I put my wheels on a lathe and balanced them, and then the same thing with the tires, just to see how far off they were. It was interesting, but in the end there will not likely be any benefit for a truck as heavy as mine. Plus, the tires are so out-of-round that the offset required to balance them was enormous. One of my coworkers balanced the wheel/tire combinations on his B4, but also said there was no difference.

I would imagine balancing the rotating assemblies of an on-road car could be beneficial.