(a) This subchapter does not authorize the operation on the national system of interstate and defense highways in this state of a vehicle of a size or weight greater than authorized in 23 U.S.C. § 127, as amended.
(b) If the United States government authorizes the operation on the national system of interstate and defense highways of vehicles of a size or weight greater than those authorized on January 1, 1983, the new limit automatically takes effect on the national system of interstate and defense highways in this state.