A trailer fender could need replacing for many different reasons. It could be rusted, split, or damaged in an accident. A fender that is badly damaged could be difficult to remove, especially if it is crumpled where the bolt brackets are. Proper tools will be needed to take off the old and to install the new trailer fender. Getting the right fender is required to fit correctly. If the company that manufactured the trailer is known, then the dimensions should be available from them. Otherwise the fender will need to be measured for correct fit.

Before beginning any work on the trailer, make sure it will not move. Blocking the front and rear needs to be done for safety purposes. Start by removing the old fender. A hammer, pry bar, hacksaw, wrenches, and other tools might be required to remove it, especially one that is crumpled. If the bolts are still impossible to get at, a cutting torch will need to be used. Care must be used to ensure no fire is started. 

The new fender will need to be measured and holes drilled in it for the mounting bolts. Before installing, the fender will need painted to match the rest of the trailer. This is a lot easier to paint than after it has been put on. Let the paint dry before putting on the fender. The paint will still need to cure, which could take up to sixty days, above 60 degrees. This means no waxing until then.

The new fender will need to be carefully set in place and bolts put in as soon as the holes line up. Tighten the bolts until the fender is secured. Some trailers will need the wheels removed to be able to get to the bolt holes. The trailer will need to be put on jack stands after the wheels are removed so the fender can be installed safely.

Future damage can be prevented to the trailer by parking it away from other vehicles as much as possible. With many trailers parked in a congested area, a lot of them will suffer fender damage, a lot of times from unknown drivers. Pulling a trailer always requires more room and caution should be taken during lane changes and cornering. Backing up a trailer requires a skill that many never learn. Always park away from docks and other backing areas. A few precautions will keep a trailer looking good and free from damage for many years to come.