OT: Nitrogen filled tires

Things seem pretty slow in SED today, so let's talk about "Hot Air".
(Like the kind in your tires.)

Every so often I read something like this:
http://fleetowner.com/news/topstory/fleet_nitrogren_beats_air/
suggesting Nitrogen is better than air for improved mileage, lower
tire wear, reduced Global Warming, etc....

The trick is you fill your tires with Nitrogen instead of compressed
air.

Huh?! Air is 78% (or so) Nitrogen anyway.
Is there anything to this, or is this a classic signal-to-noise
problem...??
Notice too that the article does not mention any service stations so
equipped...

-mpm

 

Quick! Start a nitrogen franchise, and make big bucks!

Waste of cash.

http://www.cartalk.com/content/columns/Archive/1997/September/05.html
http://www.straightdope.com/columns/070216.html

Michael

 

I do it by filling the tyres with normal air, then putting a small
amount of magnesium metal or benzene-1,2,3-triol into the tyre, this
will absorb the oxygen. I get incredible millage, but the tyres keep
wearing out quickly, mainly from the inside


Martin

 

It would be useful if Drexan's cost per nitrogen fill-up were given -
then, one could determine the break-even time, if any, for the whole
fleet, using nitrogen fill-ups vs. the cost of the additional fuel
consumed. Since this information is not given, though, I'm going by
the $100 per fill-up quoted in the Car Talk article... and, clearly,
there, it is not worth it for the individual user. $100 can buy at
least two fill-ups for my Camry (though, probably not for an SUV...)

Michael

 

You could fill a tire with a high-molecular-weight gas, like a freon
or something, and it might leak less.

I used to fill my bicycle tires with propane, for that reason and to
avoid pumping. Of course, that has at least two tricky side effects.

John

 

Unintended castration and... ???

I'm glad to see Cecil didn't actually poo-poo the idea, but he's
certainly skeptical.
As for Click & Clack, (a lot of the time), they might be confusing N2
with NOS.?

If people are making $100 bucks a pop putting Nitrogen in tires,
electrical engineering might not have been the best choice in
retrospect.

-mpm

 

Mine have nitrogen in them. I've got a lifetime free refill plan
(part of the usual lifetime service plan, it was cheap), the tire
station makes the N2 itself from air. In my case, the water and
oxygen inside the tires led to some internal corrosion, and
occasionally the tires would just deflate due to broken beads,
especially in the winter. The tire station cleaned them up and put N2
in, they say they've seen good results with it.

Whenever my tires get low, I bring it in (no appointment, no charge)
and they suck all the old N2 out and refill with fresh N2, and I drive
away.

They claim the tire pressure is less affected by the tire temperature,
too, which may account for the 3% fuel savings in that article.
Truckers spend a LOT of money on fuel, so tiny savings are a big deal.

 

Well the Montreal Metro runs on N2 inflated rubber tires.
http://emdx.org/rail/metro/principeE.html

 

Going flat on very cold days.

John

 

PV = nRT for any gas, right?

John

 

If there was moisture trapped inside, tire temperatures have a wide
enough range that you could get phase changes.

G.

 

Except that "n" changes when you hit the dew point.

At least, that's my guess. I just don't want the water and oxygen
inside my tires any more. It sucks changing a tire in a snowstorm.

 

Any *ideal* gas. A Van der Waals gas comes closer:
(P + a / V^2)*(V - b) = n*R*T

Note that, for P >> (a / V^2), V^2 >> a and V >> b, or for a = 0, b = 0,
this reduces to an ideal gas. Any gas looks ideal, if the volume is large
enough.

Tim

 

Good for up to about 10 atmospheres. Then you get to use something
else to compensate since the gas is no longer ideal.

http://en.wikipedia.org/wiki/Equation_of_state#Cubic_Equations_of_State
http://en.wikipedia.org/wiki/Van_der_Waals_equation

Michael

 

Required on most aircraft for safety reasons: the tires can
get hot enough under severe braking to ignite internally and
explode.

Actually, they can do so anyway, but via a relief valve.

Not sure about the alleged benefits. Has anyone tried sulfur
hexafluoride? (Despite the name, it's dead inert and has a high
molecular weight.)

--Damon

 

"suck out the _old_ N2..."

Bwahahahahahaha!

Must be Slowman's kid ;-)

...Jim Thompson

 

wrote in

and about 20% reactive oxygen.
A FIVE percent drop in tire pressure affects your mileage.

Then why do high-end race cars run N2? They would not bother if it didn't
matter.And they have close relationships with tire manufacturers,who ought
know about such matters.

N2 does not combine with the tire compound like the reactive O2 does.

 

"dead inert"? a *fluoride* compound? It even sounds toxic.

 

Next time, insist on Helium. Places that fill tires with
Helium instead of Nitrogen always have lots of repeat
customers, so it *must* be good!

A related question: I am about to install new speakers in
my convertible. Should I point them to the rear for better
gas mileage, or point them up for better traction? :0

 

However, there is a very significant difference between
the conditions under which a racing tire operates - for
all of its hour or so (if that) of life - and those seen in
passenger-car service. Do you think that MIGHT have
something to do with the use of nitrogen in racing, such that
those same reasons wouldn't apply at all in everyday use?

Bob M.