Rigid 29er Canti Forks

1+, right now it have 28c on mine, but it does look like the max clearance would be just 35c, depending on the manufacturer and model of tyres of course.

the 30c Schwalbe CX Pro tyres fit nicely though, a good size and plenty of grip

I've run 38c tyres on mine since getting it (not all the way to the back, but pretty much). Marathon Plus right now. Forget the trye I was using before, but it was some cheapo hybrid tyre, I suspect.