Tyre Health-Check: How Old Is Too Old?
Tyres are the forgotten essentials of a car, rarely spared a thought and taken for granted until a flat occurs, roadworthy test is failed, or the tyres fail to produce sufficient grip, ruining any immediate driving plans and remind you that it's time for replacement.
Consider that the average Australian driver notches up 13 to 14,000 kilometres annually. All that's between the vehicle and the road is the tyres. It is really important for safety reasons that you're aware of the age of the tyres. As well as ensuring the tyres are run at the correct inflation pressures and inspected frequently for excessive wear, check for embedded objects in the tread grooves and any damage.
Do tyres last indefinitely?
Tyres, whilst hardwearing and seemingly ageless, are in fact perishable. Tyres are manufactured by combining natural & synthetic rubbers with textile fabric plies and steel cords. There is a mixture of other important ingredients contained in the various rubber compounds embedded within the tyre. These materials convert the tyre, after vulcanisation, into a strong, elastic and very durable product. Amongst these ingredients are antioxidants and antiozonants. These powerful protective agents greatly assist the tyre to resist the effects of weathering but despite technological advances in construction, tyres won't last indefinitely.
How long do I have before my spare tyre or current fitment is considered unsafe due to ageing?
Tyres can be considered too old long before their tread wears down. If you need a measure of time, most reputable tyre manufacturers advise against the use of tyres that are more than five to six years old, regardless of use.
How does a tyre break down?
Natural rubber, Styrene Butadiene (SBR) and polybutadiene (IR) rubbers are the principle elastomers contained in tyres which are produced with very long molecular chains, containing double bonds along their length. These double bonds actively react & combine with both oxygen and ozone. The chemical reactions, accelerated by heat and/or sunlight, subsequently over time either reduce the length of the molecular chains (making the rubber softer) or in the case of styrene butadiene polymers, makes the rubber harder. In either case, the performance of the rubber is adversely compromised.
The deterioration can be prevented by adding antioxidants and antiozonants to the rubber compound before vulcanization. At one time, ozone cracks were commonly seen in automobile tyre sidewalls, but are now seen rarely thanks to the use of these protective agents. A common and low cost antiozonant is a wax, which bleeds to the surface of the tyre's tread and sidewall area and forms a protective layer, but other specialist chemicals are also widely used.
How does tyre pressure influence ageing?
Tyres operated with pressures below the recommended levels, will develop greater heat build-up, which is a major contributor to tyre ageing. To increase the safety for you and other road users, as well as prolonging the tyre's life, increasing fuel efficiency and to reduce premature tyre ageing, it is wise to ensure that the inflation pressures are maintained in accordance to the vehicle's placard.
How can I tell if something is wrong with my tyre?
While it is certainly better to have a JAX Tyres' expert assess your tyre for ageing, some quick indicators include:
- Cracking in the tyre wall, in particular the lower sidewall
- Distortion in the tread area
- Cracking at the base of the tread grooves
- Deformed tyre carcass
- Tyre tread distortion
- Excessive vibrations during operation
It should be noted also that the tyre may not show any physical signs of ageing. However if you suspect that the tyres on your vehicle are older than five to six years, then it is highly recommended to get them checked out by an expert.
As well as tyres installed on motorised vehicles, it is advisable to check those on caravans and trailers. When towing either a caravan or trailer for safety reasons check your tyres thoroughly no matter how long the journey.
Does climate have an effect on the ageing of tyres?
The warmer the climate the faster the tyres will age. Exposure to high ambient temperatures can accelerate the tyre ageing process, which could lead to tyre failures, as described previously. Environmental conditions like exposure to sunlight and coastal climates, as well as poor storage and infrequent use will hasten the ageing process
How can I quickly check the age of my tyres?
Most tyres are manufactured to include the U.S. Department of Transportation (DOT) code on the lower sidewall. This code consists of four digits, which indicate when the tyre was manufactured. For example an 0212' code means the tyre was made in the second week of 2012.