Bill-
Just read through this topic and wanted to give you a heads-up on one drawback to using any type of inside-the-tire dynamic balancing media: after installing the product if there is a percieved balance problem, the tire cannot be spin-balanced without removing the balancing media first. The beads or powder will throw the balance machine off every time due to the way it moves around inside the tire. They can be trued if they're out of round without removing the balancing media, but not machine balanced.
Of course, no amount of any type balancing will be able to compensate for a physical defect of a tire or wheel, so that should be checked and ruled out.
:):)