Tyre Wear - Everything You Need To Know!
Tyres are the only area of your vehicle that make contact with the road you are driving on. For your vehicle to steer, brake and stay on the road safely it is vital your tyres are kept in good condition and checked regularly.
The outer surface of a tyre is made of rubber with a tread pattern. The grooves of the tread create traction with the road surface you are travelling on meaning your vehicle sticks to the road and moves in the direction you instruct it to! The body of a tyre contains an area of compressed air this provides cushioning that protects the wheel rim and absorbs shock.
Rubber is not an everlasting material so the tread pattern on your tyres will wear each time you drive somewhere. Because of this tyres will need to be replaced again and again to maintain a safe and legal vehicle.
If you are found driving with illegal tyres you could be fined up to £2,500 and receive 3 points on your licence - per tyre.
What is the Legal Tyre Tread Depth?
When a tyre is brand new the tyre tread is around 8mm. The legal minimum tyre tread is 1.6 mm over ¾ of the tyre. Tyre tread below this measurement is not thought to provide enough traction to the road to ensure safety when driving.
However, many experts believe tread of 1.6mm is too shallow and recommend using 3mm as the minimum measure of when to change your tyres. This is because research conducted by MIRA found 3mm to be the critical measurement, when tyre tread depth became lower than this the stopping distance needed started to increase. The difference between the stopping distance when braking on a wet surface when tyres were at 1.6mm tread depth was found to be up to 44% longer than a tyre with a tread depth of 3mm.
How do you check the tread depth on a tyre?
Experts recommend the tread of your vehicles tyres should be checked every 2 weeks and at the very least once every month.
There are several ways you can check the tread depth of your tyres:
- Use the 20p test – to use this method insert a 20p into the groove of your tyre tread, if the outer band isn’t visible your tyres are legal, if the outer band is visible it is time to get your tyres replaced.
- Buy a depth gauge – these handy tools provide a more precise measurement of tread depth than the 20p test and are readily available for under £10
- Look at your tyre tread wear indicators - Most tyres will have a raised area at the bottom of grooves, once the rest of the tread is in line with this area you are near the legal limit and should get your tyres replaced
- See a specialist – tyre centres and garages will know exactly what to look for when checking your tyres, so if you are in any doubt you should ask an expert.
Tread depth is not the only reason your tyres could be deemed illegal so it is important to check general condition. Check for cuts or breaks in the rubber larger than 25mm or 10% of the section width which has caused the inner cord to become exposed and any bulges or lumps that may indicate failure of the tyre structure.
It is also important to remember it is illegal to use a spare tyre outside of its stated limitations. In many vehicles, a full size spare tyre is not supplied. Instead many vehicles include a space saver spare wheel. This reduces cost and as space saver tyres are lighter, it also reduces the weight of the vehicle leading to better fuel economy and a slightly reduced emissions figure. However, space saver tyres are not intended for long term use and most are designed for a maximum distance of 50 miles at a maximum speed of 50mph – enough to get you to the nearest garage.
Safety risks of worn tyres
- The risk of hydroplaning is vastly increased if you are driving with worn tyres. When the tread depth is minimal on a tyre it loses the ability to channel water away from where the tyre meets the road surface. This can lead to a layer of water between the vehicle and the road which reduces grip and increases the risk of losing control over steering and skidding.
- Worn tyres are more prone to air leaking. Worn tyres are more likely to lose air pressure much more quickly than a tyre with deep tread. This loss of pressure causes the tyre to become underinflated and so the rate of tyre wear increases. Underinflated tyres also affect steering and braking as well as increasing fuel costs.
- The increased risk of a blowout. A tyre with a small amount of tread reduces protection to the tire casing. Objects on the road such as nails or glass can more easily puncture the tyre and lead to a blowout, where this is rapid loss of inflation which causes loss of control over the vehicle.
- Poor grip on snow and ice. Most tyres will have small grooves called sipes. When the tyre surface makes contact with the road sipes expand creating an area of low pressure that increases traction. On worn tyres this traction is lost making driving in snow and ice much more dangerous as your risk of losing control goes up due to poor grip.
- Hot tyres. The grooves in tyre tread provide movement of air that keeps the surface cool. Losing tyre tread reduces this passage of air so heat in the tyre increases and as the heat goes up so does the risk of tyre failure.
What are the Consequences of having tyres that do not meet legal standards?
If the police find you to have tyres with tread under the legal limit of 1.6 mm you risk a fine of up to £2,500 and 3 points on your licence. This is per tyre so if all 4 tyres are illegal you could be fined £10,000 and receive 12 points and so potentially lose your driving licence. Those consequences will leave you far worse off than a new set of tyres.
Additionally, if you are in an accident and are found to have illegal tyres you may find your insurance is invalid, leaving you with the very expensive task of paying up for repairs to your vehicle and if you are at fault and have damage someone else’s car their repairs too.
How can I reduce tyre wear?
Replacing tyres can be an expensive job and is likely to be a yearly event. However, the good news is by looking at your driving habits and some basic car maintenance you can reduce tyre wear and so lengthen the time in between tyre changes.
- Maintain correct tyre pressures – an over or under inflated tyre will lead to excessive tread wear ono the outer or central portions of the tyre surface.
- Avoid harsh braking – this is unavoidable in an emergency situation but harsh braking can rub bare patches on the tyre surface so in day to day driving try to keep your braking smooth and controlled
- Avoid hard cornering – this will create an area of increase wear on the outer edges of the tyre
- Avoid aggressive acceleration – this will cause ridging or distortion on the tyre tread
- Do not use excessive speed – at high speed tyres will heat up more quickly and so degrade more quickly than if lower speeds were used.
Despite the risks, it seems all over the UK drivers were taking their chances with illegal tyres during 2016. Last year 10,766 drivers being handed endorsements with the average fine being a massive £2,700.
Have you checked your tyres this month?
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5 May 2017
Written by Natalie Faughy