Section 902.121  Standards Applicable to Motor Vehicles with  GVW in Excess of 8,000 Pounds

a)         This rule shall apply to motor vehicles with a gross vehicle weight in excess of 8,000 pounds, except passenger cars.

b)         No person shall operate or cause or allow the operation of a motor vehicle subject to this rule at any time under any conditions of highway grade, load, acceleration or deceleration in such a manner as to exceed the following limits:

1)         On highways with speed limits of 35 miles per hour or less, 86 dB(A), measured with fast meter response at 50 feet from the centerline of lane of travel, or an equivalent sound level limit measured in accordance with procedures established under 35 Ill. Adm. Code 900.103;

2)         On highways with speed limits of more than 35 miles per hour, 90 dB(A), measured with fast meter response at 50 feet from the centerline of lane of travel, or an equivalent sound level limit measured in accordance with procedures established under 35 Ill. Adm. Code 900.103.

c)         No person shall operate or cause or allow the operation of a motor vehicle subject to this rule, powered by an engine with engine speed governor, which generates a sound level in excess of 88 dB(A) measured with fast meter response at 50 feet from the longitudinal centerline of the vehicle or an equivalent sound level limit measured in accordance with procedures established under 35 Ill. Adm. Code 900.103, when that engine is accelerated from idle with wide open throttle to governed speed with the vehicle stationary, transmission in neutral, and clutch engaged.