I don't remember 100% of all the dimensions, but test measures on mine were a width of 3 comfortable inches between the forks, a 2.75 inch wide tire would fit without issue. And I also saw that a 27.5 inch diameter wheel with that same fat tire would fit as well.
I've been looking over various wheels seeing what I want to install. I know I want disk brakes, which will take a bit of modding to make it work, but it will work.
Anywho the forks are rather robust feeling/looking, so I think they should handle the disk brakes. The fat tire would behave as a shock absorber since the forks dont absorb s**tzu.