How to Use a Tire Pressure Gauge

A tire pressure gauge reliably and accurately measures air pressure in a tire. Measuring tire pressure every two to four weeks helps prevent issues from over or underinflated tires. This article covers how to check tire pressure using a variety of tire pressure gauges.

Table of contents

• How to measure tire pressure
• Improper inflation & its causes
• Types of tire gauges
• Tire pressure gauge pros and cons summary
• FAQs

How to measure tire pressure

The best time to check tire pressure is in the morning before operating the vehicle. Cold tires give a more accurate reading. After operating a vehicle, wait at least 3 hours before checking the tire pressure. If it is necessary to drive the vehicle to a gas station to check tire pressure, driving further than one kilometer will reduce the accuracy of the reading.

The following steps describe how to measure tire pressure:

1. Determine the recommended tire pressure
   1. The recommended tire pressure is listed in the vehicle’s manual. It may be engraved on the inside of the driver’s door. Finally, it is also likely engraved on the tire itself.
2. Remove the valve cap from the tire you want to check.
3. Place the head of the tire pressure gauge that has the valve stem onto the tire’s air valve.
4. Read the output on the tire pressure gauge.
   1. If the tire pressure is within the recommended range, replace the valve cap and move on to the next tire.
   2. If the tire pressure is too high, release some air and recheck the tire pressure until it is within the recommended range.
   3. If the tire pressure is too low, add air to the tire and recheck the tire pressure until it is within the recommended range.

Improper inflation & its causes

It is not necessary for tire pressure to be perfect, but it should be within the optimal limit listed in a vehicle’s manual. Both underinflation and overinflation will reduce the tire’s performance.

Underinflation

Underinflation can lead to:

• Increased fuel consumption
• Increased rolling resistance, meaning the automobile expends more energy to keep the tires moving at a constant speed
• Poor braking performance
• Uneven tread wear on the edges of the tire (Figure 3)

The causes of underinflation include:

• Permeation: A tire loses pressure through its sidewall.
• Puncture: Small nails and screws puncture a tire and cause it to lose pressure at lower rates which may go unnoticed.
• Weather: The tire pressure may drop if the temperature drops significantly. For example, if there's a 5.6 °C (10 °F) drop in the temperature, the tire pressure may reduce by 0.07 bar (1 PSI).

Overinflation

Overinflation can lead to:

• Irregular wear
• Poor handling
• Uncomfortable rides because the tires have uneven contact with the road

The causes of overinflation include:

• Improper filling: Drivers overinflating the tire when filling it with air
• Weather: Rising temperatures can raise tire pressure. A 5.6 °C (10 °F) increase in the temperature can increase tire pressure by 0.07 bar (1 PSI).

Types of tire gauges

There are three types of tire pressure gauges:

• Standard
• Digital
• Stick

Read our pressure gauge overview article for more information on how pressure gauges operate.

Standard

A standard pressure gauge (Figure 1) is also called a dial tire pressure gauge or analog tire pressure gauge. Some advanced standard gauges have features such as:

• A bleeder valve that releases excess pressure that accumulates when the tires’ temperature increases.
• A button that deflates the tire for minor adjustments.
• A rubber extension hose that adds length to the pressure hose. This extension is ideal for trailer or caravan tires that require extra reach.
• Up to 2 inches shock-resistant dial cover that offers protection if the pressure gauge is dropped.

Digital

A digital tire pressure gauge’s (Figure 4) LCD screen makes it easy to read. It is dust and dirt-resistant and usable in the dark. On the downside, digital pressure gauges require batteries and are bulkier than stick gauges. An automatic tire inflator is often found at a gas station. It works like a digital tire gauge. They are more advanced because they connect directly to an air compressor and can deflate and inflate tires automatically.

Stick

Stick gauges resemble a ballpoint pen. The key components include:

• A metal outer shell
• An inner plastic measuring rod

When air pressure is applied, the inner plastic rod extends out from the bottom of the gauge. Large numbers with division marks between them give the reading. For example, the pressure gauge in Figure 5 reads approximately 32 PSI.

Tire pressure gauge pros and cons summary

Digital pressure gauge

Pros

• Calibration: A calibrated digital pressure gauge is more reliable and accurate than a standard or stick pressure gauge.
• Ease of use: Digital pressure gauges are easy to read.
• Durability: Digital pressure gauges are made of more durable materials to protect the electronic components within.

Cons

• Power: Digital pressure gauges require a power source, such as batteries.

Stick pressure gauge

Pros

• Size: Stick pressure gauges are small and easy to store in a vehicle.
• Ease of use: Stick pressure gauges have minimal components, making them easy to use.
• Power: Stick pressure gauges do not require an external power source.

Cons

• Accuracy: Stick pressure gauges are less accurate than standard and digital gauges.
• Readability: Stick pressure gauges are not as easy to read.

Standard pressure gauge

Pros

• Features: Standard pressure gauges come with extra features such as extension hoses and deflating valves.

Cons

• Readability: Reading a standard gauge’s output is not as precise as reading a digital gauge.

FAQs

How does a digital tire pressure gauge work?

A digital tire pressure gauge measures pressure using a sensor and converts it into electrical signals. An integrated microprocessor converts the electrical signals to numeric values, which appear on the digital display of the gauge.

Is there a difference between a motorcycle tire pressure gauge and a truck tire pressure gauge?

It depends on the tire gauge and the valve on the motorcycle and truck. Truck tires need a higher PSI compared to motorcycles. In petrol stations, most tire pressure gauges are designed to inflate any tire.