Replacing Trailer Fenders

This post was written by ghoj on September 21, 2017
Posted Under: Powersport Trailer Equipment,Trailer Lights & Wiring,Utility Trailer

Trailer Fenders

Fenders, while seemingly innocuous, are actually an essential part of your trailer. Fenders protect your boat and trailer as well as other vehicles on the road from debris. Fenders can also provide a stepping point for accessing both your boat and trailer. For these reasons and many more, it is important to maintain and care for your fenders and when the time comes, find a suitable replacement.

That being said, you may be wondering where to begin. The process we use to determine which replacement fender you need is based in large part around narrowing the search. As you will see below, this is done using basic observations and a few simple measurements.


Observations about your trailer  

  • Who manufactured your trailer?
    • If possible, identify who manufactured the trailer. This is a useful piece of information and can really help narrow your search. Your trailer’s registration or title are both good resources if the trailer’s markings are no longer there. If it is not possible to identify the brand you can still find your replacement fender without it.
  • What is your tire size?
    • While tire size can slim down the options, this is not the only factor used to determine your fenders size. Just because a fender has a description that calls for use on “x” sized tire, it does not mean that it cannot be used with other sized tires.
  • How many axles are on your trailer?
    • The number of axles on your trailer will help determine what fender you need and assist in narrowing the search.

Observations about the fender

  • What material is the fender made out of?
    • Generally speaking, most fenders are made out of one of three materials, plastic (available in black, white and grey) steel (galvanized or raw) and aluminum (diamond plate or smooth)
  • How does your fender bolt to it’s mounting bracket?
    • Plastic fenders typically bolt to the mounting bracket in one of two ways. Karavan style “Top Mount” or Standard style “Side Mount” (As shown in photos below).
    • If the fender is steel, take note of whether it is welded or bolted to the trailer.

Left: “Top Mount” Holes                        Right: “Side Mount” Holes

  • Does the fender have lights?
    • If the fenders have cut outs for marker lights, you will have to make a few observations.
      • How is the light fixed to the fender? Rectangular/round rubber grommet, etc (See photo below)
      • What color is the light?
      • Is the light LED or incandescent?
      • If it does have lights, you will have to know if the fender is on your left side (Driver’s/Road side) or Right side (Passenger’s/Curb Side)

Left: Circular Style                                      Right: Rectangular Style

  • What style is the fender?
    • Does the fender have rounded ends or “Jeep Style” square ends?

Left:  Standard Oval Radius                                 Right: Jeep Style

Measuring the fender

  • Overall length: Trailer fender overall length is measured by going from the farthest point of the fender to its parallel opposite.

  • Inside length: Fender inside length is typically taken when attempting to replace plastic fenders that have 1 or more steps incorporated into its design. It is measured between the inside mounting flanges of the fender (where it will bolt to the mounting bracket)

  • Width: Width is very simple, just measure from the back face to the front face of the fender at its widest.


  • Height: The easiest way to measure height is with the fender removed from the trailer. Simply place the fender on a flat surface and measure from the ground up.


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