my tyreman machine plastic/teflon for center hub. so the wheels fit nicely.Are your rims a perfect fit to the hub? Did you install center cone?
Previously I had this problem also. The tyre shop boss where i do my balancing, he always centralized the rims for me. Later on he manage to measure and find me some center cones. Nowadays no problem at all with balancing vibration.
On wheel balancing is good, but problem is, every time you need to remove your wheels for any repairs, the balancing runs and need to re-balance. Now on Off wheel balancing, I have no problems at all.....