Properly adjusted mirrors can lessen blindspots

Q: How do you properly adjust your side mirrors? I think most people adjust them so they can see the side of their own car, but I read something years ago that you should adjust your mirrors outward, which will more effectively cover your blind spot. Is there a recommended method?

A: I think we can agree that the goal of adjusting your mirrors is to see as much of what’s behind you as possible. With that in mind, you don’t want to see a big chunk of your own car.

If your side-view mirror is tilted in too far, you’ve got a lot of overlap between that mirror and your rear-view mirror, but you’ve increased the size of the blind spot to the side of your vehicle. The other problem is that it leaves less space to see other things behind you.

You can be confident that of all the threats on the road, the rear quarter panel of your car is not one of them, so don’t fill your mirror with it. The law requires that you set up your mirrors so that they reflect the highway at least 200 feet behind you, but doesn’t give any further instructions.

The perfect setup would be one with no visual gap between the rearview and side view mirrors, and the moment you lose sight of a vehicle in your side view mirrors as it passes you it appears in your peripheral vision.

Alas, it’s unlikely that you drive a car that’s capable of achieving mirror perfection. I set out on a quest to find a car with no blind spots, but all I came up with were lists of vehicles with the fewest blind spots. That means you’re going to settle for a compromise.

The Washington Driver Guide recommends that you adjust the side mirrors so that you can see a small amount of the side of your vehicle. That approach should provide a slight overlap between your side- and rear-view mirrors, along with moderate blind spots toward the side of your vehicle.

A second recommended method comes from the Society of Automotive Engineers. To set your left side view mirror, lean your head against the window on the driver’s door and adjust the mirror until you can see a sliver of the rear of the car. Do the same for the passenger side mirror, with your head roughly in the center of the car. That shifts your mirrors even wider than the driver guide recommendation.

You’ll end up with smaller blind spots on the sides of your vehicle, and possibly two narrow blind spots to the rear of your car.

Which method should you use? It might depend on your vehicle. For example, if you don’t have good visibility from your rearview mirror (like when towing a trailer) the method in the driver guide will probably work better. Either way, your mirror adjustment is only as good as the situational awareness you bring to your drive, as you scan both mirrors and blind spots.

Doug Dahl writes a weekly column for this newspaper. He is with the state Traffic Safety Commission.