What Size Air Compressor Do You Need for Filling Tires?

Of all the many uses of an air compressor, one of the most common is tire inflation. Many homeowners would agree that this alone is reason enough to have a compressor on hand. But before you go out and buy a compressor for inflating your tires, you want to be sure you get a model that’s up to the task.

What size air compressor you’ll need for filling tires depends on the size and pressure requirements of your tires. Most compressors of any size can inflate small-to-medium tires but may not work well for larger truck tires. The compressor’s CFM and PSI capabilities are the most important factors.

Tire Size & Recommended Pressure

The main things to consider when looking for an air compressor for tire inflation are the size and recommended PSI of the tires you’ll be inflating. If you just want a fast and easy way to fill up bike tires or wheelbarrow tires, virtually any compressor will do – you’d just want to be careful when using a large and powerful compressor, to avoid overfilling and bursting your tires.

It’s when you move up to automotive tires that you might start to run into difficulties. Typically, tires on sedans, mid-size SUVs, and smaller trucks aren’t very large and only need to be filled to a recommended pressure of around 32-36 PSI. Even the smallest compressors are usually more than capable of filling these from empty. 

But larger tires, such as those on larger SUVs, trucks, and RVs, often require inflation up to 100 PSI. This may be too much for some portable compressors that have a lower operating PSI. 

Selecting the Right Size Air Compressor for Filling Tires

There are a few key criteria to consider that will determine whether or not a given compressor can be used to fill your tires – and how efficiently it will do so.

PSI

Perhaps the most important factor is the air compressor’s maximum PSI rating. PSI (pounds per square inch) is the measurement for how much air pressure the compressor can provide. If the tire requires more pressure than your compressor can provide, you won’t be able to fully inflate the tire – it will only inflate to the maximum pressure output of your compressor. 

For instance, if your compressor has a maximum operating pressure of 70 PSI and you try to inflate a truck tire to 100 PSI, you’ll only be able to put 70 PSI of pressure in the tire.

As a general rule, it’s best to use a compressor with a maximum operating pressure of at least 10 PSI higher than the recommended tire pressure. So if your tire needs 100 PSI, you’ll want a compressor capable of generating 110 PSI or higher. An equal PSI could also work, but the air exchange will go slower the closer you get to the max pressure, so it could take a while.

On that note, most compressors with storage tanks have two gauges – one for tank pressure and one for regulated pressure (the pressure going through the air hose). When using such a compressor, you’ll want to make sure the regulator knob is set at least 10 PSI higher than the inflation pressure you’re trying to achieve – otherwise you won’t be supplying adequate pressure even if the tank pressure is maxed out.

CFM

Another important factor is the compressor’s CFM rating. CFM (cubic feet per minute) is a measurement of the rate of flow the compressor can provide. This mainly impacts how quickly and efficiently you can fill your tire. It’s important to note that CFM should always be measured in the context of air pressure. That is, it’s usually measured as x CFM @ x PSI. For example, a compressor that can provide 1 CFM @ 100 PSI will likely be able to provide 2 CFM @ 50 PSI.

This is important because you generally don’t want to go any lower than 1 CFM at the necessary tire pressure – unless you don’t mind spending a lot of time filling your tires. So, say your compressor offers 1 CFM @ 50 PSI but only 0.6 CFM @ 100 PSI. If you’re inflating a small car tire to 36 PSI you should have no problem, but filling a big truck tire to 100 PSI could take a very long time.

Tank Size

The size of the air compressor tank will make a difference in how long it takes to fill your tires and how long your compressor pump will have to run. If you’re just topping off a tire or two (adding a few pounds of pressure to each tire), a 1-gallon tank should be more than enough to get the job done in one go. If you’re filling a tire from empty, however, it will probably take multiple cycles to fill the tire completely – the larger the tire, the longer it will take. This means you’ll have to wait while the tank recovers (refills).

Naturally, the larger the tank, the less waiting you’ll have to do. Portable 3-gallon and 6-gallon compressors are typically better for larger tires. Many small compressors designed to be kept in vehicles are designed to provide a continuous supply of air so you won’t have to wait for the tank to refill at all.

Duty Cycle

An air compressor’s duty cycle rating is the recommended amount of time the pump should be on during a given usage cycle. For example, a 50% duty rating means the compressor pump isn’t meant to run more than half the time you’re using the compressor – i.e. the pump should spend 1 minute off for every 1 minute on – to avoid overheating/wearing out the pump.

A larger storage tank can help in this regard since you’ll be able to draw on the stored air while you let the pump cool down. However, many very small compressors that can be plugged into your car are designed for continuous use – although they can still get overly hot after very long periods of use.

Cord & Hose Length

One more thing to think about is the length of your compressor’s power cord and air hose. In general, it’s best to avoid using extension cords with air compressors, as it can cause power issues that degrade the motor. It’s always better to use a longer air hose, even though this can result in a slight loss in air power. 

Since it’s not always convenient (or possible) to bring your tires to your compressor, you’ll want to be sure you can bring your compressor (or the inflator tool) to your tires. To this point, there are a few battery-powered portable compressor options out there.

In Conclusion

The most important thing when choosing a compressor for tire inflation is to make sure the compressor’s max PSI exceeds (or is at least equal to) the tire’s recommended inflation pressure. 

Beyond that, the rest of the factors will determine how quickly and efficiently you can get the job done. No one wants to spend an hour or more filling up their tires, so you’ll ideally want to find a compressor powerful enough to fill your tires rapidly and with minimal interruption. The key is to strike a balance between power and portability, depending on your needs. Thanks for reading!

Justin

Justin is a full-time blogger with a passion for anything DIY. When he's not hanging out with his wife and son, you can find him putting the finishing touches on yet another home project he's taken on. He's also the creator of AllAboutAirCompressors.com.