I keep hearing all this advertizing about filling tires with nitrogen.

They run cooler.
Tires won't rot
Better milage.
Tires look better. (kidding)

Does anyone remember science class? 78% of the air we breath is nitrogen. Only 21% is O2, the rest of the atmosphere is the rare stuff, argon, ect.

I'm I just behind the times or am I on the money here?

 

pure nitrogen will not expand and contract under heat like the mixture we breath will. the pressure is constant at any driving temp. race cars use nitrogen in the tires. i dont know about that other stuff, but i dont see why not.

 

Nitrogen is an inert gas, will not expand or contract with temp. changes. Tire will be at the same pressure hot or cold. It is also clean(no oil from air compressor) so no contaminates to attact tire from inside.
Clark

 

That can't be true! Anything expands with heat. Inert means it will not burn. I'm not trying to argue with you, but that is one of the "sales pitches" they are using to sell the service.

 

Im confused as well.

PV=nRT
Pressure*Volume = #of moles*gas constant*temperature.
And in a tire V, n and R are constant.
Which means P changes with T.

 

From how stuff works:

Most of the teams remove the air from the tires and replace it with nitrogen. Compressed nitrogen contains less moisture than compressed air. When the tire heats up, moisture in the tire vaporizes and expands, causing the pressure inside the tire to increase. Even small changes in tire pressure can noticeably affect the handling of the car. By using nitrogen instead of air, the teams have more control over how much the pressure will increase when the tires heat up.


Now I get it.

 

But we are talking about racing right? High speed, non stop, racing.

 

I think any gas expands with an increase in temperature. Nitrogen has the benificial characteristic of not migrating through rubber like air does. Constant pressure for a much longer time is maintained with straight Nitrogen.

 

I think that this (below in blue text) sums up the issue pretty well. The only thing that the science supports is that the N2 should be dryer and therfore reduce corrosion inside the rim.
However the "geniuses" in our state have decided to start putting calcium cholide on our roads and that is a far bigger corrosion issue than a little moisture in the tire.


"The question about nitrogen in tires has come up in other lists on the web as well. Let me clarrify a few points.

1. Air is 78% nitrogen, N2, and 21% oxygen, O2. So even if you put air in the tire, it's already 78% nitrogen. Many of the so called nitrogen generators don't produce much more than 90% nitrogen.

2. At relatively low pressures (ie tire pressures) N2, O2 and water vapor will all behave as ideal gases, and follow PV=nRT. Pressure will increase or decrease to the same extent as the temperature increases or decreases regardless of which gas is in the tire. (Even at 300 psi, which is about 20 atm, there is little deviation from ideality.) Therefore the comments about N2 not changing in pressure as the temperature changes are without merit.

3. The rate of effusion (or diffusion) of a gas through a porous membrane depends on the molar mass and to some degree on the molecular diameter. N2 and O2 are almost the same size and N2 is lighter than O2 (28 g/mol vs 32 g/mol) so if either gas were to effuse out of the tire, nitrogen would do it more quickly. Luckily, tires are designed not to be porous membranes.

4. N2 and O2 both have essentially the same specific heat capacity, about 1.0 J/gK, and thermal conductivity, about 0.00026 W/cmK. Water vapor has a specific heat capacity of about 2 J/gK. But remember, water vapor will constitute less than 1% of the air in the tire. So the idea that N2 has different heat handling properties is also without merit.

5. The ozone, O3, in the atmosphere, which is a ground level pollutant, will do a great deal more damage to your tires than the O2 inside the tire. For instance, don't leave a condom out in the air in Los Angeles for a few days. It will develop lots of tiny holes and weaken.

spdracer22 says that dry air is preferably to air with a lot of water vapor. As a tire heats up, the very small amount of H2O present will be in the vapor state which may contribute to the overall pressure very slightly.

Several have suggested that N2 in a high pressure tank is more portable and requires no electricity. That would make sense, particularly for aircraft tires.

I find no reason to believe that N2 is going to produce a "better ride" or "better handling".

The bottom line is that for general passenger car tires or truck tires there is nothing to be gained (other than portability) by using nitrogen rather than air. The biggest gain will be $$$ by the companies that sell nitrogen handling equipment and the tire merchants that appeal to ignorant customers. And who is the biggest loser? Yep, the consumer."

Regards,

Jim B

 

I've been putting compressed air in my tires for a long time now and this new Dodge is getting the same. This new compressor is an oil-less type and I figure that's enough high tech gar-bah-ge for now. "Sue Me".

 

We have been big-time in the tire business for 48 years and running, since before I was born.

This Nitrogen foolishness is the biggest snake oil deal I have seen in a long time.

The average home mechanic can't even discern that he has a low tire until it blows out; how on earth is he gonna feel any difference in the type gas in his tires??

This is as good a place as any to relate an experience I had a few weeks back.

I was rather busy when the phone rings. It is this preppy efeminate punk and he wants to know what we charge to change the air in his tires and when can he get an appointment. I thought it was a joke; he was dead serious. Turns out some of the genuine farm boys at school had convinced this idiot that the air should be changed in his tires on a regular basis. I told him that we got $12/tire for standard sizes and $14/tire for low profiles. Easiest $56 I ever made.

 

Everyone knows you shouldn't run summer air in your tires during the winter.

Summer air is much warmer, and takes up more volume.
Winter air is cooler, so takes up less volume.

You'd surely have a blowout if you still had summer air and the temperature dropped below freezing.
Change it every fall at the latest.

Same thing goes for the spring air changeout.



phox

 

Thats just mean... charge some kid to change the air in his tires.

I just gotta know, did you really deflate and reinflate every tire or jsut tell him you did?

 

one of the disadvantages of air is that you heat it up during the compression process and that affects pressure after the fact. At least with the equipment I use at work it doesn't get heated(it starts out as liquid and is warmed to a gas, so the pressure should not fluctuate after that point(until the tire heats up). in my job the preferred is nitrogen with the alternate being DRIED compressed air for corrosion reasons. The other advantage (atleast at work) is it is easier to haul the nitrogen converter around that the air compressor due to the pressure required(200-3000psi). Try to find a portable air compressor that can develop 3000+ psi!

 

Never run southern hempishere air in the northern hemispere tires either. The air below the equator will spin the tires in the opposit direction.