WAC 204-90-090 Brakes.
(1) Service brakes: A special motor vehicle shall be equipped with brakes acting on all wheels. The service brakes, upon application, must be capable of stopping the vehicle within a 12 foot lane, and:
(a) Developing an average tire to road braking or retardation force of not less than 52.8% of the gross vehicle weight;
(b) Decelerating the vehicle at a rate of not less than 17 feet per second; or
(c) Stopping the vehicle within a distance of 25 feet from a speed of 20 MPH.
Tests shall be made on a level, dry, concrete or asphalt surface free from loose material.
(2) Parking brakes: A special motor vehicle shall be equipped with a parking brake operating on at least two wheels on the same axle which, when applied, shall be capable of holding the vehicle on any grade on which the vehicle is operated. Parking brakes must be separately actuated so that failure of any part of the service brake actuation system would not diminish the vehicle's parking brake holding capability.