Slow leak in driver's side's rear tire

I got an advertisement from a local dealer recently offering to fill the tires with nitrogen for $39.99 for four.
Without going into the specifics of air being 77% nitrogen already, how does he purge the oxygen, the fact that nitrogen molecules are almost exactly the same size as oxygen molecules, or anything else technical about what tires are full of, I can tell you for certain that the dealer is full of hot air. $10/tire? He has GOT to be kidding.

3 Likes

No , the dealer is just using Nitrogen as a way to have a high profit service. Even if they sent out a flyer saying that nitrogen was unnecessary there are people who would insist that it was.

I’m wondering if Corollaguy had nitrogen filled the last time he took his car in, bought into the hype, and is trying to convince us to follow suit

Or maybe he works in some capacity at a dealer and is convinced that nitrogen is the best thing since sliced bread

Even when I was at the dealership, I never bought into the nitrogen “fad” . . . to be honest, it was more of a burden than a benefit. Meaning it was a burden for the mechanics. We lost time, which meant we lost money :rage:

Either way I’d take those silly green caps off.

An AC is all-metal, isn’t it? A tire is rubber: if I evacuate it, won’t the tire collapse and the rubber crack irremediably?

Whether inflation with nitrogen is valid or not, those who buy their tires from Costco get nitrogen inflation–and re-inflation–gratis for the life of the tire. Why would anyone pay a premium price for a service–that may or may not have validity–when it is available at no extra cost for Costco customers?

:thinking:

Costco made all their mount/fill services to use nitrogen, at least in the location I live in.
They even posted some board urging owners to get back and to “nitrogen flush” if you needed to add some air on your own.
Sounds like somebody found a good niche to make “hey, you see how we care about our customers” rosy picture.
Still, it was not a once or twice I had to get back to them for tires to be re-balanced after they supposedly balanced them or to rotate my tires after they were supposedly to rotate them.

1 Like

You don’t pull one atmosphere of mercury of negative pressure on a tire as you would on an AC system.

Just several inches of water column is enough to remove the air.

Tester

I had my tires installed at Costco . . . if I mounted my own tires at work, some “do gooder” would probably film it, and report it to the local news with the headline “civil service worker caught on camera mounting tires and installing them on his personal vehicle” with the implication being that I probably stole the tires from the warehouse

That said, yes, Costco filled the tires with nitrogen

Yet . . . they still lose air over time. I have to fire up the compressor in my garage occasionally. Nitrogen will not change that

I’ve rotated my tires personally and can attest there are no nails

As far as I’m concerned, they have little benefit for regular use

My last set wasn’t filled with nitrogen, and they didn’t lose air any faster than my current set

? This makes no sense. Atmospheric pressure is about 32 feet of water; removing only 1 foot leaves 97% of the air behind.

If I inflate a tire to 29.4 psi I triple the number of molecules in it (atmospheric pressure = 14.7). If I add nitrogen only the nitrogen content rises to 93% - no flushing of oxygen required.

                               Atmospheric              Tire @ 30 psi
  1 Pressure                              14.7                44.7
  2 Oxygen                                 3.1    20.7%      3.1        7%
  3 Nitrogen                              11.5      78%      41.5       93%

As I wrote in a thread 6 years ago:
‘It is noticed that the permeability of nitrogen is smaller than that of oxygen. This behavior is common in gas permeation in polymers, became the former gas has lower solubility and diffusivity in polymer than the latter. It is reasonably assumed that the difference of molecular size affects the diffusivity because the diameter of nitrogen molecule (3.1-3.3 Å - there are 10 billion Å in a meter) is larger than that of oxygen molecule (2.9 Å).’ (‘Airtight Butyl Rubber Under High Pressures in the Storage Tank of CAES-G/T System Power Plant’, Fumihiro Terashita, Journal of Applied Polymer Science, Volume 95, Issue #1, pp. 173-177) Not only is the oxygen molecule smaller but more soluble in rubber.

‘Polymer Handbook, Fourth Edition’ (Brandrup, Immergut, and Grulke, Wiley Interscience, 1999), page VI/566 'Permeability coefficients of gases through various elastomers. cites permeability constants of 2.22×10-13 cm3-cm/cm2-second-Pascal for nitrogen, 4.08×10-13 for oxygen at 80°C. (.119×10-13 for nitrogen, .242×10-13 for oxygen, at 20°C) for CIIR: chlorinated isobutyl isopropene rubber, the most common component of modern tires

I think it’s BS. But I’d fight for your right to use nitrogen if you’d like.

2 Likes

The nitrogen machines that we use deflate the tires to 5 PSI (so as not to disturb the bead), inflate with nitrogen, deflate to 5 PSI, then inflate to the selected pressure, all five tires at once. This can be done with the vehicle on the floor but we always lift the vehicles. I wouldn’t want to see a vacuum applied to a tire.

interestingly, it makes air in tires to increase nitrogen/oxygen ratio “naturally”

This would be a good application for an inner tube, which you could empty.

A gas travels across a membrane as a function of its partial pressures on either side of the membrane. A tire with a lower partial pressure of a gas on its inside absorbs that gas from the atmosphere, it’ll even absorb some if that results in the tire gaining pressure (ΔG = ΔP×V - T×ΔS - increasing other gases increases entropy), in a practical tire case this will be unnoticeable.

If you can get a tire to 97% nitrogen the partial pressure of oxygen in the tire is 1.1; in the atmosphere it’s 3.1, thus the tire will absorb oxygen until they’re equal. The same happens independently with nitrogen: its partial pressure in the atmosphere is 11.5, it’s 43.6 (assuming inflated to 30) in the tire: nitrogen will leave until they’re the same. Oxygen will come in and nitrogen will leave.

It is likely an easy fix but a tire shop probably won’t touch it if the tires are 20 years old.

1 Like

This subject comes up pretty regularly - so I wrote a web page on the subject:

http://barrystiretech.com/nitrogeninflation.html

Bottomline: There is no advantage to using nitrogen for a street tire.

The supposed advantage of more consistent pressure is vaporware - it doesn’t exist. ALL gases - even water vapor (aka steam) - behave according to the Ideal Gas Law at the temperatures and pressures tires experience. See the data on the web page.

The advantage of slower leaking - yes, but it is not as big a deal as some think and regular pressure checks cancel that out. Plus, the biggest issue with leaks is between the rim and the tire (see many threads on the website about leaky tires!)

And why do they use nitrogen in race tires? For one, air compressors are banned where fuel is used (pit lane and infield garage) so they use nitrogen bottles to power the air wrenches - so why not use it to inflate your tires. Frankly, the issue of water vapor in race tires seems to me like a myth.

1 Like

For the same reason, I might add, as the teams use nitrogen rather than compressed air
 safety.
Compressed air, whether from a compressor or a tank, will accelerate a fire. Nitrogen will smother it.

I agree with the conclusion that it makes more sense to just use the nitrogen in the tires too. Especially since they can’t use air anyway. The water vapor is IMHO just one more myth, probably started by a tire salesman trying to sell nitrogen
 at $10/tire
 :grin:

Hi Random Troll,

You should immediately visit nearest tire repair store. Let them diagnose the cause and they will give you best advice to fix this issue. It’s possible there is a tiny puncture or problem with valve. But don’t risk your life, go straight to tire repair store NOW.

Might try Nitrous Oxide for a really bouncy ride


LOL, yeah, do it wrong and it’ll bounce you off the moon!