Crust recently modified the description of its Lightning Bolt Canti frameset, changing the "fits 48 without fenders, 42 with" statement to "Suits a 42b tire perfectly". Based on that change, someone had asked whether a Crust Lightning Bolt Canti could fit a 48.
I mounted some RH Juniper Ridge tires (650b x 48) this afternoon on mine, and they do "fit", but I can see why Crust might have changed the description. It's pretty close at the fork crown and chainstays (~3-4mm). Granted, these are knobby tires, so a smooth tire might have a little more room.
Interestingly, my RTP 26 x 55 wheels fit beautifully with maybe even clearance for fenders, although the brake mounts are in the wrong place. I'm almost curious enough to have someone reposition them.