A system for determining a tire contact area parameter includes a sensor module on the tire. The sensor module has a sensor that receives a sensor signal which is dependent on a mechanical tire load at a predetermined measuring point on the tire. A first evaluation device evaluates the sensor signal and provides data based on the sensor signal. The data contain a data element which indicates a time point in the sensor signal. The time point characterizes a passage of the measuring point through the tire contact area. A second evaluation device calculates the tire contact area parameter by evaluating the data provided by the first evaluation device. The first evaluation device analyzes the sensor signal based on a predetermined evaluation criterion with respect to the signal quality of the sensor signal to provide signal quality information of the sensor signal.