Air pressure measuring device (10) for a vehicle wheel (2), having a valve body (11) which constitutes a first element (31) and which can be inserted in a through-hole (5) in a vehicle wheel rim (1), having a cap nut (30) which constitutes a second element (32) for axially tensioning valve body (11) on the vehicle wheel rim (1), wherein when the air pressure measuring device (10) is in the installed state a threaded connection (35) is created between the valve body (11) and the cap nut (30), consisting of a thread (40) formed on the valve body (11) and a thread (41) formed on cap nut (30), wherein, in order to create one of the two threads (40, 41) both elements (31, 32) are made from materials of different hardnesses, a self-cutting thread (40) is produced in the element (31) that is made of the harder material, and a deforming section (39) is produced in the element (32) that is made of the softer material, in and in which the other thread (41) can be created by cooperation with the self-cutting thread (40).