Question about steering wheel shaking while driving

[Luce]

Wide tires on a light car with a manual rack and pinion steering is very susceptible to polar imbalance.

Imagine there is a heavy spot on the outside edge of a tire, and they try to fix the imbalance with a weight on the inside edge of the wheel, but opposite side. A static balance will look good, but as the wheel spins, the 2 heavy spots will try to move the wheel so that the 2 heavy spots are in plane and make the wheel wobble. At the perfect resonant frequency of the steering system, it will become a very obvious left right shake.

ALSO, if the other wheel has a similar polar imbalance, when the wheels are synced, it'll be more pronounced, then you make a slight turn and they become antisynced and the 2 shakes will cancel.

Most heavier cars with narrower tires and power steering are far less susceptible and most shops are not that picky about the polar balance. The only way to see the polar balance is with spin balancing. The old bubble thing won't show it.