US Patent 7100436 Tire pressure gauge

A multi-functional tire pressure gauge includes a housing, an air-guide seat, a diaphragm, a helical seat, an annular seat, a tread-measuring device, a display panel and an air-guiding device. The multi-functional tire pressure gauge can measure tire pressure and tread's depth simultaneously. Specifically, when the diaphragm moves up and down under the effect of the tire pressure, the helical seat converts the up-and-down motion of the diaphragm into circular motion, so that the index pointer can display tire pressure value. Furthermore, the probe extending in treads of the tire can obtain the depth of the tread.