Tire designing method and program

A program executable by a computer, for predicting a change with time caused by use of a pneumatic tire to allow the computer to design a tire, the program including:

• a model preparing procedure of allowing computing means of a computer to tentatively select at least one of a tire profile shape, a shape of a tire component member and a physical property data of the tire component member as a parameter and allowing the computing means to prepare an initial tire model representing the pneumatic tire by using a finite number of elements;
• an inner pressure filling processing procedure of allowing the computing means to perform a calculation of a first inner pressure filling processing performed on the prepared initial tire model;
• a time-varying change predicting procedure of allowing the computing means to modify at least one of a stress acting on the initial tire model by first the inner pressure filling processing and the physical property data used for the initial tire model corresponding to a predetermined measure of elapsed time to deform the initial tire model and allowing the computing means to predict a tire profile shape after a change with time by using the deformed initial tire model;
• a margin of safety calculating procedure of allowing the computing means to execute at least a calculation of a second inner pressure filling processing of the tire model after the change with time, which has a tire profile shape after the change with time, to calculate at least one mechanical characteristic quantity of a maximum principal strain, a maximum principal stress and a maximum strain energy density in each of the elements of the tire component members in the tire model after the change with time and allowing the computing means to calculate a margin of safety of the tire component member in the tire model after the change with time by using the thus calculated mechanical characteristic quantity, whereby the margin is stored in storage means of the computer;
• a repeating procedure of allowing the computer to repeat the model preparing procedure, the inner pressure filling processing procedure, the time-varying change predicting procedure and the margin of safety calculating procedure until the calculated margins become equal to or larger than a reference margin of safety;
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• a parameter determining procedure of allowing the computer to determine the tentatively selected parameter, with which the calculated margins become equal to or larger than the reference margin, as a design parameter of a tire.