Much research has been conducted to simulate the hydroplaning phenomenon of tires by using commercial explicit FEM (finite element method) codes such as MSC.Dytran and LS-DYNA. However, it takes a long time to finish such a simulation because its model has a great number of Lagrangian and Eulerian elements, and a contact should be defined between the two different types of elements. The simulation results of the lift force and the contact force are very oscillatory. Thus, in this study a new methodology was proposed for the hydroplaning simulation by using two separate mathematical models. An FDM (finite difference method) code was developed to solve Navier-Stokes and continuity equations and to obtain the pressure distribution around a tire with the inertial and viscous effects of water taken into account. An FE tire model was used to obtain the deformed shape of the tire due to the vertical load and the pressure distribution. The two models were iteratively used until a converged pressure distribution was obtained. Since the converged pressure distribution could not be obtained near or at the contact zone due to very shallow water, an asymptotic method was also proposed to estimate the pressure distribution. This new simulation methodology was applied to a straight-grooved tire, and its hydroplaning speed was finally determined for a water depth of 5 mm, 10 mm, 15 mm and 20 mm. Moreover, a new simulation methodology using LS-DYNA was proposed, and the two methodologies were compared in terms of accuracy and efficiency.