California's 55 Mph Truck Limit Is the Widest Split in the Country
Date Published
California's truck speed rule is short, absolute, and takes no account of what the sign beside the road says for everyone else.
The rule
Cal. Veh. Code 22406 provides that no person may drive certain vehicles on a highway at a speed in excess of 55 miles per hour.
There is no exception for a freeway posted at 65 or 70. The statutory limit governs, and on a rural interstate signed at 70 the gap between a car and a truck is fifteen miles per hour, the largest in the country.
Which vehicles it catches
The section lists them. A motortruck or truck tractor having three or more axles, and any motortruck or truck tractor drawing any other vehicle. A passenger vehicle or bus drawing any other vehicle. A schoolbus transporting any school pupil. A farm labor vehicle when transporting passengers. A vehicle transporting explosives. And a trailer bus.
Two of those are worth noticing. A two axle truck tractor is caught the moment it is drawing anything, and a passenger vehicle towing is caught as well, which surprises drivers who do not think of themselves as operating a commercial vehicle at all.
What it means in practice
A fifteen mile per hour differential is a real operational fact rather than a technicality. It affects planned transit times across a long state, it puts heavy vehicles into a persistent overtaking relationship with passenger traffic, and it is the reason lane restrictions and truck lane provisions matter more in California than in states where everyone runs the same speed.
Where to look for the rest
The chain control rules that apply in California winter conditions are in 13 CCR 1072, a regulation rather than the vehicle code. The two sit in different bodies of law, which is a recurring feature of state trucking regulation: the speed rule is statutory, the equipment rule is administrative, and finding one tells you nothing about where the other lives.