Contact pressures and energies beneath soft tires - Modeling effects of central tire inflation-equipped heavy-truck traffic on road surfaces

Much has been made of the use of tires with low-inflation-pressure systems called central tire inflation (CTI) systems. Great benefits have been noted in numerous trials, including the reduced requirement for truck maintenance, improved gradeability, longer tire life, improved ride for drivers, reduced road rutting, and reduced road maintenance. Reports of successful field trials in the literature are confirmed by other supporting theoretical studies. However, the studies reported in the literature tend to relate to unsealed, unbound roads. Given that in some quarters there is now a desire to extend the benefits of the use of CTI to sealed roads, new questions arise. A full-scale, laboratory study was carried out at the University of Ulster, Northern Ireland. Both the normal and shear contact stresses were measured with a high-speed data logger connected to electronic sensors in the apparatus's bed plate, as a tire ran over them. Tire pressures and loads were varied in this factorial study. The contact stresses were measured, and conclusions based on their distribution across the tire ``contact patch'' were presented. In addition, contact energies were inferred, and the consequences for sealed pavements were suggested.