Is 40 PSI Good Tire Pressure? [Tire Wear, Pressure Limit]

If you are asking this question, chances are you are new to owning a car or you are just not sure what would be the ideal tire pressure for your car.

The simple answer is that 40 PSI should be good enough for most cars. However, you can only be sure that it is good once you check the recommended tire pressure rating.

In some cases, the 40PSI tire pressure might be too low or too high.

40 PSI: Is it too High or Good Enough?

40 PSI is often a measure of good pressure for most cars that are supposed to be using such a pressure limit. However, not all cars would need 40 PSI. Some can require as low as 35PSI and it will still be good.

The 40 PSI mark is also not good for large trucks. They would need something higher.

The range of 32 to 40 PSI would be good mostly for those who want to drive sports cars or mostly passenger cars.

The specific pressure amount is based on the type of car. Of course, you should also check the pressure when the tires are cold to get an accurate reading.

Each tire brand and car model will have the recommended tire pressure you should be using.

First, look at the car’s manual to understand more about the ideal car tire pressure. Then, look at the tire sidewall to see the recommended tire pressure too. This allows you to always have the right tire pressure in the tire.

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When the tire is inflated to the right pressure, you should mostly expect a stable, safe, and smooth ride.

What Causes Tire Pressure Changes

It is expected that you can experience a drop of 1 to 2 PSI naturally because of wear and tear. Of course, there will be other factors causing this change too.

Weather and climate can sometimes make you think your tire is underinflated or overinflated. Nevertheless, the changes are not too much to the point you might think there is a problem with your tires.

During hot weather, air expands, and the tires too. It is the opposite of cold weather conditions. So, do not worry so much about such changes.

Consider checking your tire pressure once a month. This ensures it is always under control and can be adjusted properly before it is too late.

Too Low or Too High Pressure: What Are the Effects?

As mentioned earlier, 40PSI may be underinflation or overinflation in some cases. It is key to understand the impact of overinflating and underinflating your tires. Keep reading below to learn more.

1. Overinflated tires

When the tire is overinflated, it means the middle part of the tire will be the only one in touch with the road surface. So, you end up with a reduced surface area that comes with its own challenges.

One thing you will note is that the ride quality becomes stiffer. The result is having a harsh ride. This harsh ride leaves you with a worn car suspension and also you will not enjoy a long drive to your destination.

Another thing to keep in mind is the performance of the tires over potholes and road debris. In case you hit a pothole with such a tire, you end up damaging it. The chances of having a tire blowout increase.

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Traction and handling would also be affected. Since the tire now has a small footprint, you may experience a compromised grip.

Your car might not turn as properly as it used to. Also, you may experience compromised handling.

Overinflation would lead to tire wear faster than you want. This is because all the weight is now in a small area. In case you see premature wear in the center of a tire, it means you keep overinflating the tires.

When only a small part of the tires are in touch with the ground, you would also be worried about braking. Some tests show that overinflating can affect how well the car stops.

2. Underinflating

Not putting enough pressure on the tires would mean the tires have more surface area in touch with the road, but it also includes the sidewalls.

The sidewall is not built to be as strong as the thread area. For this reason, being flexed all the time can make it less stable and lead to other issues.

Underinflated tires tend to generate more heat as you drive. Also, they might have structural damage too. You also end up with tires that cannot absorb better as they should. They will transfer this shock to the car’s wheels.

Fuel efficiency is also not so good when the tires are underinflated. Underinflation leads to more rolling resistance and you also experience more heat.

The engine needs to work harder to move the car. The result is a dent in your fuel efficiency by almost 5%.

The handling and driving dynamics would also be affected. The softer tires would generally make the steering a bit compromised. If the steering is compromised, you will not have the best control over the vehicle.

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It is expected that tire wear will still be an issue. This is because there is more added stress to the sidewalls which increases tire wear by 25%.

Below is a video on the effects of overinflating and underinflating your tires

YouTube video

How to Maintain Tire Pressure

There will be a few things to always have in mind if you have hopes of having a properly driving car. We will look at things to consider if you want to keep the tire pressure within the right range.

Look at the rated tire pressure

The tire should always be kept at the right tire pressure. Looking at the tire’s sidewall should give you the appropriate tire pressure.

Sometimes the tire writings get faded too. So, look at the car’s manual and adjust the tire pressure accordingly.

Maintain the tire pressure at the right amount

Sometimes it is best to keep the tire pressure within the right range. This can mean checking the tire once a week to determine if the pressure is good enough. If you notice underinflation, adjust it accordingly. The same applies to overinflation.

Check tire pressure before long trips

Going on a long trip with incorrect pressure is not something we would recommend. That is why you have to consider checking your tire pressure first and then adjusting accordingly before setting off.

Also, check the tire pressure when you get to your destination. A significant drop sometimes means there is a problem with your tire.

How Manufacturers Determine Tire Pressure

You have probably also wondered how car manufacturers come up with recommendations on the proper tire pressure to use. Well, there are a couple of things to keep in mind.

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The load capacity and the car’s weight are the leading factors that determine the recommended tire pressure you should be using. This is then taken into account in addition to the standardizing organization recommendations.

Organizations such as Tire and Rim Association (TRA), Japanese Automotive Tire Manufacturers, and the European Tyre and Rim Technical Organization (ETRTO) all offer guidelines to car manufacturers about standard tire sizes.

The organizations would also release more information about the inflation tire and maximum load capacity of the tires.

The procedures used to arrive at the tire information are mostly standardized. These organizations also consult each other which is why the recommendations often do not vary much.

Other than the standardizing organizations making recommendations, the car manufacturer still has to do its own consultations to give the final recommendations.

It is only the car manufacturer that would understand the steering feel, fuel efficiency, ride comfort, and handling.

Car manufacturers perform numerous tests to ensure that you get the proper tire pressure recommendations. They do this in collaboration with tire manufacturers to ensure there is a good balance of air when the car leaves the factory.

How to Check Tire Pressure

Your tire pressure is key in how you drive the car, so having it checked properly is important too. Here are the steps to follow when checking the tire pressure.

  • Check the tires when cold. This is vital to get an accurate reading as hot tires mean the air is heated and expanded.
  • Unscrew the tire valve cap and insert a tire gauge into it. Keep holding until the hissing sound stops and you should have your reading.
  • Start pumping pressure into the tire to the desired pressure in case it was low. Some air pumps will slightly deflate the tires back to the required air pressure.
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Here is a video on how to check and inflate a tire

YouTube video


What is the recommended tire pressure for a passenger car?

Each car might have a different recommendation, but the most recommended would be 32 to 40 PSI. Always consult your car manual to know how much air to use.

How often to check car tire pressure?

Checking once per month should generally be enough for most people. In case you notice one tire is too low, have it checked and get repaired in case of a puncture.

Is the ride quality affected by an over-inflated tire?

Yes. This is because there is reduced tire contact with the road. So, you can expect a harsher ride than normal.

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