It is very hard to give a certain answer in feed, there are so many variables. Visibility, how hard is it raining? has it just started raining? is the road already soaked. As a rule of thumb it sould be 4 car lengths, but probably wise giving 6 for extra safety, certainly as the speed increases if you were on a motorway for example.
If you are unsure of a safe following distance, the 2 second rule is an easy method for such safety aspects.If driving in poor weather then increase this distance.
2 seconds is the normal slow to stop at approx 30 mph.
A way of assessing if the vehivle infrontis 2 seconds away is to pick a sport on the road side like a lighting pole. as the car in front passes it cound one, two and then you should just be passing it. If you get there quicker then slow down and create more space.
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On a dry road the brakes and tyres are supposed to give 1G deceleration. If wet conditions reduce this to 0.5G, the stopping distance at any speed is multiplied by 2 (doubled).
Another important thing is that the stopping distance goes with the square of the speed, so doubling the speed gives 4 times the stopping distance.
That depends on the speed of the vehicles. As speed goes up, safe following distance goes up.
25 feet
You should stop 50 feet behind a school bus.
at a set of red lights. how many feet should you be behind the vehicle in front of you?
100 ft4 seconds
Use the 2 second rule.
You must be at least 500ft
100 yards
A driver should be able to see at least 200 feet behind them in their rearview mirror.
In most areas it is 150 feet behind. I have been places where it is 300 feet behind.
100 feet or 4 seconds ferore the turn but when it's like raining or anything like that 200 feet. It gives people behind time to think if their paying attention.To maximise safety, it is best to signal for at least three seconds before you make a turn (this is a legal requirement on New Zealand roads).In the UK there is no specific distance. The signal should be clear and unambiguous and suit local conditions.
10 feet