Casper, WY Noise Ordinances: Vehicle Noise (2026)

Section 8.20.050 of the Casper Municipal Code makes it unlawful to operate a motorized vehicle within the city limits at a sound pressure level exceeding the limits in Table 8.20.050, measured the same way as the district decibel standard, when the vehicle is traveling at forty m.p.h. or less or is in a posted zone of forty m.p.h. or less. The table sets the ceiling by weight and vehicle type: vehicles over ten thousand pounds are capped at 90 dB(A), vehicles under ten thousand pounds and motorcycles are capped at 80 dB(A), and domestic power equipment is capped at 80 dB(A), each measured at or beyond twenty-five feet from the roadway.

Subsection E separately requires every vehicle operating in the city to carry an adequate, properly maintained muffler in constant operation, and bars modifying the exhaust system from its original factory configuration in a way that would defeat that requirement, addressing the underlying cause of most vehicle noise complaints rather than just the decibel reading. Casper regulates a specific vehicle-noise practice more strictly in a separate title: Section 10.20.055, in the vehicle equipment chapter, flatly prohibits any person from operating or using a vehicle engine compression brake within the corporate limits of the city, with no exception for weight class or road grade, going further than the general decibel approach of Section 8.20.050.

A related provision, Section 10.20.050, separately bars unnecessarily racing an engine, backfiring, or causing other unnecessary engine noise. Together, these sections give Casper three distinct tools against loud vehicles: a numeric decibel ceiling, a mandatory-muffler rule, and an outright ban on compression brakes.