Idaho Truck Mud Flap Law
Idaho makes you run fenders, covers, or flaps behind the rear wheels of trucks, buses, trailers, and semis (49-949). They hang within 10 inches of the road when the truck is empty and span the full tire width. If a body or fender already does the job, no separate flap is needed. At roadside an inspector eyes coverage and that empty-truck gap. A missing or short flap draws a correctable equipment infraction, not an out-of-service order.
What Idaho makes you run
Idaho makes you run fenders, covers, or flaps behind the rear wheels of trucks, buses, trailers, and semis (49-949). They hang within 10 inches of the road when the truck is empty and span the full tire width. If a body or fender already does the job, no separate flap is needed. At roadside an inspector eyes coverage and that empty-truck gap. A missing or short flap draws a correctable equipment infraction, not an out-of-service order.
Coverage and clearance
- Required: Yes
- Coverage: Full width. The fender, cover, or flap spans the full width of the tire, running from above and forward of the tire's center rearward.
- Ground clearance: Within 10 inches of the road surface when the vehicle is empty (Idaho Code 49-949).
- Fine: Infraction. A low fixed-penalty equipment ticket, usually correctable, not a misdemeanor.
Idaho Mud Flap FAQ
Are mud flaps required on trucks in Idaho?
How low can mud flaps hang in Idaho?
What is the mud-flap fine in Idaho?
Reference information for planning, not legal advice. Traffic laws change and this can be out of date, so always confirm the current statute and obey posted signs before you rely on it. Last reviewed July 2026. Source: https://legislature.idaho.gov/statutesrules/idstat/title49/t49ch9/sect49-949/. See our Terms & Disclaimer.
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