Found these today. Perhaps it is old news but I found it significant.
Chain Regulation Expands
ODOT has amended the state's chain regulations to add a new snow zone condition. Under the new condition, you must use chains if your vehicle is: Rated 10,000 pounds gross vehicle weight (GVW) or less and is towing. A single drive axle vehicle rated over 10,000 pounds GVW whether towing or not. Chains must also be used on the trailer or vehicle being towed if it has a brake that operates while in tow. More information including minimum chain requirements and examples of the snow zone signs is available under 'Winter Travel'.