Techtip17

Technical Tip no 17

Tyre Life

The following article originated from the British Rubber Manufacturers Association.
Tyre aging:
Most drivers use the remaining tread depth of their tyres to determine when
they should be replaced. In most cases, this approach is entirely appropriate since
tyres usually wear out before the effect of ageing becomes critical. However, there are
certain circumstances where the ageing process or, in other words, a deterioration of the
rubber compounds can render a tyre unserviceable even if it is unused.

Rubber compounds used in modern tyres contain anti-oxidising chemicals which slow down the
rate of ageing. However, they cannot eliminate ageing altogether. In addition to poor tyre
maintenance factors such as poor storage, infrequent use, environmental conditions, including
exposure to direct sunlight and operation at costal climates, all accelerate the aging process.
As most of these influencing factors are outside the control of the tyre manufacturer, it is
difficult to predict the life span of a tyre. In ideal conditions, a tyre may have a life expectancy
that exceeds 10 years from its date of manufacture. However, such conditions are rare.

Tyre aging is often identified by small cracks (crazing) appearing in the tyre sidewall and
other flex areas. Regular inspection will identify this symptom before it leads to tyre failure.
However, tyre aging may not exhibit any external indications and, since there is no non-destructive
test to assess the serviceability of the tyre, even an inspection carried out by an expert may
not reveal the extent of any deterioration. Furthermore, deterioration in vehicle ride quality or
the onset of vibration may signify the imminent failure of a tyre, which must be investigated without
delay. Tyres fitted to spare wheels, caravans and trailers are particularly vulnerable to the “ageing”
process.

In the absence of legislative control governing the age at which tyres should be removed,
given all of the above factors, BRMA members strongly recommend that unused tyres should not
be put into service if they are over six years old and that all tyres should be replaced 10 years
from their date of manufacture.

British Rubber Manufacturer’s Association.