I have tried a couple of options on my 2014 129s the std wheel and WTB tyre combo is ok, I swapped to a set of Easton Havens which are have a wider rim,+5mm I think, and tried a couple of tyres, a Specialized Purgatory 2-3 is very tight with about 5mm clearance running tubeless, I am currently running a 2.25 Nobby Nic which is narrower, I am finding it better, it rolls fast and seems grippy on my local trails in N Lancs.
Richard