The main benefit of nitrogen-filled tires is that the loss of tire pressure is slower, because the gas in the tire escapes more slowly than air does. With more stable tire pressure, the thinking goes, you'll get better gas mileage and get full tire life since you're always rolling on fully inflated tires.

Which does same thing check tire pressure once month.

Quoted from my post.

Washington DC is full of hot air without Nitrogen. :blahblahblah:

Agree, but it’s non useable….:22yikes:

On the periodic table of elements Nitrogen is just before oxygen, therefore, nitrogen atoms are slightly smaller than oxygen atoms, but not by very much.

The atom N is smaller than the atom O. However, the compound N2 is larger than the compound O2. Since we have to deal with the compound rather than the atom….

Regardless of what you fill your tires with, remember to check your value stems periodically to be sure they are snuggly in place.

????

If they are not snuggly in place is there any air in the tire at all??

Is it to much to ask to post actual factual data, when that is the issue?

Gas Density (molecular)
O2 32 grams / mole
N2 28 grams / mole
Oxygen is 14% denser per mole than Nitrogen

Gas molecular size:
Nitrogen 0.305 nanometers (nm)
Oxygen 0.299 nm
In their gaseous state, both nitrogen and oxygen molecules have an effective diameter of about 3 x 10-10m.
Nitrogen molecules are 2% larger. This is a result of their internal atomic structure.

OP
With respect to the OP (operating premise) that the tire pressure and atmospheric pressure have some relationship, that is bill shut [intentional]. The internal and external pressures are unrelated.

Tires
As to the tire temperature recommendations (ideal gas law), it is important to remember that the temperatures used must be absolute zero based, so Kelvin or Rankine. Did any of you, who posted those guidelines, ever check to see whether they were correct? It would be useful and instructive to do so.

Racing and nitrogen
Why would race cars, presumably cars racing long enough distances to make tire changes (?) use nitrogen rather than air. I have no idea. Thermal conductivity differences? Elimination of water vapor? Are brakes and wheels reasonably thermally isolated. After all, the tires are only used for minutes, not hours. They are put on "cold" and get heated up through tire friction. I have never heard a credible argument for it, but I don't doubt that it is important for some forms of racing.

Disclaimer
I have no automotive engineering background.
Physics, chemistry, math, finance, economics/behavior/game theory, and software have had my focus (other than sports).

Methinks he means "valve caps"...

No, valve stems can leak air very slowly if they are not tightened down properly. There is a rubber gasket in the stem that needs to be compressed to hold in air. Over time the stems can loosen and require being snugged down, typically only about 1/4/ to 1/2 turn. Sometimes the rubber gasket in very old valve stems can corrode and the valve stem needs to be replaced. A valve stem wrench can be purchased at any auto parts store, or in the automotive department of a box store, for less than $5. A package of replacement valve steams can be purchased on Amazon for under $10.

Valve caps don’t hold in air, they protect the valve stems from weather and debris.

Don't forget to trim your nose hair....

I stand corrected.
https://www.getnitrogen.org/pdf/graham.pdf

Correct me if I am wrong but the valve stem is a 1" to 2" piece of rubber and metal that is inserted into the rim from the inside of the tire. It's purpose is to allow the tire to be filled with air through the use of a valve within the stem. There is usually a valve stem cap that screws onto the outer end of the valve stem to keep dirt out of the valve. In newer vehicles the valve stem frequently contains the sensor for the tire pressure monitoring system (TPMS). In all cases that I am aware of, the valve stem is replaced from inside the rim meaning the tire must be at least partially removed from the rim itself. The hollow rubber/metal valve stems can be fairly inexpensive but I know those that contain the TPMS sensor cost more than $10 each.

Perhaps you are referring to the valve itself which is within the stem. Those can be removed and replaced. In all the years I have owned vehicles (cars, trucks, motorcycles, bicycles, lawn tractors, golf carts, wheelbarrows, boat trailers, etc) I have experienced a bad valve only one time. Maybe I've been luck and it happens more often than that. I have never needed a replacement valve (I had the entire stem replaced that one time) but it's good to know they are available.

Ok, my bad, poor semantics. I should have said valve stem CORE (pictured below with tool). Advice still stands, they can come loose and should periodically be checked. They tend to become loose when frequently inflating/deflating and when running tires at low pressure. I had problems with the stem cores loosening on my truck when oversanding on the beaches at Cape Cod several days in a row (the tires are deflated to 11 psi to drive on the beach and then filled back up to 36 psi when getting back on pavement). The cores frequently loosen on my ATV as well. The tires on an ATV run between 3.5 - 5 psi. I’ve never had a problem on cars, but I did need to replace one on a golf cart.