Vehicle Mod Laws in Tennessee

Replacing the exhaust system is legal in Tennessee, 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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Tennessee bars exhaust sound pressure above 95 dB on any motor vehicle other than a motorcycle — one of the few states with a real statutory number.

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Smoked or tinted film on headlights and taillights is illegal in Tennessee. 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; the plate must be clearly visible and maintained free from foreign materials. A trailer-hitch ball is excepted.

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For passenger vehicles altered in altitude, Tennessee caps bumper height at 22 inches above the ground, measured to any point on a load-bearing member of the horizontal bumper bar. Four-wheel-drive recreational vehicles must fall within 14 to 31 inches.

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Tennessee requires no cover but allows only two auxiliary road-lighting lamps lit at any one time, in addition to the two required headlights.

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Tennessee bars modifying a vehicle so the body or chassis contacts the ground or the fuel tank is exposed, and since July 1, 2024 the squat law bans any stance leaving the front fender 4 or more inches above the rear — which outlaws rear-only lowering. Bumper height is capped at 22 inches, which limits lifting rather than lowering.

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Underglow is legal in Tennessee, including while driving, subject to color and flashing limits: No red or blue visible from the front and no flashing toward the front.

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Tennessee has no fender-coverage or protrusion rule for passenger cars.

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Apart from the manufacturer's standard installed shade band, no material may reduce windshield light transmittance below 70% — so an aftermarket banner is not permitted. A printed windshield banner is not legal in Tennessee.

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

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