Tire pressure in your car – all you need to know

Drivers often underestimate tire pressure levels. Only a few users realize that proper wheel pressure can be related to the load or even the speeds achieved. Driving with too low or too high tire pressure makes it difficult to realize the potential that even the best car tires could provide. This also means degraded stability, reduced comfort and premature wear and tear not only of the tires but also of suspension components. Check out what you need to know about tire pressure.


What is the tire pressure for my car?

Among drivers, it is considered that the universal range for passenger cars is 30-35 psi. Inflated tires should provide the right level of traction. However, following this rule is somewhat of a shortcut. So it is better to go to some trouble and look for information about the recommended tire pressure for a particular car. This is usually not difficult. If you want to accurately measure the pressure in the wheels, it is worth getting a good-quality tire pressure gauge. Cheap products of unknown origin do not provide accurate tire pressure readings.

Recall that without being sure about the recommended tire pressure, you can drive a passenger car with wheels inflated to 30-35 psi. But this is only a half-measure. So it is better to look for reliable tire pressure information for a specific car model. Guidance, because often car manufacturers provide several values. And differences in one model can exceed 7 psi. Of course, this is an extreme value, but it is encountered, for example, in minivans, whose load capacity is 1300–1600 lb. Also, if the car has been approved with several tire sizes, it may happen that, for example, 195/65 R15 tires require a pressure of 31 psi, while 205/60 R16 tires require 2-3 psi more. Note that in a heavily loaded car, especially in a station wagon or minivan, the rear wheels should have much more air than the front wheels.

Mentioning variable pressure recommendations, it is worth mentioning that in some cars, such as BMW, the manufacturer recommends increasing the pressure when the driver intends to drive at speeds higher than 100 mph. Information on tire pressure values can be found in the service booklet. If you don't have access to it, there are several other ways to find out what value to inflate your car's wheels to. You can find relevant graphics in such places as:

- A-pillar near the driver's door;

- the area around the fuel filler flap;

- the trunk (usually near the spare wheel recess);

- the glove box in the dashboard.


When should tire pressure be checked?

Specialists from the allcars.site blog have some tips for you. Foremost, you should check the tire pressure before every long trip. The frequency of verification of the level of pressure in the wheels also depends on the age of the tires. For tires no older than 5 years old, it is enough to check the degree of inflation once every four weeks. On the other hand, in cars where the DOT of the tires indicates that they are more than 5 years old, it is a good idea to perform this activity twice as often. 

Checking the pressure is also recommended when you can see differences on individual wheels and when there is a risk of damage to the tire or rim. Why does the frequency of checking the pressure depend on the age of the tire? It's simple - over time, the rubber evaporates, in addition to causing minor damage, through which air slowly but steadily escapes. Also, the age and type of car valves matter – with leaking ones, even more than 7 psi (0.5 bar) can escape in a week.

Does tire pressure drop in cold weather? Yes, it is, so the conditions under which it is best to check tire pressure are important. It is optimal to perform this on an unheated tire. Outdoor conditions are also important, the lower the temperature, the pointer on the pressure gauge will show lower values. For this reason, too, it is important to check wheel pressure regularly. An inconspicuous difference of 50 degrees Fahrenheit (10 degrees C) is even as much as 3 psi (0.2 bar) - of course, the relationship works both ways.


What are the risks of Incorrect tire pressure? 

The correct pressure in car tires is crucial because of the way the tread works. It makes the contact surface between the tire's footprint and the asphalt optimal. What does this do? Firstly, it intensifies the grip of the wheels on the road and guarantees safety. In such a situation, not only the tire manufacturer's solutions work properly, but also electronic assistants such as ABS, ESP and ASR. In addition, correct pressure guarantees even abrasion of the brake pads. As a result, the driver will be able to enjoy the full life of the tires envisioned by their designers.

If a driver does not take care of proper air pressure, car tires will, eventually, be damaged. An example? If the tire pressure is too low, the tires resist especially intensively on the asphalt with side zones. Improper pressure is capable of shortening the life of a tire significantly - experts mention a quarter! And this usually means the need to buy a new set several thousand kilometers ahead of time! Long-term driving on improperly inflated tires - specifically, with too low a pressure - also causes damage to the internal structure of the tires, deteriorates driving characteristics, and increases the need for fuel.

Insufficient air pressure is also responsible for increasing the index of susceptibility to aquaplaning. As the tire's footprint reflecting on the asphalt is distorted in the inner part, the tread elements cannot work properly while driving and, for example, drain water fast enough. The effect of too low a pressure is also to generate too high a temperature. A notoriously overheated tire in the worst-case scenario can even blow out!

What happens when the pressure is too high? In the first place, the tire structure becomes more susceptible to the formation of damage. As a result, a dynamic drive over a curb or other obstacle encountered on the road can lead to a crack, a bump and a sudden loss of air. In addition, overinflated wheels stiffen suspensions. Thus, vibrations are transferred to a greater extent to suspension components such as bushings or shock absorbers, shortening their lifetime. In addition to this, the obvious effect is a deterioration in handling characteristics. A tire with too much pressure has a tread that is arranged in a semicircle. This means that the sidewall only does a small amount of work.


How does tire pressure sensor work?

For years, drivers relied almost exclusively on themselves to monitor the condition of tire pressure. Changes in this regard took place in the middle of the second decade of the current century. It was then that in the European Union, the US and Canada, the installation of TPMS pressure sensors in new cars was made mandatory.

There are two TPMS concepts in use today. The first - direct - uses pressure sensors that are attached to the valves, to the rim or to the inside of the tire. This solution allows determining the real pressure in a particular wheel. The second system - indirect - is not as precise since it does not so much as monitor the real pressure level but determines the possible loss of the said pressure based on the wheel rotation (speed). In cars with indirect sensors, the tire pressure warning light on the dashboard only indicates that a pressure problem may exist. 

How does the TPMS system work in practice? A light in the shape of a tire cross-section appears on the dashboard, along with an exclamation mark. When it illuminates in yellow, the pressure in the car tires is too low (important note - the yellow light is not used by all manufacturers). Red is a sign that the pressure level is close to zero and that you cannot continue driving, even at low speed.

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How tire pressure is measured?

Car electronics can be unreliable and can play tricks, such as sending false messages about tire pressure. Therefore, if only for this reason, all drivers, as well as owners of cars equipped with TPMS sensors, are advised to have a tire pressure gauge and compressor. In theory, you can check and refill the pressure at a gas station. But this is quite a risk. It turns out that widely available compressors with a pressure gauge can significantly distort the measurement. So it's better to get a "private" tire pressure gauge and use it as needed, that is, before every long trip, regularly and whenever you have doubts about the pressure in the wheels.

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