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Tire pressure material

4K views 15 replies 8 participants last post by  Insightful Trekker 
#1 ·
I have read that filling your tires with Nitrogen instead of air is good for an extra 1 - 2 mpg. Has anyone here tried this? Has also been stated that N gas will not dissipate out of your tires as quickly as air causing you to have to adjust the pressure less often. Has anyone else tried this here?

Right now I have a CRX HF and I can get 52 mpg on teh interstate. I want an insight badly but can't afford a new one. Do teh used ones make good buys in general? Always looking to stretch my mileage some.
 
#2 ·
Why would it increase fuel mileage?

Normal air from an air compressor is 79% nitrogen, you are only increasing the nitrogen content 21%. If your tires are inflated correctly (wherever you feel safe), mileage should be the same for air or nitrogen.

I don't see where it could be worth the time & trouble.

Regards,
 
#3 ·
The only advantage to using Nitrogen in tires is, the pressure will not change when the tires heat up during driving. That is one reason why cars that are raced used it. Their pressures are critical at high speeds, so it's important they keep it there during long races.

It has nothing to do with mpg or air escaping from the tires.
 
#5 ·
According to this article, it does affect mileage 1 - 2 % and N gas doesn't migrate from the tires as fast. Here is a reprint from Environmental Resorce Center's webpage (ercweb.com). Look at the 11th paragraph of the article. You can argue with them if you want.




Resist said:
The only advantage to using Nitrogen in tires is, the pressure will not change when the tires heat up during driving. That is one reason why cars that are raced used it. Their pressures are critical at high speeds, so it's important they keep it there during long races.

It has nothing to do with mpg or air escaping from the tires.




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#6 ·
Belbo said:
According to this article, it does affect mileage 1 - 2 % and N gas doesn't migrate from the tires as fast.

<snip>
Sorry Belbo reRead the article again.

Mileage will only be affected *if* tire pressure is neglected. And you can neglect it longer using nitrogen before the lower pressure MPG loss begins. We Insight hyper-milers already *overinflate* our tires for even better MPG. :D

I think once you investigate the cost of nitrogen you may change your mind. ;)
 
#9 ·
Where ya find it?

We have nitrogen bottles (3000 + psi) here at the airline for viarioius stuff, but where would you find it out in the 'real world' ?
For mine, I could sneak my portable air tank to work and sip off 100 psi or so and then pump up with that. If I could find an adapter / filler/ air chuck for the tank from the main bottle.
 
#12 ·
Interesting points, or maybe misconceptions.

1) Why do you think tire pressures won't change when the nitrogen heats up? Gas laws are gas laws, they don't care which gas you're using. And of course air is about 79% N2 anyway...

(The reason N2 is used for things like filling aircraft landing gear struts is that it's much less reactive than O2, so your strut seals & such don't deteriorate as fast.)

I see they've still got that old error about buying gas at night because it's cooler, therefore denser. Most gas stations have underground tanks, which stay at a pretty constant temperature year-round. And even if the tanks were above ground, 10,000 gallons or more of gas has a lot of thermal inertia :)

And if anyone followed the EPA link, and paged down to the least fuel-efficient cars... since when is a Bentley considered a COMPACT?!?!
 
#13 ·
james said:
<snip>

Gas laws are gas laws, they don't care which gas you're using. And of course air is about 79% N2 anyway...

<snip>
Yup, but pure N2 dosen't expand as _much_ when heated as the nitrox blend commonly used.

The "gas" laws do take account for the different properties of the gas in question.
 
#16 ·
Re: Over inflating

SteveChicagoSC said:
Won't over inflating to 40psi cause uneven tire wear?
In a "conventional" tire, yes :!:

However due to some quirk in the OEM LRR's even dangerously overinflating them to 60 psi (xcel has done it for thousands of miles) the "wear" pattern is one of _underinflation_. Edges wear first. :(

Something about the extra stiffness in the cord and how the tread flexes. And I don't think there's even a remotely safe "over inflation" psi that could equalize this pattern.

HTH! :)
 
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