I have now mounted my old crosser With Bontrager Paradigm TLR (internal width 19 mm) with Pirelli Cintaurato Gravel H 35c tires and I think this (as you said above) is pretty close to max, although you might fit 37c... AND secondly it looks really kick ass with the tan sidewalls and dark rims...
http://community.vintagecannondale.com/showcase/2004-cannondale-cyclocross-800.1779/
I have the exactly same as this one (allthough this one is not mine) and this is also the one with the 37's on. Maybe wise to stick with something sub-38 i guess. The clearance for my current 32c vittorias is...
I’m upgrading my old crosser with some new wheels and will put some wider tires on it than the 32c i have on now. What’s the maximum I can fit? In the gallery is a similar frame with 37c wtb riddlers... That must be pretty close to the max? Thinking about rims with internal width 19 mm, tubeless...