Originally Posted By: fdcg27
Back in the day, bubble balancers were what we had.
They worked just fine and I drove many smooth miles on static balanced tires.
How far back was that? "Back in the day" of the early 1960's (and maybe a long time before that), well-equipped shops already had dynamic balancers. Bubble balancers, (if competently used) gave better results "back in the day" than they can now, because tires and wheels are generally wider now.
If a hypothetical tire is perfectly balanced except for one heavy spot on the left side, and another equally heavy spot on the right side 180 degrees around the circumference from the first one, it would show up as perfectly balanced on a bubble balancer, or any other static method. Yet, it would shake the car. The wider the tire (i.e., the farther apart the aforementioned hypothetical heavy spots are in the axial dimension), the worse the imbalance and consequent vibration.