Ariz. Rev. Stat. § 28-5432
A. This article applies to all of the following:
B. This article does not apply to:
C. The following motor vehicles, trailers and semitrailers are exempt from the gross weight fee prescribed in section 28-5433:
2. A motor vehicle, trailer or semitrailer that is owned and operated by a nonprofit school that is recognized as being tax exempt by the federal or state government if the motor vehicle, trailer or semitrailer is used exclusively for any of the following: