Highly pre-loaded rubber bearings are characterized by a extraordinary strength combined with superior functionality, but place special demands on the numerical simulation. Not only the strongly non-linear material behavior has to be considered but also the effects of the hydrostatic pressure inside the bearing due to the preload. The spring characteristics and the fatigue strength of the bearing can be simulated only realistically if these effects are considered in the simulation. For this purpose, a material model is to be developed in combination with a suitable testing method that enables the required material properties to be determined in a practical manner. The procedure will be implemented in a software that has an interface to commercial FEM software and determines the bearing's fatigue strength as result of the calculation.