What Laws Affect Your Trucks’ Mud Flaps?

When planning your semi trucks’ custom mud flaps, the law is probably not the first thing that springs to mind. However, there are legal requirements for mud flaps. As with many regulations affecting trucks, mud flap laws vary by state. Here is some helpful information on these laws. You don’t want to get your new custom mud flaps from WillCo Extrusion only to learn that they don’t meet your state’s requirements.

Federal Mud Flap Laws

You may be surprised to learn that the federal government has no laws affecting mud flaps. While the Federal Motor Carrier Safety Administration has regulations for many aspects of semi trucks, mud flaps are not among them.

State Requirements

Most states have laws governing the size and placement of mud flaps on trucks. The laws that affect you depend upon which state you operate out of and which ones you drive through.

Some states have requirements about the dimension of the mud flaps. For example, Maryland requires that they be the same length as the width of the tire.

Other states have regulations for the distance between the road and the flap. Arizona, Delaware, Missouri and Texas require that mud flaps be no more than eight inches from the ground. Alaska has a similar regulation but only requires 14 inches or less.

New York requires that mud flaps be placed no more than 1/3 the distance from where the bottom of the mud flap contacts the wheel. This is intended to ensure the flap offers proper protection from debris.

Some states tackle this issue based on the angle the debris can escape from the wheel. Michigan, Oklahoma and Pennsylvania require the flap block debris at a minimum of a 22.5-degree tangent angle.

To find the specific mud flap laws the affect you, contact your state’s department of transportation. As a rule of thumb, avoid having mud flaps that hang more than six inches from the ground.

Order Custom Mud Flaps

If you want new mud flaps for your trucks, WillCo Extrusion can help you with custom designs. Contact us or complete our order form to get started.


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We can create anything you desire. We store your logo at our facility, but you still own it. Standard block lettering is also available if a logo is not needed.

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