Maintaining correct tire inflation pressure is very important since it helps optimize tire performance and fuel economy while over-inflated tires are just as problematic as under-inflated ones.
In fact, driving with under-inflated tires is one of the biggest causes of tire failure, according to the National Highway Traffic Safety Administration.
Besides, under-inflated tires can cause many other problems such as wearing out more rapidly, handling poorly and reducing fuel efficiency.
In addition, over-inflated tires are more susceptible to damage from road irregularities, and this also creates a bumpier ride.
Overfilling your tires is just as dangerous as under-filling them, so it’s important you know what is recommended for your vehicle.
This article will give you everything that you need know about your recommended tire pressure. These include:
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Recommended tire pressure, where to find it?Since tire pressure is so important to your safety and your car’s overall performance, it is important to know which level of tire pressure is right for your vehicle.
In fact, how much air pressure your tires need depends on several factors, including the type of vehicle, the type of tire and the intended use of the vehicle etc.
Air pressure in tires is measured in pounds per square inch or PSI. You can find your tire pressure both inside your car and on the sidewall of the tire.
How to find recommended tire pressure inside your carYou could find the manufacturer’s optimum or recommended tire pressure for your car on a sticker in the door jam, or in your owner’s manual. Some car models even place the stickers on the trunk lid, in the console or on the fuel door. For best results, look for a placard on the inside of the driver’s door, like the example in the photo below.
How to find maximum tire pressure on the sidewall of your tiresSomewhere on the sidewall of your tire, just below the big, bold letters of the manufacturer, for example, you might have noticed the words ‘Max.
Press. 35 PSI.’ (pounds per square inch).
That number tells you the maximum cold pressure needed for your tire to carry its maximum load.
Most typical tires require about 32 to 35 pounds per square inch (PSI) of air, says Rod Tate, owner of highly rated Colony One Auto Center in Stafford, Texas.
Large trucks require much larger tires with PSIs of 50 to 60. Heavy-duty vehicles can go even higher. For example, tire in the picture below requires 41 pounds per square inch of air.
However, the tire’s maximum pressure is NOT necessarily the most suitable pressure for every vehicle upon which the tire can be used (almost all vehicle manufacturers’ recommended tire inflation pressures are less than the tires’ maximum pressure).
You really should follow the recommended pressure printed somewhere inside your car or in the manual rather than the maximum pressure. In the next section, I will explain why.
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Why is maximum tire pressure not the best?If you insist on inflating your tires to the max PSI, there will be more likely that two things below will happen
Since tires inflated to the max cannot give as much on the sidewall, you might see superior cornering, but it could be at the risk of your braking threshold.
One quick corner and your back end could slide out.
When your tires are inflated too much, the rubber rounds out at the top of the tire when you are driving, and the center will quickly wear out. You will also reduce your traction and you could even cause a blowout.
Therefore, maximum pressure is not the best, rather, recommended pressure is. I need to repeat here that the pressure listed on the sidewall is a maximum pressure only, but not a recommended pressure. Instead, you should use the air pressure recommended in the vehicle’s owner’s manual or tire information placard label.
How to check your tires pressure?Therefore, maximum pressure is not the best, rather, recommended pressure is. I need to repeat here that the pressure listed on the sidewall is a maximum pressure only, but not a recommended pressure.
Instead, you should use the air pressure recommended in the vehicle’s owner’s manual or tire information placard label.
After knowing the most appropriate pressure for your car tires, you should check whether your tires have such pressure. In addition, checking the pressure of your tires regularly is one of the most important – and most often overlooked – regular maintenance that you should do to ensure your safety and quality of your driving. Monitoring the amount of air in your tires will let you know if you have a small leak and can help you avoid an unexpected flat tire.
Frequently checking your PSI becomes even more important in the fall and winter, when outside temperatures drop and weather conditions fluctuate causing your tires to lose air more quickly. Generally speaking, your tire will gain or lose one PSI for every 10-degree change in temperature, which means if you have a sudden drop of 30 degrees, you could lose three PSI overnight. If your tires were already low, this could cause tire damage, steering problems or even a flat tire.
Some experts recommend that you should check the air pressure every time you refuel; others say once a month is sufficient.
How to check tire pressure properly? Checking tire pressure is easy. You can do it right at home or at the gas station. Just be sure you check the pressure when your tires are cold, or have not been driven in several hours. This will give you the most accurate reading.
The most important piece of equipment you need is an accurate tire pressure gauge. You can find battery-operated digital gauges, or more traditional stick-type gauge found at most gas stations. A good gauge should not set you back more than $15 – a worthwhile investment for a longer life for your tires.
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Make sure you have your manufacturer’s PSI handy when you are checking your tire pressure, and then follow these steps:
By checking tire pressure once a month, you will get a good idea how they are performing. If your tires are fairly new and continue to leak air, you should consult your dealer or mechanic. You may have a faulty valve or other damage that is difficult to detect which could unfortunately result in the need to replace the tires completely.
But with proactive maintenance, you could catch an issue before it becomes a problem, and just end up needing a small repair.
Often, it is hard to spot an under-inflated tire until it is too late – in other words, it is completely flat. Of course, you could carry a gauge around at all times to measure the pressure, but that is not exactly convenient. Instead, watch for these signs and symptoms of tires that are under-inflated.
When your tires are under-inflated, your ride can be less smooth than usual. You may even find that it takes longer to brake.
When a tire is not inflated properly, it wears down more quickly. If you notice that one or all of your tires are wearing out faster than usual, it may be because they are under-inflated.
Tires that are under-inflated can make your vehicle quiver and shake, which is not a pleasant driving experience.
Under-inflation can even cause tires to become misaligned, with comes with it is own variety of problems.
These are all things that you need to know about recommended pressures of your car tires. After reading this article, you will never confuse about the right pressure of your tires and will know how to check it.
Please share your ideas with me if you have other tips for this.
When it comes to driving safety, tire pressure is always one of the hottest topics. Why does tire pressure matter? What the heck is that little annoying symbol on my dashboard? Should I under-inflate my tire during the winter? How often should I check my tire pressure?
We got tons of questions like this from our community, so for today, let's dive deep into the world of tire pressure, put our geeky glasses on and figure out everything you need to know about your tires.
1. What's The Recommended Tire Pressure For My Car?
The recommended tire pressure varies based on the vehicle makes determined by the manufacturer after thousands of tests and calculations.
For most vehicles, you can find the ideal tire pressure on the sticker/card inside the driver’s door for newer cars. If there’s no sticker, you can usually find the info in the owner’s manual. Normal tire pressure is usually between 32~40 psi(pounds per square inch) when they are cold. So make sure you check your tire pressure after a long stay and usually, you can do it in the early morning.
2. How To Check The Tire Pressure?
After knowing the proper tire pressure of your vehicle recommended by the manufacturer, you should check your tire pressure regularly to make sure that you are in good shape.
You can check your tire pressure in auto part stores, the mechanics, gas stations, and at home. To check tire pressure at home, you need:
As tire pressure changes with the temperature a lot, and recommended tire pressures are cold inflation pressure, you should start with cold tires if possible.
We mostly check the tire pressure after one night's rest to avoid the heat from the friction of the last drive, and before the temperature goes up.
Unscrew the valve cap and press the tire gauge onto the valve stem hard enough until the hissing sound disappears. There should be a reading as long as the gauge is well connected to the tire.
You can then note down the tire pressure of each tire, and compare them with the ideal psi you read from inside your driver’s door or in the owner’s manual. Make sure you read in detail, as for some vehicles, front and rear tires have different recommended psi.
If you find a tire underinflated, use the air compressor to fill your tires. You can either buy an air compressor in the auto parts store or use one in a gas station. Remember to rest your tires for at least half an hour to make sure they’re cold and the reading is accurate.
If you have to fill your tires when the tires are hot, inflate them 3~4 psi above the recommended psi, and check again with your gauge when they are cold. It’s ok to overinflate a bit when filling the tires, as you can let the air out with the gauge.
After filling the tires, use your tire pressure gauge to check the tire pressure again and make sure they are in a good range. Let the air out a bit if they are over-inflated by pressing the gauge harder on the valve stem.
3. How To Maintain Proper Tire Inflation?
Tire maintenance is essential for the overall performance of your vehicle, and we highly recommend that you check your tire pressure every time you inflate your tire, each 10°F (5.6 °C) temperature change, and every 30 days.
Be mindful that don’t wait until the TPMS(Tire Pressure Monitoring System) light come on before you check the tire pressure, as the normal TPMS may:
..For more information about the tire pressure monitoring system, please check our post about TPMS: What is TPMS and Why Does it Matter?
Thus, we highly recommend that you check your tire pressure regularly, especially before a long drive or heavy load driving. Also, temperature affects the tire pressure a lot, and we will explain it in the next section.
4. How Does Temperature Affect Tire Pressure?
First of all, the rule of thumb is for each 10°F (5.6 °C) decrease in temperature, the tire pressure will drop by one psi for most passenger vehicles. When it comes to commercial truck tires, which are often inflated to over 80 psi (twice as much as a passenger vehicle tires), the change of tire pressure according to temperature is doubled to 2 psi for every 10°F.
For the non-nerdy readers, just remember this rule of thumb and keep in mind that you will need to monitor your tire pressure during different seasons or a sudden temperature change.
For those who want a deeper dive into how psi's are determined, here's the science behind it.
The equation we use to calculate the relationship between tire pressure and the temperature is called the Ideal Gas Law. It is a good approximation of the behavior of many gases under many conditions. (Appx1) It works well for most low-pressure gases. When applied to tire pressure calculation, the error is less than 1%.
First, we take the Ideal Gas Law equation and apply it to our circumstance:
where,
P = absolute pressure
V = gas volume in the tire
n = the number of molecules of gas in the tire
R = universal gas constant
T = temperature
Since we are trying to examine the pressure change according to the temperature, let's assume two tire pressures P1 & P2 at their set temperatures T1 & T2.
Given the n and R are both constants, and the gas volume in the tire is also a constant, we can take those constants out of the equation, and suddenly we get this straightforward one:
Let's say the temperature drops from 100°F to 50°F, the tire pressure at 100°F is 35 psi, so what's the tire pressure now at 50°F?
(the metric system is getting in the way, huh?)
Absolute Pressure = tire pressure + sea level air pressure (14.7 psi). So,
Put all that into the equation,
So a 50°F drop in temperature lowers the air pressure by 4.5 psi, which is pretty much the same according to our rule of thumb.
5. How Does Tire Pressure Affect Driving
Both overinflation and underinflation affect your tire performance a lot, and serious problems might occur. According to NHTSA(National Highway Traffic Safety Administration), driving on underinflated tires increases a driver's chance of being in a serious accident by 300%.
So how will a bad tire pressure affect driving safety? We will explain in detail below.
The grip is mostly associated with the size of the contact patch between the tire and the road. An over-inflated tire radically decreases the contact patch while an under-inflated tire does the opposite.
A larger contact patch gives you more grip, and this is the exact reason why lots of racers will intentionally decrease their tire pressures to create a larger contact patch on a dry race track.
However, despite the fact that an under-inflated tire will cause more fuel consumption and improper tear and wear of the tires, for most daily commuters, it might cause an even scarier problem, which is hydroplaning.
Hydroplaning is a hazardous event when a layer of water builds between the wheels and the road surface, leading to a loss of traction that prevents the vehicle from responding to control inputs. (Appx2)
Hydroplaning occurs when the pressure of the tire pushing on the ground is equal to the water pushing back up on that tire.
The size of the contact patch, given the force or the weight of the tire, is the same, directly affects the average pressure the tire's putting down on the road. The larger the contact patch (by deflating the tires), the less pressure it puts on that same area. So there's a causal relationship between your tire pressure and the possibility of a hydroplaning event.
Here's a more visual explanation of what is happening between a properly-inflated tire and an underinflated tire when driving on a wet road.
To avoid a hydroplaning event, ALWAYS inflate your tires properly. Also, check your tires' treads, which make the water flow around the tires more efficiently, and of course, driving slow is always a big plus.
How tire pressure affects tire wearThe contact patch directly decides the pattern of the tire's wear and tear. You don't want your tires to wear out prematurely just because you have an over or under-inflated tire.
Imagine you are a ball rolling on the ice, there's no friction between the two surfaces, how much extra force do you need to apply to keep the ball moving? Zero (Thanks, Newton). The same applies to your fuel consumption when it comes to driving on the road. The rolling resistance between your tires and the road significantly affects fuel economy, and by now we should all know the logic behind this, lower tire pressure leads to a larger contact patch, which causes higher rolling resistance, and thus, poor fuel economy.
A Michelin study showed that your tire is accountable for at least 1/5 of your total fuel consumption and a 1-bar of pressure drop (14.5 psi) would increase your fuel consumption by 3-5%.
6. Special Conditions For Tire Pressure Manipulation
There are of course circumstances where you want to manipulate your tire pressure to meet specific requirements.
Like the aforementioned track race, or if you are driving on sand, mud, etc. However, as a daily commuter, we strongly suggest you regularly check your tire pressure, preferably once a week and anytime you might take a long road trip, and always keep the tires properly inflated!
Conclusion
Tire pressure is always a hot topic regarding driving safety, and it's important to keep an eye on the tire pressure to maximize fuel efficiency and safety.
Before you go
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Appendix 1 - Ideal gas law - Wikipedia.
Appendix 2 - Aquaplaning - Wikipedia.
What should be the optimal pressure in car tires. What to do if less or more than the nominal. How much to “pump” and how to do it correctly - with or without a load. Should it be different in winter or summer?
The wheel of a car with normal air pressure is in full contact with the road surface. There is a uniform wear of the profile and a better grip is provided. If the pressure is reduced, then the tires will hum, when pumped - whistle.
It becomes more difficult to control the car on the road, it will bounce in the pits. In overinflated tires, the tire becomes hard and the grip surface is significantly reduced. It can be damaged by a sharp hole, besides, the tread wears unevenly on an overinflated tire, its service life decreases, and driving comfort decreases.
The main disadvantage of overinflated tires is that they increase the stopping distance of the car. This is due to the smaller area of contact with the road surface. They are more sensitive to steering control, but increase the stability of the car in corners. For this reason, the pressure in the tires of sports cars is higher than usual. Also, when the car is fully loaded, manufacturers advise to pump up the rear wheels a little (by 0.2 - 0.3 bar).
The fuel consumption of the car will increase, and the tires wear out faster. In addition, the angle of inclination of the wheel changes, while the internal structure of the tire is weakened, because. the center of the tire is slightly pressed upwards. Optimum transmission of force to the road is carried out only by the edges of the tire.
Low pressure increases the internal temperature of the tire, which increases resistance. This leads to its complete destruction.
As a result, fuel consumption increases by up to 5%, and tire wear by 25%.
If a driver drives 20,000 km per year on uninflated tires, he will need an additional 540 liters of petrol per year. The car is less stable in corners, has a longer braking distance, and the wheels are less steerable, which can lead to a skid.
Each car model has its own nominal tire pressure in winter and summer. It is written on a sticker that is attached to the inside of the door on the driver's side, on the glove box lid, on the back of the gas tank hatch, in the spare wheel niche. When pumping up the wheels, be guided by this particular figure. They can also be found in the vehicle's owner's manual.
Normal tire pressure in a modern car is in the range of 2 to 3 bar. You need to check it before the trip, when the tire is cold. When the car is moving, due to the friction of the wheels with the road, the temperature rises, the pressure increases.
To find out the optimal value, you need the car to stand for several hours, and preferably all night.
At negative air temperature, for every 10°C relative to zero, the pressure drops by 0.1 bar. In hot weather it rises. 1 bar is approximately equal to 14.5 psi, 0.9896 atmospheres or 1 kg/cm2.
Do not inflate to the pressure indicated on the tire. This figure indicates the maximum value that the tire can withstand. Read more in the article about marking and designations. Also pumping with nitrogen - does not give any advantages.
Check the pressure with a pressure gauge. It is tightly inserted into the open nipple. If you hear a whistling sound, it means air is escaping from the tire. Firmly press or screw the pressure gauge into the nipple until the end.
It turns out that it is impossible to accurately set the pressure in the wheel using compressor pressure gauges. After all, any valve (nipple) is an obstacle to the air flow.
This is easy to check for yourself on a completely flat car tire. If you insert a pressure gauge in the first second of compressor operation, it will show a pressure of at least 0.4 bar. But as the tire is inflated, this error decreases.
How to correctly inflate the car wheel. If you “pump up” a little more, then you get a different result in all wheels, because. Different valves create different back pressure. Therefore, the surest way is to pump up to a obviously higher pressure, for example, 0.2-0.3 "atmosphere" more. Then check the actual pressure with a pressure gauge, bleeding the tire if necessary.
When the pressure is lower than recommended, you can pump up the wheel with a compressor. If you accidentally pumped over, then press the nipple, and the air will begin to come out back. When you take out the nipple, the air can bleed a little - it is recommended to pump the wheel a little, by 0.1 atmosphere.
When inflating the tires of any vehicle, you must always maintain the pressure set by the manufacturer, since failure to comply with this important rule adversely affects the operation of tires, and also affects further road safety.
What should be the correct pressure in the tires of the car (table). Let's talk about the dependence of the degree of pumping on weather, road conditions and methods of verification.
Most front-wheel drive vehicles (both domestic and foreign) can be fitted with rims with a radius of R13 - R16. However, R13 and R14 wheels are almost always included in the basic package. The value of the optimal pressure in the tires of the car is selected according to its mass at full load. In this case, the climatic and road conditions in which the vehicle is operated must be taken into account.
Most owners of vehicles with R13 and R14 wheels (the most common radii) are interested in: what should be the optimal pressure in the tires of a car? According to the recommendation of the manufacturer of the tire of the thirteenth radius, it is necessary to inflate to 1.
9kgf/cm 2 , and R14 wheels up to 2.0 kgf/cm 2 . These parameters apply to both front and rear wheels.
In principle, it is necessary to maintain the same tire inflation both in summer and winter. However, it is recommended not to inflate the tires slightly in winter. This is required for:
You also need to know that with a sharp change in temperature (for example, after the car left the warm box in the cold), due to some physical properties, a decrease in tire pressure occurs.
Therefore, before leaving the garage in winter, it is imperative to check the tire pressure and, if necessary, pump them up.
Do not forget about the constant monitoring of pressure, especially when the temperature changes and in the off-season.
The recommended tire pressure R13 with the onset of summer is 1.9 atm., This value is calculated taking into account that the car will be half loaded (driver and one or two passengers). When the vehicle is fully loaded, the pressure of the front wheelset must be increased to 2.0-2.1 atm, and the rear - up to 2.3-2.4 atm. The spare tire should be pumped up to 2.3 atm.
Unfortunately, the road surface is by no means ideal, so most motorists specifically prefer not to inflate their wheels a little. Because thanks to this, all the bumps and flaws in the road are not so felt when driving. Often in the summer, the pressure in the wheels is reduced by 5-10%, and with the onset of winter, this figure increases slightly and amounts to 10-15%. When driving on smooth roads, it is best to maintain the tire pressure recommended by the manufacturer.
Despite the fact that most domestic and foreign cars have wheels with a maximum radius of R14, yet most owners install wheels with a larger radius (R15 and R16) to improve the appearance of their vehicle and improve some of its characteristics.
Therefore, it is necessary to know what should be the optimal pressure in tires of this size?
Here, too, everything depends on how much the machine is loaded. When it is half loaded, the tire pressure threshold should not exceed 2.0 kgf / cm 2 , at full load this value is already 2.2 kgf / cm 2 . If a large amount of various heavy luggage is transported in the luggage compartment, the pressure in the rear wheelset must be increased by another 0.2 kgf / cm 2 . As you can see, the pressure in tires of the fourteenth radius is approximately equal to the pressure in R15 and R16.
Alas, even most experienced drivers completely ignore the procedure for monitoring the pressure of the car's wheels, considering this procedure to be absolutely useless. Checking tire pressure is carried out using a pressure gauge, which can be integral with the pump, or be a separate element. Do not forget that the error of any pressure gauge is usually 0.
2 kgf / cm 2 .
Pressure measurement sequence:
This procedure should be performed monthly if the vehicle is used regularly. Measurement should be done before leaving, when the rubber is not yet warmed up. This is necessary to accurately determine the readings, since after warming up the tires, the air pressure inside them increases. Often this is caused by dynamic driving with a constant change in speed and sudden braking. For this reason, it is ideal to measure before driving, when the tires on the car have not yet warmed up.
Recently, almost all tire stations have introduced an expensive service of filling tires with nitrogen.
