Guides

The same sentence appears in states that mandate chains and states that never have. Reading it as a requirement is the single most common error in published chain-law tables.

A 2026 amendment equalised Idaho's truck and car speed limits. Most published comparison tables still list Idaho as a split-limit state.

Eighty thousand pounds gross, twenty thousand on a single axle, thirty-four thousand on a tandem. A vehicle can satisfy all three and still be illegal.

Hawaii is the only state whose intrastate commercial driving age is neither 18 nor 21. It is widely reported as 21, and the statute says something more interesting.

California sets chain requirements by vehicle configuration rather than by a single weight threshold, and one combination can be banned from a chain control area outright.

Michigan's split only applies where the posted limit is above 65. A separate provision drops heavy vehicles to 35 while reduced loadings are enforced.

Three numbers govern a property-carrying driver's day, and they do not measure the same thing. One is a driving budget, one is a clock that does not stop, and one is what resets both.

One year for a first major offence, three if the vehicle carried placarded hazardous materials, and life for a second in a separate incident. The federal floor binds every state.

Utah does not run a single statewide chain rule. It designates segments by class, and the class decides whether the requirement reaches only heavy vehicles or every vehicle on the road.

After Idaho equalised in 2026, seven states keep a split speed limit on at least some roads. Five are western; two are not.

Federal width law is unusual. States may not permit more than 102 inches on the National Network, and they may not require less. Hawaii is the exception.

An 18-year-old can hold a valid CDL and still be barred from crossing a state line. Two narrow federal exemptions and one apprenticeship route change that.

Wyoming sets an ordinary fine for ignoring a travel restriction and a much larger one where the violation shuts the highway. The second figure is the one that shapes behaviour.

Montana has the highest car speed limit of any split-limit state, which makes its ten mile per hour truck differential the most visible in daily driving.

An Oregon chain sign is not a single instruction. It selects one of four escalating requirements, and only the top two compel a heavy vehicle to fit chains.

California holds trucks to 55 on every highway in the state, including freeways posted at 70 for cars. No other state has a gap that large.

Idaho can require chains on Lookout Pass, Fourth of July Pass and Lolo Pass. Everywhere else in the state chains are permitted but never compulsory.

Montana's chain provision has no season attached. The one date range in the statute governs studded tires, not chains, and the two are regularly confused.

Nine states can compel a commercial vehicle to run chains. Most of the rest only permit them. Here is the difference, and why the two are constantly confused.

Every other chain law waits for a sign. Washington also requires vehicles over 10,000 lb to carry chains on twelve named routes from 1 November to 1 April, whether or not chains are required that day.

Colorado sets a higher weight threshold than its neighbours and applies the rule across the whole State Highway System. It also reaches vehicles that are not commercial at all.

Nevada's rule turns on a single weight line. At or below 10,000 lb you may choose among traction devices, chains or snow tires. Above it, the regulation says chains.