Vehicle Mod Laws in Utah

Replacing the exhaust system is legal in Utah, 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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Utah 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 Utah. 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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A frame is banned if it obscures or blocks readability of the plate number or the registration decal.

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Utah caps frame height at 24, 26, or 28 inches by GVWR class, limits the body floor to 3 inches above the top of the frame, and prohibits frame stacking.

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Light bars are legal to mount in Utah; keep them off on public roads — at most four front lamps over 300 candlepower lit, no red/blue to the front, and no cover requirement.

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Utah sets a genuine 3-inch minimum: no part of the vehicle other than tires, rims, and mudguards may sit less than 3 inches above the ground, and the body or chassis may not contact the roadway.

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Underglow is legal in Utah, including while driving, subject to color and flashing limits: No red or blue visible from directly in front, no flashing or rotating, and rear-facing light must show red.

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Utah requires mudguards or flaps on vehicles altered from the original manufacturer's frame height — as well as on trucks of 10,500 lb GVWR or more, truck tractors, and trailers of 750 lb or more. They must be at least as wide as the tires they protect and directly in line with them.

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Non-transparent material is allowed along the top edge if it does not extend more than 4 inches down or beyond the AS-1 line, whichever is lowest. A lower-left-corner patch of 3 by 4 inches is also allowed. A printed banner can be legal in Utah if it stays within the strip described above.

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

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