According to Arizona Revised Statute 28-5201 (L08, Ch. 147, sec. 3), this is the definition of a commercial motor vehicle:
1. "Commercial motor vehicle" means a motor vehicle or combination of motor vehicles that is designed, used or maintained to transport passengers or property in the furtherance of a commercial enterprise on a highway in this state, that is not exempt from the gross weight fees as prescribed in section 28-5432, subsection B and that includes any of the following:
(a) A single vehicle or combination of vehicles that has a gross vehicle weight rating of eighteen thousand one or more pounds and that is used for the purposes of intrastate commerce.
(b) A single vehicle or combination of vehicles that has a gross vehicle weight rating of ten thousand one or more pounds and that is used for the purposes of interstate commerce.
(c) A school bus.