Theory test / Safety margins
Safety margins theory test questions
Up to date with the current Highway CodeLast reviewed October 2026
Safety margins is about leaving yourself enough time and space to react. The questions centre on stopping distances, the two-second rule, and how rain, ice, snow, fog, wind and heat change the gap you need. It also covers how ABS behaves, how to deal with a skid, and how much room to give other road users when you pass them.
Learn the typical stopping distances table from Rule 126 properly, because the test asks for exact figures. Overall stopping distance is thinking distance plus braking distance. On a dry road: 20 mph is 12 metres, 30 mph is 23 metres, 40 mph is 36 metres, 50 mph is 53 metres, 60 mph is 73 metres and 70 mph is 96 metres. Thinking distance goes up by 3 metres for every 10 mph, from 6 metres at 20 mph to 21 metres at 70 mph, while braking distance grows much faster.
The usual trap is mixing up the multipliers. On high-speed roads and in tunnels leave at least a two-second gap. Double it to at least four seconds on wet roads, because stopping distances are at least doubled in the wet (Rule 227). On ice, stopping distances can be up to ten times greater than on dry roads (Rule 230). If you have to stop in a tunnel, leave at least 5 metres to the vehicle in front.
Another common mistake is assuming ABS shortens your stopping distance. Rule 120 says it helps you keep steering control while braking hard, not that you will stop sooner. In a skid, take away the cause by releasing the brake or easing off the accelerator and steer the same way as the skid (Rule 119). If the steering goes light in heavy rain, the tyres are probably riding on water: ease off and slow down gradually.
Space when passing matters too. Rule 163 asks for at least 1.5 metres when overtaking a cyclist at up to 30 mph, more at higher speeds, and at least 2 metres at under 10 mph for horse riders. Drop back from large vehicles so you can see ahead and the driver can see you, and keep well back from motorcyclists in strong winds. In fog, use headlights when you cannot see more than 100 metres, and never speed up to get away from someone too close behind.
Try 5 free questions
No account needed. Pick an answer to see whether it is right and why.
What is the typical overall stopping distance for a car travelling at 30 mph on a dry road?
The free questions with answers
1. What is the typical overall stopping distance for a car travelling at 30 mph on a dry road?
Answer: 23 metres (75 feet)
At 30 mph the Highway Code table gives 9 metres thinking distance and 14 metres braking distance, a total of 23 metres. The other figures are the distances for 20, 40 and 50 mph.
Highway Code rule 126
2. You normally keep a two-second gap on a dry road. What gap should you leave when the road is wet?
Answer: At least four seconds
Stopping distances are at least doubled in the wet because the tyres have less grip, so the two-second gap should be at least doubled to four seconds (Rules 126 and 227).
Highway Code rules 126, 227
3. Compared with a dry road, how much longer can your stopping distance be on an icy road?
Answer: Up to ten times longer
Rule 230 warns that stopping distances can be ten times greater on ice than on dry roads, so the gap in front needs to grow by the same amount.
Highway Code rules 126, 230
4. What is the typical thinking distance at 70 mph?
Answer: 21 metres
Thinking distance rises by 3 metres for every 10 mph, from 6 metres at 20 mph to 21 metres at 70 mph. Add 75 metres of braking distance and the total at 70 mph is 96 metres.
Highway Code rule 126
5. You are driving in heavy rain and the steering suddenly feels very light. What should you do?
Answer: Ease off the accelerator and slow down gradually
Light, unresponsive steering in the wet usually means water is stopping the tyres gripping the road. Rule 227 says to ease off the accelerator and slow down gradually, without sudden braking or steering.
Highway Code rule 227
Questions people ask
- What is the overall stopping distance at 30 mph?
- 23 metres on a dry road: 9 metres thinking distance plus 14 metres braking distance. That is roughly six car lengths, and it will be at least double in the wet.
- How do I measure a two-second gap?
- Watch the vehicle in front pass a fixed point such as a sign or bridge, then say "only a fool breaks the two-second rule". If you reach the point before you finish, you are too close.
- Does ABS make my car stop in a shorter distance?
- Not necessarily. ABS stops the wheels locking so you can keep steering while braking hard, but Rule 120 warns you not to assume it will stop you sooner, especially on loose or wet surfaces.
- How much bigger should my gap be on wet or icy roads?
- At least double on wet roads, so four seconds or more. On icy roads the gap may need to be up to ten times greater than on a dry road (Rules 126 and 230).
Other theory test topics
Rule references: The Highway Code (GOV.UK), Open Government Licence v3.0. Questions and explanations are written by PassRank and are not the official DVSA revision questions.