Monitoring device for a vehicle, warning device for a vehicle, warning system and method for operating a monitoring device

The approach presented here relates to a monitoring device () for a vehicle. The monitoring device () has at least one measuring device () with a sensor unit () and a transmitter unit (). The sensor unit () is designed to sense a physical parameter in the area of the wheel in a coupled position on a first section of a wheel hub () of a wheel of the vehicle while the vehicle is moving. The transmitter unit () has a fastening device which is shaped in order to fasten the transmitter unit () in a fastening position on a second section of the wheel hub () of the wheel or on a wheel rim (), the transmitter unit () is designed to wirelessly send a sensor signal () representing the physical parameter to a warning device in order to enable monitoring of the physical parameter.