Small diameter tyres are increasingly being used in heavy vehicle applications. While they give operational advantages in some situations they may have a negative impact on pavement wear. This study, carried out between 1996 and 1997, investigated the implications for pavement wear of using small diameter tyres in place of standard sizes.
Two aspects of small diameter tyres are investigated. The first is how the use of small diameter tyres influencs the vehicle – pavement interface in terms of tyre-contact patch size and pressure distribution. The second relates to vehicle dynamics. Small diameter tyres have lower mass and higher stiffness, which alter the vehicle dynamics and consequently the dynamic wheel forces. The implications for pavement wear of these changes are assessed.
For a typical New Zealand pavement, the tyre-contact effects of small diameter tyres results in an increase in subgrade strains of about 5% over a correctly inflated standard tyre. This corresponds to a 21% increase in pavement wear. However, the common practice is to use higher inflation pressures than required for standard size tyres which causes an increase in subgrade strains and pavement wear. The increase is similar to that generated by correctly inflated small diameter tyres.