This paper describes the quantification of three-dimensionaltyre/pavement contact stresses for vehicle tyres. The Vehicle-RoadSurface Pressure Transducer Array (VRSPTA) system was developedto measure contact stresses under moving loads, i.e. Stress-In-Motion(SIM). Prediction equations for quantification of these stresses,based on tyre inflation pressure and loads for seven (7) differenttyre types, are given. Tyre inflation pressure predominantly controlsthe vertical contact stresses on the pavement at the tyre centre,whereas the tyre load controls those at the tyre edges.

Analysis indicated that during instantaneous overloading /under-inflated conditions the maximum strain energy of distortion(SED) in the asphalt surfacing occurs close to the tyre edges,while under instantaneous uniform vertical stress conditions theSED is within the asphalt surfacing at the tyre centre. In additionto improved load/contact stress idealization for modelling, thisfinding may have important implications for the design of relativelythin asphalt surfacing layers for pavements.