The Maximum Load rating is mathematically derived from a number of factors, and is measured at the point when the scar size rate of change/increase (RoC/RoI) is less than 0.01 mm/min. Most scar size increases can be expressed with the following equation:
With this data, we can deduce the point at which the oil film layer is able to fully withstand the pressures without breaking. This is typically referred to as "film strength".
This rating typically varies from 15,000 PSI (poor) to 150,000 PSI (excellent).