[supereal]

If the tire inflation is correct all around, and there isn't lots of play in the steering gear or other parts, it is likely the toe-in of the front wheels is incorrect. I have seen this in Model A's so bad that the car had to be stopped to get rid of the wobble. If the toe in shows about zero to 1/16", but the shimmy is still there, swap the front and back wheels and tires. If that cures or changes the problem, look for a bent wheel or out of round tire. Tire balance may contribute to the problem, but usually not to a severe degree.