Code of Alabama
Article 2 - Size and Weight.
Section 32-9-22 - Exemptions - Generally.

(a) There shall be exempt from the provisions of this article trucks, semitrailer trucks, or trailers owned by the United States, or any agency thereof, the State of Alabama, or any county or city, or incorporated town; nor shall the provisions of this article apply to implements of husbandry temporarily propelled or moved upon the highways; nor shall the provisions of this article apply to trucks, semitrailer trucks, or trailers used exclusively for carrying 50 bales or less of cotton.
(b) If any truck, semitrailer truck, or trailer shall be licensed by any city or incorporated town and the registration plate or plates issued as evidence of the license shall be conspicuously exhibited on the truck, semitrailer truck, or trailer, in the manner required by law, the provisions of this article shall not apply to the operation of such vehicles within the limits of the municipality or within the police jurisdiction thereof; provided, that municipalities may provide by ordinance maximum limits with respect to the weight, height, width, and length of trucks, semitrailer trucks, and trailers within their police jurisdiction; provided, that the maximum limits prescribed shall not be less than those fixed in Section 32-9-20 and may impose license taxes on such vehicles and require all such vehicles to have affixed thereto, in some conspicuous place, a registration plate or plates.