As used in this chapter, the term "off-road vehicle" means any motorized vehicle designed for or capable of cross-country travel on or immediately over land, water, snow, ice, marsh, swampland, or other natural terrain and not intended for use predominantly on public roads. It includes, but is not limited to, four-wheel drive or low-pressure tire vehicles, two-wheel vehicles, amphibious machines, ground effect or air cushion vehicles, and any other means of transportation deriving power from any source other than muscle or wind, except that such term shall exclude any motorboat; any military, fire, or law enforcement vehicle; any vehicles used exclusively on airports; all farm machinery, farm tractors, and other self-propelled equipment for harvesting and transportation of forest products, for clearing land for planting, for utility services and maintenance, for earth moving, construction, or mining; and self-propelled lawnmowers, snowblowers, garden or lawn tractors, or golf carts, while such vehicles are being used exclusively for their designed purposes.