Mud Flaps

Mud flaps hang behind the wheels and stop the stones, gravel, water and mud thrown by the tyres from hitting the bodywork, the car behind and spectators. The flaps here are universal sheets of 500 × 300 mm, supplied in pairs, in 3 or 4 mm thickness and five colours.

A tyre on loose gravel flings stones backwards hard enough to chip paint, crack lights and dent panels. A flexible flap catches them close to the tyre and turns them down, where they spend their energy on the ground. Flexibility matters, because a stiff flap tears off in ruts and when reversing, while a supple one folds and recovers.

Rally regulations cover mud flaps in detail: the material, the minimum thickness, how much of the tyre width they cover and how close to the ground they hang. The 4 mm flaps carry the FIA label in their title, for events run to international rules.

Choose by thickness, size and colour:

• Thickness: 3 mm flaps are lighter and more flexible, for road cars and for events whose rules set no minimum thickness. The 4 mm flaps resist tearing on gravel and suit events that call for FIA flaps.
• Size: at 500 × 300 mm, the sheets leave room to trim them to the width of the tyre and the height of the arch.
• Colour: black, white, red, blue or yellow in both thicknesses, to match a livery or contrast with it.

Mount each flap on a stiff bracket or the arch lip with bolts and large washers, so the fixings cannot pull through. Set the height with the car at ride height and loaded as it will run. Check the clearance at full bump, and at full lock for flaps behind the front wheels, so the tyre never catches them.

Before trimming, read the current rules of your series. On a gravel event, look over the brackets and bolts after each stage.