Every motor vehicle and combination of vehicles, at all times and under all conditions of loading, on application of the service brake, shall be capable of: Developing a braking force that is not less than the percentage of its gross weight tabulated in subsection (c) of this section for its classification; Decelerating to a stop from not more than 20 miles per hour at not less than the feet per second tabulated in subsection (c) of this section for its classification; and Stopping from a speed of 20 miles per hour in not more than the distance tabulated in subsection (c) of this section for its classification, this distance to be measured from the point at which movement of the service brake pedal or control begins. Tests for deceleration and stopping distance shall be made on a substantially level (not to exceed plus or minus 1 percent grade), dry, smooth, hard surface that is free from loose material. The following table sets forth the tabulations referred to in subsection (a) of this section: 1 2 3 4 Brake system application and Braking force distance in as a percentage feet from of gross vehicle Deceleration an initial Classification of or combination in feet per speed of 20 vehicle weight second m.p.h A Passenger vehicles with a seating capacity of 10 people or less including driver, not having a manufacturer’s gross vehicle weight rating…… 52.8% 17 25 B–1 All motorcycles…………… 43.5% 14 30 B–2 Single unit vehicles With a manufacturer’s gross vehicle weight rating of 10,000 pounds or less…………………… 31% 10 20 C–1 Single unit vehicles With a manufacturer’s gross weight rating of more than 10,000 pounds………………… 43.5% 14 40 C–2 Combination of a two– axle towing vehicle and a trailer with a gross weight of 3,000 pounds or less…………………… 43.5% 14 40 C–3 Buses, regardless of the number of axles, not having a manufacturer’s weight rating…………………… 43.5% 14 40 C–4 All combination of vehicles in driveaway– towaway combinations… 43.5% 14 40 D All other vehicles and combinations of vehicles …………………………… 43.5% 14 50