Once mounted, the mirrors must be adjusted. You need to adjust the mirrors while the trailer you’re going to be pulling is connected to the towing hitch. If you can do this in a vacant parking lot where you can drive around and test your field of vision, so much the better.

Single driver: Sit in the driver’s seat as you normally would while you’re driving. Adjust the mirror side-to-side until you can just barely see the side of your truck or car in the mirror. Now adjust the up-and-down position of the mirror until you can see the road at the rear of the trailer. Repeat this process for the mirror on the passenger side.

Multiple drivers: If there will be more than one person driving, use thin strips of electrical tape to mark where the mirror will be set for the first driver. Adjust the mirrors for the second driver and mark the settings for them as well. If you’re using permanent replacement mirrors that move using the interior controls, those controls may be able to save settings for multiple drivers.