How to Set Up and Adjust Towing Mirrors

The first time you hitch a trailer wider than your vehicle, you notice something a little unsettling: your mirrors have gone half useless. Where there used to be a lane and the road behind, there's now the side of a trailer, and the traffic you need to see has slipped into a blind spot. Towing mirrors are the fix, and setting them up well is the difference between a relaxed drive and a white-knuckle one. It only takes a few minutes in the driveway. Here's how to set up and adjust your towing mirrors so you can see down both sides of the trailer and the lane behind it.

Why your regular mirrors don't cut it

A trailer that's wider than your tow vehicle blocks the view straight back and down its own sides. Your factory mirrors were aimed to show the lane beside your car, and now they show sheet metal instead, which leaves you guessing about anything alongside or behind the trailer. Your rearview mirror is usually blocked entirely, so the side mirrors are all you've got. And the blind spot isn't a small pocket the way it is in a car; it runs the length of the trailer, so a vehicle can ride hidden alongside you for a surprisingly long stretch.

Towing mirrors solve it by reaching out past the width of the trailer. Set right, they let you see down the full length of the trailer on each side, plus the lane and the road beside and behind it, so you can change lanes, merge and back up without guessing.

There's a legal side too. Many states require a clear view a set distance behind when your load blocks the inside mirror, and some require mirrors on both sides when you tow. The rules vary, so check your state, but the practical standard is simple: you need to see down both sides and behind.

The mirror types you'll run into

There are a few ways to get that extended view, and which one you need depends on your vehicle and how wide the trailer is.

Factory tow mirrors are the built-in kind that extend, telescope or flip out to a towing position. On a truck with a tow package you may already have them, so you just pull them out and aim them, and if they're powered you adjust them from the door switch. Clip-on or strap-on extensions slip over your existing mirror and reach farther out, and they're the answer for a car or SUV that didn't come with tow mirrors. They're inexpensive and come right off when you're done.

Split-view mirrors combine two views in one housing: a flat section up top for judging distance and the lane, and a convex section below that shows a wider, closer band to catch your blind spot. And a small stick-on convex spot mirror can be added to almost any mirror, aimed right at the blind spot the flat glass misses. If your mirrors are powered and heated, that's a real help in rain or cold, since a fogged or iced mirror is no mirror at all, but the aiming is the same either way.

A narrow utility trailer might not need any of this, but a wide enclosed trailer or a car hauler almost always does, so size your mirror solution to the trailer you're actually towing.

Set them up with the trailer attached

Here's the key that people miss: aim your mirrors with the trailer hitched and yourself sitting in your normal driving position. The trailer's width is exactly what you're setting up around, so aiming the mirrors on an empty truck gets you nowhere.

Aim for this. The inside edge of each mirror just catches the rear corner of the trailer, and the rest of the glass shows the lane and road running back beside it. That way you can see the whole side of the trailer and still have most of the mirror showing you traffic. Use the flat or main part of the mirror for the long view down the side, and aim the convex part, or your stick-on spot mirror, at the blind spot just off your rear quarter, where a car likes to hide. Don't forget the up-and-down aim while you're at it. You want the horizon sitting roughly a third of the way down the glass, so you catch both the road surface beside you and the traffic coming up on you.

Do both sides the same way, and take the extra minute on the passenger side, since that's the one you can't check with a quick glance over your shoulder. When it's set, one sweep of both mirrors should account for everything beside and behind you.

Confirm you've killed the blind spots

Before you trust the setup, prove it. Have someone walk slowly from the back of the trailer up along each side while you watch the mirrors. There's usually a moment where they slip out of the mirror before they appear in your side vision, and that gap is your blind spot. Adjust until the gap is as small as you can make it.

Then do a walk-around, get back in, and take a slow lap of a parking lot, checking a lane change to each side at low speed. It's far cheaper to find a problem there than on the highway.

One thing to keep in mind: convex mirrors make objects look farther away than they really are. That car in your spot mirror is closer than it appears, so give yourself extra room on every lane change.

Use them, and reset for the next trailer

On the road, lean on your mirrors. A trailer's blind spots are bigger and longer than a car's, so check before every lane change and keep scanning them on the highway rather than trusting a single glance.

And remember that a mirror setup is specific to the trailer. Swap a narrow utility trailer for a wide enclosed one and your careful aim is suddenly wrong, so re-aim whenever the width changes. It only takes a minute, and it's the minute that keeps you out of trouble. Fold extendable mirrors back in only when you're parked, and never drive with them stowed, since a folded tow mirror hands back the exact blind spot you set them up to erase. If you're about to practice reversing, know that you'll be living in these mirrors, so read more about how to back up a trailer.

What about insurance and damage protection?

Before towing a rented trailer, contact your auto insurance provider to ask whether your policy covers liability and towing-related damage claims.

Eligible rentals booked through Big Rentals also include Basic Rental Protection at checkout. This added protection can help limit your financial responsibility for certain damage or theft events during the rental period.

For full details on how Basic Rental Protection works, including deductibles, exclusions, and renter responsibilities, review our FAQ and platform terms.

The Short Version

• A trailer wider than your vehicle blocks your regular mirrors, so you need towing mirrors to see past it
• Options run from factory extendable mirrors to clip-on extensions, split-view mirrors and small stick-on convex spot mirrors
• Always aim them with the trailer hitched and you in the driving position
• Set each mirror so its inside edge catches the rear corner of the trailer and the rest shows the lane behind, with the convex part aimed at your blind spot
• Confirm the setup by having someone walk the sides while you watch, then test a lane change in a lot
• Convex mirrors make things look farther away than they are, so leave extra room
• Re-aim whenever you switch to a wider or narrower trailer

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