You might have a wheel out of ballance or a bent rim. To Check put your car in neutral and set the parking brake on fully, then after jacking the car up Try to spin Each front Tire as fast as you can then feel the tire and see if there is any play in/out up/down. I had to do this on an
Old Truck turns out that is was a bad tire that the cord's bunched up a bit. Hope this helps.
g6 Racing Team