I am amused by the nitrogen defenders here. The guy isn't saying most of what they say is not true, he is just, using basic physics and mathematics repeatable and provable by anyone (unlike people's impressions/speculation), saying that the gains are so miniscule that for the road its not worth spending money on. His final point about idiots thinking that because they have 'pure' nitrogen they don't need to check tyre pressures is the most important one, I think. Its your money, fill them with nitrogen, carbon dioxide (even better than nitrogen!) or whatever. But still check your bloody pressures!

 

Regarding aircraft tyres, they are not so much filled with nitrogen as emptied of oxygen (the regulations state a maximum allowable concentration of O2) to reduce the chance of the tyre exploding from the sudden forces on touchdown when the plane lands.

 

And F1 teams, well they have millions to spend on making the perfect rivet, so filling the tyres with nitrogen for the small gains is peanuts.

 

 

 

I understood aircraft tyres were filled with nitrogen to control (perhaps predict would be a better word)  the pressure variances due to altitude and temperature, reduce corrosion and most importantly the fact it doesnt burn or react violently to oils and greases 

 

Similar to the need of motor sport teams I imagine

Anyone got a elephant for sale

A nice experimental comparison of thermal expansion N₂ versus air versus CO_2.. (Scroll down to "The gas test", subtitle "Ideal Gas Law Formula Shmormula" )

Just in case anyone believes that nitrogen has some physics-defying thermal stability.

 

Had a look at that web page, unfortunately he does not do things in a proper methodical way & does not understand various factors as follows:-

1. He does not state how "dry" the air is eg the relative humidity of the air used to fill the "air bottle".
2. Those gauges are not the most accurate, nowhere on their website is the accuracy stated for them, similar sized & type are between 2% -5% which is not accurate enough, with the dial being too small to read for better readings.(should have used a Newbow 4" 1% certified accurate gauge, nice & easy to read very small changes) 
3. The maximum temps in his test are between -28C & +56.6C. This is not enough, if you use tyre warmers they get the tyres to +75C to +90C & then the tyres run in at over 100C for most rally & race without talking about F1!
4. He does not state what the altitude is where he is & does not consider those variations either!
5. He states that he noticed the CO2 bottle defrosts differently to the other two & yet does not know why, nor explain why, proving his "superficial" interest.

Read here for tyre pressures increasing with load, speed, outside temps etc.

 

http://www.bbc.co.uk/sport/0/formula1/20264491

 

http://www.caranddriver.com/columns/a-look-behind-the-tire-hysteria

 

Basically driving a car on a nice 80mile round trip on back roads on a summers day will stress your tyres to over the 56C this bloke tested. The more load you have the more stress, the more "briskly" you drive the more stress, the more you brake the more stress. Thus the internal temps increase. Then you have the external temp of the ambient air & the heat from the tarmac also. 

 

Factor in like several people on this forum do, a nice drive over the mountain passes. So that's a change in external pressure which affect how the tyres behave. Then those very step & twisty ascents & descents, loads of heat build up there also from the brakes heating the wheels in the wheel well.

 

If you fill & check you tyre pressures at sea level near the sea on a rainy day where the RH is say 68%. The garage is using poorly maintained equipment (filters not drained etc which can be common). You will have just filled up with a lot of moisture laden air. When the tyre is exposed to cold external temps (0C) the moisture in the air inside the tyre will condense & form water inside the tyre which leads to corrosion. Then when you go on this nice drive as mentioned above, or like others here do, take the car on track, that water will start to turn from a solid into vapour & then into steam (100C). This will affect the tyres handling & the rotating balance of the tyre.

 

Just go look on Demon Tweeks or other such like "shops", look at how hot the tyre warmers get, look at the Relative Humidity (RH) meters for tyres.

 

If you drive "briskly", or go on track days, or do nice "back road" or mountain pass trips, or even load your car up & do several hrs on the motorways the amount of water in your tyres will affect the tyres themselves.

 

You don't have to have Nitrogen, but it is advisable to leave your tyres in the sun on a hot dry day until they get hot. Then fully deflate them & then re-inflate them. This will ensure that they are drained of as much "wet" air & inflated with as much "dry" air as possible. Make sure the inflation equipment is drawing in hot dry air & that any filters etc fitted are drained.

As many new cars now have tyre pressure and temperature monitors built into the wheels, we should start a Brisky Thread were people can run their car over a variety of conditions (fast motorway, track, city etc) and see how the temps and pressure vary before, during and after the runs. It doesn't matter so much that the measurements are super accurate, more that they are precise and consistent.

 

I am assuming that many of use are still using good old British air, but that some will be using the foreign Johnny of Nitrogen

 

 

 

 

Also it will be interesting to see if the Elephant gets hot and experiences an increase of internal pressure.

Edited 21 September, 201510 yr by Lady Elanore

Some fair comments there fabdavrav. 

 

I dare say some more scientific experiments have been done, but that was just something I found quickly to illustrate the point that nitrogen isn't a 'special case gas', as seems to be claimed widely in these discussions.

 

All the bottles were at the same altitude, and so I don't see that objection having any relevance to the comparison.

 

The condensation effects are intriguing, but don't to my mind seem relevant to the parameter being measured - pressure.

 

 

Bear in mind that warm air can hold a lot more moisture than cold air, so you might need to be a bit careful that what intuitively seems like the right approach w.r.t. filling tyres with air on a hot day may be counter-productive.

So basically if I get all of this right.  Since I started driving in 1970 I have been risking life and limb by putting air into my tyres.  It makes me wonder how I managed to get this far.

 

OK hands up anyone who has had a tyre blow out on them or even a puncture recently.  Not many I would imagine which again is remarkable considering you have been putting air in your tyres.

 

Dons hard hat and heads to the shelter at the bottom of the garden.

I get a puncture about every 2 years on average. usually screws and nails :( I do drive above average miles per year and often go to places which are under construction, so that might help explain it.

Some fair comments there fabdavrav. 

 

 

 

The condensation effects are intriguing, but don't to my mind seem relevant to the parameter being measured - pressure.

 

 

Bear in mind that warm air can hold a lot more moisture than cold air, so you might need to be a bit careful that what intuitively seems like the right approach w.r.t. filling tyres with air on a hot day may be counter-productive.

 

Dry air is important, eg low RH% level, hot dry days are more likely to have a low RH%, although you can have a low RH% on a very cold day, say -15C, my accurate digital weather station at home lets me know the outside temp & RH%

 

Condensation is funny as I studied it in relation to buildings & was taught about various "steam" related stuff by an ex specialist heat transfer engineer............

 

Water is held in air as moisture & will condense on a surface So in std double glazing the air gap can drop in temp, so on a cold night the external air temp drops & the house inside is warm, condensation forms on the glass facing the internal air. On an Argon filled air gap the gap temp does not drop so the condensation forms on the outside face of glass.

 

The main problem with tyres is that temps can go to 100C & beyond, so any water/moisture in the tyre can form steam which is not what you want.

 

In terms of aircraft, external air pressure on the tyre (flying at altitude) causes the air inside to react differently, so Nitrogen is used as more stable. In terms of rally/race (not talking F1) when the temps are starting at 75C & need to be 100C then steam formation is not advised! 

 

In terms of plodding along in a car, normal driving, not worth it.........................HOWEVER if you track day or "Briskly" drive your car like many on this forum do, then defo seek out "dry" low RH% air as I suggested in previous post..............

I never got how they remove the air already in the tyre before merely adding nitrogen to it. Do they fully collapse the tyres while beaded with a vacuum then re-inflate it? If not it would seem even more insulting to call it pure nitrogen. 

Tyre temperatures.

http://trackdayguru.com/tyre-management.html

Dry air is important, eg low RH% level, hot dry days are more likely to have a low RH%, although you can have a low RH% on a very cold day, say -15C, my accurate digital weather station at home lets me know the outside temp & RH%

 

Condensation is funny as I studied it in relation to buildings & was taught about various "steam" related stuff by an ex specialist heat transfer engineer............

 

Water is held in air as moisture & will condense on a surface So in std double glazing the air gap can drop in temp, so on a cold night the external air temp drops & the house inside is warm, condensation forms on the glass facing the internal air. On an Argon filled air gap the gap temp does not drop so the condensation forms on the outside face of glass.

 

The main problem with tyres is that temps can go to 100C & beyond, so any water/moisture in the tyre can form steam which is not what you want.

 

In terms of aircraft, external air pressure on the tyre (flying at altitude) causes the air inside to react differently, so Nitrogen is used as more stable. In terms of rally/race (not talking F1) when the temps are starting at 75C & need to be 100C then steam formation is not advised! 

 

In terms of plodding along in a car, normal driving, not worth it.........................HOWEVER if you track day or "Briskly" drive your car like many on this forum do, then defo seek out "dry" low RH% air as I suggested in previous post..............

Most of that seems wrong, but I'd rather not get into an argument with you, so I'll leave you with those beliefs. If you'd like to hear my counter-arguments to all those points, drop me a PM.

Tyre temperatures.

http://trackdayguru.com/tyre-management.html

 I like that info, at least it states the tyre temps up to 70C for road design tyres & 100C for track design car tyres..............

 

 

both well beyond the 56.6C the bloke tested on that web site..................

Most of that seems wrong, but I'd rather not get into an argument with you, so I'll leave you with those beliefs. If you'd like to hear my counter-arguments to all those points, drop me a PM.

 PM sent

I wonder if I filled tyres with 'Helium' that car would be lighter and go faster...LOL

One of my mates was a tech advisor for Feroda in AU.  They couldn't work out why the ABS on some gas trucks was out of calibration when they had a full load on.  They put the truck on a weigh bridge and it was several tonne lighter when fully laden.  Sounds like BS to me as I thought that all gasses were transported in liquid state but it's a good story when he tells it.

 

 

Regarding aircraft tyres, they are not so much filled with nitrogen as emptied of oxygen (the regulations state a maximum allowable concentration of O2) to reduce the chance of the tyre exploding from the sudden forces on touchdown when the plane lands.

 

 

 

Apart from what you correctly state above, there are several other reasons:

Nitrogen stops clumps of ice forming in the wheel assembly.  This prevents an out of balance situation on landing.

Nitrogen is inert - less chance of fire / explosion (caused from overheating brakes, etc).

Nitrogen has a reduced chance of oxidation of the rubber or alloy components

Nitrogen has a reduced pressure variation due to temperature.  It can be up to 60celcius on the tarmac and minus 50celsius when at altitude.

 

I used to production plan for an aircraft wheel shop - I didn't have the foggiest until I started there. 

 

The guys used to bting in the wheels/tyres off there own car - this was back in the mid-90s.  They all knew doing car tyres was a **** but it made them feel good.