Yep, I know this is an older post, and I gave some "deeper" confusing physics answers, I could have sworn I gave the simple explanation as well, but it's not here. My memory must be failing:unhappy:
Anyway I just got a PM requesting a more simple answer to what I mistakenly thought I already had put here. Thanks for helping me get the cobwebs out. Here is a more direct aswer to why this happens:
Anyway, the better answer is:
Imagine when you accelerate in a car, force(pseudoforce) wants to move things into the back seat, away from the direction of movement.
The out of balance wheel is held in place by the axle but, it does move(vibrate) some, in the direction of the heavy spot.
The weights inside the tire move opposite the direction of movement,(heavy spot) self balancing the tire. Movement continues until things reach equalibrium.
I have replaced both tires on my K8 and use dynabeads and think their great!