This SAE Recommended Practice establishes a uniform procedure for the level road test of the brake systems of new trucks, buses, and combination of vehicles designed for roadway use and falling in the following classifications:

Light trucks and buses: 6001 - 10,000 lb (2700 - 4500 kg) gvw

Truck and bus: Over 10,000 lb (4500 kg) gvw

Combination of vehicles (fowing vehicle over 10,000 lb (4500 kg) gvw)