Transmitter mounting structure for tire condition monitoring apparatus

A mounting structure for a transmitter of a tire condition monitoring apparatus that enables the transmitter to be attached to wheels having different cross sectional shapes. A wheel has a drop center (23) and a rim (24) formed integrally with the drop center at a predetermined angle relative to the drop center. The mounting structure includes a valve stem (60) arranged on the rim and having a basal end. A casing (80) houses the transmitter. A coupling fixture (70) couples the casing and the valve stem. The coupling fixture includes a coupler (73) coupled to the basal end of the valve stem, an anchor (74) for anchoring the casing, and a connection (75) for connecting the coupler and the anchor so that the coupling fixture is resilient. The angle between the coupler and the anchor is greater than a predetermined angle before the coupling fixture couples the casing and the valve stem.