This SAE Recommended Practice applies to commercial vehicles above 4540 kg of gross vehicle weight rating equipped with air brakes used under normal operating conditions. The procedure incorporates high and low-temperature test matrices, but does not fully account for the effects of the environment on brake squeal. Much research is currently underway in this area. This document defines brake squeal as a peak noise level of at least 80 dB(A) between 500 Hz and 17 kHz for air disc and drum brakes on on-road vehicles.