A ground-fixing system for a tire characteristics sensor housing (10) comprises: a fixing plate (1) comprising a plurality of recesses (2) of a given profile distributed over the surface of the fixing plate; and a plurality of fixing pins (3) of substantially corresponding profile, similarly distributed on a fixing face of said sensor housing (10), the shapes and dimensions of the recesses (2) and of the pins (3) for fixing being provided so as to allow, on the one hand, in a position of insertion of the pins, engagement of the latter in said recesses and, on the other hand, in a locking position of the pins, fixing of the sensor housing (10) on the fixing plate (1).