Just bought new tires and had Dyna Beads put in for balancing. I remember hearing that the beads come in a bag and it takes a while for the bag to disintegrate and release the beads. Is that correct ?...
I, too, like to add them to new tires after they are balanced at the dealer. That way, they can compensate for any wear through the years.
Even Dynabeads can be defeated if the tire is grossly unbalanced side-to-side, which basically is a defective tire. This defect is sometimes indicated by a tire that takes a lot of lead weight to balance on one side of the tire but not on the other side of the tire at that spot.