I got my 700c x 40 Schwalbe Duremes today and mounted on Velocity Dyad 25mm rims, their actual measurement is 38mm wide. On my 730 there is still quite a bit of room. The only issue might be a bolt on the back of the front derailleur. If not for tha bolt, the frame would accomodate much fatter tires, I believe. Maybe even Schwalbe Big Apple 50's.
