[s-cars] Everything You Always Wanted to Know About Nitrogen, But Were Afraid to Ask

[Steve Marinello]

Very nicely compiled, but do you actually get 30k-50k miles on your 
performance tires?  I think these Bridgestones will be toast by 15k.  
Even less of a potential impact.  Now, let's just assume that it's still 
worth it to use Nitrogen for someone.  Are they looking to keep a bottle 
of pressurized gas in their garage to adjust/add gas to raise the 
pressure back to spec?  There's one thing I definitely don't want in my 
garage...unless I've got welding gas bottles already.  Anyone else ever 
see a high pressure bottle of N2 take off after falling and knocking the 
head off?  Not pretty.  Looks just like an airborne torpedo.  At least a 
steel reinforced wall stopped the one I saw...after it had punched half 
way through.   And God forbid your garage catches fire...  Way too 
little advantage for the potential risk for me.

Steve

Vincent Frégeac wrote:
> Hi All,
>
> Since I had to dig into the Nitrogen in tires debate for my work, I thought
> I could as well share my findings with you. So, here are some facts:
>
> The FAA requires Nitrogen in Tires: TRUE
> - After a plan crash, caused by a burning tire igniting a fuel line when the
> landgear was retracted, the FAA conducted studies that concluded that the
> time the tire burnt after the landgear was retracted would have been
> noticeably reduced if the tire would have been filled with Nitrogen, since
> this would have reduced signigficantly the volume of oxygen around the tire.
> Conclusion for us: Except if you have upgraded your car with Mr. Fusion
> engine and retractable wheels ala Back to the Future, you shouldn't care
> about the time your tires will burn when your urS landgear are retracted.
>
> The race cars benefit from Nitrogen in Tires: TRUE and FALSE
> - The pressure in a race car tire will increase by up to 50% due to the
> temperature. Predicting the increase in pressure is very important to
> racers, so they want the same pressure to temperature correlation in every
> tire they use in a race, whenever they have been filled. By filling a tire
> with bottled gaz, they are sure to have the exact same gaz in their tire,
> while outside air has a different humidity content when it's sunny and dry
> than when it's pouring rain. On the other hand, they could achieve this
> reproductibility with any dried bottled gaz, including air. The advantage of
> nitrogen is it's the cheapest readily available bottled gaz with controled
> content. Now, you can think that you're racing your car too, but a typical
> car tire will increase it's pressure up to 10% when driven normally, up to
> 20% when driven hard, which mean that a 1psi difference in a F1 tire will
> become a 0.4 psi in your tire when driving hard. Beside, you are not
> changing your tires every few hours, just adding some air once a month, let
> say, worse case scenario adding 5% of air (If you're adding more, you have a
> slow leak and should do something to it). So, if this 5% of air is 100%
> different than the air of last month, you will experience a difference of 5%
> of 0.4psi when you're driving hard, aka 0.08psi. Now, if you're able to tell
> by the way your car handle that your LR tire is at 33.48psi after the 3rd
> corner after your home when last month it was at 33.40psi only, and this
> difference in handling really annoys you, you should go with Nitrogen, but
> for all of us who don't have a bionic seat of pants, F1 cars using it is not
> a good reason to go nitrogen.
>
> Nitrogen keep it's pressure over time: FALSE
> A Consumer Report studies have compared leakage of 20 new tires when filled
> with air an Nitrogen. The psi drop was anywhere from 1 to 8 psi over a
> period of 1 year, depending on the tire. The difference between air and
> nitrogen was between 0.2 to 1 psi. Now, this study was done with tires left
> on a rack, so we cannot say the absolute psi drop would be the same when
> driving. However, we can expect the ratio to be the same, which is nitrogen
> filled tire will loose pressure at 80% of the rate of air filled tire.
> That's better, but they still loose pressure. The difference of pressure
> drop is 20% when switching from air to Nitrogen but up to 800% when
> switching from one tire brand to another. So, first conclusion, choosing the
> right tire is much more important than choosing the right gaz, and we all
> know we choose our tire because of their handling, their fatness, their cool
> factor, any reason but gaz permeability. Since we don't care about a 800%
> difference in pressure drop over time, why should we care about a 20%
> difference. Second, Nitrogen still leaks at 80% of the rate of air, which
> means than instead of checking your tire pressure every month, you will be
> able to check your pressure every month and a week (in an ideal world with
> no nails, no leaking valve, no leaking mags, no tire monkeys, etc.)
>
> Nitrogen protect wheels: TRUE and FALSE
> Bottled Nitrogen is dry and somewhat inert. It won't promote rust or
> oxidation even over a very long period of time. On the other hand,
> compressed air, with its combination of oxygen and humidty, does a very good
> job of promoting rust, which can have a visible effect with steel wheels.
> Are you running on steel wheels!!!?!! Beside, IME, steel wheels rust much
> faster on the outside than on the inside (below the tire) so even if the
> nitrogen protect the inside of the wheel, you still have to change the
> wheels because they're all rotten on the outside. Now, oxydation of
> aluminium does exist too. It is much slower and produce a very fine white
> powder, and Nitrogen will also stop aluminium oxydation. But have you ever
> changed your mags because of oxydation of the inner part?
>
> Nitrogen doesn't change pressure with temperature: FALSE
> This is derivated from race cars using nitrogen. The reason they use
> nitrogen is predictability. Bottled nitrogen is standard, so it will always
> react the same way, but it is still a gas so the pressure is still more or
> less _proportional_ to the temperature in Kelvin. The difference with air is
> that air contain humidity and humidity will have an influence on the way
> pressure change with temperature. So pressure change won't be predictable.
> But as mentionned earlier, in our car, it means an unpredictability of
> 0.1psi each time we check and adjust the pressure. Do you really care about
> a difference of 0.1psi in the 2-3psi variation of your tire pressure when
> the tires warm up?
>
> Nitrogen allows a longer life of the tire: TRUE and FALSE
> >From what I have found, this have not been proved on car tires. While there
> was no side-by-side comparative study for trucks either, some trucking
> company have reported up to a 48% increase in thread life but, more
> important, the possibility to recap the tire up to 5 times instead of 2-3
> times, after they switched from air to nitrogen. So, on truck tires with a
> 250-300Kmiles thread life which are recaped to last over a million miles, it
> does make a difference. Does it on the 30-50Kmiles high performance tires we
> use? Still to be proven. Beside, are you recaping your high performance
> tires. I suppose you don't.
>
> Nitrogen gives a better gas mileage: FALSE
> This is a deduction from the fact that nitrogen leaks less but I found no
> comparative study. The deduction come from the fact that Nitrogen leaks less
> than air, which is somewhat true. As said earlier, over a year, a nitrogen
> filled tire will loose 2.2 psi only when a air filled tire will loose
> 2.7psi (average of 20 tire brands tested). I don't think a
> 0.5 psi difference over a year will make a difference, especially if you
> check your tire pressure every month. Beside, the choice of tire will vary
> this pressure drop from 1.0 psi to 7.8 psi, so the choice of your tire is
> much more important than Nitrogen. Do you consider the air permeability of
> the rubber when you choose your performance tires? I think not. So if you
> don't care about a 800% difference in pressure drop, why should you care
> about a 20% difference?
>
> Of course, this is just what I found. YMMV. Someone on another list has even
> reported a 3MPG difference when switching from air to Nitrogen (but he
> forgot that he was switching from worn out tires with unknown pressure to
> brand new tires with on-spec pressure at the same time ;-)
>
>
>
> Vincent
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