How to check your tyres - tread depth, pressure and damage explained and how to do the 20p test
October is national Tyre Safety Month. It might seem like a strange thing to dedicate a whole month to but it’s a serious issue with life or death implications for every road user.
Tyres are your car’s only point of contact with the road and their condition has a major impact on your safety while driving. Driving on tyres with insufficient tread or the wrong pressure can affect your car’s steering, handling and braking, increasing your chances of losing control and being involved in an accident.
Neil Worth, chief executive of breakdown organisation GEM Motoring Assist, explains: “Correctly inflated tyres with good levels of tread allow all the other safety systems on a car to work effectively. In a sudden emergency this could be significant in determining the outcome and protecting those involved.
“Under-inflated tyres reduce your vehicle’s ability to grip the road, and also compromise handling. This can result in unpredictable vehicle behaviour, and increases the risk of a tyre blowout. Over-inflated tyres have a smaller contact area with the road, leading to increased stopping distance and reduced grip.”
Defective tyres also pose dangers to your finances and licence. Over or under-inflated tyres harm fuel efficiency and if you are caught driving with bald or damaged tyres you can be given a £2,500 fine and three penalty points per tyre - that’s enough for an automatic ban if you have four faulty tyres.
But keeping your tyres in good condition is a simple matter of carrying out a few regular checks.
Check your pressure
You should check your tyre pressures are at the correct level at least once a month and before every long journey. Your owner's manual will have the correct pressures for your specific tyres and the data is also often on a sticker inside the fuel filler cap or door surround.
Remember to adjust the pressure depending on the car’s load - your manual will give the correct pressure for light and heavy loads.
Check the tread
The legal minimum tread depth is 1.6mm across the central three quarters of the tread, around its entire circumference. However, most experts recommend that tyres are replaced once the tread falls below 3mm.
A proper tread gauge only costs a few pounds but if you don’t have one you can use the 20p test. Push a 20p coin into the tread of the tyre. If the outer band of the coin is obscured when it is inserted, then your tread is above the legal limit. If you can see the outer band, your tyre may be illegal and you should get it checked by a professional immediately.
Check for damage
A quick visual check is often enough to identify damage which, if ignored could create serious problems.
Look for anything stuck in the tyre and check for cracks, splits or bulges anywhere around the tyre. Any of these could indicate further internal damage and a weakening of the tyre. At best this could lead to an inconvenient flat, at worst it could cause a dangerous blowout while driving.