A tire module for attachment to an inside of a pneumatic tire for vehicles includes a device for measuring and/or monitoring the air pressure in the tire. A transmitter for transmitting radio signals, which contains information regarding the air pressure in the tire, includes a mechanical-electrical transducer having a flexible piezo-electrical element, which converts alternating changes in shape of the piezo-electric element caused by the rolling tire into electric energy and includes a storage unit for the electric energy, which is connected to the transducer. The transducer may contain a circular, disc-like, piezo-electric element, which in the following is described as piezo disc and on which an electrical voltage generated through the piezo effect is tapped off on contact points which are located on opposite sides of the piezo disc.