Tank trucks dynamics can get worse because of fluid sloshing in partially filled tanks. During braking manoeuvres, fluid sloshing may lead to load transfers causing rear wheels to lock up and loss of directional control, while during turning or lane changes, it may cause rollover. In this paper, a methodology for evaluating the interaction between fluid sloshing and vehicle dynamics is proposed. The fluid and the tank are modelled using the computational fluid dynamics code FLUENT, based on the Navier-Stokes equations and incorporating the Volume of Fluid (VOF) and the moving mesh techniques. The motion of the tank is determined based on the response of a 14 degrees of freedom vehicle model subjected to the forces due to the fluid sloshing. Straight line braking manoeuvres and lane change manoeuvres have been carried out to evaluate the effects of fill level, baffles and tank shape.