Werner, you straighten the runout of the wheel by selectively shrinking specific spokes to pull the rim in that direction. You shrink the spoke by heating it with a torch flame. It will ruin the paint, so best to do it before you paint them.
You can static balance the wheel+tyre with stick-on weights that are commonly used on fancy sports car wheels.
You can dynamic balance 1930-31 wheels and tyres, with the hubcap off and an adapter, because they have a larger diameter hubcap. I think the opening is too small on the 1928-29 wheels to do this. (If anyone has done it, please post pictures.)
In addition to the wheel having a wobble, I have seen tyres molded with a side-to-side movement. Best to move them to be spares and put 4 straight running wheels and tyres on the ground.
