Described is a device (51) for monitoring the state of inflation of vehicle wheel tires, the wheels comprising a rim (100) and a respective tire (101) delimiting a hollow space (103) inside the wheel from the outside environment (104). The device (51) comprises: a first end (53) equipped with a self-closing valve connectable to means for inflating and deflating the tire (101); a second end (99) sealingly connectable on a hole (102) in the rim (100) of the wheel; a cavity (62) interposed between the two ends (53) and (99) and sealingly delimited by a wall (81) which is integral with a body (52) of the device and by an elastically deformable partition (203) having an inside face subjected to the pressure inside the tire and an outside face subjected to the atmospheric pressure of the outside environment; means (221) for generating and transmitting electromagnetic signals and a power source (215); a switch (208) mounted in the cavity (62) and configured to drive the means (221) for generating and transmitting electromagnetic signals, where the deformable partition (203) comprises a contact element (222) operating on the switch (208) in such a way as to activate it in response to a deformation of the partition (203) itself. The device is adapted to be mounted in place of the inflation valve of a vehicle wheel tire in order to provide the driver of the vehicle with indications about the state of radial deformation of the tire, without increasing dimensions and weight compared to the original valve and without creating obstacles to fitting and removing the tire.