What Is the Right PSI for Semi-Truck Tires?

The right PSI for semi-truck tires is a subject often debated within the trucking community. However, how much PSI in semi truck tires largely depends on the truck, the tires, and the maximum load.

It’s important to note that there are a number of factors that have an impact on what PSI you should be using.

More often than not, you can look up the tire manufacturer’s recommendation as a baseline. Then make allowances for the conditions you’ll be driving in, load weight, and some other factors.

What we do know for sure, is that if you do not have the right PSI in your truck tires you will reduce the life of your tires and increase fuel consumption.

If the PSI is overinflated, you risk a tire blowout and can lose control over your truck. If you are unsure of your tire’s max air pressure – you can find it stamped on the tire’s sidewall.

Additionally, another reason to avoid blowing a tire is that, if they were found to be overinflated, you risk voiding your warranty.

Understanding Tire PSI

PSI stands for Pound Per Square Inch. It’s a way of measuring units of pressure or stress being applied to an area or surface per an area of one square inch.

This is the metric of choice for tires as it’s the most accurate way of knowing how inflated a tire is. It’s also easy to check and adjust, so spending a little time understanding PSI is essential for truck drivers.

The Science of PSI

PSI, or Pounds per Square Inch, denotes pressure in terms of the weight in a unit area — in this case, a square inch. PSI describes the amount of air pressure inside a tire, and manufacturers set a target PSI for the tires they may use. The tires will operate at their safest and most efficient when the tires are properly inflated according to the target PSI (along with a few other factors, described in the next section, “Determining the Correct PSI For Your Semi-Truck.”

A tire that is properly inflated will improve fuel economy, ensure even tire wear, and will help avoid blowouts. If the tire’s PSI is too low — or underinflated — it spreads the contact area of the tire, which will add more drag and lower your vehicle’s fuel efficiency. It will also cause flexing and pressure in the tire wall, leading to a dangerous blowout.

If a tire’s PSI is too high — overinflated — then there are other significant risks to safety and major impacts on your vehicle’s efficiency, as well. When a tire is overinflated, the tread will be a bit more rounded, which will concentrate wear to the center of the tread and cause uneven wear. You may also notice that the vehicle feels like it is vibrating more, or you don’t have as much control as you are used to because there is so much less rubber contacting the road.

How to Measure PSI for Semi-Truck Tires

The easiest and most common way truck drivers check the PSI on their tires is using a tire pressure gauge.

Tire pressure gauges come in various shapes and sizes, but the way you use them is always the same. You simply push the end onto the air valve on a tire, as you open the valve the pressure inside the tire will register on the gauge.

One of the reasons the PSI can vary/change is due to the temperature of the tire. More specifically, the air inside the tires contracts in colder temperatures and expands when hotter.

The reason for this is because the temperature of the tire can affect the PSI. More specifically because the air inside the tires contracts in colder temperatures and expands when hotter.

For the most accurate results, you should test the pressure at the same time and under the same conditions as regularly as possible.

What Is the Right PSI for Semi-Truck Tires?

Now that we know a bit more about why correct PSI is so important for your semi-truck let’s talk about how to figure out what you should be inflating your tires to.

First things first, take a look at the tire wall and check for the cold PSI recommendation printed there.

This is a commonly asked question, yet there is no one-size-fits-all answer. The right PSI for a truck’s tires depends on a number of factors, such as:

• Size of the tires
• Whether they are ‘steer’ or ‘drive’ tires
• How much weight the truck is carrying
• The brand of tire
• Temperature and weather conditions
• The makeup of the tire (i.e. the grade of the materials used to construct it)

To get an accurate answer to what PSI you should have in your tires, you’ll need to know your driver load and the exact size and model of tire you have on your truck.

Most semi-truck tires have a PSI range of 85 to 110, and many drivers inflate to around 95. However, you will need to determine the weight of your semi-truck when fully loaded in order to calculate the most appropriate PSI for any given situation. Heavier loads will require a higher PSI since there will be more downward pressure on the tires that can cause the tire to deform and bulge along the wall.

You can then look up the recommended PSI from your manufacturer’s handbook or look it up online. Additionally, as mentioned earlier, you can also find the max air pressure on the sidewall of your tires.

Alternately, there are tire pressure calculators available online that can help you calculate your tire pressure based on your front and rear axle weights, maximum tire load, and maximum tire pressure.

Ultimately, the best thing to do is to refer to your manufacturer’s guidelines for both your vehicle and your tires in order to get the manufacturer’s recommendation. Different tires and different trucks have many different requirements or recommendations, so they are the best source for accurate information.

It’s important to not guess or assume the right tire pressure. The implications and risks of having the wrong PSI can be costly.

The Consequences of Incorrect PSI

There are a lot of reasons why it’s important to maintain the correct PSI in your tires, and there are a number of consequences if you don’t:

Reduced Tire Life

If you over- or underinflate your tires, you may quickly notice that you aren’t getting anywhere near their expected lifespan. This is because the tire’s components will start to break down when they are not being engaged correctly, either by having too much pressure on the centerline (in the case of overinflation), excess strain on the internal components, or wear on the tire wall due to bulging when the tire is underinflated.

Wear on your tires can increase your risk of a blowout, and even if that doesn’t happen, you are cutting into your bottom line by increasing your costs for each tire you need to replace prematurely.

Fuel Consumption

Did you know that the difference of just 10 PSI will reduce your fuel economy by 1%? That added fuel cost, in addition to the accelerated wear on your tires, is another costly impact of not keeping your tires inflated correctly.

If you notice that your fuel use is going up, you might want to get out and check the pressure on your tires. Keeping them all consistently filled will help your truck keep rolling smoothly and efficiently.

Safety Issues

Underinflating will lead to higher internal temperatures on the tire, which, in turn, can lead to rapid degradation of the rubber compounding that is holding it all together (more on that in the next section). Overinflation is dangerous in a different way because it causes the tires to wear irregularly while exerting more outward force on the tire walls.

Both of these scenarios can lead to tire failures like blowouts, which are very dangerous for you as the driver and for everyone else sharing the road with you.

Imbalances

When your pairs of dual tires aren’t all inflated equally, one tire may end up taking on the bulk of the work. It can also cause shifts in your alignment, irregular wear, or, again, tire failures like blowouts.

You may notice some wobbling or instability at certain speeds when your tires aren’t all inflated to match PSI. This wobbling isn’t good for your axle, and it’s even worse for maintaining control over your vehicle — especially in inclement weather.

Loss of Control

When you are driving in wet weather and need to come to a quick stop, you want every tire putting in equal work to make sure that you have even friction and grip. If some tires are inflated differently than others, some may be making more contact than others and will be more effective when you really need them to perform.

You may also be at an increased risk of skidding or sliding when all of your tires aren’t making even contact — so check that PSI regularly!

What Is Rubber Compound Failure?

Rubber compounding is the formulation of certain chemicals added to rubber to create the material used to make tires.

The exact ingredients vary slightly from manufacturer to manufacturer. However, generally speaking, commercial truck tires are made from a mix of:

• Natural rubber
• Synthetic rubber
• Oils
• Waxes
• Filler materials, and
• Some other properties to achieve the desired elasticity and durability

Compound development goes through a number of processes during manufacturing. The end result is a high-performance, durable tire that’s designed to handle everything the road can throw at it.

On occasion, however, you may notice signs of degradation of one or more of your tires. This is often due to compound failure.

This may be due to an error during the manufacturing process, wear and damage accumulated from use, or a combination of the two.

If you’ve ever looked at a blown tire, you may have seen shredded or splintered ends. This often means compounding failed within the tire, causing the rubber to not bind properly.

This often has an effect on the temperature or pressure the rubber is able to sustain. Which results in a blowout under stress levels a perfectly manufactured tire would be able to handle.

Tires are also designed to be run at the specified PSI. If you consistently run your tires at an incorrect PSI, they’re much more likely to wear quicker, often unevenly, and are more prone to failing.

Proper Tire Pressure Maintenance for Semi-Trucks

To make sure you’re running on the correct PSI so your tires stay in good condition as long as possible, here are some basic tire maintenance tips:

Check your PSI regularly

The more often you check the PSI on your tires, the more accurately you’ll know it’s correct. This is also a good way to spot a sudden drop in pressure before heading out on the road and risking a blowout.

A good idea might be to set a recurring alert or reminder on your phone. This is a habit you don’t want to cut corners on.

Practice safe driving habits

The safer you drive, the longer your tires will last and the more consistent the PSI will be. Sudden braking and driving on bumps at a high rate of speed can all affect the PSI of a tire.

If you have had to lock up your brakes or skidded recently, it’s a good idea to do a complete tire inspection. Check the wear patterns as well as the PSI to get a good idea of their condition.

Rotate the tires regularly

It’s good practice to rotate the tires on your truck every according to the manufacturer’s recommendations.

You will want to make note of their recommendations in terms of miles driven. A local trucker who travels a few times per week will not need to rotate their tires as often as a long-hauler who travels that far on a daily basis.

Conclusion

As you can see, the right PSI for semi-truck tires varies depending on a number of factors.

Unfortunately, we can’t tell you the correct PSI for your truck tires without knowing more about your truck. Stop by for semi-truck tire service in Acampo, CA the next time you need to take care of your rig.