Vehicle Mod Laws in Colorado

Replacing the exhaust system is legal in Colorado, but a muffler in good working order is required and cutouts or bypasses are prohibited. Modifications that make the exhaust louder than the originally installed muffler are prohibited.

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Colorado 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 Colorado. 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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License plate frames are legal in Colorado as long as nothing required stays hidden. Frames are fine if the plate stays readable, including by automated plate readers.

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Colorado has no numeric lift or bumper-height limit, but it is not a free-for-all: C.R.S. 42-4-233 bars altering the front or rear suspension from the manufacturer's original design except in accordance with department specifications. Heavy-duty shocks and overload springs are expressly allowed, and overall height caps at 14 feet 6 inches.

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Colorado has no cover or switch-off statute for light bars. It permits two lamps per auxiliary category, each with a mounting-height band a roof-mounted bar cannot meet — so lighting one on the road violates the lamp rules directly — and caps lit front lamps over 300 candlepower at four.

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Colorado bars altering the front or rear suspension away from the manufacturer's original design except as the department specifies — there is no numeric allowance.

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Colorado's rule is stricter than most: a non-emergency vehicle may not even be equipped with a lamp capable of displaying red or blue toward the front, any other use of green is a violation, and flashing displays are reserved by color for emergency and service vehicles. Steady white or amber accent lighting is the safe configuration.

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Colorado's splash-guard statute expressly exempts registered passenger vehicles and trucks up to 10,000 lb empty weight, so there is no fender-coverage or protrusion rule for ordinary cars and light trucks.

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Non-transparent material is allowed with its bottom edge no more than 4 inches from the top of the windshield; it may not be red or amber and must not create glare. A printed banner can be legal in Colorado if it stays within the strip described above.

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Front side windows: minimum 27% VLT. Rear side and back windows: minimum 27% VLT.

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