Truck Mud Flap & Splash Guard Laws by State
Whether rear mud flaps are required and the dimensions that matter — tread-width coverage and maximum ground clearance, often 6 to 10 inches — plus how a DOT or CVSA inspector checks them. Covers all 50 states and DC. Reference only, not legal advice.
39Require flaps
6-10"Typical clearance
TreadWidth to cover
51Jurisdictions
01
The rule
Cover the tread, hang it low
Nearly every state makes you run rear mud flaps or splash guards behind the rearmost wheels. Two numbers get you a ticket. The first is width: the flap must cover the full tire tread. The second is ground clearance, the gap under the flap at rest. Many states cap that gap around 6 to 10 inches; some write it as a fraction of the flap-to-tire distance. There is no single federal size rule for general trucks, so the dimension is state law. Meet the strictest state on your route.
02
By state
Mud-flap rules for all 50 states and DC
Tap a state for whether flaps are required, the clearance and coverage rule, and the equipment fine.
| State | Mud flaps | Clearance rule |
|---|---|---|
| Alabama AL | Required | No set clearance |
| Alaska AK | Required | The antispray device must reach down to within 14 inches of the ground with the vehicle on level ground |
| Arizona AZ | Required | Within 8 inches of the ground |
| Arkansas AR | Required | No set clearance figure |
| California CA | Required | No clearance number in the statute |
| Colorado CO | Required | Within 10 inches of the road when the truck is empty; hangs perpendicular and stays that way in normal driving |
| Connecticut CT | Required | No set clearance |
| Delaware DE | Required | Fixed number |
| District of Columbia DC | No specific rule | No set clearance |
| Florida FL | Required | No set clearance |
| Georgia GA | Required | Ground clearance no more than one-half the distance from the center of the rearmost axle to the center of the flap, under any conditions of loading |
| Hawaii HI | Required | No statewide clearance or width dimension |
| Idaho ID | Required | Within 10 inches of the road surface when the vehicle is empty |
| Illinois IL | Required | 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 |
| Indiana IN | No specific rule | No set clearance |
| Iowa IA | No specific rule | No set clearance |
| Kansas KS | No specific rule | No set clearance for regular trucks |
| Kentucky KY | No specific rule | No set clearance |
| Louisiana LA | Required | No set clearance |
| Maine ME | Required | No set clearance |
| Maryland MD | Required | Proportional rule |
| Massachusetts MA | Required | No set clearance |
| Michigan MI | Required | No fixed inch figure |
| Minnesota MN | Required | Within 9 inches of the ground when the vehicle is empty |
| Mississippi MS | Required | Ground clearance no more than one-fifth of the distance from the center of the rearmost axle to the center of the flaps, under any conditions of loading |
| Missouri MO | Required | Fixed-number rule: flaps must hang within 8 inches of the ground for most trucks, and within 12 inches for dump trucks |
| Montana MT | Required | Trucks over 8,000 lb GVW: within 10 inches of the road when empty |
| Nebraska NE | Required | No set clearance number |
| Nevada NV | Required | No set clearance or width number in the statute |
| New Hampshire NH | Required | No fixed inch figure |
| New Jersey NJ | Required | The statute sets no inch number |
| New Mexico NM | No specific rule | no set clearance |
| New York NY | Required | No more than one-third of the distance from the bottom of the splash guard to the point where the rear tire contacts the road |
| North Carolina NC | No specific rule | No set clearance |
| North Dakota ND | No specific rule | No set clearance |
| Ohio OH | Required | Proportional rule: ground clearance no more than one third of the distance from the center of the rearmost axle to the center of the flaps, under any conditions of loading |
| Oklahoma OK | Required | No fixed inch figure |
| Oregon OR | Required | Full-width fenders or mudguards must hang no more than 10 inches above the road when the vehicle is empty, or 13 inches if attached to a dump box that raises to unload |
| Pennsylvania PA | Required | Angle rule, not a fixed inch number |
| Rhode Island RI | Required | No set clearance |
| South Carolina SC | No specific rule | No set clearance |
| South Dakota SD | No specific rule | No set clearance |
| Tennessee TN | Required | No set clearance |
| Texas TX | Required | Within 8 inches of the road at rest; a 4-inch tolerance applies, so the bottom edge may sit up to 12 inches while the vehicle is standing still |
| Utah UT | Required | No more than 50% of the rear wheel's diameter off the ground |
| Vermont VT | Required | No set clearance in statute |
| Virginia VA | Required | No set ground-clearance number and no angle |
| Washington WA | Required | No fixed inch number |
| West Virginia WV | No specific rule | No set clearance |
| Wisconsin WI | Required | Proportional rule: the ground gap can be no more than one third of the horizontal distance from the center of the rearmost axle to the fender or mudguard |
| Wyoming WY | No specific rule | no set clearance |
Sources: state vehicle-equipment codes; CVSA; FMCSA. Last reviewed July 2026. Dimensions vary by state and vehicle type; confirm before you rely on a figure.
Mud Flap Law FAQ
Are mud flaps required on trucks?
In almost every state, yes. State law requires rear mud flaps or splash guards behind the rearmost wheels of a truck or trailer to catch road spray, rocks, and slush thrown at the vehicles behind you. There is no single federal size mandate for general trucks, so the exact dimensions come from state vehicle-equipment codes, and they vary.
How wide and how low do mud flaps have to be?
The common rule is that a flap must cover the full width of the tire tread and hang low enough to block spray. Many states set a maximum ground clearance at rest, often in the range of 6 to 10 inches, and some write it as a fraction of the distance from the flap to the center of the tire, such as within one-third of that distance. Check your state's number.
Do inspectors check mud flaps at a DOT stop?
Yes. A missing, torn, or too-short mud flap is a routine equipment defect an officer or CVSA inspector can cite at a roadside or scale inspection. It usually is not an out-of-service item on its own, but it is an easy ticket and a CSA vehicle-maintenance hit, so a flap dragging on the ground or hiked up above the tire will draw attention.
Do the same rules apply to my trailer?
The requirement follows the rearmost wheels, so the trailer usually carries the flaps that matter. Spread-axle trailers, dump bodies, and equipment haulers still need coverage behind the last axle. Some states add flaps behind the drive tires of the tractor too. If you run interstate, meet the strictest state on your route rather than swapping flaps at every line.
03
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