Safety and your vehicle is about keeping your car legal, roadworthy and secure, and knowing how its safety equipment works. The theory test asks about tyres, lights, seat belts, warning lights, braking systems and protecting your car from theft. These questions are some of the most practical in the test: every one of them describes something you’ll need to check or do as soon as you own or borrow a car.
Last reviewed: September 2026. Checked against the Highway Code and GOV.UK.
What this topic covers in the theory test
Expect questions on:
- your legal duty to keep the vehicle roadworthy, and the MOT
- tyre tread depth and tyre pressures
- lights: sidelights, headlights, fog lights and hazard warning lights
- seat belts, child restraints and head restraints
- anti-lock brakes (ABS), coasting and engine braking
- dashboard warning lights
- leaving the engine running, and the environment
- vehicle security and opening doors safely
Some questions are pure recall (like the minimum tread depth), and others test understanding, such as why coasting reduces your control.
Keeping your vehicle roadworthy
Rule 89 says you must ensure your vehicle and any trailer comply with the full requirements of the Road Vehicles (Construction and Use) Regulations and the Road Vehicles Lighting Regulations. Put simply, the car has to be legal and safe every time you drive it, not just on MOT day.
Before setting off, rule 97 says you should make sure that you have a valid licence and insurance, and that your vehicle is legal and roadworthy. You should also:
- plan your route and check you have enough fuel or charge for the journey
- know where all the controls are and how to use them
- adjust your seat and mirrors so you can reach the controls and see clearly
- adjust the head restraint to reduce the risk of neck and spine injuries in a collision
Highway Code Annex 6 sets out the regular checks. Lights, brakes, steering, exhaust system, seat belts, demisters, wipers and washers must all be working. Lights, indicators, reflectors and number plates must be kept clean and clear, and windscreens and windows must be kept clean and free from obstructions. Check fluid levels, including brake fluid, at least weekly, because low brake fluid can result in brake failure.
Cars need an MOT test by the third anniversary of their registration, and then every year after that. According to GOV.UK, you can be fined up to £1,000 for driving a vehicle without a valid MOT. Our documents guide covers MOTs, tax and insurance in more detail.
Tyres
Tyres are your only contact with the road, so they come up often. According to Highway Code Annex 6:
- The minimum legal tread depth for cars is 1.6 mm across the central three-quarters of the breadth of the tread and around the entire circumference.
- Check tyre pressures at least weekly, and before a long journey, when the tyres are cold. Warm or hot tyres can give a misleading reading.
- Tyres must be correctly inflated to the vehicle manufacturer’s specification for the load being carried.
Incorrect pressures affect how the car grips, steers and brakes, and under-inflated tyres wear out faster. The correct pressures are in your vehicle handbook, and they may be higher when the car is fully loaded.
Lights
Rule 113 says you must ensure all sidelights and rear registration plate lights are lit between sunset and sunrise. You must use headlights at night, except on a road with lit street lighting, which generally means a 30 mph limit (20 mph in Wales). You must also use headlights when visibility is seriously reduced.
Other lighting rules to know:
- Dazzle: you must not use any lights in a way that dazzles or causes discomfort to other road users (rule 114).
- Fog lights: you must not use front or rear fog lights unless visibility is seriously reduced, and you must switch them off when visibility improves (rule 114). Rule 226 says to use headlights when you can’t see for more than 100 metres.
- Hazard warning lights: use them when stationary to warn that you are temporarily obstructing traffic. You must not use them while driving, except briefly on a motorway or unrestricted dual carriageway to warn drivers behind of a hazard or obstruction ahead (rule 116).
- Parking at night: you must display parking lights when parked on a road, or a lay-by on a road, with a speed limit greater than 30 mph (rule 250).
Seat belts, child restraints and airbags
Rule 99 says you must wear a seat belt in cars, vans and other goods vehicles if one is fitted. Passengers aged 14 and over are responsible for wearing their own seat belt. There are limited exemptions, such as for holders of medical exemption certificates.
For younger passengers, rule 100 puts the responsibility on the driver: you must ensure that all children under 14 years of age in cars, vans and other goods vehicles wear seat belts or sit in an approved child restraint where required. The right restraint depends on the child’s height and weight.
Rule 101 says you must not place a rear-facing baby seat in front of an active frontal airbag, because it can cause serious injury or death to the child if the airbag goes off. Rule 102 adds that children should get into the vehicle through the door nearest the kerb, and that child safety door locks should be used where fitted.
Brakes, ABS and coasting
Several braking rules come up in the test:
- Normal braking: rule 117 says brake early and lightly, then more firmly as you begin to stop, easing the pressure just before the vehicle comes to rest to avoid a jerky stop.
- ABS: if your car has anti-lock brakes, rule 120 says in an emergency apply the footbrake firmly and do not release the pressure until the vehicle has slowed to the desired speed. ABS should help you keep steering control, but it does not guarantee a shorter stopping distance.
- After driving through water: rule 121 says test your brakes by pressing gently on the pedal, and apply light pressure while driving slowly to dry them out.
- Coasting: rule 122 warns that coasting (driving with the clutch pressed down or in neutral) reduces your control. It removes engine braking, increases speed downhill, reduces the effectiveness of the footbrake, affects steering and makes it harder to select the right gear.
Warning lights and the environment
Highway Code Annex 6 says you should be familiar with all the warning lights on your instrument panel. If a warning light comes on and stays on after the engine starts, you should find out why rather than ignoring it. For example, if the charge warning light stays on, the battery isn’t being charged and you should have it checked as soon as possible. Your vehicle handbook explains each symbol.
Looking after your car also helps the environment. Rule 123 says you must not leave a parked vehicle unattended with the engine running, or leave the engine running unnecessarily while the vehicle is stationary on a public road. Generally, if you expect to be stationary for more than a couple of minutes, switch off the engine, unless you are in queuing traffic or diagnosing a fault. Smooth driving, planning ahead and avoiding harsh acceleration and braking save fuel and reduce emissions.
Security and opening doors safely
When you leave your car, rule 239 says you must switch off the engine, headlights and fog lights. You should also make sure you won’t hit anyone, such as a passing cyclist or pedestrian, when you open your door.
This rule includes the technique often called the “Dutch reach”. Where you can, open the door using the hand on the opposite side to the door, for example your left hand for a door on your right. This turns your body so you naturally look over your shoulder for cyclists and other road users coming up behind.
For security, Highway Code Annex 6 advises that when you leave your vehicle you remove the ignition key and engage the steering lock, lock the car even if you’ll only be away for a few minutes, close the windows completely, and never leave children or pets in an unventilated car. Take valuables with you or lock them in the boot, and never leave vehicle documents in the car. It also suggests fitting an anti-theft device such as an alarm or immobiliser, and having your registration number etched on all your windows as a cheap deterrent to professional thieves.
Common mistakes learners make
- Thinking the tread depth rule only applies to part of the tyre. It covers the central three-quarters of the tread, all the way around.
- Checking tyre pressures straight after a long drive, when warm tyres give a misleading reading.
- Leaving rear fog lights on after the fog has cleared.
- Using hazard warning lights to excuse bad parking.
- Pumping the brake pedal in a car with ABS instead of pressing firmly and holding.
- Believing passengers aged 14 and over are the driver’s legal responsibility for seat belts. They are responsible for themselves.
- Leaving the engine running while defrosting the car unattended.
Quick-reference table
| Item | Key figure or rule | Highway Code / GOV.UK |
|---|---|---|
| Car tyre tread depth | At least 1.6 mm across the central three-quarters, around the entire circumference | Highway Code Annex 6 |
| Tyre pressures | Check at least weekly, when cold | Highway Code Annex 6 |
| First MOT | By the third anniversary of registration | GOV.UK |
| Seat belts, children under 14 | Driver’s legal responsibility | rule 100 |
| Rear-facing baby seat | Never in front of an active frontal airbag | rule 101 |
| Fog lights | Only when visibility is seriously reduced; switch off when it improves | rule 114 |
| Headlights | Use when you can’t see for more than 100 metres | rule 226 |
| Parking lights at night | On roads with a speed limit above 30 mph | rule 250 |
Practice questions
These practice questions are written by Get Driving Test Ready to help you revise. They are not official DVSA questions.
Q1. What is the minimum legal tread depth for car tyres?
A) 3 mm across the central half of the tread
B) 1 mm across the whole tread
C) 1.6 mm across the central three-quarters of the tread, around the entire circumference
D) 2 mm across the outer edges only
Answer: C. Car tyres must have at least 1.6 mm of tread across the central three-quarters of the breadth of the tread and around the entire circumference. (Highway Code Annex 6)
Practise this on the road: Ask your supervisor to show you the tread wear indicators on your practice car's tyres and how to check them.
Q2. When should you check your tyre pressures?
A) Only at the MOT
B) When the tyres are cold
C) Straight after a motorway journey
D) When the tyres are warm, for an accurate reading
Answer: B. Check pressures when the tyres are cold. Warm or hot tyres may give a misleading reading. (Highway Code Annex 6)
Practise this on the road: Practise checking tyre pressures before a drive when tyres are cold, using the figures in the car's handbook.
Q3. You're carrying a 12-year-old passenger in the back seat. Who is legally responsible for making sure they wear a seat belt?
A) The child
B) Nobody, because they're in the back
C) The driver
D) The child's parent, even if not in the car
Answer: C. The driver must ensure that all children under 14 years of age wear seat belts or sit in an approved child restraint where required. (Highway Code rule 100)
Practise this on the road: Before moving off, practise checking that every passenger has fastened their seat belt, especially children.
Q4. Where must you never fit a rear-facing baby seat?
A) In a car with ABS
B) In the rear seat behind the driver
C) In front of an active frontal airbag
D) In the rear middle seat
Answer: C. You must not place a rear-facing baby seat in front of an active frontal airbag, because it can cause serious injury or death if the airbag deploys. (Highway Code rule 101)
Practise this on the road: Ask your supervisor to show you where the airbag warning labels and passenger airbag switch are in your practice car.
Q5. Your car has anti-lock brakes. How should you brake in an emergency?
A) Use the handbrake first
B) Pump the brake pedal on and off
C) Press the footbrake firmly and keep the pressure on
D) Brake gently and steer hard
Answer: C. With ABS, apply the footbrake firmly and don't release the pressure until the vehicle has slowed to the desired speed. (Highway Code rule 120)
Practise this on the road: Ask your instructor to demonstrate or talk you through a controlled emergency stop in a safe, quiet place.
Q6. Why is coasting downhill in neutral a bad idea?
A) It damages the clutch plate immediately
B) It reduces your control of the vehicle
C) It makes the footbrake work better
D) It is only allowed on motorways
Answer: B. Coasting removes engine braking, increases your speed downhill, reduces the effectiveness of the footbrake and affects steering, so you have less control. (Highway Code rule 122)
Practise this on the road: On a downhill stretch, practise staying in gear and controlling your speed, and discuss why you avoid coasting.
Q7. When must you switch off your rear fog lights?
A) When you reach a 30 mph limit
B) After 10 minutes of use
C) When visibility improves
D) Only when you park
Answer: C. You must not use fog lights unless visibility is seriously reduced, and you must switch them off when visibility improves. (Highway Code rule 114)
Practise this on the road: Ask your supervisor to show you the rear fog light switch and warning light, and when it should be switched off.
Q8. When may you use hazard warning lights while moving?
A) When towing another vehicle
B) Briefly on a motorway or unrestricted dual carriageway to warn drivers behind of a hazard ahead
C) Whenever you are driving slowly
D) When parking on double yellow lines
Answer: B. You must not use hazard warning lights while driving, except briefly on a motorway or unrestricted dual carriageway to warn drivers behind of a hazard or obstruction ahead. (Highway Code rule 116)
Practise this on the road: Find the hazard light switch without looking, and discuss with your instructor when hazard lights are and are not allowed.
Q9. You're about to open your door after parking on a busy street. Which technique helps you spot cyclists coming from behind?
A) Opening the door quickly so you're out of the way sooner
B) Relying on your door mirror only
C) Sounding your horn before opening the door
D) Using the hand on the opposite side to the door
Answer: D. Where you can, open the door with the hand on the opposite side, for example your left hand for a door on your right. This makes you turn and look behind. (Highway Code rule 239)
Practise this on the road: Each time you park at the roadside, practise opening your door with the far hand and looking over your shoulder first.
Q10. You'll be stationary for a while, but you're not in queuing traffic. What should you do with the engine?
A) Leave it running with the handbrake off
B) Rev it occasionally to keep it warm
C) Switch it off
D) Leave it running to keep the battery charged
Answer: C. You must not leave the engine running unnecessarily while stationary on a public road. Generally, switch off if you expect to be stationary for more than a couple of minutes. (Highway Code rule 123)
Practise this on the road: When waiting to pick someone up, practise applying the parking brake and switching off the engine instead of idling.
Next steps
Head back to the theory test hub to see all 14 topics. Related topics: safety margins, which covers braking and stopping distances in detail, and vehicle handling, for controlling the car in different conditions. Road warning signs are covered in our warning signs guide. For the in-car vehicle checks examiners ask about, see our show me, tell me questions.