GM Service Manual Online
For 1990-2009 cars only

Test the brakes at different speeds with light pedal pressure and with heavy pedal pressure. Avoid locking the wheels. Avoid sliding the tires on the roadway. Locked wheels and sliding tires do not show brake efficiency. A locked wheel and a sliding tire reduce the tire friction on the roadway.

Test the brakes on a dry, clean, reasonably smooth and level roadway. You cannot accurately test brake performance without these conditions. The tires will not grip the roadway equally if the roadway is wet or greasy or covered with loose dirt. A crowned roadway causes the weight of the vehicle to shift toward one side. The wheels bounce on a rough roadway.