Is anyone running nitrogen in the all season run flats on their Countryman? Did it cause any issue with the auto tire pressure monitoring?

Many thank, always, for any input. Jonbettie

 

I'm running N2 and no issues to report.

 

I've been using N2 in tires on both cars before the CM4 and the main experience is a significantly lower pressure loss rate over time compared with compressed air. No other issues.

 

I have nitrogen but don't have the all seasons and I am not having any issues

 

What is the benefit in putting nitrogen in your tires?

 

Fom what I understand the N2 molecules are larger than oxygen and leakage over time is reduced. Pressure also stays consistent with changes in temperature and altitude.

And, many thanks for your replies. Jonbettie

 

Increased tire life, better fuel efficiency, you don't have to check your pressure as often (not that you need to check it now with TPMS)

Nitrogen will cause no issues for TPMS, as jonbettie the natural leakage that occurs with all gases is less with nitrogen then with oxygen (well actually plain old air we use, its not pure o2), so its actually superior to use as your TPMS would go off less. Down side is of course tire places usually charge you (or charge you more) for it. It also has no water vapor in it (air we normally use does) so its actually better for the tire, rim, TPMS and valve, as less corrosion occurs, as well.

 

Our CostCo here in the Springs does it for no charge if you are member. Have seen tire places do it at for $10 per tire. Just be sure you get the green valve stem caps.

 

This is really the main benefit. Nitrogen is going to expand with heat just like air will. Removing the water just makes the expansion more consistent. If you aren't flushing your tires out with nitrogen regularly there is going to be some oxygen in there anyway due to partial pressures trying to reach an equilibrium.

In any case nitrogen is probably better for you TPMS since you would minimize the corrosion issue.

 

I've found that all the local Costco tire shops use N2, and I can just drive up to the automatic dispenser, set the pressure, and inject the tires. For a new visiting car to Costco, I usually ask for a set of green valve caps so that my next visit will seem like I belong. Sometimes I've even purchased the tires at Costco, too.

 

Ye, but it still has a bigger molecule, so no matter how hot it gets your still going to lose less compared to normal air .

 

(This is my field - Polymer Engineering)
Even though oxygen has a larger MW it has a slightly smaller electron cloud than nitrogen (they are diatomic so they are shaped like a jellybeans). Permeation of essentially ideal gases in rubber will be size controlled. The bottom line is that a pure nitrogen will have a slower permeation rate than air which is 78% nitrogen and 20% oxygen (plus others).

I just found a Consumer Reports study and they did find a slightly lower pressure loss with nitrogen than air. You can Google it and easily find it.

Other comments in this thread on water (common in pressurized air) and oxidation of the interior of the tire are interesting. Tire liners are typically polybutadiene rubber. It is one the most permeation resistant elastomers. Since polybutadiene contains double bonds in the backbone it is susceptible to oxidation which hardens the rubber and makes it less effective as a liner. It is reasonable that nitrogen would be a better gas for inflation.

This is the first I have ever heard that tire shops were offering nitrogen. It makes sense to me to pay a little extra to avoid having to fill the tires as often. I am not sure the oxidation will occur fast enough to be a factor versus natural wear of the tires but it is possible from a science perspective.

Hopefully I didn't bore to many people. I will be asking for nitrogen next time I rotate my tires!
CN

 

How can I tell if I have N2? Our Highlander uses it and sports green valve caps.

 

Yep thats it, they are suppose to use green valve caps when its filled to indicate.

 

My Mini dealership didn't put green caps on

 

AFAIK, no Mini will come with Nitrogen. It's usually done by tire shops, although my new Mazda3 has green caps, so maybe some Japanese car co. are doing it.

 

Thanks for that!

Cheers,

Charlie

 

Our Discount Tire includes N2 free and has a dedicated filling station - you just pull in and they do it for you.

 

Wow, I thought I was reasonably informed but I missed this completely. I have been using Discount Tire for years. Thanks!

(The cave I live in is very comfy).

 

If I put helium in my tires will my MINI float?

Dave

 

It's German they would probably suggest hydrogen.

 

just run normal air. normal air has almost 80% nitrogen allready. as for making your tires last longer, this might be true if your tires lasted 50 years or so. but for the life of a normal tire you will not see any difference. hell, the sun will kill your tire faster. and as for your tire loosing less air. yes its true, but people should be checking their tire pressures often just like your oil so thats not really an issue.

at the end of the day it is your car and your money. run what you like :D
i know i run normal air in my tires even though i have a nitrogen tank in the garage (use it for filling shocks)

 

JudgeS. My new CMS came with N2 in the tires from my dealer, and I was given a card to register them. This gives you a list of shops to get nitrogen put in your tires if needed locally, for no charge. Irvine mini in social is where I purchased my CMS.

 

Just out of curiosity, since I am certainly NOT an expert on transport phenomena, do you know roughly what that difference in permeability is?

Curious because by increasing the concentration of nitrogen in the tire vs the outside air, wouldn't you be increasing the permeation rate of N2 out of the tire?

Assuming 49.7 psia in the tire and 14.7 psia atm., 79% N2 in air:
With air you are at a N2 partial pressure of 39.3 inside the tire, 11.6 outside the tire, so a difference of 27.7

With 100% N2, you are at a n2 partial pressure of 49.7 psi inside, 11.6 outside, so a difference of 38.1, or about 37% higher than air. So I would assume the permeability of O2 vs N2 in rubber has to be quite a bit higher?

Also interesting on the CR study. Would be good to know if they were using dry air as a comparison. Funny tire manufacturers did not think nitrogen was necessary. Not sure a 1.3 psi difference in a year is significant enough for me to worry about anyway

 

Permeability of oxygen is about 3 x that of nitrogen through rubber, mainly
because even though oxygen is a heavier molecule than nitrogen, it's more compact, and therefore, smaller.
http://www.getnitrogen.org/pdf/graham.pdf
This also means that when you top up tires with regular air repeatedly, they eventually
become more nitrogen rich and oxygen poor anyway.
The fact that nitrogen supplied for filling tires is extremely low in water vapour
compared to regular air is the main benifit of using N2 for tires.
The slower leakage is also a benefit, but a negligible one if you check tire pressures regularly.
The reduced oxidation of the lining of the tire with N2 probably doesn't mean much in real life.