In the externally pressurized air bearing-rotor system, characteristic of air flow between rotor and bearing directly effects dynamics of bearing-rotor system. Mathematical model of the air flow and numerical solution of this model are very important in externally pressurized air bearing. The air flow is modelled using Reynold's equation and pressure distribution is obtained using numerical solution methods. One of these numerical solution methods is Alternating Direction Implicit method used to obtain pressure distribution between rotor and bearing. However, this method has convergence problems especially with increasing radial clearance (c>100 mu m). In this study, the effects of numerical solution parameters such as time step, grid size and convergence criteria, and grid boundary integration on the pressure distribution between rotor and bearing are investigated for radial air bearing with high values of clearances (to 250 mu m).