No Wheel Weights!???

Trying to track down a high speed steering wheel shake. Wheels and tires are about 2 weeks old. New Cooper Cobra tires mounted on new Wheel Vintiques 63 Mopar steelies. No wheel weights on any of them, inside or out. No shaking with the old skinny 14" wheels and tires.
Odds that all four were in balance? Odds that someone forgot to balance the wheels?