Buying guide for Best tire pressure gauges
Poorly inflated tires can lead to a host of problems that not only affect your vehicle but can also be dangerous to you and your passengers. All of that can be avoided with regular checks using a low-cost tire pressure gauge.
At BestReviews, it’s our job to research the wide range of choices available and give you the information you need to make the right buying decision.
The following shopping guide has been put together to answer all your questions about tire pressure gauges.
The importance of proper tire inflation
Warnings can sound overly dramatic, but tires with too little or too much air can lead to numerous problems.
Too little air
Tires wear out: More of the rubber is in contact with the road, so your tires wear more quickly.
Tires overheat: The overheating of a tire can lead to the tread section separating from the casing (or carcass), resulting in a blowout.
Car handling worsens: While traction might actually increase slightly, the sidewalls aren’t doing their job properly so handling suffers and you can’t stop as quickly.
Car uses more fuel: Incorrect inflation increases fuel consumption. The U.S. Department of Motor Vehicles (DMV) gives figures of 0.2% more fuel for every pound per square inch of under-inflation.
Too much air
Tires lose grip: When tires “round out,” less rubber is in contact with the road, reducing grip.
Tire’s contact patch wears out: A smaller contact patch (or footprint) means weight isn’t distributed properly. The center wears out more quickly than the edges.
Tire pressure gauge features
There are three main types of tire pressure gauge: pencil (also called stick or rod gauges), mechanical dial, and digital.
There are four pressure measurements you’ll see on tire gauges. Depending on the gauge you buy, it will measure in one or more of these:
Pounds per square inch (psi) is the most common.
Atmospheric air pressure (bar) is equal to the pressure felt at sea level.
Kilopascals (kPa) is a European standard that isn’t widely used.
Kilograms per centimeter squared (kg/cm2) is another European system.
Pencil, stick, or rod
These gauges have been around almost as long as tires! When pressed onto a tire valve, escaping air forces a piston down the main body of the gauge. A calibrated rod is attached to the piston, and the air forces a certain amount of the rod out of the end of the body. The higher the pressure, the more of the rod appears. You read the tire pressure off the rod nearest the end of the body of the gauge.
Pros:
Low cost
Simple to use
Fits in pocket (small versions)
Can reach inner tires on commercial vehicles and trucks with dual tire setups (large versions with twin heads)
Large range (10 psi to 160 psi)
Cons:
Mechanical dial
Also called analog tire pressure gauges, these used to be seen only in commercial environments but are now widely available.
The best use Bourdon gauge mechanisms. The principle is that a flattened, curved tube will try to straighten when pressurized. Attach a pointer, and as the tube unwinds you’ll get a pressure reading. Others use a calibrated spring or bellows (though bellows gauges are usually only used in low-pressure applications).
Pros:
Easy to read dial
ANSI certified (many)
Reliable in all conditions
Tube attachment for reaching awkward valves
Bleed valves
Can be dismantled for repair
Very durable
Cons:
Usually offer one or two measurement scales
Many only read in two-pound increments
Bulky
Dropping can damage spring-type gauges
"When measuring tire pressure, press firmly and release quickly to take a reading. Do it a couple of times to double-check. Holding the gauge on the valve too long can allow air to escape to the point where you need to add more, so have a way to reinflate your tires nearby. If the tire is overinflated, you can use the gauge to bleed air out."
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Digital
While versions that are intended for commercial vehicles look much like a large pencil gauge with a digital readout at one end, most are pocket-size devices. These use sensors to measure pressure and a microprocessor to display the information on a liquid crystal display.
Pros:
Very compact
Very lightweight
Clear display
Easy to read in low light
Offers all four measurement systems (many)
Very accurate
Auto shutoff to extend battery life
Large, more detailed measurement range (5 psi to 150 psi in half-pound increments)
Cons:
Few certified for accuracy
Only commercial models practical for use on dual wheels
Can be affected by cold
Requires batteries
Low power can result in false readings
Not very durable
A note about accuracy
All tire pressure gauges have variable accuracy. There’s an initial “push” required to get things going, so very few can measure down to zero. And mechanical devices tend to be stiff at the start.
All gauges deliver the highest accuracy in the middle of the range. On high-quality gauges, the degree of inaccuracy can be plus or minus 1% to 5%, which can make a big difference if you run high-pressure tires. Tire technicians and manufacturers recommend that you buy a gauge that has approximately twice the pressure range you need. If your car tires should be at 32 psi, a gauge that reads to 60 psi is ideal.
Expert Tip
Never rely on gas station tire pressure gauges. They are usually badly treated and get little or no maintenance. Indeed, most gauges on tire inflators, whether mechanical or electrical, are built to a lower standard than stand-alone tire pressure gauges.
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Tire pressure gauge prices
Few essential tools are as cost-effective as a tire pressure gauge. From cheapest to most expensive, you’ll only spend between about $5 and $20. If you consider the money that properly inflated tires will save you, even the most expensive gauge will soon pay for itself. There really is no excuse not to have one.
Basic pencil gauges cost around $5 or $6.
Cheap digital devices start at about $10.
Even the very best tire pressure gauges seldom exceed $20.
Tips
Test tire pressure in the morning. The best time to use your tire pressure gauge is in the morning, when the day is coolest. Your vehicle has been stationary for at least two hours, so there hasn’t been any friction to increase the air pressure in the tires. You should measure tire pressure at least once a month.
Maximum pressure and optimum pressure are different things. Tires have a maximum pressure marked on the sidewall, which relates to the maximum load the tire is designed to carry. But tires usually fit a number of different vehicles, so it’s not an accurate guide. Your vehicle manufacturer provides a recommended, or “optimum,” pressure and that’s what you should use. It’s noted in the owner’s manual and often on a plate on the edge of the driver’s door.
Dust and grit can affect tire pressure gauges. Grime can cause the pencil to stick and other gauges to give false readings. Pencil and mechanical dial gauges are easy to clean, and some can be dismantled for a thorough service. Digital gauges are usually sealed, so it’s best to store them in a clean environment when not in use.
- Buy a gauge with twice the pressure you need. Tire technicians and manufacturers generally recommend this. Some models read to 150 psi, which might seem very high, but that’s the kind of gauge you should buy if you’ve got RV tires that need 80 psi.
FAQ
Q. Why does my tire pressure vary?
A. Loss of tire pressure can be caused by something as simple as bumping up against a curb, which momentarily breaks the seal between tire and wheel rim, so air escapes. Damage to the wheel rim can lead to slow leaks, as can a faulty tire valve. And while increased tire pressure is less common, dramatic changes in temperature can cause the air inside to expand. A long highway trip can have a similar effect.
Q. Is low tire pressure really all that dangerous?
A. Yes. The National Highway Transportation Safety Administration says that there are 11,000 accidents and 200 deaths each year that can be attributed to tire problems. That’s underlined by Dan Zielinski of the tire trade body, the U.S. Rubber Manufacturers Association, who tells us that under-inflation leads to heat buildup, which can cause the tread to separate from the tire.
Q. I understand psi and bar, but what are kPa and kg/cm2?
A. Both can be found on digital tire pressure gauges, though these are more often used in scientific measurement.
A kilopascal (kPa) is equal to 1,000 pascals. It’s also 1,000 newtons per square meter, or one kilogram per meter per second squared. One kPa = 0.145038 psi.
One kilogram per centimeter per second (kg/cm2), also written as one kilogram of force per centimeter per second (kgf/cm2), is seldom used, and is generally replaced by pascals or kilopascals. One kg/cm2 = 14.2233 psi.
