Nitrogen vs regular air for tires

mdyaman · 29th January 2011, 03:03

My service center has been advertising nitrogen filled tires for some time now. Does anyone here have any experience w/ nitrogen filled tires and pros/cons?

The main theme they say is that it maintains tire pressure longer, including in extreme temperatures (hot and cold), and that b/c nitrogen is "dry" as compared to regular air where it won't slowly rot the inside of your tires out from condensation, etc.

any truth to this, does it matter and make that much of a difference?

petesamprs · 29th January 2011, 03:47

pure dealer profit. save the cash.

air is 78% nitrogen.

mdyaman · 29th January 2011, 04:10

Quote:

Originally Posted by petesamprs

pure dealer profit. save the cash.

air is 78% nitrogen.

Lol, good point!

RandysV10 · 29th January 2011, 04:24

Already had it in the tires when I picked it up. Hadn't noticed any problems, it is advertised to help keep any condensation from forming on the inside of the rims. Don't know that I'd run out and replace regular air for it.

unfoundhorsepower · 29th January 2011, 04:26

Nitrogen is an inert gas....very stable, what it does for tires is: The pressure does not fluctuate much at all from hot to cold, It is very stable and does not promote tire oxidation, internally...many owners of restored cars fill their tires with it for long term storage....10 years... Does anybody who drives their car all the time need it ???NO...a waste of $$$$$$$...It DOES NOT help to keep your tires inflated any longer than regular air does, on a daily basis.

Revo · 29th January 2011, 06:10

Quote:

Originally Posted by unfoundhorsepower

Nitrogen is an inert gas....very stable, what it does for tires is: The pressure does not fluctuate much at all from hot to cold, It is very stable and does not promote tire oxidation, internally...many owners of restored cars fill their tires with it for long term storage....10 years... Does anybody who drives their car all the time need it ???NO...a waste of $$$$$$$...It DOES NOT help to keep your tires inflated any longer than regular air does, on a daily basis.

That's a misconception.

The tire pressure DOES fluctuate from hot to cold with pure nitrogen, and it's much more than "not much at all." The advertisement gimmick is that the amount pure nitrogen fluctuates is less than that of air, but air is nearly 4/5's nitrogen as it is...

To put it in perspective, Nitrogen is an ideal gas. For ideal gasses, PV=nRT. P = Pressure in Pascals, V = Volume in cubic meters, n = number of moles, R = 8.314 (gas constant), and T is temperature in Kelvin.

To compare an ideal gas pressure at two different temperatures, the V, n, and R cancel out and leave P/T = P/T.

80* F = 26.7* C = 299.81 Kelvin

38 PSI = 262000 Pascals (Pa).

So lets say the temperature falls to 40*F on a cold night. That's 4.4* C = 277.6 Kelvin.

Punch that into the P/T = P/T equation and you your new pressure is 242590 Pa, which is roughly 35 PSI.

M55555 · 29th January 2011, 11:01

Great advice. Basically, it's not needed and is a waste of money. Just a plow by service shops to charge more for something you don't need.

q8kamikaze · 29th January 2011, 12:11

is it that expensive ?? i filled my tires in nitrogen for a cheap price (15 dollars only) .

Frye · 29th January 2011, 15:16

Quote:

Originally Posted by q8kamikaze

is it that expensive ?? i filled my tires in nitrogen for a cheap price (15 dollars only) .

That's dinner for three nights here

tmiked · 29th January 2011, 16:41

The simple answer is its probably not worth it.

The complete answer is a little more complicated.

The pressure fluctuation benefit is because the nitrogen is highly compressed (to ~3000 psi) and is therefore very, very dry.
Most garages 'shop air' is compressed to ~125-200 psi and contains much more moisture from the humidity in the air.
At temperature, the vapor pressure of the water raises the tire pressure more than with totally dry air.
For this reason, I keep a filled SCUBA tank around for filling my tires.
Its air, not nitrogen, but it is as dry as the nitrogen in bottles.
and it is very handy on track days.

Pure nitrogen due to the lack of oxidation, may be slightly beneficial to tire life.
I suspect with modern tires, its not an issue.

.