The road and traffic laboratory of the technical research center of Finland has developed gauges to measure strain and stress in bituminous and unbound layers and in the subgrade and has also developed a sophisticated microcomputer system for collecting and handling data. These gauges have been used in research concerning pavement design and to measure the response due to moving vehicles at the virttaa test field. The aggressiveness of different axle loads; single, tandem, and tridem axles; single, twin, and wide-base tires; and tire pressures have been compared at speeds of 50 or 80 km per hour. Thispaper describes the effects of tires and tire pressures. Two twin tire and three wide-base tire types were compared. Three axle loads were used for each type. Three tire air pressures were used for each axle load and tire type. The load was seldom evenly distributed on both twin tires. That condition was simulated with different tire pressures (500 kpa and 1000 kpa) in the twin tires. Certain tire/pavement contact pressure distribution measurements were also made. This paper appears in transportation research record no. 1227, rigid and flexible pavement design and analysis: unbound granular materials, tire pressures, backcalculation, and design methods.
Abstract