kinda depends on road or trail surface, conditions of the day (temp & precip) & also what's underneath the day's precip. obviously if it's just cold & no precip that's like now, you get a little rain on pavement it's a little different than rain on dirt making mud. you get sleet on top of wet mud, that's one thing. if that mud freezes hard & you get rain that's another thing. if you have dry conditions & get a cpl inches of fluffy powder that's another thing. you get a base layer of snow & ice & then get 2-6" of fresh wet gloppy snow that's another. dry pavement with fresh wet snow with road salt mixed it to make super slush that's whole different animal altogether. I'd start with close to max pressure. but air down the front cuz the rear takes more of your weight. then judge your weight, the road or trail, the conditions & fine tune your pressure from there. as an example, when I commuted through the winter using a 700c roadified hybrid with 35mm Marathon studded winter tires (on plowed roads) I maxed the pressure but then tapped the valves to soften them just a tad. I wanted the tires hard enough so the studs dug down to find whatever pavement they could. but soft enough to flex over irregularities (like frozen lumps under the snow & slush) to maintain contact & not rebound abruptly. with wider tires you'll just have to find what works best for you. I had an epic blizzard ride on an old MTB that took twice as long as it should have cuz I was riding thru 4-5" of fresh cold snow, with tires aired waaaay down & riding on grass & sidewalks that were not plowed or shoveled. major mistake for the 13 mile 1way trip. after turning around I aired up the tires as hard as I could with my hand pump (still well under max) & rode home on pavement through the plowed snow & slush another 13 miles & it took half as long as the 1st 13 miles