The economics of heavier trucks have been investigated extensively in Australia. This includes vehicle operating costs, pavement and bridge costs and safety characteristics of larger and heavier trucks. This paper will describe the process of integrating pavement damage and safety issues in assessing truck size and weight limits. It will include the effects of vehicle configuration, tyres and suspensions on road wear and on the safety-related characteristics of rollover stability and vehicle handling. It will be concluded that improvements are necessary in several areas of truck design, particularly suspensions. Progress in addressing the suspension issue through international research co-operation at the OECD, and at the national level in Australia, will be described. The significance of the work described lies in the large potential economic benefits of higher size and weight limits, provided that adequate vehicle designs in terms of road wear and safety are available. The paper has not been offered elsewhere.