A method and means 10 of monitoring the pressures present in a vehicle's tyres 14 comprises sensing a tyre pressure 17 and transmitting 18 a signal 20 representative of the tyre pressure for a plurality of the vehicle's tyres 14. The pressure signals 20 are received 22 via an antenna located on the vehicle 12 such that the signal from each of said plurality of tyres 14 has a unique signal amplitude pattern. The said signals 20 are then processed 24 to automatically identify the location FR, FL, BR, BL of each tyre 14 from the said patterns. The processor 24 then generates signals to convey tyre pressure and location information to the occupant of the vehicle. Each of the pressure sensors 17 may include an identification code which is sent via the transmitters 18 to the receiver 22 for use in the signal processing. Vehicle speed information may also be supplied to the processor 24 for use in identifying the tyre locations. The unique signal amplitude pattern and its associated location may be pre-programmed into the processor 24. An intermittent signal protocol may be used for the pressure signal 20.