Section 225 Of Article 1. Taxable And Exempt Property From California Revenue And Taxation Code >> Division 1. >> Part 2. >> Chapter 1. >> Article 1.

. (a) A trailer, semitrailer, logging dolly, pole or pipe dolly, or trailer bus, that has a valid identification plate issued to it pursuant to Section 5014.1 of the Vehicle Code, or any auxiliary dolly or tow dolly is exempt from personal property taxation.
  (b) The exemption provided for in subdivision (a) does not apply to a logging dolly that is used exclusively off-highway.