Wis. Stat. § 341.409: Reciprocal registration exemption agreements for federally recognized Indian tribes or bands.

(1) The secretary with the approval of the joint committee on finance may enter into a reciprocal registration exemption agreement with the governing body of any federally recognized Indian tribe or band. The reciprocal agreement may exempt designated classes of vehicles registered by the Indian tribe or band from the registration requirements of this state if:

(a) The vehicle carries a registration plate showing valid registration by the Indian tribe or band.

(b) The Indian tribe or band registering the vehicle allows reciprocal privileges to similar classes of vehicles registered in this state under conditions substantially as favorable to this state as to the Indian tribe or band.

(2) The reciprocal agreement may include restrictions, conditions and terms of reciprocal privileges relating to registration, including any proportional registration taxes or fees deemed advisable by the department.

(3) The department may adopt rules to implement this section.