Illinois Truck Mud Flap Law
Illinois requires rear splash guards on second-division vehicles, and a truck tractor by itself is exempt, so the rule lands on your trailers (625 ILCS 5/12-710). Flap and contour types both cover the full tread width. A flap hangs within 12 inches of the ground loaded and stays within 30 degrees of vertical; a contour guard sits within 6 inches of the tread. It's a petty equipment offense, usually correctable. Officers eyeball full-width coverage and flaps that aren't riding high.
What Illinois makes you run
Illinois requires rear splash guards on second-division vehicles, and a truck tractor by itself is exempt, so the rule lands on your trailers (625 ILCS 5/12-710). Flap and contour types both cover the full tread width. A flap hangs within 12 inches of the ground loaded and stays within 30 degrees of vertical; a contour guard sits within 6 inches of the tread. It's a petty equipment offense, usually correctable. Officers eyeball full-width coverage and flaps that aren't riding high.
Coverage and clearance
- Required: Yes
- Coverage: Full tread width of the tire or tires being protected, for both the flap and contour types.
- Ground clearance: Flap type: hangs within 12 inches of the ground when loaded to maximum legal capacity, deviates no more than 30 degrees from vertical, and its bottom stays within 15 inches of the ground when moving. Contour type: sits within 6 inches of the tread surface, bottom within 12 inches of the ground loaded, with a 2-inch lip extending toward the wheel center.
- Fine: Petty offense equipment violation (625 ILCS 5/12-710); typically a low-dollar, correctable fix-it citation rather than a moving violation.
Illinois Mud Flap FAQ
Are mud flaps required on trucks in Illinois?
How low can mud flaps hang in Illinois?
What is the mud-flap fine in Illinois?
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 Traffic laws change and this can be out of date, so always confirm the current statute and obey posted signs before you rely on it.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://ilga.gov/legislation/ilcs/documents/062500050K12-710.htm. See our Terms & Disclaimer.
More for Illinois
Check Illinois before you roll
Live weather, closures, and hazards on one map. Free, no account.
Open Live Map →