California Vehicle Code 34501.12
The Vehicle Code requires the California Highway Patrol (CHP) to "regulate the safe operation of" large vehicles, including trucks with three or more axles that weigh more than 10,000 pounds. (Veh. Code, 34500, subd. (a).)
The CHP complies with this mandate, in part, through the "Biennial Inspection of Terminals Program" (BIT).
Pursuant to the BIT, a vehicle's "motor carrier" must schedule a vehicle inspection by the CHP at least every 25 months, and the motor carrier may not operate the vehicle without the CHP inspection having been performed and a safety compliance report having been issued. (Veh. Code, 34501.12, subds. (d)(1), (e)(1), (g)(1).)
In most cases, the "motor carrier" is "the registered owner of a vehicle."
However, if the registered owner "leases the vehicle to another person for a term of more than four months," then "the lessee is the motor carrier." (Veh. Code, 34501.12, subd. (a), (a)(1).)