Cal. Rev. & Tax. Code § 6024
"One-way rental trucks" are motortrucks of a kind required to be registered under the Vehicle Code, not exceeding the manufacturer's gross vehicle weight rating of 24,000 pounds, which are principally employed by a person in the rental business in being leased out for short-term periods of not more than 31 days to individual customers for one-way or local hauling of personal property of the customers, and which upon acquisition or being employed in this state by the person are identified to the board, in such manner as the board may prescribe, for employment in such one-way or local hauling. Upon the leasing of such a truck to a customer, the person shall make known to the customer the fact that the vehicle is designated as a one-way rental truck and any taxes imposed by this part which are payable measured by the rentals.
Ca. Rev. and Tax. Code § 6024