Abstract: A tire pressure monitoring device includes a pressure gauge pivotably mounted to a base which can be attached to a tire valve stem. The pressure gauge includes a ring-shaped piston and spring mounted in a transparent sleeve. Other embodiments use an electronic pressure sensor to generate a digital pressure display. Optionally the device may include a transmitter to provide pressure data to a display in the interior of a motor vehicle.

Abstract: A tire pressure monitoring device includes a ball disposed within a tube which has an opening, at one end, in communication with the interior of the tire. The tube has a transparent window along its length to allow the position of the ball, within the tube, to be visualized. The transparent window has graduations, calibrated to allow the tire pressure to be determined by the position of the ball within the tube. A magnifying glass can be provided over the transparent window to allow the graduations to be more easily seen. The device can be made integral with a tire valve stem or as an accessory item which can be connected to a conventional tire valve stem. The device continuously displays the tire pressure without causing air to be vented from the tire.