Some after-market wheels will puddle rainwater on the inner hoop, and that will feel like your wheels are out of balance. My Forgelines did it (fronts only) on a recent rainy trip. When I got home I went into the tire dealer and had them rebalanced, and they said they were only a "little" out of balance. After the rebalance they were perfect again, but they were dry. I notice the puddle of water accumulate on each wheel after each wash, and driving does not expel the water. At speed the puddle will stay in one location and make the wheel out of balance by a couple of ounces. The only way I can get it out is to stick a towel through the mesh openings and soak it out.
I never noticed this puddling problem with my stock 20" wheels.