In this thesis, wheel/rail interface optimisation, and particularly the problems of wheel and rail profile design are considered. The research task pursued by this thesis engenders investigation of a range of problems. First, geometric properties of contact between wheel and rail are investigated. Then, physical properties of rolling contact between wheel and rail are studied with the help of contact mechanics. Railway vehicle dynamics are then considered using multibody dynamic approach. Finally, a numerical optimisation method is used for the design of the wheel profile. All these disciplines are combined in one wheel (rail) profile design procedure. The wheel (rail) profile design procedure is developed with the idea that the rolling radius difference (RRD) function, to a large extent, describes the wheel/rail contact properties. Therefore, for a known optimal RRD function, a wheel profile that delivers the required contact properties defined by this RRD can be determined. Wheel and rail profile measurements are used to analyse wheelset contact properties in order to design the target RRD function. The problem of finding a wheel profile corresponding to the target RRD function is formulated as an optimisation problem. The dynamic performance of a vehicle with the designed wheel profile is tested for stability, wear, and dynamic contact stresses using the ADAMS/Rail computer package. In this research, three railway system types are considered - tram, metro, and conventional railway. Using the developed design procedure, new wheel profiles are designed for each above mentioned case, solving for, respectively, the problems of flange wear, stability (as a result of excessive tread wear), and RCF. In the first two cases, wheel profiles were successfully implemented on the respective networks. Successful application of the design procedure to real-life problems has proven its usability and expediency.