Maryland Code, Transportation § 22-105

(a)(1) If any Class A (passenger) vehicle, any Class E truck with a manufacturer's rating or registered gross vehicle weight of 18,000 pounds or less, or any Class M (multipurpose) vehicle has been altered in any manner that would reduce the effectiveness of its bumpers or suspension or render the vehicle dangerous in the event of a single vehicle accident or a collision with another vehicle, it may not be operated on any highway in this State.

(2) Nothing in this section may be construed to exempt a vehicle from the application of paragraph (1) of this subsection solely because the vehicle is in compliance with the provisions of subsection (b) of this section.

(1) In the case of a Class A (passenger) vehicle, 20 inches;

(2) In the case of a Class M (multipurpose) vehicle, 28 inches;

(3) In the case of a Class E truck with a manufacturer's rating or registered gross vehicle weight of 10,000 pounds or less, 28 inches; or

(4) In the case of a Class E truck with a manufacturer's rating or registered gross vehicle weight of more than 10,000 pounds but not more than 18,000 pounds: