40C slicks are a (too) tight fit, Nano doesn't look like it has any knobs poking out of the sides but you'd have at best zero mud clearance and at worst a tyre casing rubbing on the chainstay, depending on how big they come up on your rims compared with a true 40mm.
Realistically, you don't want to go over 35C on a pomp if you intend to get dirty.
40C slicks are a (too) tight fit, Nano doesn't look like it has any knobs poking out of the sides but you'd have at best zero mud clearance and at worst a tyre casing rubbing on the chainstay, depending on how big they come up on your rims compared with a true 40mm.
Realistically, you don't want to go over 35C on a pomp if you intend to get dirty.