Nitrogen in new car tires!

[jakobnev]

PV=nRT

text

[Ed-in-Maine]

I ran N2 in the tires of an RX7 Spec racer back in the early 1990's. It was an experiment. In racing conditions i.e. big fluctuations in tire temperatures it helped since the N2 didn't change pressure as much due to temp. SO it saved a ton of messing around to get the tires pressure set up. But back then it was expensive an not easy to get.
Today in everyday street cars, I suspect like others have said it's all about marketing. I'm not sure half the population even knows what a Turbo is and don't get me started on this "i" nonsense.

But all else being equal I'd take it. I've have no problem telling the service center NO to all the other BS things they would like to charge for.
Ed

[basjoos]

The main effects I've noticed when comparing compressed nitrogen to compressed atmospheric air is that when installed in a new tire, the tire with compressed air will lose about 10psi (when initial pressure is 60psi) over the next 6-8 months as the oxygen in the air oxidizes the interior rubber of the tire and is removed from the gas mixture inside the tire. This oxidation caused pressure drop diminishes with time and is negligible in a 5 year old tire.

The other main difference is in the humidity (dewpoint) of the gas in the tire. Compressed nitrogen is generated by boiling liquid nitrogen and so has zero water content. Most garage air compressors just compress the local atmospheric air and don't have an air dryer inline to remove the excess water. Atmospheric humidity rises as the pressure increases, so the 40% relative humidity in the garage's air is over 100% by the time the air compressor has bumped the pressure up to 140psi and put it in the storage air tank (they have to drain the accumulated water from the storage tank from time to time). This humidity drops some when you fill your tire from the storage tank, but the humidity of the air in the tire is still well over that of the initial garage atmospheric air. You can sometimes see this humidity in the air when changing tire as the garage pulls the valve stem and the air rushes out of your tire. This increased water content in the compressed air in the tire is just another gas in the mixture and will react like any other gas to temperature changes. Any corrosion it might do to any exposed steel on the inside of the wheel would end once all of the oxygen in the tire has reacted with the rubber and exposed steel.

I don't see how nitrogen could show much difference in pressure fluctuation with temperature changes when compared to atmospheric gas. All gases follow Charles's gas law and any deviations of nitrogen from that of an ideal gas would be minor.

[Ladogaboy]

Originally Posted by jakobnev

PV=nRT

Who are you calling a pervert?

[mbrac]

Originally Posted by jamesqf

On the other hand, how much mpg will you lose, riding around on underinflated tires until you can get into the dealer to have them inflated with pure nitrogen, instead of the 80% nitrogen you can get everywhere?

And I bet the dealer won't inflate them beyond the too-low manufacturer's recommended pressure, either.

I got my tires at Tire Barn - I think it's a national chain - but they will let you inflate yourself to what ever pressure you like - I run mine about 5-6 lbs. over manufacture recomended - just saying.....

[euromodder]

I'm having a tough time accepting serious improvements from N2 over (dry) air - given the equally common air on the outside of the tire.

Water vapour will make a difference, especially when it transitions between the gas and liquid phases due to temperature.


One of my previous cars sat mostly disused for nearly 2 years.
Its rear tires stayed on long enough to show signs of rubber rot and cracking on the outside , but when they got replaced, the insides were just about as pristine as the new tires.


Why not fill up the tyres with atmospheric CO2