Guide to stopping distances
From the moment we start learning to drive, the two-second rule becomes the holy grail for car stopping distances.
However, while this rule provides helpful guidance, there are various other factors that will affect your car’s stopping distance.
Here are the key factors you should be aware of.
Speed
It’ll come as no surprise to see speed on this list, after all, speed is the main factor that determines the Highway Code braking distance.
Your brakes can only decelerate your car by a certain amount per second, so the faster you’re going, the longer it takes to stop.
Because of this, the typical stopping distance at 70mph is 96 metres, while the stopping distance at 50mph is 53 metres, little more than half as much. The stopping distance at 30mph is just 23 metres, about six car lengths.
Reaction
We all experienced that nerve-racking moment in our driver lessons, as we waited for our teacher’s clipboard to slam against the dashboard as a part of our emergency stop training.
Out on the roads, emergency stops aren’t choreographed, and our reaction times need to be factored into the equation.
Thinking distance is the distance between the driver realising they need to brake and when they actually brake.
Thinking distance is calculated at 3 metres for every 10mph. So, thinking distance at 30mph is 9 metres, at 70mph it is 21 metres, and so on.
It’s worth bearing in mind, though, that your individual reactions might be different. As such, it’s important to stay alert while driving so you can get on the brakes quickly in an emergency.
Tread
Our tyres are arguably the most important parts of our cars. They affect braking, grip, handling and ride quality, and it’s important to ensure they have the minimum legal tread depth.
Remember, this is the bare minimum tread depth you need to have across 100% of your tyre’s central zone – if there are any flat spots, cracks or bulges, you should get your tyre checked immediately.
If your tyre shows any signs of damage or is already below the minimum legal tread depth, you can use our Autocentres or Mobile Experts to help. With our Mobile Experts, we can come and replace your tyres at home or work without you having to take to the public roads in an unroadworthy state.
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Wet weather
Bad weather can affect your tyres’ ability to grip the road, leading to an increase in overall stopping distance. This can be worsened further by poor visibility, making reaction speeds slower.
Stopping distances in rain can be much longer than on a dry road. Wet weather poses other hazards too, such as aquaplaning (when your tyre’s tread becomes completely waterlogged and you skid across the surface like ice).
Wet brakes can be less effective, so on rainy days you should use them lightly and regularly so that they dry out.
When driving in adverse weather, always allow for more braking distance.
Snow and ice
Driving in wintry conditions can be tricky, and snow and ice have a big affect on braking distance.
The total braking distance on ice can be so far that the only safe course of action is to drive much more slowly. For snowy and icy conditions, you can expect your braking distance to be multiplied by ten – five times greater than in rain!
You can improve your grip on snow and ice by fitting either all-season or winter tyres to your vehicle, as these are designed to perform better in these conditions.
Discover our winter and all-season tyres
How to remember stopping distances
Clearly, there are many factors that affect braking distance, but it’s useful to have a knowledge of specific stopping distances.
According to the Highway Code, the following stopping distances should be used as a general guide:
Speed (MPH) |
Stopping distance (metres) |
20 |
12 |
30 |
23 |
40 |
36 |
50 |
53 |
60 |
73 |
70 |
96 |
Remember, these stopping distances will vary according to the factors mentioned.
Hopefully, this has helped you gain a greater understanding of stopping distances, helping keep you safe out on the road. For more motoring guidance, head over to our advice and help guides. You’ll find a wide range of high-quality motoring products and services over at Halfords.com.
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