How to Calibrate a Tire Pressure Gauge

January 27, 2012

Calibrating a tire pressure gauge is an important aspect in car maintenance. Inaccurate readings can lead to all sorts of problems such as a burst tire. Anyone that has experienced a blowout knows that it's not a good experience, especially when driving at speed. It is possible to calibrate a tire pressure gauge to ensure that the correct air pressure is in your tires at all times. To calibrate a tire pressure gauge, you will need space, and the procedure can take a little time to do.

Materials Needed:

  • 25 meters of hose pipe
  • A person to help
  • Water
  • A high building, at least 25 meters high
  • Tire pressure gauge
  • 25m tape measure
  • Marker pen

Step 1 - Mark The Hose

Unravel the hose and unwind the measuring tape to 25m and place this alongside the hose. Using your marker pen, mark off every meter and make obvious 10m, 20m and 25m points.

Step 2 - Stand on Top of the Building

Stand on top of the top of the building and let the hose unravel. It is very important to keep the hose as straight and as kink-free as possible. Connect the end at ground level to the tire pressure gauge.

Step 3 - Check the Calibration

Slowly fill the hose with water to the 1m mark. This should give a reading of 1.4223 PSI. If the gauge appears accurate, then continue to fill with water. You should find that for every metre of water in the hose, the PSI increases by 1.4223. The following readings will prove useful, as operating a calculator can be tricky when keeping the hose straight.

  • 10m - 14.2 PSI
  • 20m - 28.4 PSI
  • 25m - 35.5 PSI

Step 4 - Recalibrate the Gauge

If you find after the first meter, your gauge is not showing 1.4223 PSI or thereabouts, then recalibrate the gauge accordingly and repeat from Step 2. If you find that the calibration is impossible to achieve, the chances are that you have a faulty tire pressure gauge and you will need to replace it. The above method is accurate to 0.8 percent.

Step 5 - Shorter Hose

It is possible to use a shorter hose which negates the need for high buildings, friends and lots of water. The accuracy, however, decreases as checking a gauge with 3 meters of hose does not provide the same level of accuracy that 25 meters provides. It is an option, however, should you not have the equipment needed, and it is better than no calibration at all.  Pressure gauge calibration is more accurate using longer rather than shorter lengths of hose.

Step 6 - Gas Station Gauges

Though many rely on gas station gauges, there are many reports that tire pressure readings vary. This has led to the rise in sales of digital tire pressure gauges, some of which are accurate and some are not. If you are thinking of buying a digital gauge, ensure that you do your homework and buy one with good reviews from trusted sources such as a garage or workshop. It is also possible to have a gauge calibrated professionally. There is always a cost involved with this option. 

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