Oddly enough the best place I have found for special ordering parts (espeicially when I am not sure of the technicallities of what I am ordering and need help) has been the Dallas REI on 635.
They have beaten Binc and RBM on price and quick turnaround every time I have needed a part.
Binc told me I would have to replace a rim on my daughters bike because it was "too far out". A tech at REI had it trued in both planes in less than 15 minutes and only charged me $5.00.
If you are a member the return policy is very forgiving...
I am going to try special ordering new treads for my volae from them since they have been able to get pretty much anything else I have needed. That way if I don't like them I can return them