We have a F350 4x4 dually with an Arctic Fox 811, and plan on using the rig through many of the coming fall and winter months in BC, Yukon, ID, MT, OR, CA and WA. I found that Washington State require...
In California, the usual requirement is "chains req'd, 4WD with M&S tires ok". Following that there is a chains req'd for everyone, but that almost never happens - it goes from the former to "road closed". So if you have 4WD the chains will rarely be used (in California).