Answer
Does the steering wheel itself vibrate? does it vibrate when you are
rolling in neutral? swap the tires from front to rear and see if its any different, if it is
a bad tire you might feel wobble in the steering wheel when the tire is in front, but
a wiggling if its in the rear. if the condition goes back and forth when the tires go back and forth, you have done a good deal of narrowing down for free.