In fact, the nitrogen gas itself might only be 95% pure. The big issue is the gas won't have moisture in it. Potentially contaminating air in the tire prior to filling is reduced during the bead seating process.

Typically they will put green caps on the stems with NO2 embossed on top.

 

So this is the dealer letting out the factory fill, replacing all of it with nitrogen and changing the caps. Interesting.

I can't imagine the dealers I have worked with doing that at all, much less for for free. I suspect they would have just changed the caps. I would have tests run to find out for sure.

My two 2014 F-type V8S models both came with the crappy grey plastic valve stem caps. I guess I have to make do with ordinary air in my tires.

Oh well, I have had to replace half of it anyway from dealers dropping my preferred air pressure settings when the car was in for service. And in fact now that I think about it, I replaced all of it in the right rear for a flat repair. Would hate to have three with nitrogen and one with air. At least I don't have to match up the other three now.

Thanks for the reply. I am going to go sulk now, bemoaning the fact that I wasn't given a complimentary nitrogen fill when I bought either of these cars.

 

With the seasons changing, don't forget to drain your winter air, and put in new summer air.

 

Where do you get the summer air? Will spring air be okay for now?

 

Exactly. As Norri mentioned, the devil is in the details.

Much like oil and filter discussions, the owner should choose what makes him happiest. The car couldn't care less.

The moisture content in air is of utmost importance in aviation for good solid technical reasons. None of these conditions exist with motor cars.

I think the suggestion that the dealer and not Jaguar being responsible for installing the magic green caps is the most probable scenario. None of the cars I've seen on our local dealer's floor has them.

 

I came across this which amused me at least:

'So: suppose you start with 40 psi air. After some time, the O2 leaks out. Now, 32 psi.
So you refill with air- 8 psi partial pressure, of which about 1.6 psi is O2.
Then that leaks out. You are now at 38.4 psi.
Refill with 1.6 psi of air... of which .3 psi is O2. That leaks out.
Now you are 39.7 psi... pure N2.'

 

Well, that leaves me out as the State of Maine still has winter-like temperatures - or quite close to; particularly if you factor in the gusts of winds lately - so I guess winter air will have to suffice.

Also, some of us don't have "crappy grey plastic stem caps" or "green caps with NO2" on them....

 

There is a logical fallacy in the idea that different size molecules
will leak through a permeable solid at the same rate, not the least
of which is the presumption that the tire carcass is in fact permeable
at some rate that is noticable over the period of a year.

If it is permeable and presents paths of different sizes, then molecules
of different sizes will leak at different rates.

Take a sieve with two sizes of openings. Call those sizes 1 and 2, with
2 being the larger.

If you pour a gallon of particles that is size 1 or smaller into the sieve,
the particles can flow through both the size 1 and size 2 openings in
the sieve.

If you pour a gallon of particles that is between size 1 and size 2 into
the sieve, then the particles can only flow through the size 2 openings
while being blocked by the size 1 openings.

Since it is the same volume of particles exiting through a smaller
surface area, it will take longer to flow through.

Size 3 particles won't flow through the sieve at all, even though
the sieve has holes.

I believe that there are benefits to nitrogen in filling tires, particularly
when done at no cost. I would also happily touch up a tire with air
from any old compressor while on the road. The thought being that
the dilution is not significant.

There are cases of tires that have been impossible to balance until
they were dismounted and drained of water.

If a tire starts with nitrogen then there is less chance, even when
diluted with unconditioned air, that significant amounts of moisture
will form.

About the same as waxing a car. The paint is fine, but adding the
wax has benefits.

++

 

Yeah... the winter blend is more volatile.. helps to keep up the pressure. Don't leave it in during the summer months or the tires will vapor lock. They might not even roll out of the garage.

 

I try to keep some equatorial air on hand for those in between times.

 

..... and at which point the leakage rate would drop noticeably if we are to believe the myth. If it were true, there would be no need to create the energy wasting nitrogen machines we see at tire shops.

 

My car was delivered to me with the green nitrogen stem caps and, I was told, nitrogen in the tires. I had already purchased stem caps - one set the British flag and another set with an "R" logo. However, the stems used for the nitrogen are quite a bit longer than normal tire stems and the "N" stem caps are longer than normal caps so, while the stem caps I purchased will fit on the stem they only cover half of the threads so look as though they do not fit and so I have not used them.

 

The plot thickens. Now the dealer would have had to dismount the tires, replace the TPMS equipped rims with special, longer TPMS sensors, change out the air for nitrogen, add the special caps...possibly in a vacuum...and not charge anything for it. Wow.

 

I think the affinity stem caps are just shorter than normal plastic caps. I was sent a set of "growlers," which I put on in place of the green caps, and there is some stem thread showing.

Surely, you jest about the rest.

 

I installed a set of the growler ones as well, I like them fine and haven't noticed any threads showing. They do keep dirt out of the valve, which is after all their purpose. I think the stock caps are designed to sell the cool ones at the parts counter. They work great for that based on how many of us have bought replacements.

Yes, I am jesting about this thread. It's interesting that people can get that into what is in their tires or even have an opinion on it at all. I can't find any summer air here in Enumclaw yet, but I still have some equatorial air left. You are lucky you have the nitrogen...

 

N02 is primarily used in aircraft tires for the simple reason that in the case of a fire or an electrical fault at altitude in the wheel well, if the tire casing is comromised the N02 provides no fuel for the fire, were as 02 would.

Do not use steel stem caps on aluminum stems, the consequent dissimilar metal corrosion will make life difficult in the future.

If moisture content in air for your tires is a concern, then come to Minnestoa in January when it's 25 below and fill your tires. Air that cold is virtually devoid of any water content. ��
Another member struggling with the rotating TPMS phantom warning problem.
Regards,
White Bear.

 

I suspect you mean N2. NO2 would provide plenty of fuel to a flame with explosive effect. N2O is just laughable.

 

For what it's worth, my dealer has a machine that fills the tires with nitrogen while or after actually sucking out the air, or whatever previous gas was in the tire. I assume that's how nitrogen fills are done.

Tires are delivered to the dealer filled with regular old fashioned UK air. It's the dealer that replaces with nitrogen. No dismounting done, just a drain and fill so to speak.

 

The suck and replace machines are only marginally effective in removing air from a mounted tire, not that there's any point in using nitrogen in the first place.

I was in my local Ford dealer last week. They were offering a special of only $30. for a nitrogen 'top up'. Disgraceful.

 

"Tires are delivered to the dealer filled with regular old fashioned UK air."

There's the motivation for changing to nitrogen - to get rid of all the excess moisture from home!