Getting to grips with your car tyres
Millions upon millions of tyres are in daily use on the UK roads and we all depend on them as soon as we get behind the wheel.
But how much thought do we actually give to tyres? Do we ever look at them? We probably don’t, unless we’ve got a flat or it’s MOT time, and yet our lives literally depend on them, as over half of all fatal accidents involve the skidding of a vehicle.
Look at a piece of A4 paper. That surface area is roughly all the contact each of a car’s four wheels have with the road. That contact is used to accelerate, brake, corner and absorb bumps. Now, consider winter weather conditions and you begin to realise just how much we ask of our tyres. Perhaps you should give yours some attention this weekend; below is a summary of the most important points to look out for.
The most important check you can carry out is tread depth. Tread is vital to road safety because the tread pattern allows water to escape as the wheel rolls forwards; it’s estimated that at 60 mph, each tyre can displace up to 10 litres of water a second. However, if the water remains, it forms a barrier between the tyre and road surfaces, there is even less contact with the road and a skid becomes much more likely.
The check is very easy to carry out. Most manufacturers place a ‘rib’ across the groove of a tyre, which shows the minimum legal tread depth (1.6mm in a continuous band in the central three-quarters of the breadth of the tyre). When the tread wears down and becomes level with the top of the rib, the tyre not only needs changing, it’s illegal.
To find the rib, look at the tyre wall and, near the tread, you will see a small triangle, which points towards the rib.
Too much pressure?
To keep tyres functioning well, it is essential that the pressure is checked regularly when the tyre is cold, and that it matches the figures quoted in your vehicle’s handbook. An over- or under-inflated tyre greatly affects the area of the tyre that comes into contact with the road surface. It also affects the way the tyre walls flex, particularly when braking and steering – which is when you need it most.
Tyre pressure also needs to be adjusted to suit fully laden vehicles, so if your car has been stuffed to the gills for a family holiday, you should refer to your car’s handbook and readjust the pressure.
All tyres gradually lose pressure over time, even new ones. Make sure yours are correct every week by checking them with your own pressure gauge – the ones on garage forecourts can be unreliable, so get your own to double-check. Reliable gauges can be purchased from around £5 and, as an extra incentive, the correct pressure will save on your fuel bill.
Inspect and protect
When you are checking the pressure, also have a good look around the tyre. You are looking for lumps, bumps, foreign objects, uneven wear patterns or anything that just doesn’t seem right. Get the local garage to have a look if you’re uncertain.
We all kerb wheels from time to time while parking and this pinches the rubber. When the tyre gets hot – particularly at motorway speeds – these areas can become unstable and cause a puncture. Save yourself the misery of changing a tyre on the hard shoulder in the rain by inspecting them regularly. While you’re checking the rubber, have a quick look at the metal rim. If it’s damaged, get it checked out at the garage.
When the time comes to replace a tyre, it really does pay to get good advice and choose one that is most suitable for your particular needs. All tyres come with speed ratings and maximum loads, which are printed in code on the tyre wall. Your dealer should listen to your requirements and help you select a tyre that is suitable for you, and suitable for your car. Tyres must be of the same size and match the tyre on the other end of that axle.
Never buy a second hand tyre, as you have no way of knowing its history. This is one area where buying cheap really could cost you very dear.
Care for your spare
On your weekly check, don’t forget to have a look at the spare. On most modern cars, the spare is smaller and for temporary use only, in order to get you home in an emergency. Most spare tyres have inflation pressures of about 60 pounds per square inch, often double that of your normal tyres. These tyres can only run up to a certain speed and this speed is printed clearly on the tyre wall, together with the required tyre pressure. Do not exceed the speed rating, or you’ll need a second spare!
Tyres for towing
Ever wondered why you always see caravans with punctures at the side of the road? Trailers and caravans are left standing throughout the winter in one place. One area of the tyre becomes a little deformed by standing in this position for months on end. The tyre starts to degrade and split, but it looks OK on a quick inspection and the tyre pressures are right.
The holidays start and the quick dash to the coast laden with the kitchen sink tests the tyres to the limit. Any small split starts to grow, resulting in a puncture at motorway speeds.
Many caravans and trailers have no spare, or if they do, there is no jack or wheel brace to undo the wheel nuts. Check you have all these things out before you set off and save yourself the stress of a breakdown.
Time for change
Check your boot for all the necessary tools to enable you to change the tyre, should a puncture occur. When you change your car, have a good look to see where the tools are, and check they fit. Most alloy wheels come with locking wheel nuts. To take the nuts off, you need an adaptor that fits into the wheel brace and then fits your individual wheel nut. Most adaptors are kept with the spare wheel, but you might also find it in the glove box.
It is far easier to sort all these things out at home rather than on the M25 in a rainstorm and, although kicking a tyre to check on its welfare is probably marginally better than not checking them at all, checking them properly could save your life.
Posted on Aug 12th, 2011 by Lyons Davidson