Studs are the only answer to ice, it's true with its 35 mm tires or 4" tires (
Top Contact Winter tires are the only exception to this rule ... and they don't make it for fatbikes). With studded tires, you want high pressures for icy conditions, for me (170 lbs / 77 kg), I ride 12-14 psi with
Dillinger 4 tires. The only draw back, at these high pressures, deep snow is very difficult to ride. This YouTube edit from a race on a frozen Lake Minnetonka shows my high pressure tires are great on the bare ice, and I struggle (& fall) in the deep snow.