Abstract: A device for monitoring a vehicle pneumatic tire in-situ on a wheel rim comprising a probe to be sealably mounted to the rim with a hollow stem projecting through the rim into the air cavity of the tire. A temperature sensor mounted in the stem to be exposed to the temperature in the cavity, and the interior of the stem being in use in direct communication with the air cavity. A head at one end of the stem to be external attached to the rim for mounting the probe thereto, and respective conductor extending from the stem through the probe head to project therefrom in a direction generally parallel to the surface of the rim and to convey processable information relating to temperature and pressure conditions within the tire cavity.The probe head is interlockable with an anchor member secured to the wheel rim.The probe is used in conjunction with a terminal.