Most people rely on a tyre’s tread depth to determine its condition.

Les Mc Master, Chairman of the Motor Industry Workshop Association (MIWA), points out that the rubber compounds deteriorate over time, regardless of the condition of the tread. “An old tyre can be just as hazardous as a tyre with worn tread,” he says.

The age warning also applies to spare tyres and ‘new’ tyres that have never been used but are old.

Cracks in rubber will begin to develop over time. They will appear on the surface and inside the tyre. This cracking can eventually cause the steel belts in the tread to separate from the rest of the tyre. Improper maintenance and heat accelerate the process.

The DOT-code on the inside of a tyre provides information on its production date. Tyres produced after 2000 have a four-digit DOT code instead of three. “The first two digits indicate the production week and the second two indicate the year,” he explains.

“It’s impossible to judge how long a tyre will last since factors such as heat, storage and conditions of use reduce the life of a tyre.”

Aging of tyres is exacerbated by exposure to sunlight, heat and coastal conditions which weather rubber. “It’s important to bear in mind that this principle also applies to spare tyres and tyres that are sitting in a garage or shop. Consider how a spare tyre lives its life. If you own a truck, the spare may be mounted underneath the vehicle, exposed to the dirt and the elements. If your spare is kept in the boot, it’s baking in a miniature oven all day.”

While most spare tyres never see the light of day, if a tyre has been inflated and mounted on a wheel, it is technically in service even if it’s never been used. A tyre that has not been mounted and is just sitting in a shop or garage will age more slowly than one that has been put into service. But it ages nonetheless.

Avoid buying used tyres and to check the date on all new tyres purchased. “Just because a tyre looks new doesn’t mean it wasn’t manufactured years ago and has been left standing in a shop, aging while it waits.

“The safety hazards of driving on an old tyre should not be underestimated,” concludes Mc Master.