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      02-15-2011, 06:28 AM   #1
strongdeo
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Kwikfit and Uniflate

Has anybody tried inflating their tyres with Uniflate at Kwikfit or other distributors int he UK? Apparently you get more tyre life, better fuel consumption and dont need to top up the pressures as often!

I tried the search facility and it lloks like uniflate has not been discussed on here before.

See this http://www.uniflate.com/
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      02-15-2011, 06:33 AM   #2
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"uniflate" is just nitrogen. It is a waste of money. Air is 79% nitrogen to start with, so paying a large amount of money to inflate your tyres with 100% nitrogen is totally pointless.

The remaining 21% of air which is not nitrogen is carbon dioxide, oxygen and water vapor. All of these, just like nitrogen can keep your tyre inflated.

The "better fuel consumption" in the weblink is misleading: it says that having correctly inflated tyres gives you better fuel consumption. They have provided zero evidence that filling your tyres with nitrogen gives you better fuel consumption and there is a reason they have provided zero evidence: because it doesn't do anything.

Now commercial airlines may use nitrogen in their tyres instead of air but that is because (a) using pure nitrogen reduces the already infinitesimally small risk that the air in the tyre could leak out, feeding a fire which was already in progress (b) this is the main reason: airplane tyres may operate in a 100 degreee temperature range from about -50C at altitude to +50 sitting on the tarmac plus they may have thousands of cycles of ground +50C/altitude -50C all happening within the space of an hour of each other. Dry nitrogen will not form ice crystals which any water vapor in air could, when the airplane is at 35,000 feeet and it is -50 outside.

None of the above paragraph applies to cars, so again, paying for pure nitrogen in your car tyres is a waste of money.

Last edited by kaishang; 02-15-2011 at 06:45 AM.
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      02-15-2011, 06:55 AM   #3
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^^ Perfect answer.

In summary - waste of time.
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      02-15-2011, 07:33 AM   #4
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My local fitters use nitrogen as a matter of course and I've never noticed any difference. I guess this could be similar to an Optimax/V Power argument though.

However I did read somewhere once that 'premium' car brands ship their vehicles from the factory with nitrogen filled tyres. Something to do with better ride comfort.

Probably bollocks mind.
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      02-15-2011, 07:58 AM   #5
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      02-15-2011, 08:02 AM   #6
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Quote:
Originally Posted by rich1068 View Post
My local fitters use nitrogen as a matter of course and I've never noticed any difference. I guess this could be similar to an Optimax/V Power argument though.

However I did read somewhere once that 'premium' car brands ship their vehicles from the factory with nitrogen filled tyres. Something to do with better ride comfort.

Probably bollocks mind.
It is total bollocks. Whereas V-Power has a higher octane rating (whether that helps you car or not is moot) but inflating tyres to the same pressure with N2 as opposed to air cannot possibly make a difference to the ride as that's scientifically impossible.
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      02-15-2011, 08:07 AM   #7
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I'm not an expert but remember reading about the Nissan GT-R which uses nitrogen in there tyres as it doesnt expand and contract as much as air at different temperatures?
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      02-15-2011, 08:09 AM   #8
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I'd go for some helium in my tyres!
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      02-15-2011, 08:22 AM   #9
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Quote:
Originally Posted by Kal View Post
I'm not an expert but remember reading about the Nissan GT-R which uses nitrogen in there tyres as it doesnt expand and contract as much as air at different temperatures?
Can't see it. Air is 80% N2 anyway and O2 & N2 have the same specific heat capacity and O2 is slightly more dense at the same temperature. This could make a tiny difference to expansion (but tiny) and if you fill your tyres with air it's 80% nitrogen in the first place.

It really is snake oil, as Del said.
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      02-15-2011, 08:31 AM   #10
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Gonna get me some a that there snake oil!
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      02-15-2011, 08:54 AM   #11
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OKAY!

That sounds like a pretty conclusive answer. But does it make any difference to how ofter you have to inflate your tyres? One problem I have is that I am so lazy I nver check my pressures and therefore mytyres on average are always under-inflated. Will this mean that I dont have to inflate my tyres as ofter because 100% N2 does not escape thru the tyre wall?
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      02-15-2011, 08:59 AM   #12
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A different approach might be to not be lazy?

And if you are inherently bone idle I'd guess you'd check the nitrogen filled tyres even less often
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      02-15-2011, 09:59 AM   #13
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      02-15-2011, 11:04 AM   #14
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A while back I had 4 new tyres on a previous car and the chap at kwik Fit 'gave' me a free fill of nitrogen.

Got the car home and not trusting the pikey fitter thought I had better check my pressures to the ones on the door frame. Surprise surprise there was a variance of up to +/- 3lb difference in pressure to what it should have been. Having put the pressures 'right' I decided never to trust a tyre fitter to put in the 'correct' pressure again. Paying for the privilage of too little or too much nitrogen is just crazy.

As has been said - it only really has a place on aircraft or in top end motorsport where tyre temp stability is more crucial.
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      02-15-2011, 02:07 PM   #15
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Quote:
Originally Posted by strongdeo View Post
But does it make any difference to how ofter you have to inflate your tyres? One problem I have is that I am so lazy I nver check my pressures and therefore mytyres on average are always under-inflated. Will this mean that I dont have to inflate my tyres as ofter because 100% N2 does not escape thru the tyre wall?
Not really but it might help....

Rubber lifespan will indeed be better with Nitrogen simply because there is no oxygen present - an oxidant.

Will it still leak? I expect it still will, all rubber is porous and thats why tyres go down all by themselves in time.
However, it may pass less N2 than a normal mix with 21% O2 which will pass and/or react with the materials inside.

Bear this in mind - when a tyre monkey fills your tyres with N2, I bet they don't go to great lengths to purge the existing air out.
How would they do that? When you think about it, it will never be a pure N2 fill.
You would need to assemble the whole wheel/tyre assembly in a N2 filled cabinet and inflate slightly to seal the beads at the least before removal.
Yeah, right

So in essence, its all pointless in a car tyre.

The biggest issue with pressure/temperature stability is probably the moisture content in the fill, and we are still talking TINY changes in expansion.
The advantage here is that an N2 generator rig or cylinder is probably supplying totally dry N2, but you 'could' dry normal compressed air for the same effect (but most compressors in garages simply don't.)

Another far bigger point of note is the accuracy (claimed or otherwise) of the domestic tyre pressure guage.
I wonder how many of you have them calibrated regularly, or even cross compare them?
How repeatable is the result - take ten measurements and see the deviation in the instrument/your technique.

Likely you wont see better than 0.5psi in either case.
Some BT and Digital gauges I have tried can vary by over 2psi.

I am an instrumentation engineer by trade, the source of my info.

Steve
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      02-15-2011, 05:49 PM   #16
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Nitrogen may actually leak out (or reverse osmos or whatever it does) more than oxygen, the other big component of air because oxygen is a heavier molecule. There's a though, if you put nitrogen in your tyres, it will be about one gram lighter.
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      02-16-2011, 05:06 AM   #17
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Quote:
Originally Posted by xenon View Post
Can't see it. Air is 80% N2 anyway and O2 & N2 have the same specific heat capacity and O2 is slightly more dense at the same temperature. This could make a tiny difference to expansion (but tiny) and if you fill your tyres with air it's 80% nitrogen in the first place.

It really is snake oil, as Del said.
Motorsport have used nitrogen for decades because it doesn't expand or contract between hot or cold (well, very little anyway), so the set pressure stays the same throughout the operating temperature.

That's why F1 down to go karts use nitrogen in their tyres.

Using regular air, even in a road car, your pressures can easily increase by 5psi when warm compared to when cold. Thats why you have to fill them cold so you don't run the risk of underinflation if you filled hot and then they cooled.
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      02-16-2011, 05:10 AM   #18
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How come then in F1 they're always balthering on about how when the cars are behind the safety car, brakes cool down, tyre pressures reduce and it's generally not a good thing. Brundle once remarked how the ride height differed by an inch between hot and cold tyres.

The thermal expansion coefficient between N2 and O2 is actually not that different and as air is 80% N2 anyway the difference is miniscule.

Certainly for aircraft it's to avoid moisture (icing) and so this lovely compressed air cannot feed a fire. I assume it was similar for F1 but I don't buy the temperature stability aspect.
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      02-16-2011, 05:37 AM   #19
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Mmm, gas gets hot and pressure increases, S.O.P. That's how internal combustion engines work....
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      02-16-2011, 05:44 AM   #20
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Quote:
Originally Posted by kaishang View Post
Mmm, gas gets hot and pressure increases, S.O.P. That's how internal combustion engines work....
Indeed, different gasses expand different amounts for the same rise in temperature, but I don't buy the reason for use in car tyres.
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      02-16-2011, 08:14 AM   #21
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Quote:
Originally Posted by kaishang View Post
Mmm, gas gets hot and pressure increases, S.O.P. That's how internal combustion engines work....
This all sounds like Hot Air to me
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      02-16-2011, 04:37 PM   #22
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Quote:
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Indeed, different gasses expand different amounts for the same rise in temperature, but I don't buy the reason for use in car tyres.
Dont' shoot the messenger - i'll ask my bro at the weekend why they use nitrogen in race cars.

He currently is chief mechanic and team manager for the AMD golf BTCC team, he's run Oz touring cars, Euro GTs, British GTs, US LM Porsche (winning Rolex Grand Am team) and others so hopefully he'll know!

I'm sure its for thermal stability / dryness / inert qualities etc..
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