An apparatus for monitoring the condition of a pneumatic tyre including a pressure sensor(s) to measure an internal pressure within the tyre. A speed sensor(s) measures a rotational speed of the tyre. A controller is configured to receive data from the pressure sensor and the speed sensor and output indications related to a condition of the tyre. The controller determines the output indications by tracking the internal pressure with respect to time during use of the tyre, identifying at least one change in internal tyre pressure in a time interval. The time interval is between a first reference time and a second reference time, the reference times corresponding to points at which the speed sensor indicates different rotational speeds of the tyre. The controller further monitors the pressure change as a function of rotational speed of the tyre to provide an indicator of tyre condition.