Currently using 2.25 nobby nics evo's running tubless, anything less than 30 psi they feel a bit squirmy and roll on the rim a bit too much. The NN's have got very thin sidewalls though. I've got 2.1 UST versions on my other rims and they feel fine.
Just fancy trying some Maxxis tyres, Ignitor, Advantage or High Rollers