Nitrogen at Costco for your tires

[ViperRichRT10]

My father just gave me a brochure from Costco advertising that they now use nitrogen to inflate tires. The brochure states that it is better because the pressure does not fluctuate with temperature and there is no moisture inside the tire. They claim better tire life and performance. They will fill your tires with nitrogen at no charge for members even if you did not buy your tires from them. Has anyone done this? Opinions?

Thanks,

Rich

 

[Cudaman]

If they use helium it will make the car get better gas milage because it will make the car lighter on its tires.
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I am just kidding....


Cudaman

 

[ViperRichRT10]

Then you'll be flyin!

 

[Mike Adams]

We use it in go karts all the time much more consistant tire pressure. As tires temp goes up pressure doesn't change and near like it does with regular compressed air

 

[Chuck 98 RT/10]

It's what the track rats use.

 

[VPRTKMIKE]

NITROGEN IS WHAT THEY HAVE BEEN USING IN NASCAR FOR YEARS.IT DOES NOT BUILD AS MUCH PRESSURE WHEN HEATED,BUT STILL HAS SOME MOISTURE NEED TO USE A DRIER INLINE.

 

[Donzi]

Vprtkmike, turn off your caps lock button.

 

[onerareviper]

Yep,

I got it. Although, I experienced an slight increase in tire pressure. Started at 30 pounds, drove on highway for 10 minutes at normal speeds, rechecked (32-33 pounds). Given, this is probably a few pounds less than regular air. I say go for it...

BTW - THEY ALSO DO FREE PLUG/PATCH ON TIRES IF YOU'RE A MEMBER (THE RIGHT, TIME CONSUMING WAY) . AND NO, YOU DIDN'T EVEN HAVE TO BUY THE TIRES FROM COSTCO.

Warning - They put these stupid looking bright green valve caps after finishing. Just tell them to use your old ones.......

 

[ViperRichRT10]

I think I will go do this tomorrow morning. Thanks for the heads up on the green caps. I'll make sure I keep my nice ones in my pocket for safe keeping!

Rich

 

[IEATVETS]

If they use helium it will make the car get better gas milage because it will make the car lighter on its tires.
Well said cudaman.
And vprtkmike, turn the caps lock button off please, there is no need to yell

 

[Cal Viper]

Sounds like hokum to me. The gas laws still apply. When volume is constant, pressure varies directly with temperature and it doesn't make any difference what the gas is.

 

[joe117]

I believe the moisture causes most of the pressure change with temperature.

Nitrogen is probably better but for the street, I don't think it will make enough difference to notice.

The way most tire guys mount the tires, slathering lots of slime, will get moisture in the tire. That's the thing to watch out for.

How do they get all the air out of the tire when they fill with nitrogen?

 

[FE 065]

I was recently in a rifle scope factory where the air is purged from the assembled scope in the final stage of assembly, then refilled with nitrogen so the prism and lenses don't get moisture on them...

 

[ViperRay]

I agree with Joe. It's predominantly the water vapor that expands the tires with heat (of course all gases expand when heated).
In cases where tire longevity is an issue, there would be less oxidation of your tires with nitrogen (fleet cars which may be retreaded?).
There's also less migration of nitrogen than O2 so tires won't lose air as quickly.
Keep in mind that "air" is 78% nitrogen.

 

[ViperRichRT10]

Well...I went this morning to have nitrogen put in. They said it would take them 4-5 hours just to get nitrogen. Screw it, I will stay with regular old air! Also, the free nitrogen ends on the 31st of August! Screw it...

Rich

 

[GraphiteGTS]

I'll stick with air.

 

[Russ M]

What happens if you are low on nitrogen? And there is no costco close by?

 

[Miles B]

Great points. Gas law does still apply, so the "nitrogen expands less" point is BS. Less water vapor will cause less expansion and less of the corrosive effects on the inside of the tire. But like joe says, there is a heap of water in there anyway - the soapy goo they use to slip the tire on. And yes, how do they get the dirty "air" out first? If my idiot brain is workin correctly, inflating your tires to 35psi will mean there is still 2 parts "air" to 5 parts nitrogen.

I call BS.

They use nitrogen in plane tires, and I believe, they purge all the air and water out first, to stop the water vapor freezing at altitude. Otherwise it gets in the rubber, freezes, and slowly perishes the tire. Since I don't drive my car at 35,000 ft, I figure I don't need to worry.

 

[AndyR]

Here in Cincinnati, all of the big tire chain, Tire Discounters, now use N2 also.

 

[pavenom]

Not only does Henry's Gas Law still apply (PV=nRT) but do remember that good old air is approximately 80% nitrogen anyway. If Costco runs out, just use good old air and your 80% of the way toward your nitrogen fill up.
PAvenom

 

[luc]

On a race track, the air pressure will increase anywhere between 6 to 8 psi between a cold tire and after a few laps when the tire is at optimum temperature.

With nitrogen the increase is usually between 1 to 2 psi so obviously nitrogen work and it's why we use it on race cars.

You have diferent grades of nitrogen depending on purity/moisture, 2 examples will be nitrogen that you find at a welding shop and "medical grade" nitrogen.

As for the question regarding how to purge all the air from the tire,it's very simple:
Since nitrogen is sligtly heavier than air, you just rotate the tire until the valve is at the 12 position.
you remove the valve "guts" with a regular valve tool,fill the tire with nitogen to about 20psi, let's the tire deflate completly, re-instal the valve and inflate again with nitrogen.

Remember that even if you don't purge the tire with nitrogen but simply let all the air escape,and for example inflate the tire with 22psi of nitrogen, you will still only have a very small % of air (1/22)compared to nitrogen.

Luc.
00GTS
1965 Shelby/Mustang race car (550hp)
1969 Mustang race car (650hp)
1991 Roush Mustang T/A

 

[Miles B]

That's not quite true. Atmospheric pressure is about 14.7psi above vac, 22psi in your tyres is 14.7+22 = 36.7.

This will be about 91.2% nitrogen, as opposed to all normal air, which is about 78% nitrogen.

I still don't see how "pure nitrogen" can have that large a difference in thermal expansion, from "78% nitrogen", in race tyres. Please explain to me how the ideal gas equation changes for nitrogen.

 

[Cal Viper]

It must be the change in state of water. A little bit of liquid water condensed inside a cold tire would become a lot of gaseous water inside a hot tire, and would significantly affect the pressurization. Purging the tire a couple times with any dry gas should do the trick. A dryer on the air compressor would probably suffice.

 

[luc]

Miles,

Air contain 78.084% N2 but also:
02 20.9476%
Ar 0.934%
CO2 0.0314%
Ne 0.001818%
CH4 0.0002%
He 0.000524%
Kr 0.000114%
H2 0.00005%
Xe 0.0000087%


The volume of air will change by 1/273 for each Celcius, or a tire at 0 f with 80psi will become 96psi at 100 f

I think that the answer in in the moisture or vapor content of the air, especially when you consider that water expend 1800 times from liquid to vapor (212f) .

Luc.

 

[Miles B]

So really it's more that your race tyres are water free? How do you get them on without some water to slip them over the rim?

 

[Miles B]

Also, your numbers are off for the example you gave.
0f (255.37 K), 80psi (above ambient):
PV=nRT
(80+14.7)V = nR(255.37)
reduce these to get a constant of 2.6966.

100f (310.93 K), same volume:
(P)2.6966 = (310.93)

P = 115.3 - 14.7 = 100.6 psi above ambient.

 

[Miles B]

Do you have any numbers on the temp of the gas inside the tire when it is warmed? If so, we can see how true these claims are.

 

[luc]

Miles,

Racing tires optimum temperature is usually between 180f to 230f,depending on brand,compound (soft,hard,)etc.
But can go up to 300f at which poin the tire start to blister.

I will assume that after a certain period of time the gas inside the tire will be at a slightly lower temperature since the sidewall run cooler than the contact patch of the tire.

As for mounting the tire without water/soap, depending on the tire, mounting equipment and operator,sometime it's possible,sometime it's not.
You also can use a light silicon (spel?)or teflon spay.

If the tire was mounted with water/soap, i will purge the tire with nitrogen may be 5 or 6 times in order to remove as much moisture as possible.

That tires inflated with nitrogen only expend 1 to 2psi compared to 6 to 8psi with air, is not a claim but a fact, any racers can tell you that.

As to why, like i said before, I believe that's come from less water vapor

luc.

 

[onerareviper]

Put down the pocket protector, and step away from the abacus....



Anyway, after the change I was at 30 pounds. Drove on highway for 10 minutes at normal speeds, rechecked (32-33 pounds). Probably a few pounds less than regular air, but nothing ground breaking. Maybe I'll to some agressive driving and measure the change.

 

[Miles B]

luc,
I don't get it, but if you say that's what you've seen, there must be some reason I have overlooked or don't know about.

The only thing I have so far, is if the amount of gas and size of container is held constant, taking a gas from 90F @ 25psi to 200F will raise the pressure to 33psi. That's according to the ideal gas equation, so pure nitrogen should follow it reeeeally closely.

I dunno. Maybe the tyre grows slightly as it heats or something?