a method of simulating a tire rolling on a road at a certain speed by using a computer apparatus 1 comprises the steps of : modeling a flexible tire model 2 for numerical calculation by using finite elements having at least one elastic element , changing at least one elastic element of the flexible tire model 2 to rigid elements so as to make a rigid tire model 5 , accelerating the rigid tire model 5 , returning the elasticity of each element of the rigid tire model into the original elasticity when the speed of the rigid tire model 5 has reached the certain speed , and obtaining at least one physical parameter related to the flexible tire model 2 .