Your car's tires play many valuable roles in the safety and function of your vehicle — from helping you navigate twists, turns, and stops like a pro to carrying the full weight of your car. That's why it's important to pay special attention to these essential components.
Fortunately, maintaining the proper tire pressure on your vehicle is one of the easiest yet most effective ways to care for your car tires. Learn how to check air pressure and inflate your tires with this helpful guide.
Underinflated tires can not only reduce fuel efficiency, but it can also run the risk of getting into an accident, losing proper steering control, damaging various components of your vehicle, and more. If you notice that your tire's air pressure levels have dropped, it's best to prioritize inflating them as soon as possible.
Checking your vehicle's tire pressure is a relatively simple task. You'll want to start by purchasing a tire gauge. These vary in price depending on the type you choose (i.e., digital, basic, etc.) but can usually be found for well under $40. It's also essential to keep a tire gauge on hand, as some gas station air hose gauges are not always accurate. Many modern cars and trucks also display the tire pressure for each tire on the dashboard. Once you have your tire gauge in hand, it's time to determine the proper pressure for your vehicle.
Find the correct inflation level. To do this, you can either look for the recommended pressure on the sticker within your driver's-side door jamb or consult your car owner’s manual. This is the tire pressure specification when the tires are cold, meaning not driven for a few hours.
Remove the valve stem cap from your tire. Some cars and trucks have green valve stem caps with an “N” on them - this means the tire is filled with nitrogen instead of air (air is mostly nitrogen). If your tires have these green valve stem caps, you can find some special stations that dispense nitrogen, but be aware that you can use normal air as well.
The inflation pressure specifications are the same regardless if the tire is filled with air versus nitrogen.
Connect your air pressure gauge to the tire’s valve stem until you receive a reading.
If the pressure level number seems unrealistic, remove the gauge and try again. This time, ensure that the indicator is connected firmly to the valve stem.
It's not always possible to tell if a tire is underinflated by giving it a quick once over. So, check your PSI levels with a gauge each month and after extreme temperature changes. You'll also want to check your pressure levels when your tires have had time to cool down since air expands within your tires while driving.
Filling your tires with air at a gas station is relatively simple. Bring your tire gauge and some spare change since some are coin-operated and are not always accurate in their pressure readings. Try to make this the first stop if you are running errands so that your tires are still relatively cool from sitting for a few hours.
Then, follow these steps:
Can't find an air filling station near you or just want some help? Head to your local Firestone Complete Auto Care. We'll give you a free tire inspection and refill your tires free of charge. And if you need new tires, we've got you covered there too!
We all know that routine maintenance is important for everything from our computers to our cars. But sometimes, we fall short. One of the most neglected routine car maintenance tasks is to check tire pressures and inflate them as necessary.
That’s why newer cars have tire pressure warning lights, or tire pressure monitoring systems (TPMS), that let you know when you have under- or over-inflated tires (when any tire is 25% underinflated).
Older vehicles don’t have this useful warning light. So, don’t wait for a rupture to check or change a tire. Use this guide to learn how to check the pressure (PSI) of your vehicle tires and how to inflate them to the proper air level.
Why should you check your tire pressure?The number one reason why you should periodically check your tire pressure is SAFETY, but there are monetary and handling reasons as well:
Proper tire pressure (as recommended by the manufacturer) is needed to drive safely and efficiently. According to a 2009 report by the National Highway Traffic Safety Administration:
“…about 28% of light vehicles on our Nation’s roadways run with at least one underinflated tire.
Only a few psi difference from vehicle manufacturer’s recommended tire inflation pressure can affect a vehicle’s handling and stopping distance. Poor tire maintenance can increase incidences of blowouts and tread separations. Similarly, underinflation negatively affects fuel economy.”
When your tires are underinflated, the tires get fatter, increasing their surface area. This causes high heat generation and extra resistance that could result in higher fuel costs, blown out tires, tire wear, and loss of control.
If you feel like you’re spending too much at the gas pump, it might be your tires. According to the US Department of Energy:
“You can improve your gas mileage by 0.6% on average—up to 3% in some cases—by keeping your tires inflated to the proper pressure. Under-inflated tires can lower gas mileage by about 0.2% for every 1 psi drop in the average pressure of all tires.”
In addition to safety and fiscal concerns, keeping your tires properly inflated will also reduce your impact on the environment.
When your tires are properly inflated, you’ll pay less for gas, replace your tires less often, and improve your handling and stopping distance. You’ll also feel better knowing that you are emitting less carbon dioxide and other harmful substances into the atmosphere.
PSI stands for pounds per square inch. The recommended PSI for your vehicle’s tires is determined by the vehicle’s manufacturer and the recommended tire size.
One big question that we get is whether you should follow the recommended PSI level on the tire itself or the recommended PSI level printed in your owner’s manual or on the placard inside of door edge, glove box door, or fuel door.
Do NOT use the max PSI that is printed on the tire sidewall. This is not the recommended PSI level. The pressure amount on the tire is normally the maximum allowed pressure. The correct PSI level is almost always less than what you see printed on the side of the tire.
Over-inflation can lead to poor handling and comfort, overheating and blow outs. Over 40 PSI is a dangerous level for most vehicles!
Make sure you always use the recommended PSI as provided in your owner’s manual and don’t go any more than 5 PSI over the recommended level. You should make sure, however, that your tires are appropriate for your vehicle. You can do this by checking the car’s owner’s manual or the placard that is on the inside of the driver-side door, glove box, or fuel door.
Most car tire pressure recommendations range from 30-35 PSI.
How often should I check tire pressure?A question in many minds is when is the appropriate time and frequency for checking and inflating vehicle tires.
A quick google search will reveal a variety of different opinions and suggestions. Some say that you should check your tire pressure every 2nd visit to the gasoline station, while others say once every 3-6 months is OK.
Most tire and vehicle manufacturers, on the other hand, will say that you should check your tire pressure at least once every month, or every second trip to the gas pump.
Your tires will lose around 1 PSI each for every month that goes by.
Unfortunately, not one answer will fit every situation. There are several factors that influence how often you should check your tire pressure, including:
Did you know that for every 10°-drop in temperature, you lose 1 pound of pressure?
If you have a leaky valve or a small puncture, you will lose air pressure much more quickly. This is one more reason why you should frequently check the tire pressure on all of your tires.
Since tire pressure constantly fluctuates, it’s important to check it periodically (at least once a month) and add air as necessary.
How to Check Tire PressureFinding out the tire pressure of your tires is incredibly easy. All you need is a pressure gauge (click here for additional items you should have in your vehicle).
Just make sure that you are checking your tires when they are relatively cold. If you check your tire pressure after a long drive, you will get an inaccurate reading since heat will temporarily increase the tire pressure reading.
Unfortunately, not all pressures gauges are created equal. Some are better than others. We recommend shelling out a couple extra bucks for a digital reader. The pop-up, stick-type versions are notoriously inconsistent and unreliable. A reliable gauge will be well worth the investment. Prices range from about $5 for the stick-type and about $30 for the digital and dial-type pressure gauges.
You can also check your tire pressure at most gas stations or auto repair shops. Discount Tire offers free tire pressure checks and inflation.
Here are the steps for checking your tire pressure:
It should only take you a couple minutes to check the air pressure of your vehicle’s tires. As soon as you restore tire pressure to the recommended levels, you’ll start experiencing the safety and savings that come with this regular maintenance task.
Watch this video for more information on how to check your tire pressure:
How to Inflate TiresHere are the steps for adding air to your tires:
If your local gas station’s air pump doesn’t have this capability, then you will need to fill up the tire, check the pressure with your gauge, and then add or release air as necessary. Some air pumps will have a built-in tire pressure gauge. Once the PSI level is set, feed coins into the machine until you hear the air coming through. It will be pretty noisy.
Check the air pressure as you go and refill or release air as necessary.Remember, just one drop in PSI can lower your gas mileage by about 0.2%. For every 3-4 PSI units that your tire is underinflated, you are burning around 1% more fuel.
If your tires are flat, then you probably have a leak. Add air and see if you can drive around without the pressure dropping. If you hear air escaping the tire while you are filling up, then it’s time to replace the tire.
Tip: Learn how to use the air pump properly first. Some automatic air pumps at gas stations have a handle/switch that you need to depress in order for the air to flow. When you let go of the handle, a tire pressure gauge will pop out showing you the tire pressure. At the same time, air will be slowly released. If your air pump has this kind of handle, then you will want to hold down the handle for most of the time, periodically releasing it to check the pressure reading. Consult your own tire pressure gauge for accuracy.
When should I replace my tires?If you check your tire pressure at least once a month as recommended, you’ll also get a good idea of the general condition of your tires and when you should replace them.
We recommend using the penny test:
Source: bridgestonetire.com
Click here for more car maintenance tips. Click here for car winterization tips.
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Inflating car tires with nitrogen instead of ordinary compressed air is offered in many tire shops and car services - the availability of this service in recent years has become commonplace, like the offer to wax the car body after washing. As with many products with unobvious practical benefits, the use of nitrogen in tires is fraught with controversy.
Physics and life
Sellers of nitrogen, convincing the car owner to use the service, list a wide range of benefits. Among them is the reduction of leaks through the tire surface due to the fact that nitrogen molecules are larger than the oxygen and water vapor molecules contained in atmospheric air. Also mentioned is the smaller mass of nitrogen compared to air for the same volume of gas pumped into the wheel.
In addition, it is generally claimed that filling tires with nitrogen instead of atmospheric air containing oxygen and water avoids corrosion, that is, oxidation of the inner surface of the wheel and the metal elements of the tire cord. They promise even more stable tire pressure with temperature changes.
Opponents of the use of nitrogen indicate that it is already about 80% in atmospheric air, and no more than 95% in technical nitrogen, which is used in tire shops. In addition, they point out, referring to a school physics course, that replacing air with nitrogen cannot make the pressure stable, since the coefficient of thermal expansion for all gases is the same. The effectiveness of using nitrogen to reduce leaks is also questioned: they are more noticeable when a tire is leaking or a valve is malfunctioning. Yes, and the mass of 1 m3 of nitrogen (at a temperature of 0 ° C and a pressure of about 100 kPa) is less than the mass of a “cube” of air by about 25 g.
We have reached out to several tire companies for expert comment.
From what angle do experts see this issue?
Pirelli
In terms of everything, there is absolutely no difference between tires filled with nitrogen and tires with regular air, unless you are a professional race car driver and every unit of measurement is important to you. Due to nitrogen, for example, you can make tires lighter by only a few hundredths of a gram, and you will definitely not feel any difference in driving comfort on ordinary roads. All other arguments in favor of nitrogen are also dubious. For example, nitrogen is widely believed to protect the inner carcass of tires from oxidation and corrosion. But the cord threads are already so well hidden in the thickness of the rubber that they do not come into contact with air. Another opinion is that a tire with nitrogen almost never deflates. This is also a controversial statement: the tire deflates due to factors such as age, the presence of punctures, etc., and not from what it is inflated with.
Thus, inflation with nitrogen will not bring harm to the tire, but there will not be any particular benefit either. But checking your tire pressure regularly is something that will really help you ensure safe and comfortable driving and maintain tire life.
Bridgestone
In recent years, the service of filling car tires with nitrogen (both cars and trucks) has become very popular and causes heated debate. An interesting fact is that initially only tires of racing cars were filled with this substance. Subsequently, European and American tire shop owners took over and began to offer this service in their service centers. Not so long ago, about 10 years ago, the practice of inflating tires with nitrogen reached the post-Soviet countries.
The whole long list of arguments in favor of using nitrogen can be summed up in a more general phrase: tires filled with nitrogen are more comfortable to drive. In our opinion, this is a little trick of the experts, since it is enough to pump a couple of tenths of the atmosphere into the wheels less, and you can feel the softness when driving.
An impressive argument in favor of this service is the following judgment: Nitrogen in the wheels improves driving safety, and it is not in vain that it is used on race tracks. Indeed, the wheels of racing cars are filled with nitrogen. This is done for safety reasons, since tires inflated with nitrogen, at high speeds, as a result of increased friction, heat up less than tires pumped up with oxygen. However, under normal operating conditions, the difference in pressure when the tire is allowed to heat up will be thousandths of an atmosphere, which can not always be noticed even experimentally.
Summing up our position, we can say that filling with nitrogen will not lead to significant improvements in handling on the road, increased driving performance, increased tire wear. But the final decision, of course, remains with the car owner.
Continental
Inflating tires with nitrogen comes from elite motorsport, where split seconds count. In general, the riders wanted to stabilize the pressure during severe tire temperature fluctuations, as well as reduce air leakage from a light sports tire during long-term and heavy loads.
When we talk about civilian cars, tires and conditions, this procedure is completely unjustified, because the air we breathe contains about 80% nitrogen. Continental believes that road safety is more affected by regular, at least once a month, checks on tread height and tire pressure.
Michelin
Nitrogen is an inert gas. In fact, it is just dry air without oxygen (air contains about 79% nitrogen). The physical properties of nitrogen reduce pressure loss due to the natural permeability of tire materials. Unfortunately, there are other possibilities for leakage (tire-rim interface, valve (nipple), valve-rim interface, wheel) that cannot be guaranteed to maintain pressure when using air or nitrogen to inflate tires. Tires manufactured by Michelin are designed to perform as expected when inflated with air or nitrogen if the customer adheres to the pressures recommended by the vehicle manufacturer and indicated on the vehicle data plate or by the tire manufacturer.
Regardless of whether the tires are inflated with air or nitrogen, it is very important to check the tire pressure regularly, as low tire pressure leads to the following consequences:
■ Reduced directional stability,
■ Reduced wet traction,
■ Increased sensitivity to road hazards,
■ Reduced tread life,
■ Increased fuel consumption,
■ Reduced tire life due to excessive heat generated from for excessive deformation.
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Tire pressure significantly affects driving parameters: comfort, car handling, economy and safety. It is important to maintain the pressure recommended by the manufacturer and check it regularly. Let's figure out how to do it right.
When driving on asphalt, incorrect tire pressure (both high and low) leads to a decrease in the contact patch with the road.
An overinflated wheel clings to the surface only in the central part, which leads to its rapid wear. A poorly inflated tire, on the contrary, "sits" on the sidewalls, leaning on the shoulder areas of the tread and pushing the central part inward. Here's what it looks like:
Both under-inflation and over-inflation in tires create many problems for the driver.
1. Increased wear on the central part of the tire tread.
2. Reduced ride comfort, hardness of potholes and road bumps.
3. Increased load on the car's suspension due to reduced tire damping effect.
4. Risk of tire damage and herniation due to shock loading (getting into a pit or pothole).
5. Reduced control stability due to reduced contact patch.
1. Increased wear of the tread sidewalls (shoulder areas).
2. Severe deformation of the rubber when driving over bumps, which increases the risk of tire damage.
3. An increase in tire temperature, which threatens to delamination of the carcass and can lead to tire explosion at high speed.
4. Increased risk of hydroplaning on wet roads.
5. Risk of tire breaking.
6. Increased fuel consumption.
Reduced pressure hits the driver's pocket hard: a pressure drop of 20% (which is not uncommon: it is enough, for example, to deflate the wheels to 1.8 atmospheres instead of the 2.2 prescribed by the manufacturer) reduces tire life by 25-30% and increases fuel consumption fuel by 3%.
There is no universal tire pressure: it depends on the size of the tires, the characteristics of the car (primarily weight) and road conditions. Therefore, it is important to follow the factory recommendations, maintaining exactly the tire pressure that the engineers expected when designing the car.
The recommended pressure for your machine can be found in the operating instructions and on the sticker in the door frame.
If, depending on the configuration, tires of several dimensions were installed on the car, then the pressure recommended for them may differ - look in the table for your exact wheel size. The manufacturer may prescribe an increase in tire pressure at the maximum load of the machine. For the spare tire (Spare tire), the required pressure is also indicated on a separate line - note that it is much higher than the standard one.
So, you have found the necessary pressure parameters, it remains to decipher them. In physics, pressure is measured in pascals, in real life - in anything: in bars, atmospheres, pounds-force, kilogram-force ... Drivers and tire workers usually use the term atmosphere, but such a unit is often absent on pressure gauges (pressure measuring devices) . Let's clear up this confusion.
Atmosphere is a non-systemic unit of measurement, approximately equal to atmospheric pressure on the surface of the Earth. Since it has become widely used, it was necessary to somehow equate it with correct physical units.
For simplicity, one atmosphere is considered equal to one bar, one kilogram-force and one hundred kilopascals.
In addition to the technical atmosphere (at), there is also the physical atmosphere (atm), which is slightly larger. Again, for convenience, they are considered equal. But all these assumptions introduce an error, so if you need accurate tire pressure, measure it correctly - in pascals or bars. Moreover, manufacturers usually indicate the pressure in these quantities.
Imperial pounds-force (aka PSI, “psi”), popular in the USA, is more difficult to translate, here you can’t do without a calculator. In the table, we have collected together all pressure units with exact values, and also approximately brought them to each other to simplify calculations:
| Pressure units | |||||
| Pascal | Bar | Technical atmosphere | Physical atmosphere | PSI | |
| 1 Pa | 1 N/m² | 10-5 | 10. | 9.8692•10-6 | 145.04•10-6 |
| 1 bar | 105 | 1x106 dyne/cm² | 1.0197 | 0.98692 | 14.504 |
| 1 at | 98066.5 | 0.980665 | 1 kgf/cm² | 0.96784 | 14.223 |
| 1 bar | 101325 | 1.01325 | 1.033 | 1 bar | 14. |
| 1psi | 6894.76 | 68.948•10-3 | 70.307•10-3 | 68.046•10-3 | 1lbf/in² |
It is advisable to check tire pressure daily, before driving. But this is only possible with a very measured rhythm of life. In reality, checking at least once a month is already an excellent indicator for the average driver. But before traveling a long distance, checking the pressure and visual inspection of tires and rims should be done in any case.
It is necessary to measure the pressure in cold tires, that is, before driving. During driving, the tires heat up, which increases the pressure by about 10%. Therefore, never release supposedly excess air from hot tires: after cooling, the pressure will be below normal.
If you had to inflate a hot tire during a trip, inflate it 10% more than the nominal value, and check the pressure again when the wheels have cooled down - no earlier than 3 hours after stopping.
Always check the pressure in all tires. Different tire pressures seriously affect handling and can cause the car to pull to the side. Do not forget about the "spare tire": it should always be inflated in case of an unexpected wheel change on the road.
For long periods of driving at high speeds (more than 160 km/h), car manufacturers advise increasing tire pressure by 0.2-0.4 bar from the recommended value. This will slightly improve the handling of the car, although it will negatively affect comfort. But such advice is relevant for driving on high-speed autobahns, and not for everyday urban use, especially in Russia.
Before a long trip on a dirt road or a road with a muddy surface (mud, snow), it is reasonable, on the contrary, to reduce the pressure in the tires - this will improve the grip.
In summer, it is worth limiting yourself to reducing pressure by 5-10% of the nominal value, and in winter - by 10-15%.
The pressure in low-profile tires (especially non-standard sizes) must be monitored especially carefully. Low profile tires have two features: a low sidewall (profile) height and a large rim diameter. If the tire has the correct air pressure, only the tread is in contact with the road. Low pressure causes the sidewall of the tire to bend, causing it to touch the roadway and wear out quickly, up to complete abrasion. And punching a low-profile tire in a pit at low pressure is much easier.
When inflating low profile tires, you need to focus on the pressure indicated for a full load of the machine and the maximum allowable pressure for a particular tire. It is indicated on the sidewall, next to the inscription max pressure, in one of the accepted units of measurement: kilopascals (KPA), bars (BAR) or pounds-force (PSI).
197•10-6 
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