In this subtitle:
(1) “Exhaust emission system” means a motor vehicle engine modification designed to control or reduce the emission of substances from a motor vehicle or motor vehicle engine, of a model year of 1968 or later, and installed on or incorporated in a motor vehicle or motor vehicle engine in compliance with requirements imposed by the Motor Vehicle Air Pollution Control Act (42 U.S.C. § 1857 et seq.) or other applicable law.
(2) “Metal tire” includes a tire the surface of which in contact with the highway is wholly or partly made of metal or other hard, nonresilient material.
(3) “Muffler” means a device that reduces noise using:
(A) a mechanical design, including a series of chambers or baffle plates, to receive exhaust gas from an internal combustion engine; or
(B) turbine wheels to receive exhaust gas from a diesel engine.
(4) “Solid tire” includes only a tire that:
(A) is made of rubber or another resilient material; and
(B) does not use compressed air to support its load.