In failure studies, useful insights can be gained by examining distribution behavior from analyses performed on dimensional changes due to wear and usage conditions. The rate of wear or reduction of safety margin is represented by r . Where r is positive, X bar o is less than the limit and r is negative when X bar o is greater than the limit. This factor represents the rate of increase in distributional variation as a function of the initial distribution of the characteristic of interest, h . The equation states that something subject to linear wear becomes progressively prone to more failures once it is placed in service.
Tire pressure is known to affect the wear-out rate.
The difference in tire pressures can act like a fixed shift that reduces the safety margin. The pressure difference will also increase the wear rate. The pressure difference will also increase the wear rate r to r 1 .