By Dean B. Wisecarver
Standard, private passenger automobiles typically have an inside rearview mirror and two outside mirrors. By adjusting these mirrors correctly, you can virtually eliminate the blind spots around your car, especially that tough one just off the left rear of your car where a passing vehicle might disappear from view.
The objective of proper mirror adjustment is to give you a 360-degree view of other vehicles near your car. The outside mirrors are the key, here, and most people don't position them correctly.
Most people make the mistake of adjusting the outside mirrors to look directly behind the car. The inside mirror should be adjusted to see directly behind you, but the outside mirrors should expand that field of vision to the left and right of what you can see with only the inside mirror. As a vehicle behind you approaches to pass, it should appear in one of your outside mirrors just before it disappears in your inside mirror. As that other vehicle overtakes you, it should be visible directly in your peripheral vision before it completely disappears from view in the side mirror.
For example, imagine another car is moving up to pass you on your left (as on an Interstate highway). When the right rear side of that car is starting to disappear from your inside mirror, you should be able to see the entire front end of that car in your outside left mirror. As it advances, you should be able to directly see the front of that car out your side window before the right rear of that car disappears from view in your outside mirror. The same should be true of a car passing you on your right side.
So, if you adjust the mirrors correctly, you can see at all times that vehicle as it approaches and passes you from behind. There are no blind spots. The Society of Automotive Engineers recommends that you follow this procedure to adjust your outside mirrors:
With your car safely parked, and while sitting behind the wheel as normal, lean your head against the driver's side door window. Adjust the left outside mirror so you can just barely see the side of your car with your head in that position.
For the passenger side mirror, move your head over into the middle of the front seating area until you can just see the headrest on the driver's seat in the inside mirror. Now, with your head in this spot, adjust the outside mirror on the passenger's side until just see the side of your car.
That's it. Now, test the view in traffic. You will notice you can see all the way around your vehicle - no blind spots as long as you check all your properly adjusted mirrors before changing lanes or turning.