Setting Outside Mirrors to the Correct Angle

Fashion plays a big part in modern life but it is highly doubtful whether road safety trends should ever be subject to it. Yet there is currently a buzz going around regarding the settings for exterior mirrors. The method now being recommended is potentially risky and frankly has no benefits other than the promotion of laziness and the de-emphasis of reasonable care by drivers. No matter how well-intended, this technique should never be sanctioned.



The new method is being promoted in the USA but would apply equally in any country with left-hand-drive vehicles and is reversed for countries with right-hand-drive vehicles.
Let's consider the rationale behind the new advice (illustration: 'Car Two,' below). It states, for the USA, that when setting the left-hand exterior mirror, a driver should place his/her head against the glass of the driver's door window then align the exterior mirror to show just a thin sliver of the car bodywork. Traditional advice, however, states that the mirror adjustment should be made while seated normally for driving, not with one's head against the glass. Similarly, proponents of the new method say that the driver should lean to the right, until their head is central, across the width of the car, before setting the right-hand exterior mirror -- again to show just the very edge of the car bodywork. Once again, the traditionalists state that this adjustment should be made while the driver is sat normally in the correct position for driving.



Those who recommend the new idea of 'wider' settings for the wing/exterior mirrors claim that the method reduces the need for a driver to glance over either shoulder and that it also gives a better view through the relevant exterior mirror, of cars that are alongside one's own vehicles on a multi-lane highway. They also claim that it reduces unnecessary overlap between the views through interior and exterior mirrors (see the striped, green zones in illustration 'Car One,' below).


Car One: The 'traditional' way of setting the exterior mirrors. Note the lack of red-striped blind spots inside (i.e. below) the thick red lines. The green-striped areas denote overlap of the view from the interior and exterior mirrors.

These settings prevent any other vehicles, including motorcycles, from coming up behind, unseen.
Car Two: Setting the exterior mirrors 'wide'. Note the large, red-striped blind spots inside (i.e. below) the thick red lines, and the large areas of green above those same lines.



Depending on how wide a driver sets his exterior mirrors, this technique creates large, un-viewable blind spots that can hide other vehicles, all so that the driver concerned doesn't feel obliged to do shoulder checks.
The areas above the thick red lines denote zones which a driver may view simply by turning his/her head when appropriate. These diagrams are not to scale -- they were created using nothing more complex than the 'MS Paint' computer program -- but they still clearly show that setting the mirrors 'wide' creates two large, dangerous, rear blind spots which can not easily or safely be viewed, and that if a driver ever does turn his/her head -- an action that this technique seeks to reduce -- it creates even more unnecessary overlap than do the traditional settings.
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The question is, does this new 'wide settings' method actually do anything at all to enhance safety?

The answer is a resounding 'No!' And under several circumstances it will have exactly the opposite effect.



Before detailing why this is such a bad method, it is important to take account of those people who, through neck injury, ailment or whatever, have genuine difficulty in turning their head to glance over their shoulder. If this is the case then one of three things can be done to make life easier and to ensure that the relevant blind spots can still be checked:

-- The first is to briefly rock forward, towards the steering wheel, as one looks into the relevant mirror. This gives exactly the same 'wide' view as does setting the mirror in that position in the first place, and it avoids the driver having to turn to look over their shoulder. Nobody is advocating that a driver sits too close or remains too close to the steering wheel when driving but, as long as it is safe to do so at the relevant moment, briefly leaning forwards will not cause problems.

-- The second option is to have an additional wing mirror fitted on both sides of the car so that one on each side can be set in the proper, 'traditional' manner and the other can be set appropriately wide.

-- And the third possibility is to buy small, convex self-adhesive mirrors that can be stuck on to the bottom outer corner of each exterior mirror. These give only a small image for the driver to see but will show whether there is, in fact, another vehicle partially alongside
There are, however, at least eight reasons why you should not position the exterior mirrors for a 'wide' view:



1. On the question of overlap between interior and exterior mirrors, it is a sad fact of life that most drivers -- assuming they use their mirrors at all -- only check one mirror when they should be checking at least two. In this case, the question of overlap becomes a moot point and is quite possibly advantageous.



2. A good (meaning 'attentive') driver will always monitor all of the vehicles coming up behind at all times and, through concentration on the task at hand, will always know what vehicles may be alongside, in the relevant blind spots. In these circumstances, a shoulder check becomes necessary only to confirm the other vehicle's exact location or, for example, whether it left the highway at an interchange one has just passed.



3. If exterior mirrors are set 'wide' then on highways there is a risk that a motorcycle could be hidden from sight in the relevant blind spots and as a result the rider(s) could be killed if a driver starts a turn or a lane change. On urban roads with slow-moving traffic there is a similar danger in respect of bicyclists coming past on the right-hand side of one's vehicle, especially if near an intersection or driveway where the motor vehicle driver is about to turn right.

4. In all except two-seat sports cars and two-seat pick-up trucks, the view through the interior mirror will often be partially blocked by rear-seat head restraints, especially if such have been correctly adjusted for taller teenage or adult passengers. The heads of any such passengers will, of course, also increase any obstruction to the driver's view. The view through the interior mirror is therefore often far less than perfect which means that the view directly to the rear through the exterior mirrors becomes much more important. This facility is lost if the exterior mirrors are set 'wide'.



5. In longer vehicles, such as 7-seat mini vans* and the larger models of SUVs, the very length of the vehicle usually means that the view via the interior mirror, through the now more distant back window, is much narrower than it is in a shorter vehicle. This means that the view via the interior mirror covers a smaller angle and once again the view directly to the rear through the exterior mirrors becomes much more important
6. If a mini van or an SUV has a double back door (as opposed to a lifting/lowering tailgate) the vertical metalwork between the two back windows creates another, sometimes very significant blind spot which makes the interior mirror even less effective than in '5', above. Yet again the view directly to the rear through the exterior mirrors becomes even more important7. If a relatively tall vehicle, such as a mini van, a big pick-up or an SUV is being followed by a low car, such as a sports car, the low car may be completely hidden, below the view line of the bigger vehicle's interior mirror, but traditionally angled exterior mirrors will give a glimpse of it each time it strays out from being directly behind the larger vehicle.



8. The most obvious problem of all relates to reversing. Of course a driver must look over his/her shoulder(s) when doing this, but mirrors are usually essential, too -- especially in larger vehicles, such as SUVs and vans -- so if, for example, a driver is backing into or out of a parking space near a busy mall, how is he/she to clearly see a pedestrian who walks into the much enlarged blind spots (illustration: Car Two, above) that the 'wide' method creates? It cannot be a case of leaning the head to one side to see out of an exterior mirror because that automatically puts the other two mirrors out of alignment while this is happening and two thirds of the available mirror view is therefore lost. The only wise method of setting the mirrors so that reversing is always as safe as possible is the traditional method, never the new, 'wide' method.

[Please remember, when reversing/backing it is essential to continually check all around -- forwards, behind, over both shoulders and in all appropriate mirrors. Reverse slowly so that you have time to do this ...