How Does a Tire Gauge Work?

1. A tire gauge is used to monitor the air pressure in the tires. When it is placed on the Schraeder valve, the air pressure forces the measurement stick out, showing the amount of pressure in the tire. In the case of a tire gauge with a dial indicator, the air pressure forces the needle up to show the amount of pressure being released from the tire. The stick or needle can only move until the pressure between the tire and the gauge is equalized.
2. Air pressure must be set to the manufacturer's recommendation in order to obtain the best handling characteristics and wear. Air pressure increases as the temperature in the tire increases. All tires today are steel belted radials which have at least two plies of steel mesh located under the tread to give some protection against blow outs due to punctures. The double ply also makes a more stable footing on the road.
3. When tires are produced they are made in layers that are actually glued and heated in a mold to seal them together. When the tire pressure becomes too low, the steel belt is flexed far in excess than normal and like any other metal that is bent continuously, it gets very hot. If the tire is driven low for any amount of time or at a high speed, the heat produced by the belt flexing can exceed the heat used to seal the tire and it will come apart. This is what causes a separated tire, where the tread comes off of the tire.
4. All tires will have the maximum pressure embossed on the side of the tire. The vehicle will also have the manufacturers suggested air pressure for the front and back tires. This information is usually on the driver's door. When checking tire pressure it is a good idea to check the tires after they have been driven a few miles so that they are hot and the air is expanded. If the tire is filled to specifications cold it will be three to four pounds over when hot.
5. Many of the new vehicles have a new system for checking air pressure in the tires. This is a continuous monitoring system that uses small matchbox size transmitters. There is one transmitter per wheel. The system also has a receiver inside the car and a check tires or low tire light on the dash. These transmitters are pressure sensitive valves and have Schraeder valves or filler valves running through them.
6. If one of the tires drops two pounds of pressure, the light on the dash will come on. This is a very nice convenience, but take this advice and store it in memory: These sensors are quite expensive, which is no surprise with the way things are any more. The only bad thing with these sensors are they are not easily noticeable, if at all from the outside. If the vehicle is taken in to have tires replaced, be absolutely sure to tell the technician or manager that the vehicle has these sensors. From experience, tire mounters will not see these and damage them when they take the tires off. When the tire is broken down off of the rim it must be squeezed by the tire machine and if the claws are located over the sensor it will smash it every time. That can cost you hundreds of dollars.

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