I’ve got 2 different treads to choose from…
Schwalbe X-one 33mm (cyclocross; knobby) tire VS Serac CX Sand (filetread; no side knobs).
The X-one seems like the safer bet, but serac could be really nice in the rolling resistance department as long as the gravel is generally firm as I keep hearing it is. I’d appreciate any insight you could add.