You might be able to get away with 26x 1.5
I run 26x 1.9
My studs are 26x 2.125
If you go narrower then 1.5 I would watch how much weight you carry.
You see the whole thing about wider tires is, MORE WEIGHT.
I tend to carry a lot of stuff. Bike wieghs in @ 45 lbs with lights and winter gear etc...
Everyone has opinions... so lets hear them: