should be investigated. Remove the wheel with excessive runout and perform the same test on the brake rotor after the lug nuts are reinstalled. If the vibration began after a front wheel was removed, it is possible for rust or scale to break off the rotor and get stuck between the rotor and hub. That will make it wobble and show up with the dial indicator.
If there is no excessive runout, switch the two tires from one side, front to rear, then drive it to see if there is a change. If not, switch the two tires from the other side. If switching one pair front to rear makes the problem change, inspect the tire that was moved to the rear for a bent wheel or broken belt in the tire. Broken belts are more common on high-mileage tires, and bent wheels are more common than you would expect.
Tuesday, May 4th, 2010 AT 1:44 PM