In a tire design method, at least one of the tire cross-sectional shape, the shape of the tire constituent members, and the physical property data of the tire constituent members is selected as a parameter to generate an initial tire model representing a pneumatic tire by utilizing a limited number of elements ( 30), and the metric modification corresponding to the predetermined time processes at least one of the stress acting on the initial tire model by internal pressure filling and the physical property data for the initial tire model, to thereby make the initial The tire model is deformed, and the profile shape of the tire over time is predicted by using the deformed initial tire model. calculating the maximum principal strain in the cells of the tire model (30) by generating said tire model (30) having said predicted tire cross-sectional shape, and applying said internal pressure filling process and ground contacting process thereto, And calculating the safety margin of the tire constituent member by using the maximum principal strain. The trial selection is repeated until the calculated margin is equal to or greater than the preset reference safety margin, so that a tire with excellent durability can be designed.