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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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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

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.