Vehicle Mod Laws in South Dakota

Replacing the exhaust system is legal in South Dakota, but a muffler in good working order is required and cutouts or bypasses are prohibited. There is no statutory 'no louder than stock' rule — the standard is that the exhaust must not produce excessive or unusual noise.

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South Dakota sets no statewide decibel limit for passenger cars. A muffler in good working order is required, exhaust may not produce excessive or unusual noise, and cutouts or bypasses are prohibited.

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Smoked or tinted film on headlights and taillights is illegal in South Dakota. Headlights must emit white light and taillights must show red at the required visibility distance, and tint that dims or discolors them violates those requirements.

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Frames are legal if nothing is obscured. Plates must be conspicuously displayed and kept clear of mud, ice, and snow so as to be clearly visible.

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South Dakota sets no statewide lift, frame-height, or bumper-height limit. The only cap is overall vehicle height of the general overall-height cap, and general equipment rules — headlamp height, working lighting — still apply.

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South Dakota permits three auxiliary driving lamps but only if mounted 12 to 24 inches above the surface — a narrow window that a roof or upper-bumper bar cannot meet. No cover is required.

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South Dakota has no statute limiting how low a vehicle may be. General equipment rules — headlamp height, working lighting, nothing dragging on the road — still apply.

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Underglow is legal in South Dakota, including while driving, subject to color and flashing limits: Red visible from the front and blue anywhere are Class 2 misdemeanors, and no more than three auxiliary lamps may be used.

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No South Dakota fender, mudguard, or splash-guard requirement was found, and no limit on tire protrusion.

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South Dakota regulates windshield banners by obstruction, not transparency: material that obstructs or reduces the driver's clear view is prohibited, and sunscreening film may not reach below the AS-1 line or sun-visor point. A printed banner is illegal only when it obstructs the view.

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Front side windows: minimum 35% VLT. Rear side and back windows: minimum 20% VLT.

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