The most important thing you can do to increase the longevity of your motorcycle trailer is to store it in a sheltered, dry area. Long term exposure to the elements is the number one killer of all things mechanical. You’ve seen what happens to junker cars and bikes when they’re left out. They begin the inevitable reversion to their original elements, broken down by the sun, wind and rain.
A motorcycle trailer is no different. Constant exposure to the sun bleaches out the natural oils of rubber tires, causing them to dry and crack. UV rays will cause a painted trailer to fade while environmental hazards like acid rain, tree sap, and bird poop eat away at the clear coat on the paint. Moisture accumulates on the components underneath, eating away at metal components and corroding electrical components.
Before you store your trailer, it should be clean and dry. Storing a dirty, wet trailer creates a microclimate from whence all manner of organisms will spring to life to attack your trailer including rust and mold. If you have a stone shield (bra) on the front, that should be removed as well. Moisture trapped behind the stone shield can cause paint to blister with long term exposure. Open the trailer lid and let it air out thoroughly if you brought home anything inside the trailer that was wet. Once the interior is completely dry, close the lid to avoid providing an inviting new home for mice.
For long term storage, remove the tongue to save space. Most trailer tongues bolt to the front of the trailer and can be easily removed. This makes the trailer more compact and you won’t stumble over the tongue trying to navigate through your garage.