Never mind, I’ve just been playing with someone else’s numbers (knard = 2.76 on Flow EX, 2.98 on a RH) Using the same tyre width/ rim width ratio gives:
X King: Crest 2.33; Dually -> 2.55; Rabbit Hole -> 2.61
Dirt Wizard: Crest = 2.35; Dually -> 2.57; RH -> 2.63.
So it seems the Knard is more true to size than the Dirt Wizard, and my comments not really relevant here!
Surly said in the Instigator press release said they found the fork with the biggest clearance, and worked on the biggest wheel/tyre that would fit it, so it’s not that surprising it’s not much bigger than a “normal” tyre. I guess they had to claim on the high side with the number on the sidewall, otherwise it wouldn’t be different enough to claim it was “26+” and sell at the price they needed to sell at.