Washington Is the Only State That Makes You Carry Chains by the Calendar

Chain laws normally work one way. The transportation department decides conditions are bad, signs go up, and the requirement binds. Nothing is owed until the sign appears.

Washington runs that system and a second one alongside it, and the second is governed by the date rather than the weather.

The seasonal carry rule

Under WAC 204-24-050 subsection (2)(i), from 1 November to 1 April every vehicle over 10,000 lb gross vehicle weight rating must carry sufficient tire chains to meet the chapter when travelling twelve named routes. Among them are I-90 between North Bend at milepost 32 and Ellensburg at milepost 101, US-2 between Dryden and Index, SR-410 from Enumclaw to Naches, and SR-542 over Mount Baker.

The obligation does not depend on snow being present, on a sign being posted, or on the forecast. It is a carriage requirement fixed to the calendar and the route.

One exemption is worth knowing. Vehicles making local deliveries as shown on their bills of lading, and not crossing the mountain pass, sit outside the carry rule provided they stay out of a chain-required area.

The use rule is separate

The familiar conditional rule still applies. When signs marked chains required are posted, it is unlawful for a vehicle or combination over 10,000 lb GVWR to enter the controlled area without chains fitted. For a two-to-four-axle vehicle that means one tire on each side of the drive axle, and for a combination, one tire on the last axle of the last trailer or semitrailer.

So a driver can satisfy the use rule and break the carry rule at the same time. Running a clear pass in December with no chains aboard is exactly that case.

Two spares, and no plastic

Two further requirements in the same section catch people out. Vehicles over 10,000 lb GVWR must carry a minimum of two extra chains beyond those in use, against the possibility that conditions worsen or a chain breaks. Approved chains must have at least two side chains carrying enough hardened cross chains that one is in contact with the road surface at all times. Plastic chains are not allowed.

If automatic tire chains are fitted, the vehicle must still carry regular chains for the outside tires of every axle so equipped.

Why it is designed this way

The routes named in the rule are mountain passes where a truck that stops for want of equipment blocks everyone behind it. Requiring the equipment to be aboard for the whole season removes the judgement call about whether today looks bad enough, and that is the judgement that fails when a storm arrives faster than the forecast.