I disagree. Reasons are posted above. That is my opinion and experience.

So we DO agree on one thing. We disagree....

 

I have searched for this before, and again now, and could find NO evidence that nitrogen leaks more slowly than air from tires. Only unsupported assertions, most of them by people selling nitrogen.

Cecil Adams, of "Straight Dope" fame, did some research, and says
Nitrogen not worth paying much for.

Think about it: Air is already almost 80% nitrogen. So we're claiming that changing the remaining 22% to nitrogen is going to make a 3x difference in the speed at which the tire loses pressure? That doesn't make sense to me. Also, most air loss from tires is through the BEAD and the VALVE STEM, not through the tire wall. We're talking about simple mechanical leakage, not some kind of diffusion.

I believe nitrogen tire fill to be a waste of money, if it costs anything. But hey, it probably doesn't HURT anything, so do it if you want.

--Dan
Mach V
FastMINI.net

 

Wow, 2-3 mpg!! You would think the car manufacturers would put nitrogen in their tires at the factory. They spend millions in engineering trying to get another 2-3 mpg and all they needed was a bit of nitrogen. Or they could use helium which should get them still another mpg or two.

 

so if you are unfortunate enough to have had Costco put Nitrogen in your tires and you need to top it off , can you use plain compressed air ? With the stupid green valve caps , no one will do it for you (wife's car with her driving)

 

I got my tires mounted at a new place here and they told me they only fill up the tires with nitrogen. After he told me all the pros and cons, I told him give me air becuase I mess with tirepressures for autoX, and reinflate with a aircompressor. He told me "no, we don't have any air, you get nitrogen, you'll love it!" DUDE ALL YOUR IMPACT GUNS ARE HOOKED UP TO AN AIR COMPRESSOR

I'm getting a compressor soon so next time I get tires mounted I'm going to immediatly deflate them and inflate them with air.

 

There is no impact to mixing regular compressed air with nitrogen in your tires. After all air is 78% nitrogen -- so adding air just reduces the purity of your nitrogen.
Some have argued (mostly nitrogen distributors) that if you must mix the 2 in an emergency, you should later purge the tire and re-inflate it with pure nitrogen again. But this is bogus -- the reason given is that, if you have a pure nitrogen wheel paired with a wheel that has air/nitrogen, they will expand/contract differently as they heat, and this could cause some variance in handling . . . most agree this is bogus since the two aren't going to differ drastically (and not at all if you're adding air to all your tires at about the same rate).

I do have Costco nitrogen in both cars (only 'cause it was free) and I have topped off the tires with compressed air as needed.
By the way, after I noticed 2-days-too-late that Costco had "taken" the metal valve caps from my 3-series and replaced them with green plastic ones, I learned to ask for my original caps back when they put the new tires on my MINI -- so no green caps on my MINI (but I am running on free nitrogen).

 

I wouldn't even bother deflating them - just use air whenever you need to add pressure.

Both nitrogen and "regular air" behave almost exactly the same at the temperatures/pressures you're going to be dealing with.

Even if you have moisture in the air, it's not going to affect your pressures as the tires heat up. With 40psig of air in your tires, the boiling point of the moisture inside the tires is about 280F, which is a lot hotter than any internal tire temperatures you're likely to ever see, even on the track.

 

I agree. Most of the benefits ascribed to N2 are BS. Both N2 and O2 are very tiny, non-polar molecules with similar diffusion and solubility characteristics. From that standpoint, neither one should be any better than the other in keeping tires inflated. Furthermore, O2 and N2 behave like ideal gasses, so there is no "running cooler" or reduced pressure change as a function of temp with N2 vs. O2.

But, there is a grain of truth here. When you fill tires with N2, you set up a concentration gradient. Over time, O2 diffuses INTO the tire, keeping it inflated. It has nothing to do with N2 diffusing out thru the rubber more slowly. Nike used the same principle in their "Air" shoes, using bladders filled with SF6 (a big molecule that does not duffuse very fast thru the polyurethane bladder, but clearly not "air"). Over time, air diffused into the bladders, keeping them filled tight.

The reason aircraft and race cars use N2 in the tires is that these tires run very hot. O2 degrades SBR and natural rubber, so the tires last longer with N2. There might also be some safety improvement in a fire situation without the O2 compressed air brings.

As far as moisture, dry air is every bit as good as dry N2. Having liquid water in the tire would indeed cause large pressure changes in the tire got hot enough to boil the water. But water vapor would have little effect.

 

OK, I just finished talking to a Tread Compounding Chemist from a major tire manufacture. Using nitrogen over air has a couple advantages:

(1) A nitrogen molecule is larger than an oxygen molecule (due to the stronger, tighter bond of the O2 molecule) and the smaller oxygen molecule will diffuse through the rubber of the tire and reduce the tire pressure.

(2) The oxygen diffusing through the rubber, ages the rubber(ie: the outside of your older tires ages and cracks)

So, nitrogen looses less pressure but, would only give better tire life, mpg, etc. only if, with air, you did not maintain proper tire pressure.

Another advantage to nitrogen is the controlled moisture content, but as stated an air compressor with a water trap can minimize moisture.

Now, will any of this effect a regular street tire, proberly not. Track tires might yield a more consistant tire pressure with nitrogen.

Helium and Hydrogen would diffuse very quickly through rubber as well as the Hydrogen being very explosive would not be recommended.

 

inimini, similar minds think alike.

One more thing, when changing from air to nitrogen it is nessesary to empty the air and fill with nitrogen. Empty the nitrogen and refill three times total. This should yield 97% nitrogen. This would only need to done on the initial time.

 

Ya, what he said.

 

The smaller size of hydrogen or helium molecules would permit them to leak faster...

 

Anyone remember the "Twin tire"? Nitrogen is probably great for airplane tires. ...but regular 'ole air works just fine for the street!

 

Wow... this thread is too funny. Someone already alluded to this but how about a break down of the components of the air we breath... So if someone really wants to pay to have the other 22% of air in their tires replaced with Nitrogen, well... okay...

Nitrogen -- N2 -- 78.084%
Oxygen -- O2 -- 20.9476%
Argon -- Ar -- 0.934%
Carbon Dioxide -- CO2 -- 0.0314%
Neon -- Ne -- 0.001818%
Methane -- CH4 -- 0.0002%
Helium -- He -- 0.000524%
Krypton -- Kr -- 0.000114%
Hydrogen -- H2 -- 0.00005%
Xenon -- Xe -- 0.0000087%
Ozone -- O3 -- 0.000007%
Nitrogen Dioxide -- NO2 -- 0.000002%
Iodine -- I2 -- 0.000001%
Carbon Monoxide -- CO -- trace
Ammonia -- NH3 -- trace

 

Hey, my wife, the Major Tire Manufacturer Chemist and I got a kick discussing this one.

 

me too!

 

For all those worried about the gases in your tires here's a website describing another threat to our MINI's and life as we know it. Dihydrogen monixide. http://www.dhmo.org/

 

Can anyone comment on the use of Breathing Air, as in scuba diving or firefighter air packs, in tires. It should have almost no water or oil vapors due to extra filtering.

 

Reading this thread reminds me, I need to change my blinker fluid the next time I'm at the shop.

 

If you have access to it and think it will be worth the trouble, go for it.

 

Dry air from any source would be better than humid air, but the effect would hard to measure without going to extremes. I've always felt annoyed at any one charging for the use of an air compressor at a gas station (they already steal enough at the pump) and I can't see how the cost of filling with nitrogen could be offset by any savings you might get unless of course it's free.

 

I was wondering which fluid you used. I've found that anhydrous water works very well and Perri-air is one of the better brands.

 

I find that this is the least expensive route to take because you can just find it anywhere. I've never filled any of my tires with anything else!

 

What a coincidence, I use the same mix in my lungs!

 

Really funny Chows... until you get arrested.

I was running neon last summer and a state trooper pulled me over and arrested me for improper lighting equipment. In most states you have to include a red color additive to the rear tires while using neon.