Blind Spots and Mirror Positioning Guide

Killing your blind spots — the quick answer

Most blind spots vanish if you set your door mirrors wider than feels natural — angled out until the side of your own car just leaves view. ‘Failed to look properly’ is the single most common factor in UK crashes; correctly set mirrors plus a quick shoulder-check erase the zone a rear-view mirror alone misses. How to position all three mirrors, step by step, is below.

The good news is that proper mirror positioning can eliminate up to 90% of your blind spots, and a consistent shoulder-check habit covers the rest. This guide explains exactly how to set up your mirrors, perform effective blind spot checks, and understand the blind spots of the vehicles around you.

What Causes Blind Spots?

Every vehicle has areas that mirrors cannot cover. In a standard car, the two primary blind spots are located at the rear quarter panels — the areas diagonally behind the driver on each side.

These blind spots exist because:

1. The A-pillars (the structural pillars on either side of the windscreen) block forward-diagonal vision
2. The B-pillars (between front and rear doors) block side vision
3. The C-pillars (behind the rear windows) block rear-diagonal vision
4. Conventional mirror positioning leaves gaps between the rear-view mirror’s field and the side mirrors’ field

The BGE Mirror Positioning Method

The Blindspot and Glare Elimination (BGE) method, recommended by the Society of Automotive Engineers (SAE), is the most effective way to reduce car blind spots through mirror adjustment alone.

Traditional vs BGE Mirror Setup

Most drivers set their side mirrors so they can see the side of their own car. This feels reassuring but is wasteful — you are using mirror area to show you your own car, which is not going anywhere. It also creates large blind spots.

Step-by-Step BGE Setup

Rear-view mirror (centre):

1. Sit in your normal driving position.
2. Adjust the centre mirror to frame the entire rear window. You should see the full width of the road behind you.

Left side mirror:

1. Lean your head against the left window.
2. Adjust the left mirror outward until you can just see the left rear corner of your car.
3. Return to your normal position — you should now not see your own car in this mirror.

Right side mirror:

1. Lean your head to the centre of the car (over the centre console).
2. Adjust the right mirror outward until you can just see the right rear corner of your car.
3. Return to your normal position — you should now not see your own car in this mirror.

How to Verify Your Setup

Drive on a multi-lane road and watch a car approach from behind:

1. You first see it in the centre rear-view mirror.
2. As it moves to overtake, it should appear in your side mirror before it disappears from the centre mirror.
3. As it passes your side mirror, you should see it in your peripheral vision before it leaves the side mirror.

If there are gaps — moments where the car is visible in neither mirror nor your peripheral vision — adjust the side mirrors further outward.

The Shoulder Check Technique

Even with perfectly positioned mirrors, a small blind spot remains. The shoulder check (also called the head check or lifesaver glance) covers this gap.

How to Perform a Shoulder Check

1. Decide to change lanes — check your mirrors first.
2. Signal your intention — activate your indicator.
3. Turn your head approximately 90 degrees toward the side you are moving to.
4. Glance for one second maximum — look for vehicles, motorcycles, or cyclists in the blind spot zone.
5. Return eyes forward — make your move if clear.

When to Shoulder Check

• Before every lane change
• Before merging onto a motorway or dual carriageway
• Before turning at junctions (check for cyclists and pedestrians)
• Before opening your car door when parked (the “Dutch Reach” method — open with the far hand to force a shoulder check)
• Before pulling away from a parked position

Common Mistakes

Truck and Lorry Blind Spots — The “No-Zones”

Large commercial vehicles have dramatically larger blind spots than cars. Understanding these zones could save your life.

The Four No-Zones

1. Front blind spot — the area directly in front of the cab, extending up to 6 metres. The driver sits high and cannot see vehicles or pedestrians close to the front bumper.
2. Rear blind spot — the area directly behind the trailer, extending up to 60 metres. There is no rear window, and mirrors cannot cover this zone.
3. Left (passenger) side — the largest blind spot, extending diagonally from the cab along the entire trailer length. This is where most truck-related lane-change accidents occur.
4. Right (driver) side — a smaller blind spot along the right side of the cab and trailer.

How to Stay Safe Around Trucks

• If you cannot see the driver’s mirrors, they cannot see you. Maintain a position where you can see the truck’s side mirrors.
• Pass quickly — do not linger beside a truck. Accelerate past and move well ahead.
• Give extra space when a truck is turning — trucks swing wide and may occupy multiple lanes during turns.
• Do not cut in front — after overtaking a truck, ensure you can see the entire cab in your rear-view mirror before pulling back in.

For more on sharing the road safely, see our new driver tips guide.

Motorcycle Visibility and Blind Spots

Motorcycles present a double challenge — they are small and easily hidden in your blind spots, and they often travel at speeds that bring them into your blind spot zone quickly.

For Car Drivers

• Assume motorcycles are present — especially in filtering traffic and at junctions.
• Check mirrors and blind spots before turning — motorcycles may be overtaking or filtering alongside you.
• Look twice at junctions — a phenomenon called “inattentional blindness” means your brain may register a motorcycle but not consciously notice it.

For Motorcycle Riders

• Avoid riding in car blind spots — position yourself where car drivers can see you in their mirrors.
• Use headlights — even during the day, a headlight makes you more visible. Many countries mandate daytime running lights for motorcycles.
• Wear high-visibility gear — especially in low-light conditions.
• Assume you are invisible — ride with the assumption that car drivers have not seen you.

Blind Spot Monitoring Systems

Modern vehicles increasingly feature Blind Spot Monitoring (BSM) systems. These use radar or ultrasonic sensors to detect vehicles in your blind spots and alert you with a warning light in the side mirror housing, an audible alert if you signal while a vehicle is detected, or a haptic warning (steering wheel vibration) in some advanced systems.

BSM Limitations

BSM is an aid, not a replacement for proper mirror setup and shoulder checks. Treat the warning light as a helpful reminder, but always verify with your own eyes.

Mirror Positioning for Specific Situations

Motorway Driving

The BGE setup is ideal for motorway driving where lane changes are frequent. Supplement with:

• Regular mirror scanning every 5-8 seconds
• Extra attention to the left mirror before moving to the slow lane
• Awareness that the blind spot is smaller at higher speeds (vehicles pass through it faster)

Parking and Low-Speed Manoeuvres

When reversing or parking:

• Tilt your side mirrors downward slightly to see the kerb and rear wheels
• Use your rear-view mirror for vehicles approaching from behind
• If your car has a reversing camera, use it alongside mirrors — never as the sole reference
• Perform a full 360-degree visual check before reversing

Towing a Trailer or Caravan

Towing significantly increases blind spots. Extended towing mirrors are legally required in many countries when towing wide loads. See our trailer towing laws guide for country-specific rules.

Conclusion

Blind spots are a fixable problem. The BGE mirror method takes five minutes to set up and eliminates the majority of your blind spots. Combined with a consistent shoulder-check habit — one-second glance before every lane change, merge, or turn — you dramatically reduce your risk of a blind-spot collision.

Remember that other vehicles have blind spots too, particularly trucks and lorries. Position yourself to be visible, pass large vehicles quickly, and never assume that another driver has seen you. For more driving safety advice, explore our night driving safety tips and driving in bad weather guide. For country-specific driving rules, visit our driving guides directory.

Disclaimer: Blind spot monitoring systems vary between manufacturers and models. Always refer to your vehicle’s owner manual for specific system capabilities and limitations. This guide provides general safety advice and does not replace professional driver training.