To provide a method for filtering a signal transmitted to the central unit of a monitoring system that is equipped on a vehicle.

Pressure in a tire is measured at a period θ, and if there is a change ΔP in the pressure between pressure values measured sequentially, that change is derived. In parallel, temperature in the tire is measured at the same period θ; and when the change ΔP in pressure between two pressure values measured sequentially is larger than the absolute value of a predetermined threshold voltage Sp, the temperature difference ΔT between the two temperature values measured at the same moment as the measured pressure values is calculated. A correction factor Cp, that becomes Cp=ΔP/ΔT, is derived from the temperature difference. When ΔT=0 or the correction factor Cp is positive and is larger than a predetermined threshold coefficient Cp1, or the correction factor Cp is negative and is not between the minimum and the maximum threshold, instructions are given to the central unit so as to transmit a signal that expresses changes in the pressure.