Identification of dynamic axle loads in multiple axle vehicles requires complex calculation methods because of its hyper static solving necessity. In this study, suspension deflection method is proposed to determine the dynamic axle loads for optimisation of load distribution of a multi-axle vehicle having more than two axles. The determination of the dynamic axle loads is performed for driving conditions with a climbing angle and a longitudinal acceleration to optimise the loads at the axles of the vehicle using suspension deflection method. General equations and calculation methodology are presented for a multi-axle vehicle and a numerical example is implemented using the suspension deflection method for a four-axle vehicle as a case study. Finally, it is shown that the suspension deflection method is more simple and useful than other approaches to define the dynamic axle loads for an optimisation study of the vehicles which have multiple axles.