Vehicle Mod Laws in Maryland

Replacing the exhaust system is legal in Maryland, but a muffler in good working order is required and cutouts or bypasses are prohibited.

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Maryland sets numeric limits for vehicles up to 10,000 lb: 78 dB(A) in zones posted 45 mph or less and 82 dB(A) above that, measured at 50 feet, plus a stationary limit of 100 dB(A) at 3 feet for vehicles built after January 1, 1988.

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Smoked or tinted film on headlights and taillights is illegal in Maryland. 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 Maryland as long as nothing required stays hidden. The plate must be free from foreign materials, and that expressly includes registration plate covers — all covers, clear ones included, are banned.

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Maryland caps bumper height at 20 inches for Class A passenger vehicles and 28 inches for Class E light trucks and Class M multipurpose vehicles — and specifically rejects bumpers modified or extended up or down to compensate for suspension or body alterations.

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Maryland permits one spot lamp, two fog lamps, and two auxiliary driving lamps, with no cover requirement and a four-lamp cap where lamps exceed 300 candlepower.

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Maryland sets no minimum ride height, but a lowered car fails inspection if the bumper has been modified or extended to compensate for the suspension change.

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Underglow is legal in Maryland, including while driving, subject to color and flashing limits: Lighting must be steady — oscillating, rotating, and blinking lights are banned unless authorized — with red and blue reserved for emergency vehicles, white or amber to the front, and no white to the rear.

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Maryland tests fender coverage geometrically at inspection: fenders must extend outward far enough to cover the top of the wheel and tire, rear fenders must reach down to the wheel's horizontal centerline, and front fenders must extend forward within 45 degrees of that centerline.

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Tinting may not extend below the AS-1 line or below 5 inches from the top, so a strip above whichever applies is allowed. Because the material must be transparent, a printed or opaque banner is not legal in Maryland — only a clear tint band.

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Front side windows: minimum 35% VLT. Rear side and back windows: minimum 35% VLT. Darker limits apply behind the driver on some larger vehicles.

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