When you back up a trailer, you can't turn around and look out the rear window. The trailer is in the way. Almost everything you know about where the trailer is comes from your mirrors, and increasingly from cameras. Learning to read them well is what separates a calm, controlled back-up from a guessing game.
This article covers setting up your mirrors for towing, what to watch for in them while backing, how to get the most from a backup camera, and why it still pays to get out and look.
Why towing changes your mirrors
Normal side mirrors are set up to show the lanes beside your vehicle. When you add a trailer, two things change:
- The trailer blocks your rear view. The center rear-view mirror becomes much less useful, often showing only the front of the trailer.
- The trailer may be wider than your vehicle. Campers, enclosed trailers and boats are often wider than the tow vehicle, which means standard side mirrors show only the side of the trailer and nothing beyond it.
That's why towing mirrors exist. They extend further out from the vehicle so you can see past the sides of a wide trailer. Many states require mirrors that give a clear view of the road behind you when towing a trailer that blocks the normal view. Extendable towing mirrors, clip-on extensions, or slide-on mirror covers are common ways to get that view.
Setting your mirrors for backing
A good starting setup for backing:
- With the truck and trailer straight, adjust each side mirror so you can just see the side of the trailer along the inner edge of the mirror, with most of the mirror showing the area beside and behind it.
- Tilt the mirrors down a little so you can see the trailer's wheels and the ground near them.
- If your mirrors have a separate convex section, use it for a wider view of what's beside the trailer, keeping in mind that convex mirrors make things look farther away than they are.
Some drivers tilt the passenger-side mirror down further when backing, so they can see the curb or the trailer's rear wheel on that side, and put it back before driving on the road.
Reading the mirrors while backing
Your mirrors tell you which way the trailer is heading and how sharp the angle is.
- Straight rig: You see roughly the same amount of trailer in each mirror.
- Trailer swinging toward one side: You see more trailer in the mirror on that side, and less in the other. The back of the trailer is heading toward the side where it's growing.
- Large hitch angle: One mirror is full of trailer and the other shows none at all. That's a warning sign of a coming jackknife. See How to Avoid Jackknifing.
A helpful rule when backing straight: if the trailer appears in one mirror, steer toward that mirror with the top of the wheel, a little, to bring it back. It's the same as the hand-at-the-bottom trick, just thought about from the mirror's point of view. Then recenter the wheel as the trailer comes back.
Watching the right things
Beginners tend to stare at one mirror. Experienced drivers keep their eyes moving:
- Both side mirrors, back and forth, to track the trailer's direction.
- The trailer's rear corners, which swing the widest and are what hits things.
- The front of the truck, which swings out across the road or into a neighboring space as you turn.
- The space between the trailer and any obstacles, especially on the inside of the turn.
- Any people, vehicles or animals that might move into your path.
Backup cameras
Most new vehicles have a backup camera, but when you're towing, the vehicle's camera mostly shows the hitch and the front of the trailer. It's very useful for lining up the ball under the coupler when hitching, but it can't see behind the trailer.
For backing the trailer itself, many drivers add a camera to the rear of the trailer, either wired or wireless. Some newer trucks support trailer cameras through their own screens, and some even combine several cameras to make the trailer look see-through. A trailer camera shows exactly what's behind the trailer, which helps with:
- Seeing obstacles directly behind the trailer that mirrors can't show.
- Judging the last few feet to a wall, post or curb.
- Lining up with parking lines or the edge of a ramp.
Some camera displays draw guide lines that bend with the steering wheel to show the predicted path. On a trailer camera, these can show where the trailer will go if you hold the current steering, which is a very useful learning tool.
The limits of cameras
Cameras are a big help, but they have weaknesses:
- Distorted distance. Wide-angle lenses make objects look farther away than they are, and depth is hard to judge on a flat screen.
- Limited view. A camera pointing backward doesn't show the sides of the trailer, where it's most likely to hit something during a turn.
- Dirt, rain and glare. A dirty lens or water drops can make the image useless.
- Wireless lag and dropouts. Some wireless cameras lag or cut out, which matters when you're moving.
Use the camera together with your mirrors, not instead of them. The mirrors show you the trailer's angle and the sides; the camera shows what's behind.
Get out and look
No mirror or camera shows everything. When you're unsure, stop, set the parking brake, and get out to look. Truck drivers call this GOAL: Get Out And Look. A spotter is even better, as long as you can see them in your mirror. See Backing into a Campsite or Driveway for how to work with one.
Practicing in The Trailer Parker
The Trailer Parker's cab view works the way a real truck does. In Forward, you're in the driver's seat with a working left side mirror. Shift into Reverse and both side mirrors grow into large live panels, and a backup camera on the back of the trailer appears on the dash. The camera draws the path the trailer's rear corners will follow if you keep the wheel where it is, colored green close in, then amber, then red farther out.
Press V to cycle through cab view, reverse assist, a full-screen backup camera and a raised drone view, and hold A or D to glance left or right. A good way to train is to learn a lot in the drone view, where you can see the whole rig, then park it again using only the mirrors and the trailer camera. That's exactly what you'll have in a real truck.