If you live in South Dakota or plan to do so in the near future, you need to be aware of the laws that cover vehicle modifications. Understanding and complying with the following laws will help keep your vehicle street legal when driving on South Dakota roads. Failing to comply with these standards can be considered a class 1 or class 2 misdemeanor, with fines ranging from $500 - $1,000 and/or 30 days to 1 year in jail.
Sounds and noise
South Dakota does place limitations on the amount of sound that vehicles can produce.
South Dakota does not have specific guidelines for sound systems. However, it is unlawful to cause annoyance, inconvenience or alarm due to unreasonable noise levels. These levels, however, are subjective and not clearly defined.
- Mufflers are required on all vehicles and have to prevent unusual or excessive noise.
- Motor vehicles with exhaust cutouts are not permitted on the highways.
Tip: Always check with local county laws in South Dakota to make sure you are following any municipal noise ordinances that may be more stringent than state-level laws.
Frame and suspension
South Dakota does not restrict frame height, suspension lift height or bumper height. However, vehicles cannot exceed 14 feet in height.
South Dakota does not have any engine modification or swap regulations and does not require emissions testing.
Lighting and windows
License plates on the rear of vehicles must be illuminated with white light.
Red, blue, and green lights are permitted on authorized vehicles only, not passenger vehicles.
One spot lamp is permitted that does not hit the road surface over 100 feet in front of the vehicle.
Amber flashing lights are permitted within three inches of the license plates for drivers with disabilities. These lamps can only be used when the disabled driver is the person operating the vehicle.
Non-reflective tint is permitted on the windshield above the AS-1 line from the manufacturer, or to the lowest level of the sun visor when flipped down.
Mirrored and metallic/reflective tints are not permitted.
Front side windows must allow over 35% of the light to pass through.
Back side and rear windows must let more than 20% of light to pass through.
Sticker identifying legal tint levels is required on each tinted window between the glass and film.
Antique/classic car modifications
South Dakota offers historical vehicle plates that have the following requirements:
- Vehicle must be over 30 years old
- Vehicle cannot be used for daily or general driving
- Exhibition, parade, displays, and travel for repairs or refueling are permitted
- South Dakota Special License Plate Application is required
If you want to make sure your vehicle is street legal under the laws in South Dakota, YourMechanic can provide the mobile mechanics to help you install the new parts. You can also ask our mechanics what modifications may be best suited to your car using our free online Q&A system, Ask a Mechanic.