Only when it is cold-sounds like normal tire flat spotting. What size tire? What air pressure? Vibrations are caused by a few things-bent rims, out of balance tire, out of round tire, bad tie rod end, bad ball joint,a bad bearing, or depending on the set up-a bad bushing in the suspension. Since it only does it when the tires are cold that would eliminate most of the above. You can easily check your suspension and bearings. Hey guitarman, an alignment will not cause a vibration, it will cause other symptoms such as abnormal tire wear or a pull to one side. Your tech teacher is WRONG, as the vibration wouldn't stop after 10 miles-because the alignment doesn't change as the vehicle is driven.