This might be a stupid question but bear with me, I am new to this whole HD truck thing.

I have a 2017 F350 with 12.5/35” BFG KO2s. I live on Vancouver Island so I rarely deal with snow, but I will soon be driving to Calgary, Alberta through the Rockies for Christmas. Of course, I will be anticipating miserable conditions and heavy snow on the highways (temps around -20 Celsius). My question is what PSI you would suggest running for this kind of trip that will safe and maximize traction? I will not have a trailer attached and little to no weight in the bed. Thanks!