Nitrogen fill tires

[coreyco]

My mechanic is pushing the benefits of nitrogen claiming, among other things, a consistent tire pressure at all speeds. I am anal about tire pressure, and always comply with mfg recommendation of 33 front, 40 rear, on my stock Bridgestone Potenzas. Since this pressure now increases about 3 psi shortly after starting to drive, I'm thinking that the mfg took this into consideration when recommending cold tire pressure. If this is true, and nitrogen doesn't change pressure based on heat and driving, shouldn't I then set the pressure at 36 front/43 rear when I get my nitrogen fill?
Your thoughts are appreciated.

 

[KSXNSX]

The air you pump into your tires is already 80% nitrogen. The benefits of 100% nitrogen are probably nominal for everyday street driving.

you should probably follow the manufacturer's recommendation regardless of whether you put in ~100% nitrogen, or 80% nitrogen (i.e. air).

 

[Big_D]

Here is the straight dope on Nitrogen fill.

http://www.straightdope.com/columns/read/2694/is-it-better-to-fill-your-tires-with-nitrogen-instead-of-air

I would say no...keep PSI at the 33F/40R mfg recommended pressures.

 

[captngaryr]

This is the biggest scam going! No only is the air at the pump 78% nitrogen already, but unless you evacuate the tire first, the "pure" nitrogen will be diluted by the air that is already in the tire and you will still not get anywhere near "pure" nitrogen in the tire. Every time you fill up with the nitrogen, you will probably only increase the percentage of nitrogen by a couple of percent. Save you money and your tires by checking your tire pressures frequently and filling them with good old air.

Gary

 

[dquarasr2]

From my empirical observations, I like nitrogen.

I must admit I was highly skeptical for the longest time, resisting. Finally I relented.

The largest benefit I noticed was refilling - on my daily driver I was "topping off" the air at least monthly. It would be 3-4 PSI below optimal in about three or four weeks.

After I did the nitro-fill I could go easily six months before I needed to add air, and of course, I'd go have it topped off at the place the did the nitro-fill for me so I would not introduce oxygen and moisture (South Florida is especially humid nearly year-round).

Like I say I was skeptical but I was converted.

Do I use it in all my cars? No. Just in my DD where the effect on gas mileage due to inflation has the most impact. My "toys", my NSX included, still have regular "air" in them, and I pump them up as periodically as needed.

 

[coreyco]

The air you pump into your tires is already 80% nitrogen. The benefits of 100% nitrogen are probably nominal for everyday street driving.

you should probably follow the manufacturer's recommendation regardless of whether you put in ~100% nitrogen, or 80% nitrogen (i.e. air).

Thanks for your input.

Here is the straight dope on Nitrogen fill.

http://www.straightdope.com/columns/read/2694/is-it-better-to-fill-your-tires-with-nitrogen-instead-of-air[/URL

I would say no...keep PSI at the 33F/40R mfg recommended pressures.

That seems to be the consensus thus far.
The article was an interesting read.
Thank-you.

This is the biggest scam going! No only is the air at the pump 78% nitrogen already, but unless you evacuate the tire first, the "pure" nitrogen will be diluted by the air that is already in the tire and you will still not get anywhere near "pure" nitrogen in the tire. Every time you fill up with the nitrogen, you will probably only increase the percentage of nitrogen by a couple of percent. Save you money and your tires by checking your tire pressures frequently and filling them with good old air.

Gary

I hope it's not a scam, but I wouldn't be surprised if this were the case. When my mechanic extolled the virtues of nitrogen, he told me that his new $5K machine, evacuates and refills the tires 3X in order to get a pure nitrogen fill. He added that the larger nitrogen particles would save me regular pressure fills at the gas station, because there is less chance of pressure loss. Since I chromed the stock wheels, one tire is losing a pound a week of pressure. If the nitrogen would help preserve pressure, it's worth the $20 for all 4 wheels investment to me.

 

[Dhalsim]

but nitrogen atoms are smaller than oxygen atoms right? So nitrogen should leak out easier than oxygen.

 

[flaminio]

Fill your tires with Helium. Makes your car lighter; increases your power/weight ratio.

 

[flaminio]

but nitrogen atoms are smaller than oxygen atoms right? So nitrogen should leak out easier than oxygen.

If it's about leakage, one should fill their tires with xenon, I guess.

 

[Big_D]

but nitrogen atoms are smaller than oxygen atoms right? So nitrogen should leak out easier than oxygen.

According to the article in post #3 no...

"Filling your tires with nitrogen mainly does two things: it eliminates moisture, and it replaces skinny oxygen molecules with fat nitrogen molecules, reducing the rate at which compressed gas diffuses through porous tire walls. That means, theoretically at least, that a tire filled with nitrogen retains optimal pressure longer"

 

[bee_are_bee]

I had nitrogen in my tires when I had my S2000. Had tire pressure checked after each of three oil changes (20,000 miles). Never had to have refills and little to no loss of pressure.

 

[Dhalsim]

According to the article in post #3 no...

"Filling your tires with nitrogen mainly does two things: it eliminates moisture, and it replaces skinny oxygen molecules with fat nitrogen molecules, reducing the rate at which compressed gas diffuses through porous tire walls. That means, theoretically at least, that a tire filled with nitrogen retains optimal pressure longer"

I'm no scientist but the molecular weight of Oxygen is 16 and Nitrogen is 14 so the Nitrogen atom is smaller.

Not saying this isn't possible but..........

 

[bee_are_bee]

http://www.getnitrogen.org/pdf/graham.pdf

 

[DocL]

I've been using Nitrogen in all my cars for the past few years. My tire pressures have always remained more stable compared to air and I don't need to refill as often as air. Also, Costco provides Nitrogen for free with your membership once you've converted over.

 

[stuntman]

Nitrogen will NOT eliminate pressure increases but reduce the difference between cold and hot pressures. The biggest issue with compressed air is the moisture which greatly changes your tire pressure with changes in temp. The worst thing you can do is fill your tires up at an old gas station tire compressor with tanks saturated in moisture.

The bigger benefit to (dry) nitrogen is the absence of moisture than the 30% difference over regular air. If you live in a desert, there will be less if a benefit of dry nitrogen over compressed air than a humid place. For a street car it wont make much of a difference but does beat going to your local gas station.

Pure nitrogen might make the tire pressure increase be reduced by 2-3psi but instead of a 10psi difference of air, an 8psi differrnce still is a big change of oressure for track use.

Ive never liked the factory pressures for performance driving. It won't take nuch to get your rear tires to 45psi and reduce rear grip and have an oversteering car.


0.02

 

[Big_D]

I'm no scientist but the molecular weight of Oxygen is 16 and Nitrogen is 14 so the Nitrogen atom is smaller.

Not saying this isn't possible but..........

http://www.getnitrogen.org/pdf/graham.pdf

Quoting from bee_are_bee's link

"It is often mistakenly assumed that "molecular size" correlates directly with "molecular weight". O2 does have a greater
molecular weight (32) than N2 (28), but O2 is actually smaller in size. Thus, O2 fits through the relatively tight passage
ways between polymer chains in the rubber more easily than does N2. The difference is size between O2 and N2 is
very small, only about 0.3 times 10 to the -10th meters (0.00000000003 meters)."

Interesting stuff.

 

[goldNSX]

Some claim that nitrogen filled tires stay cooler. If it's already cold this would reduce grip, if it's too hot it would help. Right or wrong?

The constant pressure feature of nitrogen is nice but you still have to check the tire pressure monthly IMO. So I don't care to fill it up if it needs.

 

[stuntman]

Some claim that nitrogen filled tires stay cooler. If it's already cold this would reduce grip, if it's too hot it would help. Right or wrong?

The constant pressure feature of nitrogen is nice but you still have to check the tire pressure monthly IMO. So I don't care to fill it up if it needs.

No significant temp difference nor pressure consistency (as said above, maybe a 8-10psi increase from cold to hot compared to say 10-12psi increase of dry 'air'.

 

[scammy]

Just bumping this 3yr thread up has anyone used this for track only purposes only not DD and if so what was the temp differences like from going out on track to coming in after some hot laps?

 

[stuntman]

My previous statements were in regards to track use. To further expand on the difference, it depends on the temperature change. Typically there's ~1psi change per 8-12*F increase in the tire. There's not going to be a huge reduction in pure Nitrogen vs. "dry" air, but both "dry" air and Nitrogen will be far better than having excess moisture in the tire.

 

[nsxtasy]

The Tire Rack says...

Simply having a different type of gas in your tires will not make them run cooler.
.
.
.
The only benefit from running pure nitrogen in tires is the increased air retention (slower loss of air out of the tires over time). A tire that is normally maintained with the proper air pressure will perform exactly like a tire with a pure nitrogen fill. If you can get a pure nitrogen fill for free, there is no harm in doing so but very little (if any) benefit from it.

 

[scammy]

Cheers for the replies, thought someone may have been running it anyway since this was last discussed. 8-10 vs 10-12 is something but not enough to bother

 

[Aluminsx]

It's my understanding that aircraft have their tires filled with Nitrogen which makes sense with the different pressures which would happen with altitude changes. My .02 cents is that unless you can get the tires filled for free with nitrogen it's really not worth it. Why not just take the five minutes once a week and check your tire pressure.

 

[Old Guy]

The change in tire pressure due to change in temperature is pretty much governed by the ideal gas law (PV=nRT). Within the limits of the types of gas or mixes of gas that you would be used in a tire, the gas / mix will not alter the pressure change as the temperature rises (assuming the volume of the tire remains fixed). To Billy's point, the ideal gas law predicts that the pressure in the tire will increase by approximately 2.2% if the air temperature rises by 7 C (12.6 F) from 40 C to 47 C. If your starting pressure was 40 psi, this would give you a .9 psi rise. This will occur whether you are using O2, N2 or air. Also, remember that the tire air temperature will likely not be the same thing as the tread temperature after a spin around the track.

On the matter of pressure loss, setting aside the nail poking through the tread problem, my personal experience has been that pressure loss is related to valve stem leakage or leakage at the tire bead. The latter seeming to be more of an issue with aluminum rims, particularly when there are significant temperature changes. The 'larger' nitrogen molecule is not going to address those issues. However, nitrogen or dry air might help reduce oxidation of the aluminum which seems to be the source of the problem with failure of the bead to seal.