Guide to Legal Auto Modifications in Wisconsin

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If you have a modified vehicle and live or plan to move to Wisconsin, you need to know the laws governing whether your vehicle or truck is allowed on public roads. The following rules govern vehicle modifications in Wisconsin.

Sounds and noise

The state of Wisconsin has regulations regarding both the sound of your vehicle's sound system and the sound of your muffler.

Sound systems

• Sound systems cannot be played at levels that are considered excessive in any city, town, district, county, or village. If you are charged with playing music excessively loudly two or more times within three years, your vehicle may be impounded.

Muffler

• All vehicles must be equipped with mufflers designed to prevent excessively loud or excessive noise.

• Cutouts, bypasses and similar devices are not permitted.

• Modifications that create flames inside or outside the exhaust system are prohibited.

• Modifications that increase the engine noise level compared to factory ones are prohibited.

FunctionsA: Always check with local Wisconsin laws to ensure you are complying with any municipal noise ordinances, which may be stricter than state laws.

Frame and suspension

The state of Wisconsin has restrictions on frame and suspension modifications:

• GVW 4x4 vehicles have a 5" suspension lift limit.

• The braces cannot be longer than two inches longer than the standard vehicle size.

• Vehicles with a gross weight of less than 10,000 pounds cannot have a bumper height of more than 31 inches.

• The bumper must be three inches high.

• The vehicle cannot be taller than 13 feet 6 inches.

• Car bumpers can be lifted up to within two inches of their original factory height.

• Truck bumper must be no more than nine inches above factory height.

ENGINES

Wisconsin has no regulations on engine modification or replacement. There are seven counties that require emissions testing. Additional information can be found on the Wisconsin Department of Motor Vehicles website.

Lighting and windows

Lanterns

• Two fog lights are allowed.
• Two auxiliary lights are allowed.
• No more than four fires can be lit at the same time.
• Two standby lamps of white or yellow light are allowed.
• Green light is only allowed on buses and taxis for identification purposes.
• Red lamps are for authorized vehicles only.

Window tinting

• Non-reflective tinting of the upper part of the windshield above the AC-1 line from the manufacturer is allowed.

• Front side windows should let in 50% of the light.

• Tinted rear and rear windows should let in more than 35% of the light.

• Side mirrors are needed with tinted rear window.

Vintage/classic car modifications

Wisconsin offers numbers for collectors who have no restrictions on daily driving or vehicle age.

If you want to make sure your vehicle modifications comply with Wisconsin laws, AvtoTachki can provide mobile mechanics to help you install new parts. You can also ask our mechanics what modifications are best for your vehicle using our free online Ask a Mechanic Q&A system.