This post may include affiliate links. If you make a purchase through these links, we’ll receive a commission at no extra cost to you. This support helps us maintain and grow our site. Thank you for your support!
Tire pressure, measured in Pounds per Square Inch (PSI) is a trivial thing to maintain, but one of the most important factors of your car’s operation.
But how much tire pressure do you actually need? The industry standard recommends 32 PSI. But to be sure you have the correct tire PSI for your vehicle, always check the placard inside the driver’s door jam. Filling your tires to the manufacturer’s specifications is always your best bet.
There are many different factors in deciding what the PSI of a tire should be. And once you understand them, overriding the manufacturer’s specifications will grant you increases in different areas of performance. Some cars may specify that you use different PSI’s for front and rear tires, while other manufacturers make different tire sizes carry the same PSI amount. Additionally, your Tire Pressure Monitoring System is one of the main causes for impromptu repair shop trips. Knowing what they mean can be the difference between taking your car into the shop immediately versus giving yourself a grace period.
I’ve worked in a tire shop for many years, and I started out just when TPMS sensors were becoming commonplace in vehicles. I saw a huge increase in customers coming in to have us look at their tires because they saw a TPMS light. Seeing the transition from analog tire systems to digital TPMS systems really cemented the importance of tire pressure for me.
No items found.
Table of Contents
Your Car’s Tire Pressure
Your car’s manufacturer made the decision to specify your car’s PSI by factoring in components like ride height, weight distribution, handling, and fuel economy. This is why the best decision is always to fill your tires to the specified amount placed on the door jamb.
Your door jamb on the driver’s side is packed full of useful information, like total weight, manufacturer date, the location it was made. Among other things, this piece of the car has the manufacturer tire PSI recommendations glued to the side. If for some reason your car doesn’t have a tire PSI sticker, or it’s illegible, refer to your owner’s manual.
The information stamped and printed on your car is important to your tires for many reasons. One reason is that some manufacturers display their own recommended PSI on the side of the tire.
Tire stamped values may greatly differ from the amount printed on the car, which, in turn, can cause issues. For example, some tires say “inflate to 32 PSI” on the side of a tire, when the vehicle manufacturer specifies all tires should be inflated to 34 PSI. While 2 PSi doesn’t sound like much, the difference can be noticeable, whether it be in handling or fuel economy.
Your car’s tire pressure will be unique to your vehicle. Taking blanket recommendations isn’t advisable, since the vehicle manufacturer already specifies it should be. Every mechanic from master tech to lube tech always checks the tire pressures inside the door before setting the pressure. It’s safe, recommended, and fail-proof.
Tire Caveats
Some manufacturers specify a different PSI for tires located on the rear of a vehicle. There are a few reasons why they might do this. One is because the tires are different sizes, therefore a weight distribution will be needed. If a 16 inch tire is on the front, and a 18 inch on the back, if the tires were inflated to the same PSI, the ride height would be thrown off. This will cause issues in performance areas like drivability and handling.
If your car was made after 2007 it will let you know if the PSI is correct, by using the Tire Pressure Monitoring System. This electronic system reports your tire pressure to the car’s computer on a second-to-second basis. If there are any issues with any tires, your tire light will come on.
Some vehicles allow you to see your tire pressures right on the digital dash display.
Another reason recommended tire pressures might differ, or stagger, is to ensure a long lasting life by distributing wear most efficiently. For example, on the Ford E-150 vans, you’ll see the pressures for the front axle are around 50 psi, and the rear are around 80 psi.
These pressures are recommended, along with quarterly rotations, to max out the life of all 4 tires. Tires that are highly inflated on the back take most wear in the center of the tread. And tires on the front, where the engine is, are underinflated, causing more traction for the extra weight. The front tires take more wear on the edges.
So when the tires are rotated, and the air pressure switched, you’re maxing out the life of each tire by changing the stress points of the tire. The front tires are now overinflated, and the rear tires under inflated.
TPMS
Your car’s TPMS (Tire Pressure Monitoring System) is a digital solution to an analog problem.
Before TPMS, the only way you knew about a small leak would be to either spot it before it made the tire flat, or walk out to a flat.
Even more importantly, issues with tire pressures could cause a catastrophe while the car is moving. It’s for these reasons that all cars built after 2007 must have a TPMS.
Tire Pressure Monitoring Systems aim to keep tire blowouts and accidents to a minimum. Additionally, a slow leak could leave you stranded. You would not be notified of the leak, until you’re stranded on the side of a highway while other cars pass you by. TPMS systems notify you before an untimely occurrence like this can happen.
I’ve noticed lots of customers complain that their TPMS light is always on and find it to be annoying. But that’s what it’s supposed to do — it’s supposed to be more annoying than the annoyance of being stranded on the side of a highway.
The TPMS is a crucial safety device which monitors any type of pressure loss, and records it with your vehicle’s computer. Some manufacturers (most), place a small sensor inside the tire. The valve core, the object that you attach the air hose to in order to inflate a tire, acts as an antenna.
This antenna sends a beacon to your car’s computer, notifying the computer if the pressure is acceptable or not. These notifications get sent hundreds of times per second.
Each tire has a sensor, and each sensor is registered with the computer by the tire location.
| Sensor Id | Tire Location | Tire Pressure |
|---|---|---|
| 120452 | Front Right (Passenger) | 32.2 PSI |
| 120453 | Front Left (Driver) | 32.1 PSI |
| 120454 | Rear Left (Driver) | 33.0 PSI |
| 120455 | Rear Right (Passenger) | 32.8 PSI |
This is how your car’s computer will read your tire pressures, and notify you if any of the pressure’s are too low, or high, by displaying a notification on the dashboard.
Other car manufacturers take an outside-in approach. This approach uses sensors already mounted on the car that monitor wheel speed in revolutions per second.
When a tire becomes under inflated, the wheel speed sensor would measure an increase in revolutions because the tire becomes smaller in diameter.
This is the method used by a lot of imported cars like Mercedes and Infiniti. The wheel speed approach removes the need for in-tire sensors, which can be costly (they start around $125 each).
If a faster than normal, or slower than normal speed is sensed, your dashboard will notify you about the issue by displaying the TPMS light.
Specifying Your Own PSI
Once you are comfortable with setting the correct pressure in your tires, and are looking for performance improvements, it may be time to test out your own pressures.
But beware, adjusting anything more than 5 PSI can be extremely dangerous.
That being said, if you were expecting to go on a long trip and wanted to save on gas, adding 3 or 4 extra pounds to each tire would improve fuel economy. And on the flipside, if you’re tracking treacherous terrain like curved roads and dirt trails, lowering the PSI a couple pounds can improve traction.
But it’s important to know how to add and subtract pressure, before you set out to specify your own values. As a test, try adding just one pound of air to each tire and notice the difference. You’ll probably immediately notice a looser steering wheel, and over time, you’ll see savings on fuel.
While there are many different theories on tire pressures, it’s important to stick to foundations. Utilizing any other methods are considered advanced, and should only be used by driver’s with great experience in maintaining tires. And when in doubt, always use the door jamb information to set your tire pressures.
About The Author
Christopher Sparks has been servicing vehicles since 2012. After completing the automotive studies program at Camden County College, he was awarded an Associates’s Degree in Applied Science. His first job was a lube-tech at Jiffy Lube, and is currently an independent B-Technician servicing vehicles for the United States Postal Service. Christopher is ASE certified and loves rebuilding engines.
Cars that suffer from improperly-inflated tires can never deliver the exceptional engine and steering performance one might hope for. Hence, learning all there is to know about tire inflation is important – particularly the meaning of PSI in pressure.
My experienced team can save hours of research for you by compiling the most critical information into one single article. Keep scrolling for more of my take.
In this article:
What Does PSI Stand For?
PSI stands for Pounds per Square Inch, representing the minimum air pressure required for the car’s max load. You can find this spec in the manual or on a sticker on the driver’s door. Air pressure should always be kept at that ideal level.
Properly inflated tires ensure you can enjoy the following benefits:
a. Safety
Correct PSI levels ensure sufficient contact between the tire and the ground, producing enough friction – neither too low nor too high – to put premature wear at bay. Hence, you never have to worry about possible accidents, tire blowouts, or tread separations.
b. Comfort
Nothing is better than a smooth and no-bump ride from beginning to end – which can only be achieved with the right amount of inflation. As the tread wear is even, you will hardly feel any bounce or bump, even on rugged terrains.
c. Longevity
Tires devoid of premature or uneven tire wear will last far longer than expected, saving you both time and effort. Gone are the days when you have to drop by an auto shop every few months to purchase replacements or have the tires fixed.
d. Fuel Efficiency
The U.S. Energy Department has reported a significant increase of up to 3% in gas mileage when car tires are appropriately pumped. As gas pricing has become more of a headache in recent months, this competitive edge can be a lifesaver for tight-budget families.
What Is The Ideal PSI For Car Tires?
The recommended tire pressure varies slightly with car size. The safest range for passenger cars is 32-35 PSI, for SUVs is 40-42 PSI, and for trucks is 50-60 PSI. This number should be measured when the tires are cold.
“Cold” refers to the tire’s state before sunlight exposure or hours of usage. And it would be best to check your PSI when the tires remain in such a state; otherwise, the excess heat and road friction they receive during driving will inevitably increase the pressure. Any attempt to check or read the PSI will not be accurate by then.
How Should I Check The PSI Of My Tires?
For those not sure how to process, trace along with my detailed, step-by-step guide below, which I have used for years to check the PSI levels of my own tires:
Step 1. Start When The Tires Are Still Cold
As discussed right above, the manufacturer’s recommended PSI only applies to cold tires – meaning the tires have been unused for at least 3 hours or traveled less than one mile (or 1.6 km) at medium speed.
Step 2. Confirm The Required PSI In Your Manual
Any vehicle’s manual should have at least one portion discussing the PSI level in detail. If you can’t find the manual, no worries; there are still two other viable solutions:
- Look that the door jamb (driver’s side) for the information sticker
- Consult professionals, vehicle manufacturers, or car dealers
Certain cars have different recommended PSIs for front vs. rear tires. If that is your case, write these numbers down somewhere accessible; that way, you will not get confused while moving around to check each tire’s pressure.
Step 3. Use Your Tire Pressure Gauge to Check The Tire Pressure
Once making sure you have the gauge ready, perform each task one by one:
- Remove the tire’s valve cap and locate the valve stems.
- Put your gauge on that stem, then press hard until all hissing sounds disappear. At that point, the gauge should have yielded some accurate readings.
Standard gauges often have measurement units embedded in a tiny bar at the bottom. Meanwhile, digital gauges are way more convenient, showcasing the specific number on the screen; all you need to do is read it.
Regardless of your gauge type, write the reading down and repeat the above steps to the other three vehicle tires.
Step 4. Fill Your Tires to The Required PSI
For low pressure, I suggest using air compressors to refill your tires. Since air compressor models vary vastly, read their directions thoroughly to ensure proper usage.
Some drivers prefer to use air compressors at gas stations instead of buying one. If that is your case, insert coins into the machines all through until the motor starts running. After that, ensure the compressor hose reaches every tire by placing the hose end over the stem and pushing the lever hard.
Air compressors at gas stations tend to get the tires “hot”, which is why you should probably set your pressure at approximately 4 PSI higher than the recommended level (ex: if the manual says 32 PSI, inflating your tires to 36 PSI would be ideal). Do not forget to recheck after the tires eventually go cold.
Step 5. Check The PSI Again With The Gauge
After filling every tire, check your pressure again with the gauge. Use the pump or stem to release some air if you have accidentally overfilled the tires.
How Often Should I Check The PSI In My Tires?
Although it is all up to your schedule and preference, a monthly basis will be the best bet. Regularly monitoring the tire pressure gives you ample chances to catch any signal of wrong inflation or gradual loss before the situation worsens.
And that could save you quite a few bucks.
While you are at it, it would be great to examine other tire compartments, too, such as uneven patterns, damage, wear, punctures, or cuts. Have them fixed as soon as possible to ensure tire integrity and, in turn, the car’s optimal performance.
What Happens If I Overinflate or Underinflate My Tires?
The consequences of under- or over-inflated tires should be clear for now: bumpy rides, uneven wear, shorter shelf life, and compromised car safety are only some of them.
On certain occasions, straying a bit further from the recommended air pressure is fine, but do not let the extra drop/increase exceed 4 PSI.
Suppose your passenger car tires need a maximum pressure of 35 PSI; then stretching to 39 or stooping to 31 PSI should be the final limit. Anything further than that, and your car is sure to encounter danger.
Conclusion
I hope my guide has given you the answer you need about the PSI in cars.
Maintaining proper tire pressure is not difficult, but requires constant attention. Keep a consistent check schedule, especially before any long trip.