Soooooo glad I didn’t bother this year after hearing that! What with already having done Mayhem, and a couple of laps at 24/12.
Anyway… It’s about the tyres ability to clear the mud, rather than grip in those conditions. Trailrakers are probably still the outright grippiest mud tyre, but they don’t clear well. I’ve found the best clearing tyre is the Maxxis Medusa, and they do different widths too, depending on how extreme you want to go. The 2.1 is a normal size, great if you’ve got tonnes of clearance already and riding in not too extreme conditions, the 1.8″ is superb in real horrid conditions (on the rear got me round Mayhem without clogging once), but if you REALLY want mud clearance and are prepared to go very narrow to get it, they do a 1.55″ version too.
They’re not as outright grippy as a Trailraker, but they don’t hold onto the mud, so whilst you’ll spin up a bit more, you can keep on pedalling at least!