We often talk about the importance of checking the inflation pressure in tires, but is your tire pressure gauge giving you accurate information? After writing my article titled, “Take the Visual RV Tire Test” I received several emails regarding the accuracy of tire pressure gauges. One person commented, “I understand that tire pressure in an RV is crucial and can cause serious problems if not inflated correctly. Well, the problem is this, how do you know if the tire gauge is accurate? I have seen two tire gauges show as much as 16 psi difference on the same tire. Is there a recommendation as to which tire gauges are the most accurate?”
What’s funny about this is for many years, as a Maintenance Warrant Officer in the Army, I was responsible for tool calibration programs. Certain tools required regular calibration to ensure accuracy. I use a quality tire pressure gauge, but after reading this question realized that after several years of using this gauge I have never had it checked for accuracy.
Many of the really inexpensive gauges ($5) you can purchase can’t be calibrated, and if the reading is inaccurate the gauge is worthless. This is why you should spend a little more ($15-$25) and get a quality pressure gauge that can be calibrated. I am a real believer in the old saying; you get what you pay for.
If you have any doubt about the accuracy of your tire pressure gauge there are a couple things you can do to check it.
1) You can check the air pressure in a tire with the gauge in question and then check the same tire with another gauge. If there is a significant difference in the readings (4 or more psi) between the two gauges one or both gauges may be inaccurate. If both gauges read within 1 to 2 psi of each other the gauges are more than likely accurate.
2) If you want a more precise method for checking the accuracy take the gauge to a local tire dealer or fleet truck maintenance facility and ask them to check it using a master gauge. A master gauge is a gauge that is certified to be accurate. But I caution you there are lots of tire dealers who don’t have their own tire pressure gauges calibrated.
Note: Don’t depend on pressure gauges at gas stations to be accurate. These are usually abused and neglected, raising concern over accuracy.
There are several different types of pressure gauges available on the market. One important thing to keep in mind is the pressure the gauge is rated for. Most automobile tires are inflated to around 32 psi, so a 0 to 60 psi gauge is sufficient. On the other hand some motorhome tires are inflated to 100 or more psi. It is important, for accuracy and to prevent damage to the gauge, that you get the right gauge for the job. A general rule of thumb is to find a gauge that can read double what the inflation pressure is set at. This isn’t always possible especially with tires inflated to 100 psi, so find a gauge rated for high pressure, like 160 psi.
Possibly the most common type of pressure gauge is the plunge or pencil type. Some of these are calibrated and some of the cheaper ones are not. As a general rule a common plunge type gauge you would purchase will be accurate to + or – 3 psi when it is new. The accuracy of these type gauges are also affected by temperature, humidity and altitude.
Note: Always check the tire pressure when the tires are cold, before traveling. If you check the tires when they are hot you will get a false (higher) reading and if you let air out of the tires they can be seriously underinflated when they are cold.
Like everything else these days’ things are switching from analog to digital. Analog tire pressure gauges were the standard for many years, but advancements in digital technology have improved on that standard. Analog dial gauges are about as accurate as the quality pencil type gauges. In numerous tests comparing different type gauges digital gauges were the most accurate tested.
Regardless of the type of gauge you choose there are high quality and low quality gauges available. Buying a cheap digital gauge would be the same as buying a cheap pencil type gauge. Here are a few things to keep in mind when it comes to tire pressure gauges.
1) Spend a few more dollars and get a quality pressure gauge.
2) If the gauge will be used for checking dual wheels on a motorhome the chuck end of the gauge should have a dual foot design to make the job much easier.
3) Always select a gauge rated higher than the inflation pressure of the tires you are checking. Applying more pressure than the gauge is rated for can damage the gauge and affect the accuracy. If you over-pressure a gauge have it tested for accuracy.
4) Try not to drop or jar the gauge. Store the gauge in some type of protective covering or case and in an area where it won’t be hit or damaged.
5) Periodically have the gauge tested for accuracy. At a minimum compare it to another quality gauge to see if both read the same, or close to the same pressure.
6) Most importantly, once you purchase a quality pressure gauge use it on a regular basis to check your RV and automobile tires.
Remember, properly inflated tires are safer, extend the life of the tires, improve fuel efficiency and lessen the chance of unexpected and premature tire failure.
Happy RV Learning,
Mark Polk
RV Education 101
RV University
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