How can I tell if my tire has a lateral imbalance problem before installing the beads?

A: If you have weights installed now:
The most obvious indicator is a large amount of weight (comparatively)on one side of the tire, and a small, or no weight on the opposite side.

If you are purchasing new tires:
Have the tires spun on a balancer. If the machine is telling you that you need a lot of weight on one side and little weight on the other, then the tire has a lateral imbalance.