I cut the struts to fit over my road tires which measures 33.5. I tried to fit my gravel wheels with 40c Happy Mediums (measure about 42) and they were a bit tight. I think I could get them to clear, but just barely. Mine are the 45mm fenders. THe fenders are plenty wide, but I haven't got the clearance I need at the seat stay brace. Its more of a frame issue than fender. My side lugs are very close to the edges. Some 38's and I would be golden.
Looks good! I'm running (on my Scott) the SKS Longboard 45s, fit over 33c Strada Bianca's (measure to about 38) and 35c Schwalbe G Ones. SKS has the mud flap thing for a little "better" coverage, but don't have the cool hammered look.