Why does braking distance change on a wet road

In an emergency, a driver must bring their vehicle to a stop in the shortest distance possible:. This is when:. Reaction times vary from person to person, but are typically 0. Longer reaction times increase the thinking distance when stopping from a given speed. The braking distance is the distance travelled by the car once the driver has put their foot on the brakes. Thinking distance:. Braking distance:. The thinking distance depends on the reaction time of the driver which could be affected by drugs, alcohol, distractions and tiredness.

The braking distance also depends on the speed of the car, the mass of the car, how worn the brakes and tyres are, and the road surface. A fast, heavy car with worn tyres and brakes, on a wet or icy road will have a large braking distance. You might be asked to look for patterns in car stopping distances, and how they change with the speed of a car.

The effect of tread depth on your stopping distance. Tests have revealed that a tyre with the minimum tread depth of 1. This is why we always recommend changing your tyres when they reach 3mm, rather than 1. Tyre pressure. How does tyre pressure effect your stopping distance? Tyres need to maximise their contact with the road in order to provide the best possible stopping distance. It is imperative that your tyres are neither over nor underinflated.

Underinflated tyres will make more contact with the road on the outer edges of the tyre whereas overinflated tyres will make more contact in the centre. As a result of this, your tyres will wear irregularly as well as reducing the traction. This means that your tyres will be less effective at gripping onto the road surface and bringing the car to a stop, therefore increasing your stopping distance. This is why it is so important to make sure that you check your tyre pressures regularly around once a month to ensure that your tyres are wearing evenly and maximising safety and grip on the road to reduce your stopping distance.

Speed The effect speed has on your stopping distance: The speed you are travelling at greatly affects your stopping distance. Share on facebook. Share on twitter.