Vehicles subject to California Air Resources Board’s Truck and Bus regulation:
Run on diesel fuel
Were built for on-road use (have an engine that was on-road certified) regardless if they are currently used off-road
Have a gross vehicle weight rating (GVWR1) of more than 14,000 lbs.
The following vehicles are exempt from the Truck and Bus regulation.
Three Day Pass - An out of state motor carrier can obtain a once-a-year temporary permit to operate a vehicle in California for three consecutive days. The three day pass must be obtained from the ARB Executive Officer online, email or by FAX. This exemption expires 2021.
Off-road mobile equipment (Title 13, CCR, sections 2401, 2411, 2421, 2432, and 2449). Note that except for twin engine sweepers, two-engine vehicles that are designed to be driven on-road where one engine provides motive power and the other is 50 hp or greater and is integrated into the design of the chassis (for example, water well drilling rigs, workover rigs, and cranes) are classified as off-road mobile equipment.
Drayage trucks commencing (Title 13, CCR, section 2027) until January 1, 2023 (see this regulation section (l))
Pick up trucks with a GVWR of 19,500 lbs or less used exclusively for personal use
1ARB says the gross vehicle weight rating (GVWR) is issued by the vehicle manufacturer and is the weight of the vehicle plus fuel, passengers, cargo, and trailer tongue weight. It may sometimes be listed as gross weight. The GVWR is not the same as the unladed weight, gross combined weight rating, towing weight rating or registered weight rating. The manufacturer's original GVWR label is commonly found on the truck door jamb or on the inside of the door.