The aim of this study was to develop an understanding of ageing effects on the material properties of commercial vehicle tyres and whether their structural integrity and therefore safety are compromised. 

A review of published literature showed that most previous testing into ageing effects had been conducted on light goods and passenger car tyres, so the availability of relevant data on those used on heavy vehicles was limited. 

Limitations were also found in service life data from tyre management companies and fleet operators. Fitment or removal dates, driven mileage and other service data were not generally available. 

Thirty-one tyres were subjected to laboratory tests in order to assess their properties and structural integrity. Three models of tyre from one manufacturer were used, sourced from service use within the United Kingdom, and aged between 3 and 19 years. The sample contained 5 new tyres of the same make. 

Test data indicated that some physical properties of the tyres had been affected by their length of time in service. The majority of the changes appeared to occur in the first three to four years of life, beyond which changes continued but at lower rates. Effects may have been masked somewhat by the use of different tyre models, and by differences in operating conditions. 

Of the 26 tyres returned from service, 16 exhibited corrosion of their steel reinforcement cords; this was most prevalent in the outermost layers of the tyres. Corrosion was found in all tyres aged eight years or more. Although no effect on structural strength was measured, the small size of the sample allowed only for limited interpretation of this data.

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