1. A non-transitory computer readable medium containing computer instructions stored therein for causing a computer processor to perform the method of operating a tire pressure monitoring system, comprising: generating a sequence of reference values(A) based on signals representing wheel speeds of several vehicle wheels; comparing one currently determined reference value with at least one comparative value; inferring a pressure loss if the currently determined reference value falls within a predetermined range based on a threshold value; performing a noise analysis on the reference values ( 101 ); and increasing the threshold value in response to the noise analysis showing that noise of the reference values exceeds the threshold value for a predetermined amount of time (t 2 -t 1 ).