The balancing on the TT has a couple of downsides.
If this is done, then that tire MUST stay on that drum, and on the same stud position.
And if the spare is ever called into service ,,,it won't be balanced.
These reasons are probably why it has fallen out of favor, and isn't done much.
And though I do think that the drum SHOULD be balanced, it probably isn't as important as the tire. It has a much smaller diameter so it will have less effect.
It is also the reason that 3 oz of beads can correct a drum that is out of balance by more than that. The beads are right next to the tread, much further out than the drum, so the centrifical force is greater there.
