I have the same problem. Vibration in the front over 80 mph. I haven't had them road force balanced. I don't beat the tires up on the track. My BBS are hubcentric and straight.
From what I understand, the design of the suspension is such that it is very sensitive to imbalances in the wheel/tire assembly. For most people, road force balancing seems to cure it.
2008 IB E92 M3| BBS | KW | Arkym | Platte Forme A.G. | Active Autowerke | K&N | Fabspeed | Dinan | Evolve-R