Patent ID: 7563021

Claim:
A process for judging a residual lifetime of a run-flat tire during continuous running at a run-flat state in a vehicle equipped with a run-flat tire system comprising run-flat tires and detection units each arranged in the respective tire and for measuring a temperature of the tire, wherein when at least one run-flat tire among the run-flat tires is continuously run at the run-flat state by an abnormal lowering of an internal pressure, the temperature of the run-flat tire continuously running at the run-flat state is measured, and a residual lifetime of the run-flat tire is judged based on the measured temperature, wherein the residual lifetime is judged by a runnable time and/or distance calculated on the basis of the measured temperature until a trouble state of the run-flat tire, wherein the temperature of the tire is an atmosphere temperature inside the tire, wherein after the previous setting of a limit temperature being statistically the occurrence of the trouble state when at least one run-flat tire among the run-flat tires is continuously run at the run-flat state by an extreme lowering of the internal pressure, the atmosphere temperature inside tire is measured in the mn-flat tire during the continuous running at the run-flat state, and a time predicted to reach to the limit temperature is calculated by using the measured values of the atmosphere temperature inside tire and data calculated from these measured values of the atmosphere temperature inside tire, and a calculated running time and/or running distance are rendered into a runnable time and/or distance up to the occurrence of the trouble state in the run-flat tire, wherein after a relationship of the atmosphere temperature inside tire T to be measured with respect to a continuously running time t is previously determined as a function f(t) under various run-flat running conditions, when the run-flat tire is continuously run at the present run-flat running condition from a time point of measuring the atmosphere temperature inside tire, the running time and/or the running distance predicted to reach to the limit temperature are calculated by using the function f(t), wherein the function f(t) is approximately expressed by f(t) =T 0 −Aexp(−Bt), wherein T 0 is a predicted saturation reaching temperature and A and B are coefficients, and when the run-flat tire is continuously run at the present run-flat running condition from a time point of measuring the atmosphere temperature inside tire, the running time and/or the running distance predicted to reach to the limit temperature are calculated by using the function f(t).