Some Duro Wildlife weights:
1570g (Duro Racing Wildlife Leopard 26 x 3.0 DH Tire | unicycle.com)
1650 (Rubber is heavy! Duro, Duro, Duro. 3" tires)
1860g (http://www.unicycle.uk.com/unicycle-parts/tyres/duro-wildlife-leopard-26-x-3-tyre.html)
Some Surly Knard weights:
804g (http://forums.mtbr.com/fat-bikes/26-x-3-knards-893188-2.html#post11167904)
875g (http://www.bike24.com/p2113031.html)
So the Knard is roughly half the weight.