Stopping distances

Stopping distance is the distance it takes your vehicle to stop completely. It’s made up of your reaction time and your braking distance, and it’s influenced by several factors, such as

• tire tread depth - in wet conditions tire performance drops significantly when tread depth falls below 3mm, causing longer braking distances
• tire inflation - overly inflated tires would have less tire rubber in contact on the road. Hence less friction and more stopping distance; under-inflated tires have more block movement and deformation of the tire, leading to inferior performance
• tire width - wider tires have more contact on the road, which provides more friction and more stopping power
• suspension quality - poor suspension can cause a vehicle to ‘dive’ under brakes. This shifts more weight on the front wheels, and this means less braking power for your hind wheels.
• speed - the faster you go, the longer it takes you to stop
• vehicle weight - carrying heavy loads, or towing another vehicle will make it longer for you to stop
• road surface - some road surfaces are more slippery than others, for example where there has been tar bleed and the road surface is shiny
• reaction time - reaction times are affected by dehydration, illness, tiredness, alcohol and drug intake, and age and distractions (such as using a mobile phone while driving)
• anti-lock brakes - anti-lock brakes generally provide you with optimum braking performance and stops skidding, especially if the ABS distributes the braking force so that each of the wheels brakes at an optimal level (electronic brakeforce distribution)

Braking distances are longer with worn tires,  incorrectly inflated and narrower tires, worn suspension, a heavier vehicle, slippery road surface, and no ABS.

Reaction times are long if you are distracted, dehydrated, tired, under the influence of drugs or alcohol, or you are older. A typical reaction time is at least one second.