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I've heard of garages claiming that using nitrogen in your tyes increases fuel consumption. Is this actually true and has anyone tried it?

Cheers
 

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As air is 78% Nitrogen that is what is mostly going into your tyres anyway :confused:
and you win a cookie!

In certain cars Nitrogen is only used as it is more stable in pure form than normal air and under pressure it can be more dense hence better for in tyres as it allows less flex (for want of a better term).

Whether it increase MPG or not I do not know BUT if you can afford to run a car that has tyres specced to Nitrogen then are you goign to be bothered about a few MPG?
 

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Cool :thumbs:, Can I have white choc chip please :lol:
if we ever meet at a meet sure although wont buy it yet as it may go off by the time we meet!:thumbs:
 

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Nitrogen has a density I think of 0.998.. so on a road car it would make no difference.
Air has a density of 0.0013 kg/l. Nitorgen will be very similar. (water has a density of around 1.000).

Sounds like complete tosh to me
 

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Pure nitrogen is used in racing car tyres (like F1) because it doesnt expand with heat as air would.

If F1 cars used normal air, the pressure in the tyre would increase as the tyres/brakes heated up. and with the temperatures involved it would be a significant change and would effect the handling and grip
 
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Seems unlikely to me. The theory would suggest that filling your tyres with nitrogen increases the rolling resistance but I can see no reason why that would be the case assuming the tyres are correct. Unless it comes down to weight of course. Having an empty crisp packet in your boot will increase your fuel consumption but by an amount far too small to measure accurately.
 

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A while ago I tripped over some reliable research on the benefits of inflating tyres with nitrogen:
US National Highway Traffic Safety Administration Vehicle Research and Test Center (sic) Report DOT HS 811 094.

Link

The three arguments I have heard for use of Nitrogen are:

1. Nitrogen diffuses through the tyre wall more slowly than oxygen, so the tyres hold their pressure better.
2. Nitrogen filled tyres have lower rolling resistance so will save fuel.
3. Oxygen degrades the tyre so using Nitrogen the tyres will last longer.


The Answers?
Holding pressure:

Air filled tyres lost on average 2.13%/month
Nitrogen filled tyres lost on average 1.39%/month

Sounds good at first, but if you have a car tyre that should be inflated to say 32 psi (220kPa, 2.2bar); this translates into 0.68 psi/month for air and 0.44psi/month for Nitrogen. So if you assume you don’t want your tyres to be more than 1psi low, this means your pressure check interval can be reduced from once every 44 days to once every 68 days.

“It should be noted that inflation with nitrogen merely slows the rate of diffusion of gas from the tire (sic) and is not a substitute for regularly maintaining tire (sic) pressure.”

If you DO keep the pressure regularly topped up with air, after a year or so they will have about 90% Nitrogen in them anyway as the Oxygen diffuses out!
I can’t say that excites me very much!

Better fuel economy:
“The study indicated that inflating with nitrogen in place of air had no immediate effect on laboratory tire (sic) rolling resistance. However, it is estimated that at the end of 90 days of on-vehicle service with no inflation pressure maintenance, the improved retention of inflation pressure using nitrogen versus air inflation will result in a 1.5-percent reduction in tire (sic) rolling resistance.”
So NO direct benefit, but if you don’t maintain your car the nitrogen filled tyre will lose pressure more slowly, and it’s the loss of pressure that increases rolling resistance.
So another ‘meh’ from me.

Longer life:
They aged the tyres; “these oven aging conditions replicate approximately 2.5 years and 47,000 kilometers (sic) (29,000 miles) of service in the high ambient temperatures of the Southwestern United States, or as much as double that amount of service in the northernmost States”
5 years and 58,000 miles!
They did find some benefit in the use of Nitrogen on aging, but not much.
Americans seem to expect tyres to last 50,000 miles on their everyday cars and the southern states are hot too, so that could be significant for them. I wear out the tread on my tyres within 2 to 3 years, so that’s another ‘meh’ for me.

I conclude that if the tyre fitter fills my new tyres with Nitrogen for free; then thanks I’ll have it. It certainly won’t do any harm. But I won’t pay for it.

The other little factoid was that 1psi under inflation costs 0.2mpg or thereabouts.
By the way they tested 261 tyres of 30 different types.
 

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question

is nitrogen lighter than air?

if so

with 4 tyres at correct pressure will that cause the car to be lighter in weight?
 

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If F1 cars used normal air, the pressure in the tyre would increase as the tyres/brakes heated up. and with the temperatures involved it would be a significant change and would effect the handling and grip[/QUOTE]

Good Idea methinks.......:thumbs:


Might make the racing a bit more bloody exciting then !!!!!.........:rolleyes:
 

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The green valve caps look cool though...

Overall, while accepting the possibility of purified nitrogen being of benefit in certain applications, we don't think that the cost and possible inconvenience are justified for normal passenger car use.
... I still do it - it's subjective, I know, but the impression I have is that my tyres last longer, keep pressure better and the green valve caps look way cool :).
The cost was once only, I keep topped up at the garage that filled them initially.
 
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