The new Schwalbe Jumbo Jim tyres are specifically designed for fat bikes in mind, allowing a wider width and lower overall pressure.
This is especially true if you want to cycle in deep snow or loose sand. In these conditions only large volume combined with extremely low air pressure can help. Schwalbe‘s Jumbo Jim is an extremely light-bike Fat Tire. The usual Fat-Bike 4 inch width weighs in less than 1000g!