I'm one of the "lucky few" who have long-running wheel balance problems. These manifested as steering wheel shimmy and/or vibrations from the rear.
Here's a lengthy thread detailing my problems, and things I tried to fix them:
Yet another 4Runner wheel balance problem...
The problems persisted after switching from E-rated KO2's to P-rated Falken Wildpeaks.
An old hand at a different shop performed a "static balance" and no road force test. I hit the road and, shazam, no noticeable steering wheel shimmy or rear vibrations at highway speed! The ride quality was as good as it has ever been since I bought the vehicle.
That was 3300 miles ago. In the interim I've driven everything from smooth highways to rough, rocky trails. Randomly and rarely, I briefly get mild steering wheel shimmy at highway speed. The rest of the time it's fine.
Sooo...if you're having wheel balance problems, perhaps try this before new tires or other expensive fix attempts.
Here's one explanation of the difference between static and dynamic balancing:
Wheel Balancing 101 - Static vs Dynamic Wheel Balancing | E-Quipfix Ltd
P.S. After the static balance I now have far fewer weights on my wheels (the RR has a single 1/4 ounce weight). And they are in different spots on the wheel (obvious due to all the tape residue).