Hi, I’ve searched for this subject and came across the following thread https://www.scoobynet.com/wheels-tyres-brakes-13/566538-nitrogrn-filled-tyres.html?highlight=nitrogen which pointed to this link http://www.toyo.com.au/tech_info11.html which seems to generally answer my questions although it is a Toyo site.

However, I was at my local dealer yesterday and mentioned, in passing, that I was going to put nitrogen into my tyres (Bridgestone RE070s) and was warned not to without checking with Bridgestone first as it may affect the warranty. Apart from the warranty issue, I was also warned about the nitrogen possibly adversely affecting the rubber and having a potential affect on the pressures.

Having had nitrogen in the tyres on my last car I found the main benefits to be no noticeable loss of pressure and much more consistent grip although I found you had to increase the pressures significantly as the pressures do not increase nearly so much when warm. Ie you had to inflate to the anticipated warm pressure of an air filled tyre. I was not aware of any downsides except the minor cost – something like £1 per tyre which included free top ups if necessary.

Now, having a questioning mind, none of these risks appear real in my mind. First of all, “air” is 80% nitrogen. Nitrogen is virtually non reactive chemically and it is the water vapour in normal air filled tyres that causes the main pressure variations.

The following is an extract from the Bridgestone web site:
11.Nitrogen comfort fillings
More safety for you and your tyres. Nitrogen comfort fillings guarantee constant tyre pressure and offer you the following advantages over air-filled tyres:
Safety

• through less heating of the tyre and constant pressure

Cost reduction

• through lower drag
• less wear
• greater mileage
• lower fuel consumption

Greater comfort

• through shorter braking distances
• through lower drag
• less tyre wear
• greater mileage
• optimum running performance

Now, with the RE070 being such a specialist tyre and whilst I have probably answered my own questions with speculation, does anyone have any factual knowledge and experience of using nitrogen in these tyres?

 

I have filled my Toyo's with nitrogen with no adverse effects. It is nice not having to check your tyre pressures for 6 months.

 

As air is 78% nitrogen anyway- >95% nitrogen achieved by purge and re-inflate cycles will have absolutely no degradation on any rubber tyres as N2 is inert.
put in foodstuffs to prevent oxidation.

best benefit from N2 is removal of water vapour from your tyre. which in severe cases cause imbalance of tyre pressures when hot.

have 97% purity in my tyres - fortunately - tyre inflation and design of is a part of my every day job.

 

oh - i forgot to add if normal air inflated tyres have the same pressure as nitrogen - there is no reduction in drag or improvement in mpg.
the marketing statement is not quite truthfull

it relates only to those folk that never check their tyres from 1 year to the next - then N2 will have savings because its loss of pressure through the tyre wall is 2/3 rds slower

 

So what accounts for that when going from 'mostly nitrogen' to 'nearly all nitrogen' ?

 

Mostly nitrogen means remaining 21% oxygen
oxygen diffuses throug the wall faster than N2
hence when comparing Nearly all N2 > 95% to Air 78% N2

the remaining O2 IN Air will be lost quicker - hence tyre goes down relatively faster than Nearly all N2

In reality O2 Molecule/molecuar weight is smaller than N2 and will filter its way through the tyre wall.

As an extreme remember Helium in kids balloon, a day later miraculously the baloon has deflated - tiny helium molecules have squeezed through the rubber!!

 

Removal of water vapour is also an advantage in extreame colds as no ice/frozen rubber will form in the tyre. Thats why planes use N2...

Got an imported leggy gt that must of been in a cold climate as its got metal dust caps with N2 written on them and has remote start and remote heater controls.

No point using N2 unless its free and easy to get hold of in this country...also I wouldnt want to trust N2 in my tyres for 6months and still be holding pressure, my opinion anyway.

Gaz

 

http://i94.photobucket.com/albums/l1.../600570004.jpg

View of my sti with 4 simultaneous conversion of Air purge to N2 took 3 puges with overpressure 34 to 42 to 10 psi to 42 pis to 10 to 42 to 10 to 34 psi tool 12 minutes.

Only a few garages do it properly in the uk - most give just 1 inflate from flat - the problem is you only get 89% N2 - so don't get suckered into paying.

With 2 purges you get 94.5 % final purge and a 3rd purge /inflate in all gets you 97%

A big market in the USA due to mandatory tyre pressure monitoring systems, and more customer awareness than in Europe. who said all yanks are thick

 

Mark3evo

Wow, I've found an expert

I've often wondered about the residual air in the tyre. Your figure of 89% N2 that you quote; is it 89% N2 and 11% Air (or effectively 97% N2) or 11% O2?

I appreciate that it is the water vapour which is probably most important in terms of pressure increases but in terms of deflation, I have wondered why, bearing in mind I have used N2 for my tyres for several years now without any need for topping up, if you fill the tyre with air (78% N2), does the pressure go down much more than you would expect if 78% were trapped inside.

 

1. 11% O2
2. Theoretically N2 does escape but at slower rate than O2,
But if you drive like me - my tyres are generally replaced every 9 months or so.
On normal air tyres
Some wheels are damaged by shoddy Tyre fiters and some gas can escape
between the tyre bead and wheel, also through the tyre valve caused by dust particles holding schrader valve off its seat.

Your last statement confuses me - sorry. i would say pressure goes down the same - as this is the same statement.

 

Sorry re last confusion. The gist is that with 78% N2 in a normal air fill then, in theory, the tyre would only deflate to 78% of the pressure and then virtually hold its pressure for some time. My experience of old tyres used to be that they lose practically all pressure.

Whilst I appreciate N2 probably does escape slower than O2 my experience is that over the life of the tyre I have not had to top up.

Do you run slightly higher pressures than normal to counteract the lack of increase in running temperature and pressure from water vapour because I found "normal" pressures where not enough?

 

i personally run the tyres as designed 1.9 rear and 2.3 front -else the tyres wear in the centre. heated tyres in N2 will still increase in pressure as per air. ata least all 4 tyres will be consistent though

 

Some info on Toyo site i had stored in my fav's
Technical Information Issue # 11
Also a PDF file http://www.toyo.com.au/TechInfoPDFs/...0Inflation.pdf

 

All aircraft tyres are run with as near to 100% nitrogen as possible i.e only nitrogen is used from post build up inflation. One reason is the requirement for a stable pressure under extremes of temp. If you are using your car on a track then the pressures will not increase as much with nitrogen as they would with air.