A structurally simple tire monitoring system for a vehicle, for establishing tire-specific parameters, includes a valve stem with an attachment section, a fastening element and a tire air pressure sensor with a housing that has a mounting region. When the fastening element is in a locking position, the attachment section and the mounting region are releasably connected to one another using the fastening element. This is achieved in that the mounting region of the fastening element is movably supported between the locking position and an unlocking position, in which the mounting region and the attachment section can be released from one another. An elastic latching element is provided, which allows a movement of the fastening element relative to the housing toward the unlocking position, counter to a pressure exerted by the latching element. The latching element presses the fastening element into the locking position.