Md. Code, Transportation § 13–918

(a) If a Class E (truck) vehicle is operated in combination with a nonfreight trailer or semitrailer under § 13-927(b)(1) of this subtitle, the Class E (truck) vehicle shall be registered for only the gross vehicle weight of the Class E (truck) vehicle and not the gross combination weight of the Class E (truck) vehicle and nonfreight trailer or semitrailer.

(b) If a Class E (truck) vehicle is operated in combination with a freight trailer or semitrailer, under § 13-927(c)(1) of this subtitle, the Class E (truck) vehicle shall be registered for the gross combination weight, which includes the gross weight of the Class E (truck) vehicle, and the freight trailer or semitrailer with which it is in combination.