When I had a 26'er HT I used to run Specialized Storm mud tyres in the winter over here in the UK and they'd grip in any sort of slop we get.
However since building my 29'er I've been running the Ground Control S-Works and they're great tyres, but slightly lacking in proper sloppy mud.
Are Specialized planning on releasing the Storm in 29" any time soon?
Mtbr's 2016 Winter Biking GearReviews and Roundups
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Thread: Specialized Storm 29'er