Multiple leak rate methodologies are combined and operate in parallel in a system for providing optimal results under different tire conditions. The methodologies may operate continuously or alternatively. Tandem large leak rate and low leak rate algorithms and methodology, for example, may deployed in a system in which, for large leak rates, a large leak rate methodology is employed and used to trigger a warning. At some pre-designated low leak rate threshold value, the system employs a low leak rate methodology either as an exclusive diagnostic monitor or in parallel with the companion large leak rate methodology. In the low leak rate analytical system, a change in tire pressure is correlated to a change in energy within a vehicle system pursuant to the algorithm W = P * dx and derivative algorithms are used to calculate a final time and pressure drop at the final time as a basis for issuing a low pressure warning.