What you need to know about tires, inflated with nitrogen

Nitrogen instead of air in automobile tires, is it necessary?

Pumping tires with nitrogen has already acquired a mythological sense among art lovers, this is about how to RUB the blood of a Cheetah the engine block of your car. Nitrogen as inert gas, is credited with everything from a more comfortable driving to the improved mileage, reduces tire wear. How true that is? What really gives fix nitrogen in the tires of your car? Let’s find out.

If you need a sample of nitrogen, so you are able to study, then substitute your palms. The air inside the tires is already 78 percent nitrogen, even if you pumped them in regular air. So when we talk about the advantages of nitrogen, then in fact there are only 22 additional cent of the gas.

Nitrogen belongs to the noble gases, that is, it usually does not react with other substances. In the periodic table the periodic table has the seventh atomic number. This is one proton less than that of oxygen, which is in the table under the eighth atomic number. Nitrogen atoms are connected in pairs to form molecular nitrogen, or N2, this form of nitrogen found in the air.

So what kind of incredible the benefits of nitrogen? You can often hear that the tyres are inflated with nitrogen, flows away less gas that the car becomes much easier to control, improves fuel consumption and maintaining an optimum pressure even when the temperature drops.

Gas leak

First, let’s discuss the issue with the gas leak.

The kinetic diameter of the nitrogen atom is actually quite a bit more than the oxygen atom. This means that the nitrogen is a big target and therefore the probability of collision with another molecule is small. It is this argument most often when trying to prove that the pressure of tyres inflated with nitrogen decreases with time not so much. That is, it is unlikely that molecules of larger size will penetrate into the rubber of the tire and cause a gas leak.

Some sources claim that the atoms of oxygen (O2) to penetrate the rubber 3-4 times faster than oxygen. This does not mean that the tires inflated with air, blown away 3-4 times faster, because the tire already contains approximately 80% nitrogen, don’t forget about it. I’m not too well versed in this issue to understand how important these remaining 20 percent of the air, but I will help David Tracy:

I have simplified this formula and it is not intended to be used to calculate differential pressure when the tire starts to go down, but the difference in the amount of gas flowing per unit of time = zero:

The volumetric flow rate of gas exiting the bus along with the air

Vdot_Airtire = 08*vdot_N2 + 0.2*vdot_02
vdot_02 = 4*vdot_n2

Will replace and get:

Vdot_Airtire = 08*vdot_N2 + 0.2*4*vdot_N2 = 1.6*vdot_N2

So, in 1.6 times.

Tires filled with air lose air at a rate 1.6 times faster than the tires with nitrogen. It is logical that nitrogen is better, but the difference is so small that most drivers wouldn’t even notice it.

This gas consumes less fuel?

As for the claim that tires with nitrogen will optimize fuel consumption, in fact, nitrogen is not being. Tire pressure greatly affects the fuel consumption. Tires with high PSI indicator (American scale pressure) reduce rolling resistance and improve fuel efficiency, this is usually due to the quality of driving.

Tyres pumped with nitrogen, can provide more stability in terms of PSI (more on this later), but here, rather, it is about maintaining optimal tire pressure, not that the pressure makes the inside of the tire itself. That is, if you keep the tire pressure at an optimal level, then the fuel consumption will be normal, regardless of whether you pumped nitrogen into the tires or not.

Something is missing

Loudest to discuss what the tires with nitrogen can maintain stable pressure even with strong heating of the tires.

Here’s how I explained it to the representative of company BMW:

The main advantage of using nitrogen in tires — a smaller increase in pressure as the heating of the tires.

And the reason nitrogen has less risk of increased pressure is mainly in the following:

Moisture inside the tires, inflated with air, increases the pressure during heating. Worst of all, the pressure increase is highly unpredictable because it depends on the humidity of the air pumped into the tire.

Water. Humidity. Viscosity. It turns out that is not in nitrogen here, and in the absence of water vapor. About 1 percent of normal air at sea level is a water vapor and when the air is compressed and pumped into the tyre, and increased its concentration.

Water vapor is much more susceptible to pressure changes caused by thermal fluctuations. Vapor expands when heated, shrinks in cold conditions and changing the pressure inside the tire, which can cause problems in cars, so this car is very precisely set to a specific tire pressure.

While driving the vehicle the temperature rises because of friction forces and deformation of the rubber. The temperature change in this case does not depend on the ambient temperature. The tire temperature may rise to 50° for 30 minutes on the track (and much higher in a racing car), and if you look at a graph of the vapor pressure of water at different temperatures, we can see that the increase in temperature may lead to too high pressure.

Suppose the initial temperature of the tire of 15°C and it rises to 32°C. In this case, the vapor pressure of water increases more than twice. This is a serious figure.

Also, the water can freeze, therefore nitrogen is used in airplanes (and, at least two spacecraft: orbital Space Shuttle and Air Force X-37B).

Therefore, the advantage of nitrogen is that it is a dry gas, which may contain very little water vapor. You can, of course, dry and normal air, but this is extremely inefficient, difficult and expensive. Much easier to identify the nitrogen, which will never contain water vapor due to the processes used to isolate it.

In addition to maintaining a stable pressure level, there are other reasons why it would be nice to remove water vapor from the tires. Water vapor can cause rust and corrosion inside the valve stem or on the wheel. There is also a view that oxygen is entering a more intensive reaction with rubber, so if you replace it with an inert gas, like nitrogen, it will extend the tire life.

So what’s the verdict?

Yes, technically nitrogen better than simple air pumped into the tires, although sometimes it is not even close to nitrogen and water vapor.

Is it worth it? For normal driving, probably not. Although the benefits really are, it is so small that it will not even notice. And don’t forget the surrounding air with its atmospheric moisture and oxygen. Even if your tires will be 93-95% nitrogen, the air will still penetrate and will do there own business.

If you are a professional racer or just like to drive on the track, then, of course, tires with nitrogen will help you to operate the machine and will keep the pressure stable for a longer time, which will provide you a competitive advantage on the track. In any case, the extra nitrogen you just can’t hurt.

Besides, unlike oxygen, nitrogen does not contribute to the fire, so it is also a safety issue.

If you have the money and you can accurately determine that the pressure in one tire smaller than others or if you have a team of mechanics and you earn a living from racing, then please inflate the nitrogen in the tyres as you want.

And all the rest, I believe, will do very well and 78 percent nitrogen.