Disclosed is a method of indirect tire pressure monitoring. The method includes: learning test variables (DIAG, SIDE, AXLE), which describe the rotational movements of the wheels; determining rolling circumference differences (ΔDIAG, ΔSIDE, ΔAXLE) from actually determined test variables and the learnt test variables; learning at least one torsion natural frequency fp for at least one tire from the oscillation behavior of the individual tires; determining at least one shift of the torsion natural frequency Δfp from at least one actually determined torsion natural frequency and from the at least one learnt torsion natural frequency; and combining the rolling circumference differences (ΔDIAG, ΔSIDE, ΔAXLE) with the at least one shift of the torsion natural frequency fp in a joint warning strategy for detecting and warning of tire inflation pressure loss.