The condition of your tyres can affect your car’s handling, cornering and braking, and most people are aware that if their tyres are worn then they should replace them for safety’s sake. But many people believe the only indication of tyre wear is the amount of tread remaining, when in fact tyres can become old and unsafe even when not used on the road.
How tyres age
It is obvious that tyres age with regular use, and in these circumstances tread depth is a good indicator of when they should be replaced. But tyres also deteriorate over time whether they are being driven on or not. The rubber compounds from which they are made break down gradually, so even if you only drive your car infrequently or over short distances, you are still experiencing tyre wear. And even if you never drive on your tyres at all, they will still become unsafe after a certain period of time.
This includes spare tyres, which are rarely used and often sit inflated in your boot for years on end. Cracks begin to appear in the rubber, both on the surface and inside the tyre, and this can eventually cause the steel belts in the tread to separate from the rest of the tyre.
Research has shown that tyres deteriorate faster in warmer climates and particularly in coastal locations. Exposure to heat and sunlight can accelerate the breakdown of the rubber, and this is what happens to spare tyres, as they are effectively baking inside your boot on hot summer days.
Other factors that contribute to tyre ageing include conditions of use (how you drive), and how well your tyres are maintained. Driving when tyres are at the incorrect inflation pressure can also accelerate tyre wear, as can uneven tyre wear due to suspension or alignment problems. Other contributing factors include whether the vehicle is evenly loaded, whether the correct type of tyres are fitted, and whether tyres are paired evenly when rotated according to their amount of tread wear.
How to spot signs of age
One way to tell a tyre’s age is by the manufacturer’s markings, although these can be somewhat obscure and might best be left to your tyre dealer to decipher for you. A more obvious way to tell is by visually inspecting the surface of the rubber.
Look for signs of aging such as tread distortion, hairline cracks, bulging and, of course, tread wear, which should be no more than 1.6mm. Modern tyres have tread wear bars which are small bridges that form between the treads. When the tread is level or flush with these bars, it is time to replace the tyre.
Another way to check tread wear is to use a tread wear gauge, which you can purchase cheaply at any auto parts store. Alternatively, you could drop into your local tyre dealer to have your tyres checked.
When to replace old tyres
There is no commonly agreed time frame for when you should replace your tyres, as their conditions of use and storage differ with every driver. But manufacturers such as Mercedes and Nissan recommend replacing tyres six years from their production date, regardless of how they are used. They can last up to ten years, but it is advisable to have them professionally inspected every year after their fifth year of use.
Experts also recommend that when you do replace your tyres, you do so at least in pairs, if not all four at a time (rather than individually), and that you place the new pair on the rear of the vehicle to provide the best traction and handling. And don’t forget the spare! That too will need replacing at some point in time, otherwise it may let you down when you need it most.
How to keep your tyres lasting longer
Like most components in a motor vehicle, regular maintenance will keep your tyres in service for longer. This includes running them at the correct inflation pressure (you’ll find this in your owner’s manual) and having them rotated regularly to spread the wear more evenly (at least every 8 -13,000 kms). It has been estimated that simply keeping your tyres at the correct pressure can lead to a 3% improvement in fuel efficiency, so you’ll not only stay safer but save money at the pump as well.
You can also lengthen the life of your tyres by not overloading your vehicle beyond the manufacturer’s recommended weight limit, driving responsibly (not cornering or braking too sharply), and inspecting your tyres regularly for signs of age and wear.
Even if you take all of these measures, time will eventually catch up with your tyres. So when you do buy new tyres, make sure they are new. Never buy second hand tyres, as you don’t know what they have been subjected to in their lifetime – even if they have never been used, they could still be a lot older than you think.