Tire pressure indicator

A tire pressure indicator for a set of pneumatic tires of a vehicle, comprising:

• a plurality of pressure gauges respectively attached to the pneumatic tires, each of said pressure gauges including a casing having a hollow adaptor to be attached to the respective pneumatic tire, an air inlet and a finger piece for opening an inflating valve of the tire;
• pushing means disposed inside said casing adjacent to said air inlet and being movable, in response to an inlet pressure entering through said air inlet, between a first position in which said inlet pressure is below a predetermined low pressure limit and a second position in which said inlet pressure is above a predetermined high pressure limit;
• a spring-loaded push rod movably mounted inside said casing and being moved by said pushing means;
• and a signal transmitting unit provided inside said casing and having first and second switch devices which are controlled by the movement of said push rod, said first switch device activating said signal transmitting unit to transmit a first code unique to that gauge when said pushing means is in said first position, said second switch device activating said signal transmitting unit to transmit a second code unique to that gauge when said pushing means is in said second position;
• a receiver device for receiving said first and second codes transmitted by said signal transmitting unit of said pressure gauges, said receiver device including first and second light emitting units, one of said first light emitting units being activated upon reception of said first codes so as to indicate which one of the tires is under-inflated, one of said second light emitting units being activated upon reception of said second code so as to indicate which one of the tires is over-inflated wherein said first switch device comprises a first circuit board mounted inside said casing above said pushing means and being formed with a central hole to permit said push rod to extend therethrough, a first conductor spring piece provided on a top side of said first circuit board and having one end fastened to said first circuit board and an electrical contact provided on said first circuit board, and wherein said first spring piece and said electrical contact cooperatively form a normally closed switch, said push rod is incapable of pushing said first spring piece away from said electrical contact to break electrical connection when said pushing means is in said first position, and said push rod pushes said first spring piece away from said electrical contact when said pushing means is in said second position.