|
| |
Tyres |
| |
|
| |
Your tyres are the only contact that your vehicle has with the road and they play a vital role in ensuring that your journey is a safe one. Not only must they support the weight of the vehicle but they must respond to acceleration, braking and steering forces – as well as absorbing the impact of bumpy, uneven roads.
To help you ensure they are running at the best, we've compiled the following checks:
Tyre Pressure
| • |
Check and adjust tyre pressures regularly – each month the average tyre loses about a pound of air pressure. |
| • |
Check your vehicle handbook for the correct tyre pressure – under-inflation can cause rapid and irregular tread wear, overheating and increased fuel consumption.
Over-inflation can damage the structure of the tyre. |
| • |
Only check tyre pressure when your tyres are cold – never during or after a journey. |
| • |
Tyre valves should be replaced whenever your tyres are changed as the valve rubber will perish with age. |
| • |
Don't forget to check the spare tyre. |
Tread Depth
| • |
Worn tyres reduce the effectiveness of braking, steering and acceleration, particularly in the wet. |
| • |
Check the tread depth of your tyres. The minimum legal tread depth is 1.6mm, however 3mm will give you safer, more efficient tyres. |
| • |
If you don’t have a tyre tread depth gauge, a top tip is to insert the border of a 20p piece into the grooves to see if your tyres are above or below 3mm. |
| • |
Worn tyres are not only dangerous, they are illegal – you could face a fine of up to £2,500 plus 3 penalty points per tyre. |
External Damage
| • |
Check for punctures or cuts in the tyre caused by impact damage from objects in the road or nails. |
| • |
Check for sidewall damage such as splits or bulges. This sort of damage can result in sudden tyre failure so see a tyre specialist as soon as possible. |
| • |
Have your tyres checked if the vehicle has been involved in an emergency manoeuvre like sudden or heavy braking as this can cause serious damage. |
Wheel Alignment & Balance
| • |
If your wheels are out of balance you may notice your steering wheel starts to wobble above a certain speed and you may experience a vibration. |
| • |
Out of balance wheels result in premature wearing of suspension and steering components, rotating parts and tyres. |
| • |
With correct wheel balancing, you should notice a smoother ride and improved wear from your tyres. |
Tyre Tread & Stopping Distances
It has long been known that a decrease in tyre tread depth can lead to the deterioration of a tyre's performance during cornering, and straight line braking in the wet. A tyre is unable to deal with the same volume of water on the road at lower tread depths, which means that the tyre is unable to transmit traction and braking forces as effectively.
Previous studies have confirmed
this relationship, however there was a need for independent testing to quantify the effects on typical cars found on today's roads.
In 2003, the British Rubber Manufacturers Association (BRMA) commissioned MIRA to study the effects of tread depth on stopping distances. The study was carried out on MIRA's test track in Nuneaton, and 5 different tread depths were tested - 6.7mm, 4.1mm, 2.6mm, 1.6mm (the legal minimum) and 0.9mm.
Vehicles were mounted with equipment to record time, speed and distance. The tests were carried out on two different surfaces at the testing track, hot rolled asphalt and smooth concrete. In order to ensure the accuracy of the results, the tests were repeated several times.
The stopping distance was recorded at each of these depths and the points plotted on a graph of stopping distance versus tread depth. A line was drawn through the points to show the trend between stopping distance and tread depth, from which information could be taken.
The test results are displayed in the graph below. The stopping distance is different for the two road surfaces due to their different water retention properties.
From the graph of results, it can be seen that the stopping distances start to increase dramatically at tread depths of below 3mm.
At the legal minimum tread depth of 1.6mm, the stopping distance is increased by 36.8% on the hot rolled asphalt and 44.6% on the smooth concrete.
Recommendations
From the independent research, RoSPA (The Royal Society for the Prevention of Accidents) recommends that tyres are changed once the tread reaches 3mm in depth.
Tyre pressure also affects a vehicle's safety by reducing its handling capability. If a tyre is over or under inflated, less rubber will be in contact with the road which leads to increased tread wear, and may increase the vehicles stopping distance. It is recommended that you check all of your tyre pressures regularly, as well as inspecting the tyre for damage.
|
|
