As used in this part, unless the context otherwise requires:
(1) “Fee” means the tire environmental fee created by this part;
(2) “Fund” means the tire environmental fund created by this part;
(3) “Motor vehicle” means any vehicle that is self-propelled and designed to be used on public highways; and
(4) “Tire” means a continuous solid or pneumatic rubber covering encircling the wheel of a motor vehicle.