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Author Topic: Is it better to inflate car tyres with nitrogen?  (Read 15465 times)

Offline Bored chemist

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Re: Is it better to inflate car tyres with nitrogen?
« Reply #25 on: 14/01/2012 17:12:02 »
Since F1 teams don't fill their tyres up at quick fit I think we can leave them out of the discussion.

The economics of buying N2 vs drying air would depend on the number of customers (and how much you could rip them off) .
A garage that does engineering work might well have a compressed air system anyway in which case adding a dryer might be fairly cheap.
 

Offline Sprool

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Re: Is it better to inflate car tyres with nitrogen?
« Reply #26 on: 14/01/2012 20:30:38 »
http://www.uniflate.com/ Uniflate is the company that sells the N2 gear via qwikfit and other garages, it's not cylinder stuff they use, it's some sort of compressor and N2 filter with a water trap. Begs the question - why not make use of the compressor and water trap anyway just give me the old fashioned 21/78 mix compressed air.
What is a bit naughty is garages just taking the decision for you that its better (tyre wear, longevity, safety, fuel economy) and slipping the extra £5.50 into the bill without your consent whenever you get a new tyre fitted. Most people won't bother when its a one off payment but obviously to qwikfit if they are doing this to 10,000 tyres per month up and down the country thats an awful lot of extra revenue for no real significant benefit to the consumer.

Here's Uniflate's claims:
1. Better handling and road holding
2. Reduces tread wear and increases tyre life by up to 25%
3. Correct inflation pressures reduce puncture risk by up to 33%
4. Reduced rolling resistance improves miles per gallon by 2%
5. Improved pressure retention

http://www.tyrebaydirect.com/35-Nitrogen_Tyre_Inflation.html
« Last Edit: 14/01/2012 20:32:39 by Sprool »
 

Offline Bored chemist

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Re: Is it better to inflate car tyres with nitrogen?
« Reply #27 on: 14/01/2012 20:56:02 »
The first 4 of those are benefits of correct tyre pressure rather than nitrogen.
Incidentally, since they don't remove the air (and water)  that's already in the tyre then there's a limit to how much difference this can make.
 

Offline Sprool

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Re: Is it better to inflate car tyres with nitrogen?
« Reply #28 on: 14/01/2012 22:01:18 »
The improved pressure retention is an interesting one. Uniflate sent me some academic studies about the migration rate of N2 vs O2 through rubber. Depending on what model you want to believe, either O2 is faster than N2 or they are both about the same. However, the studies did not compare O2/N2 mixture (air) against N2 so in my view this is at best misleading. Sounds like cherry picking the bits that best suit the story.
 

Offline CliffordK

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Re: Is it better to inflate car tyres with nitrogen?
« Reply #29 on: 14/01/2012 23:46:49 »
As far as Oxygen and Rubber.
I've seen 50 yr old inner tubes that as long as they are protected from light & elements, they are often in quite good shape.  The rest of the tire may be completely shot though.

F1 racing can't be too concerned about gradual leakage, as I would hope they check the tire pressure before every race (probably setting each tire differently).  And, the air won't leak out in 500 miles and a couple of hours.

My guess that the N2 is a bunch of marketing hype.  How much can you sell "dry air" for when one should be using it anyway?  It wouldn't be too hard to make concentrated N2 though.  Just take a hospital surplus O2 concentrator, and run it backwards. 

And, what better way to convince people to buy a product than convince them that it is the same thing as used by F1 cars and jets. 

The next time your mechanic suggests using Indy technology in your car, you should ask them if it makes any difference if the average lifespan of an Indy engine is about 501 miles!!!  Not all of them make it that far!  And, of course, your goal is to get a bit better than the Indy average of about 1.92 mpg.

How much effort do they make to ensure you actually are using N2 in the tire?  If you inflate the tire at 1ATM with and 80/20 mix of N2/O2.  Then you increase the tire pressure to 2ATM.  Don't you end up with a mix of about 90/10 N2/O2?

 

Offline Geezer

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Re: Is it better to inflate car tyres with nitrogen?
« Reply #30 on: 15/01/2012 01:42:05 »
Good point. Come to think of it, has anyone ever checked to see how pure the N2 really is?

I'd like to see it in liquid form so I can take its temperature before I pay for it.
 

Offline CliffordK

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Re: Is it better to inflate car tyres with nitrogen?
« Reply #31 on: 15/01/2012 01:55:36 »
Good point. Come to think of it, has anyone ever checked to see how pure the N2 really is?

I'd like to see it in liquid form so I can take its temperature before I pay for it.
Just don't fill your tires with liquid N2.
The first big pothole...  then...
Well, not exactly.  The tires would explode with liquid N2 in them.  But, poorly processed gas from the liquid could be mighty cold, and would cause the tires to become brittle.

My point isn't the purity from the system.
When your tire is flat (but round, as if you just installed it on the rim), it is actually full of air at 1ATM.
If you fill it up to 30 lbs...  that is equivalent to adding 2ATM worth of additional pressure (sorry, I was off with my conversion).  So, the air in your tire is now whatever the ambient air was in the tire shop, diluted to about 1/3 original air, 2/3 N2.

You should really order an "air flush" for your tires too.   ;D
 

Offline Geezer

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Re: Is it better to inflate car tyres with nitrogen?
« Reply #32 on: 15/01/2012 02:11:06 »
Good point. Come to think of it, has anyone ever checked to see how pure the N2 really is?

I'd like to see it in liquid form so I can take its temperature before I pay for it.
Just don't fill your tires with liquid N2.
The first big pothole...  then...
Well, not exactly.  The tires would explode with liquid N2 in them.  But, poorly processed gas from the liquid could be mighty cold, and would cause the tires to become brittle.

My point isn't the purity from the system.
When your tire is flat (but round, as if you just installed it on the rim), it is actually full of air at 1ATM.
If you fill it up to 30 lbs...  that is equivalent to adding 2ATM worth of additional pressure (sorry, I was off with my conversion).  So, the air in your tire is now whatever the ambient air was in the tire shop, diluted to about 1/3 original air, 2/3 N2.

You should really order an "air flush" for your tires too.   ;D

What you'd need to do is fill them using one if Chris' Hoovers to suck all the air out (assuming that didn't actually destroy the tire) before inserting the efficacious pure nitrogen.

Come to think of it, that won't work either. The low pressure will pop the seal at the bead between the rim and the tire, so it's not that easy to get the air out. You'd have to flush it a few times with pure nitrogen as you suggest.

You could use steam to get rid of the air instead, but that would seem to defeat the purpose of the entire exercise.
 

Offline CliffordK

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Re: Is it better to inflate car tyres with nitrogen?
« Reply #33 on: 15/01/2012 02:45:45 »
Good Point.
If you mounted one of these from the 70's...  you'd be all set   ::)

http://www.ratwell.com/mirror/jrivers/AspareVWtire.htm



All you need is to add an LN2 dewar to feed the little blue pump.
 

Offline syhprum

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Re: Is it better to inflate car tyres with nitrogen?
« Reply #34 on: 15/01/2012 06:46:57 »
I have attended the Indy500 race for the last 7 years and find that engine failures are very rare, it is a rather disapointing feature of modern auto racing that modern engine control system and deliberate power restriction has made them very reliable. 
 

Offline Geezer

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Re: Is it better to inflate car tyres with nitrogen?
« Reply #35 on: 15/01/2012 07:24:18 »
Good Point.
If you mounted one of these from the 70's...  you'd be all set   ::)

http://www.ratwell.com/mirror/jrivers/AspareVWtire.htm



All you need is to add an LN2 dewar to feed the little blue pump.

Blimey! I wouldn't put my big toe under the tire using that jack.

Looks like VW bus, but the odd thing is that the wheel is attached by a combination of bolts and studs. I've never seen that on a VW before. All the ones I had only used bolts which makes it a real pain to line up the holes.
 

Offline Sprool

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Re: Is it better to inflate car tyres with nitrogen?
« Reply #36 on: 15/01/2012 18:31:19 »
Not sure how relevant indy car engine lifetimes or vw wheel fixings are to the N2 debate in tyres.  :-\
 

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Re: Is it better to inflate car tyres with nitrogen?
« Reply #36 on: 15/01/2012 18:31:19 »

 

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