Danger posed by aged tyres

Consumers’ Association of Penang (CAP) calls on vehicle owners to check their tyres for the manufacturing date, to ensure that they are not using aged tyres, regardless of tread depth or mileage, to prevent tread separation.

A survey carried out by CAP found that tyre retailers did not stock up large number of tyres in their stores. Although those found exhibited in front were within a year of manufacture,  older tyres stored at the back end of these stores did find their way to customers bargaining for lower prices. The survey also found that quite a number of dealers also exhibited used tyres for sale.

Tyre manufacturers in developed countries have long known that tyres more than six years old could pose a danger to consumers. Prompted by consumer advocates and a growing body of research on the effects of aging, authorities in these countries are beginning to address this issue.

However, a recent undercover investigation by ABC News and its affiliates, revealed that several popular stores in the US still sold tyres which were well beyond 6 years of age. A few stores even sold old tyres at discounted prices and advised customers that they were perfectly safe for use. The investigations were carried out in response to a number of freak accidents caused by tread separation. It was found that the owners had bought these tyres considered brand new, but were in fact 6 to 12 years old.

Tyres are designed to meet different criteria and some with harder compounds have longer life. In ideal conditions a tyre may have a life expectancy of 10 years from its date of manufacture.  However, such conditions are rare. Tyres like any other rubber products have limited service life regardless of tread depth and use. Research and tests have shown that over time, a tyre’s material begins to dry out and the internal structure degrades, reducing adhesion between the belts, which in turn facilitates tread separation. Chemical additives which make the rubber elastic, loose their effectiveness due to the heat and oxygen in the air and the rubber becomes brittle and cracks internally. Externally they may show no visible signs of deterioration.

Environmental conditions like exposure to sunlight and coastal climates or severity of weather as well as poor storage conditions and infrequent use accelerate the aging process. Studies also found that tyres in hotter regions aged faster. Therefore, in tropical countries like Malaysia, we should consider tyre life to be shorter, probably four to five years.

Few consumers understand the cryptic code moulded along side the maze of other numbers found on the rim of tyres. The date is a four digit code with the first two digits denoting the week and the next two digits denoting the year.

CAP calls on the Road Transport Department to regulate tyres properly, by ensuring that tyre manufacturers change the manufacturing date code moulded on tyres to non-coded fashion, so that it can be easily read by anyone. The expiry date at the end of 5 years should also be included. They should also ensure that tyres more than five years after the date of manufacture are recalled..

Furthermore, local vehicle manufacturers should include warnings in the owners manuals to have the tyres checked and replaced after five years from the date of manufacture, regardless of tread depth and use.

Customers changing their tyres to new ones should always check the date of manufacture at the time of purchase. Vehicle owners should watch out for increased air loss, noise or vibration which could be an indication that the tyres need to be removed from service to prevent tyre failure.

Vehicle owners may also have their tyres inflated with Nitrogen gas instead of normal compressed air. Nitrogen being chemically inert will help to slow the aging process. Most tyre retailers inflate the tyres with Nitrogen for free, when all 4 tyres are changed to new ones, but charge a fee for subsequent top ups.

Not forgetting the media report on 7 August 2008, CAP decries the recent trend by express bus operators to resort to using second-hand spare parts including tyres for replacement in order to weather the fuel price increase. The Road Transport Department should investigate and put a stop to such dangerous trends while Puspakom should be vigilant. Other methods should be sought to compensate for fuel price increase.

CAP press statement, 13 August 2008