Joliet, IL Noise Ordinances: Vehicle Noise (2026)

Section 21-134 of the Noise Pollution Control Ordinance sets both equipment and operational standards for motor vehicles on Joliet streets. Every vehicle must be equipped at all times with an adequate muffler or other sound-dissipative device that is in constant operation, properly maintained, free of defects that affect sound reduction, and not modified to amplify or increase noise above what the original muffler produced; interstate motor carriers regulated under 40 CFR Part 202 face parallel muffler requirements and are barred from cutout or bypass devices.

On top of the equipment rule, the section sets decibel ceilings measured with a fast-response meter at fifty feet from the travel lane: passenger cars and other vehicles under 8,000 pounds gross vehicle weight may not exceed 74 dB(A) on roads posted 35 mph or slower (76 dB(A) on a grade over 3 percent) or 82 dB(A) on roads posted above 35 mph (85 dB(A) on snow tires). Heavier trucks over 8,000 pounds face an 86 dB(A) highway limit and an 88 dB(A) stationary test limit, and motorcycles are capped at 80 to 86 dB(A) depending on speed zone.

The same section bars sounding a horn except when reasonably necessary for safe operation, and bars tire squeal from rapid acceleration or excessive cornering except in a genuine emergency. Separately, Chapter 19's traffic code addresses in-car audio: Section 19-7 makes it unlawful to operate a sound amplification system, a car stereo, that can be heard from 75 feet or more outside the vehicle while the vehicle is on a street, highway, roadway or alley, unless the system is being used to request help or warn of a hazard. Emergency vehicles and vehicles whose occupants hold a Section 3-14 license are exempted from the stereo rule.