# Nitrogen tyre inflation



## crimpleken

Hi Just taken daughters car to have new tyres fitted. I was quoted a price PLUS £1.95 per tyre to have the tyres filled with nitrogen. When I declined this kind offer and said that ordinary air would be fine I was told there was no choice and they used nitrogen for all tyres,the reasons given were longer tyre life and a better ride and did I know that F1 tyres are filled with nitrogen. The fact that my daughters Skoda will not be doing 200m.p.h. did not impress them. When I asked what would happen when the tyres were checked and needed topping up the answer was that tyres filled with nitrogen would not need topping up.
When I told them that air is 78% nitrogen anyway they said that they did not know anything about that.
Took the car to another tyre dealer and had tyres fitted there.
Crimpleken.


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## grizzlyj

I believe if you use 100% nitrogen the pressure won't change as much as they heat up with use, so the cold pressure will be constant however hard you use the tyre. Useful on a race car where +/- 1psi can make a difference.

Also reading the AA blurb on it, where they don't recommend the extra cost on passenger cars, they point out that since oxygen molecules are smaller than nitrogen molecules, 100% nitrogen will leak less. No moisture means no rusting either.

http://www.theaa.com/motoring_advice/safety/filling-tyres-with-nitrogen.html

edited cos I wasn't quite right the first time


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## davesport

Snake oil as far as I'm concerned when used in a road going vehicle. Air from your average compressor is dried to a fairly high standard anyway. As far as the oxygen affecting the inside of the tyre......what do they think is on the outside :?: The gas laws concerning temperature & pressure(Boyles law) will affect nitrogen in exactly the same way as they would affect air.



> the reasons given were longer tyre life and a better ride


 The bit about longer tyre life is marginal at best, & better ride :lol: That's a lie :!: How could that possibly be quantified :?: I defy anyone to differentiate in a back to back test.

I've gone off one one, haven't I  I'm annoyed by this too. Costco insist on filling new tyres with nitrogen & it's all bundled up in the cost of fitting the new tyre. I asked specifically for them not to use nitrogen but was told "this is not possible" Ialso asked for a breakdown of the costs IE tyre, disposal of carcase, balancing, nitrogen inflation. I recieved the same rote answer as I did for the previous question.

I think the very fact that they can include a charge of around £2.00 per wheel sheds some light on why some tyre depots are so keen for customers to have "nitrogen"

Snake oil IMO 

D.


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## Stanner

Yep - yet another ripoff.

But the Scooby/Corsa/Saxo drivers will lap it up - if they can afford to drive everwhere in 2nd or 3rd gear the chance to boast how their tyres are inflated with pure nitrogen "just like an F1 car" is cheap at almost £8 (+VAT?).

Definitely snake breath and a nice little earner - do let us know who the culprit is so we can all steer clear of them.


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## wobby

Come on now, you can't blame the garages, after all their only trying to make a little extra in these hard times! :roll: :roll: :roll: :roll: :roll: 

Wobby


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## Stanner

wobby said:


> Come on now, you can't blame the garages, after all their only trying to make a little extra in these hard times! :roll: :roll: :roll: :roll: :roll:
> 
> Wobby


So is this the "inflation" that keeps putting prices up?


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## b16duv

It's a bit like McDonalds asking if you would like to 'go large'. It's nearly all extra margin.

David :lol:


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## oilslick

*Its a con*

Racing cars use nitrogen from a bottle because it is of known consistency and no humidity. This means that when a pressure is set when the tyre is cold they will always end up with the same hot pressure. When racing cars are trying to get every small detail right to get a total bigger advantage then it helps to get everything heading in the right direction.

Actually the Oxygen molecule is larger than the Nitrogen molecule, weights are a reflection of molecule size, but not directly due to the way electrons "stack" in the orbits of different atoms. Molecular weights are 32 and 28 respectively.

(Most inert gases consist of pairs of atoms hanging around together hence the use of the word "molecule").

I think for a road car this is just a load of hype!

Grant


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## gnscloz

hi there had new tyres on bandit 1200 motorcycle filled with nitrogen def more stable than before but not sure if its the tyres or if its the nitrogen, guess time will tell


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## oilslick

*Placebo?*

Maybe there is a bit of Placebo effect too...

lol

Grant


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## gnscloz

*Re: Placebo?*



oilslick said:


> Maybe there is a bit of Placebo effect too...
> 
> lol
> 
> Grant


not unless these tyres dont need warming up before they stick.
wiyhout doubt more stable when cold


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## asprn

*Re: Placebo?*

I doubt it's "snake oil" - this is after all the 21st century western world, not a 19th century Western :roll:

I had a rear tyre explode on the RV last month on a French motorway, which highlighted the age of my tyres when on examination after I got home, I saw that the steel bands had corroded through age (despite plenty tread and no sidewall cracking).

If nitrogen reduces (or prevents?) rust, isn't that a very good reason to consider this?

Dougie.


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## DTPCHEMICALS

If nitrogen prevents rust it has to be on contact with the tyre cords Dougie.
They are encased in rubber.

Its rip off.

i will have have it in my aerosols so that I CAN CHARGE MORE. :lol: 

Dave p


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## davesport

> I doubt it's "snake oil" - this is after all the 21st century western world, not a 19th century Western
> 
> I had a rear tyre explode on the RV last month on a French motorway, which highlighted the age of my tyres when on examination after I got home, I saw that the steel bands had corroded through age (despite plenty tread and no sidewall cracking).
> 
> If nitrogen reduces (or prevents?) rust, isn't that a very good reason to consider this?
> 
> Dougie.


Yes but there still oxygen & dihydrogen oxide on the outside of the tyres carcass. I can't say I've heard of nitrogen being used to prevent corrsion forming in the steel belts/cords used to reinforce the tyre. If this was the case, it would as you state Dougie be an excellent reason to use an inert gas. I've never at any point taken a tyre off of any of my vehicles, cars or bikes & found free moisture within. Air or any other gas for that matter can be dried & all moisture eliminated IE when you fill a SCUBA bottle & most of the moisture from a compressor ends up in the bottom of the reciever.

To go back to your tyre that blew out. If I were in your postion I'd subject the rest of the rubber to some critical scrutiny to avoid a repeat failure. I'm sure you'll have done this already as it must have been an interesting experience on a vehicle of that scale. Why the steel had corroded would be interesting to find out. Not being a tyre specialist I can't begin to consider how water & oxygen could find it's way into that area of the tyre.

But your blowout has served as a wake-up call to me & I've had a good look at all of my tyres with an inspection lamp.

By way of an experiment. I've released all of the nitrogen from my tyres & replaced it with compressed air from my compressor whilst swapping fronts for rears. I'll monitor things with interest & note any changes.

Interesting video How to handle an RV tyre blowout

D.


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## 1302

Stanner said:


> wobby said:
> 
> 
> 
> Come on now, you can't blame the garages, after all their only trying to make a little extra in these hard times! :roll: :roll: :roll: :roll: :roll:
> 
> Wobby
> 
> 
> 
> So is this the "inflation" that keeps putting prices up?
Click to expand...



Your joke fell a little flat I fear...


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## chrisjrv

Soooooo, how do they get the air out before filling with nitrogen :?


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## Stanner

J99Dub said:


> Stanner said:
> 
> 
> 
> 
> 
> wobby said:
> 
> 
> 
> Come on now, you can't blame the garages, after all their only trying to make a little extra in these hard times! :roll: :roll: :roll: :roll: :roll:
> 
> Wobby
> 
> 
> 
> So is this the "inflation" that keeps putting prices up?
> 
> Click to expand...
> 
> 
> 
> Your joke fell a little flat I fear...
Click to expand...

In that case I'm suitably deflated............. :wink:


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## Stanner

*Re: Placebo?*



asprn said:


> If nitrogen reduces (or prevents?) rust, isn't that a very good reason to consider this?
> 
> Dougie.


The only way it prevents rust is because if there is no oxygen there can be be no "oxidation" and as rust is just oxidation of the iron content of the steel................... no oxidation = no rust.

Still doesn't stop it oxidising from the outside in though.


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## grizzlyj

The nitrogen that gets put in will be dry, so there will be less moisture and less oxygen, not none since as has been pointed out what was in the tyre before inflation will still be there? Unless they have a big sucking machine too?! 

I was thinking more of the rusting being to a steel wheel, which if you happen to have the sort of vehicle that will sit around a lot and not get its tyres changed too often may make getting the tyre off a lot harder, and over a long time not make the wheel too pretty internally. Neither of much consequence to anyone here I'd imagine?


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## duxdeluxe

I think that they fill aeroplane tyres with nitrogen so it must be good, indeed the only thing you should do - normal air is very bad for your tyres and they will instantly explode unless you immediately go to Kwak Fat and get them inflated at huge cost to your wallet.

A few years ago they never filled ordinary tyres with nitrogen (well they did - the air is about 78% nitrgoen as I recall), so what is the difference now? Unless of course you intend driving the van down the main runway at Heathrow at 185mph.......

Sorry - I can smell a rip off when I see one. Nice discussion, though!


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## Peter54

If you have a racing car and need Nitrogen apparently you need to buy the oxygen free type in cylinders. Not the stuff used by garages and tyre companies who have their own machine that does not remove all the oxygen. I don't know how they go about removing the air that is already in the tyre before they blow it up?


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## pneumatician

*Nitrogen or Compressed Air*

Not absolutely sure about how things may have changed since I retired.
Very few garages or tyre outlets would have had aftercoolers fitted and never driers to their compressed air systems indeed you would be lucky to find the Filter-Regulator-Lubricator systems serviced.
So what you could anticipate being inside your tyres is a Compressed air and water mixture with a possible hint of oil.
The oil will depend on where they are connecting the inflators as the tools should be lubricated the inflators not. 
Naturally the water will alternately evaporate and condense as the tyre heats and cools.

Steve


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## asprn

davesport said:


> I can't say I've heard of nitrogen being used to prevent corrsion forming in the steel belts/cords used to reinforce the tyre. If this was the case, it would as you state Dougie be an excellent reason to use an inert gas


Well, what do I know?  Nothing on this subject, which is why I posed the question.



davesport said:


> If I were in your postion I'd subject the rest of the rubber to some critical scrutiny to avoid a repeat failure


I've done far more than that. I've bought six new tyres which are being fitted in the next week of so. The existing ones were original to the 1999 van. :roll:



DTPCHEMICALS said:


> If nitrogen prevents rust it has to be on contact with the tyre cords Dougie. They are encased in rubber


As indeed I now know (making me an expert on ths subject ). Thanks for the info.

Dougie.


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## grizzlyj

I would imagine any garage saying they'll put 100% nitrogen in would have to pretty much do that, if you conveniently ignore what was initially in there of course. 

I'm not sure how anyone could automatically say that the garage equipment won't produce the same quality/purity that bottled gas suppliers would? Its quite probably the same method? I know for instance of three different qualities of "pure" oxygen, depending what you want to do with it (medical vs industrial). 

Wether the Kwik Fit type place would maintain to the same standard as the likes of BOC is quite another thing!


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## Boff

Hi!



crimpleken said:


> ... the answer was that tyres filled with nitrogen would not need topping up.


*Dangerous nonsense!*

If we assume that there is really 100% nitrogen in the tyre, then the pressure loss by diffusion compared to a tyre filled with ordinary air would be reduced only by less than 0.1 bar *per year.* So the difference could only be seen - if at all - if the tyre pressure is checked and topped up less frequently than once a year. Which would be grossly negligent, to say the least.

And in case of a puncture, even a small one, both nitrogen and oxygen leak out the same way.



crimpleken said:


> Took the car to another tyre dealer and had tyres fitted there.


A wise decision!

Some other facts about nitrogen and car tyres:

If the dealer says that ordinary air would contain too much humidity, or oil, or something else, then this translates into: _"The oil and moisture separators of our compressor system are defective and we want to make you pay for it."_

Even bottled nitrogen is not pure. Standard industrial grade nitrogen may still contain up to 5% oxygen. Nitrogen of higher purity is available. However, with e.g. 99% purity grade, the dealer would make a serious financial loss if selling it for just 2 quid per tyre.

Have you ever seen a tyre dealer _evacuating_ the tyre before filling it with nitrogen? They don't do that, they don't have the equipment for that. And, by the way, it would not be good for the tyre. But then because of the residual air in the tyre, even if using 100% pure nitrogen, the nitrogen content in the tyre will end up at about 93-95% maximum.

At the pressures found in tyres for road traffic, nitrogen and oxygen both behave practically as "ideal gases", so there is no difference between the two regarding temperature-pressure dependency, driving comfort, etc. I don't know about Formula 1, but I would guess that there significantly higher pressures are used.

It is true that the tyres of commercial aircraft are filled with nitrogen. This is however done to prevent them from catching fire from the _inside_ at touchdown.

Of course it does not do harm to use nitrogen for car tyres. Except to your wallet. :wink:

Best Regards,
Gerhard


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## Bella

*Nitrogen filled tyres*

Hi All,
Just read the above comments; after having all 5 of my tyres filled with nitrogen at ATS Euromaster, only cost £1 per tyre.
I went in to make enquires about pressure needed for my NTM vehicle; previous owner used 79.5psi all round which seemed high!
I usually check my tyre pressures 4-6 weekly, a job my knees hate me doing. I read the leaflet about Nitrogen Inflation whilst waiting for the pressure info to be found, so I opted for it in order to decrease frequency of use of foot pump!!
By the way the ATS leaflet states that it "purges the tyres of the current gas to deflate them then re-inflates them with nitrogen" .Four tyres can be done at the same time ; took 45mins to do my 5.
My tyre pressure is now 65psi , drive home was more comfortable & I'll let you know how things are in 6 months.


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## DTPCHEMICALS

How do you inflate the tyre when it has lost a couple of lbs.

Go back to tyre fitters and lose another couple of £`s

Dave p


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## teemyob

*OFN*

I use OFN for work. But I don't bother filling my tyres with it.

Don't see any great benefit.

OFN is expensive. When you consider the cost of Cylinder rental, cylinder filling etc. BOC Even charge you for collecting from there outlets.

In any event, the only true way to remove any existing air and moisture from a tyre casing would be to evacuate it with a vacuum pump. That is nigh on impossible as the casing will suck in air from the rim as the tyre case collapses. 
For even better results, the tyre would have to be as warm as possible whilst keeping held in a deep vacuum for at least 30 mins. That would make the sidewalls more pliable, thus creating more of a problem.

The only other way is to fill with OFN and then deflate. But that still leaves moisture and some air.

I think the nitrogen filling is just another money spinner.

TM


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## safariboy

The AA seem to suggest that there is no point in nitrogen for cars. The reason that they suggest for planes is (1) vibration caused by icing at very low temperatures (-40) reduced. (2) Prevent fire. No manufacturers recommend it.


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## teemyob

*helium*

Helium might save some weight!
8)

1. Racing bicyclists often go to extra effort (and expense) to reduce the weight of their bicycle. For example, a steel water bottle cage can be replaced with a titanium model at three times the price with a weight saving of about 25 grams. Perhaps inflating tires with helium instead of air would be worth considering. Air is mainly nitrogen, N2 (~78%), and oxygen, O2 (~21%). Helium, He, is much less dense than N2 or O2 (at same T and P). 
(a) What is the mass difference between air and helium used to inflate two typical racing tires? Make the following assumptions: (1) the wheels have a diameter of 700 mm, (2) the circular cross-section of the inflated tube is about 20 mm, (3) the ideal gas equation is sufficient for this approximation, (4) the tires are inflated to a pressure of 140 pounds per square inch (PSI). Note that if a tire pressure gauge reads zero, the gas in the tire is at atmospheric pressure, so 140 PSI means the gas in the tube is actually at 140 PSI plus the atmospheric pressure. Atmospheric pressure can be assumed to be 1.0 atm (14.7 PSI). [3 points] 
Using the ideal gas equation, we need volume, pressure, and temperature to determine the amount of gas in one tire (first helium, then air) and double these results for two tires.

volume 
The volume of the tire (inner tube actually) can be approximated by considering the tire a cylinder "wrapped" around the wheel rim. The diameter of this cylinder is 20 mm and the "height" is the circumference of the rim.

rim circumference (cylinder "height"): 
circumference = (PI)(d) = (3.14)(700mm) = 2200mm 
tire volume (the approximate cylinder): 
volume = (PI) r2 h = (3.14)(20mm/2)2 (2200mm) = 6.9x105 mm3 
If SI units are chosen, the volume is converted to cubic meters (m3). 
If (liter/atmosphere) units are chosen, the volume is converted to liters (cubic decimeters, dm3). 
For SI units: (6.9x105mm3)(1m/1000mm)3 = 6.9x10-4 m3

pressure (SI pressure unit is the pascal); 
(140PSI + 14.7PSI)(1atm/14.7PSI)(1.01x105 Pa/atm) = 1.06x106 Pa

temperature (No temperature given, so make a reasonable assumption) 
choosing 20oC or 293 K (There are other reasonable choices.)

ideal gas equation 
PV = nRT 
n = PV / RT = (1.06x106Pa)(6.9x10-4m3) / (8.31Pa m3/mol K)(293K) 
n = 0.30 mol 
for two tires: 2(0.30) = 0.60 mol

difference in mass between helium and air filled tires 
mass helium in tires: (0.60 mol)(4.0 g/mol) = 2.4 g He 
mass air in tires: (0.60 mol)(29 g/mol)* = 17 g air 
* see problem 5.107, p 232. Or the "effective" molar mass of air can be worked out as done in lecture from the composition of air: 78% N2, 21% O2, 1% Ar. 
difference: 17g air - 2.4 g He = 15 g difference (two tires)

(Slightly different interpretations of the dimensions given were acceptable as long as the calculations from your interpretations were done correctly.)

This weight saving is not as significant as replacing steel water bottle cages with titanium. Assuming the water bottle in the cage would be filled, a much better way to trim weight would be to fill the bottle half-full, which would would save several hundred grams! Inflating tires with helium probably isn't worth considering seriously.

(b) One disadvantage of helium compared to air (other than cost and inconvenience) is the faster rate at which helium-inflated tires would lose pressure due to effusion. If an air-inflated tire drops from 140 PSI to 110 PSI in 4 days, estimate the time a helium-inflated tire would take for such a pressure drop. [2 points] 
Graham's Law of effusion: 
rate(air) / rate(He) = [M(He) / M(air)]1/2 at constant temperature and pressure 
rate = amount of gas / time for effusion (rate is inversely proportional to time for a constant amount of gas) 
rate(air) / rate(He) = time(He) / time(air) 
time(He) / time(air) = [M(He) / M(air)]1/2 
molar mass(He) = 4.0 g/mol ; molar mass(air) = 29 g/mol 
time(He) = (4 days)[(4.0g/mol) / 29 g/mol)]1/2 
= 1.5 days


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## BrianJP

I agreed to have my tyres inflated with nitrogen last week.Next day I checked tyres and rears were 5 psi lower than they were supposed to have been inflated to.( my gauge is accurate ).
I live 20 miles from nearest tyre dealer with nitrogen so what did I do?
I just topped them up with air from a footpump. So from my point of view the exercise was a waste of time and money.


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## smartgolfer

If you have a Costco card, they will inflate your tyres with Nitrogen for free....


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## safariboy

Am I right in thinking that these lightweight high pressure tyres have to be partly deflated when not in use? If so the consumption of helium would be substantial
I was interested to see that nitrogen was produced in the garage by a machine. Presumably a relative of the ones used to produce medical oxygen in the home. I have had tyres filled with nitrogen and I am sure that that came from a cylinder.


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## davesport

You can't use helium....end of !

Helium molecules are incredibly small, yes I realise that everyone knew this already, but I mean much much smaller that either nitrogen or oxygen. Helium's an annoying gas that can find it way out of & into the most unexpected of places. The main impracticality would be topping up your tyres two or three times a week....minimum.

I'm sticking to my original postulation that it's snake oil & a money-spinner  

D.


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## safariboy

Putting the same question on another forum I am told that Oxygen diffuses through a tyre about 3x faster than nitrogen. Molecular size not significant. The mechanism is more akin to solution.

This is the reference but it does not make easy bed-time reading!
http://www.getnitrogen.org/pdf/graham.pdf
The author may also be interested in promoting Nitrogen in car tyres (BUT I do not know if that is true)

The article may well be biased towards the nitrogen camp. But I think that the general conclusion is that for us the difference is not significant.


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## Boff

safariboy said:


> Putting the same question on another forum I am told that Oxygen diffuses through a tyre about 3x faster than nitrogen.


Even if this is so - if I remember correctly it is only 30% faster - then the effect on tyre pressure is absolutely negligible:

The German automobile association ADAC has once tested this, and found that compared to tyres filled with normal air the pressure leakage from nitrogen-filled tyres is reduced by not more than 0.1 bar or 1.45 PSI *per year!*

So even if you check your tyre pressure not more frequently than once a year - which would be gross negligence anyway - you will not see any difference.

Best Regards,
Gerhard


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## Waggie

My guage doesn't go up to the required pressure for my tyres so i take the Van to ATS and ask them to check the Tyre Pressure this they do for free, They top up for free too, this also saves my Knees ;o)

Happy Motor Homing everyone ;o)


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