nitrogen in tyres (makes the truth elastic)

I saw some place claiming that nitrogen in tyres results in less pressure
variation with temperature, that's why racing cars use it. Huh?
My high-school physics told me
PV=nRT
i.e. pressure is proportional to absolute temperature, whatever gas

On 4/20/2014 6:48 PM, wrote:
> I saw some place claiming that nitrogen in tyres results in less pressure
> variation with temperature, that's why racing cars use it. Huh?
> My high-school physics told me
> PV=nRT
> i.e. pressure is proportional to absolute temperature, whatever gas
>

My guess is that nitrogen will contain less water vapor. Otherwise, I
think you're right about this.

I think the whole nitrogen-tire thing was oversold as folks "never having to check their pressures again". Blame marketing.


Yes, the variation in pressure per 10degrees F will be less than 1 lb PSI, but tires should still be checked monthly(or more freq) for deflation due to other factors - faulty or damaged valves, slow leaks due to a nail picked up or a clipped curb.


Common sense above all applies.


Semi OT: Man I just wish my dealer and the tire place would stop putting the TIRE PLACARD pressure in my tires! Maximum cold pressures listed on modern tires are often far more than the 35PSI cold we remember for ages.

My wife's pro contacts has 47psi in them all around, suggesting the dealer service techs went by the 51psi max pressure cold on those placards.

Last month mine were at 40psi(tire placard on mine says 41psi cold).
These pressures were between 10-20 FRICKN psi OVER what the b-piller stickers recommended cold!! Is it too much for you to put down the air hose, OPEN MY DOOR and read the pressures listed here?

Door sticker plus 2-4psi would be fine, thank you! That way the tires would be about spec the next morning.

On 4/20/2014 11:48 PM, wrote:
> I saw some place claiming that nitrogen in tyres results in less pressure
> variation with temperature, that's why racing cars use it. Huh?
> My high-school physics told me
> PV=nRT
> i.e. pressure is proportional to absolute temperature, whatever gas
>

You didn't allow for moisture content of the regular air
you're breathing now.

Nitrogen makes a niggling difference where every other
variable has been maximized and where every small detail is
critical, i.e., not us going to the grocery.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On Monday, April 21, 2014 8:16:43 AM UTC-4, wrote:
> I think the whole nitrogen-tire thing was oversold as folks "never having to check their pressures again". Blame marketing.
>

The real advantage to nitrogen is that it is free of oil and water unlike typical shop air. The water is what causes increased pressure variation with temperature, so that part is somewhat true although of limited concern to your average street driver. I guess buying bottled nitrogen to fill tires is cheaper than installing a filter/dryer system to make the shop air clinically clean - which would cause other problems, as traditionally shops have actually used oilers on their air lines to introduce extra oil to prolong the life of pneumatic tools.

>
>
>
> Yes, the variation in pressure per 10degrees F will be less than 1 lb PSI, but tires should still be checked monthly(or more freq) for deflation due to other factors - faulty or damaged valves, slow leaks due to a nail picked up or a clipped curb.
>
>
>
>
>
> Common sense above all applies.
>
>
>
>
>
> Semi OT: Man I just wish my dealer and the tire place would stop putting the TIRE PLACARD pressure in my tires! Maximum cold pressures listed on modern tires are often far more than the 35PSI cold we remember for ages.
>
>
>
> My wife's pro contacts has 47psi in them all around, suggesting the dealer service techs went by the 51psi max pressure cold on those placards.
>
>
>
> Last month mine were at 40psi(tire placard on mine says 41psi cold).
>
> These pressures were between 10-20 FRICKN psi OVER what the b-piller stickers recommended cold!! Is it too much for you to put down the air hose, OPEN MY DOOR and read the pressures listed here?
>
>
>
> Door sticker plus 2-4psi would be fine, thank you! That way the tires would be about spec the next morning.

Far too often those stickers are completely missing when a car is repainted.... although I suppose that is better than leaving the door jambs a different color (which I have also seen...)

N8N wrote: "Far too often those stickers are completely missing when a car is repainted... although I suppose that is better than leaving the door jambs a different color (which I have also seen...) "

That's no excuse for a tech to just go and look. And if not, it's better to put in 5lbs PSI below the maximum listed on the tire than to put in exactly what that placard stays. That way the customer is not driving home in a basketball, and they can just set them correctly the next morning.

On Mon, 21 Apr 2014 08:16:29 -0500, AMuzi > wrote:

>On 4/20/2014 11:48 PM, wrote:
>> I saw some place claiming that nitrogen in tyres results in less pressure
>> variation with temperature, that's why racing cars use it. Huh?
>> My high-school physics told me
>> PV=nRT
>> i.e. pressure is proportional to absolute temperature, whatever gas
>>
>
>You didn't allow for moisture content of the regular air
>you're breathing now.
>
>Nitrogen makes a niggling difference where every other
>variable has been maximized and where every small detail is
>critical, i.e., not us going to the grocery.

Nitrogen makes a significant different to people who are in long haul
trucking and every penny counts. That's where the whole thing came
from. I think it can save them something like 2% in fuel costs. When
you are spending thousands of dollars on fuel for a single trip, 2%
starts to add up.

Lots of information here
http://www.getnitrogen.org/pdf/Nitro...g%20Ri gs.pdf
and it's based on TESTING TIRES, not a bunch of people's opinions, no
matter how well informed they may have been.

There are HUGE benefits to running nitrogen for semi-trucks. There
are slight benefits for your car too but the difference between car
tires and semi tires as well as teh operating environment means you
don't get nearly teh benefit with car tires as you do with truck
tires. If you are racing your car you'll still want the benefits of
nitrogen though.

On Tuesday, April 22, 2014 9:04:01 AM UTC+8, Ashton Crusher wrote:

>
> Lots of information here
>
> http://www.getnitrogen.org/pdf/Nitro...g%20Ri gs.pdf
>
> and it's based on TESTING TIRES, not a bunch of people's opinions, no
>
> matter how well informed they may have been.
>

But who did those tests? If there were tests that said the effect is
infintessimal, I doubt we would see them touted.

On Sunday, April 20, 2014 9:48:03 PM UTC-7, wrote:
>
> I saw some place claiming that nitrogen in tyres results in less pressure
> variation with temperature, that's why racing cars use it. Huh?

They use it for fire protection, just as military and US commercial
jets do, because 100% nitrogen doesn't help fires burn. Someone
mentioned, 10-20 years ago, that a German airline wanted to fly to
the US with a tire filled with ordinary air, but the US FAA
prohibited it, so a nitrogen-filled tire was shipped to the airliner.