Nitrogen in car tyres

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Ge0rge

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#222719 25-Aug-2017 13:02

My better half's car needed new tyres and since I had the day off, I trundled off to the local tyre store to discuss such.

Being that the price was agreeable, I then got the sell about warranty etc etc, as well as "Would I like to pay extra to have my tyres filled with nitrogen?" No thanks. "But it will make your tyres last longer, give you a smoother ride, will stay at the right pressure and not leak, all for only $5 a tyre" No thanks.

"Are you sure? You only have to pay once and then any outlet across the country will top them up with nitrogen if you need"

But you just said that they won't leak, so why would I need to top them up? Also, the atmosphere is around 78% nitrogen already, so if I was to use air to pump up my tyres, surely the other 22% would just leak out over time, and I'd keep topping them up and eventually I'd be close to 99% nitrogen at the correct pressure anyway?

"Oh no, it doesn't work like that - you really need pure nitrogen in your tyres. You'd have to ask a scientist about the details, I just know that it works"

I'll pass thanks. Although I imagine there are plenty of suckers who don't.

Not so much a question, just a small rant about an event this morning - be interested to hear others views.

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#1852495 25-Aug-2017 13:04

SCAM and proven

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Talkiet

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#1852497 25-Aug-2017 13:05

Name and shame - that's a hell of a hard sell for something that has little if any benefit.

Cheers - N

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6FIEND

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#1852500 25-Aug-2017 13:10

...the principal benefit of using Nitrogen is that the tyre pressure will vary less with temperature changes (compared to regular compressed air).

Important on a racetrack where 1-2psi difference might equate to winning or not... Almost pointless on the road.

noroad

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#1852503 25-Aug-2017 13:14

This explains it all nicely (hint, its a scam) -

Ge0rge

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#1852507 25-Aug-2017 13:24

6FIEND:
...the principal benefit of using Nitrogen is that the tyre pressure will vary less with temperature changes (compared to regular compressed air).

Important on a racetrack where 1-2psi difference might equate to winning or not... Almost pointless on the road.

Sorry @6FIEND, they've slipped you some of the Kool-Aid while you weren't looking...

...there’s only four per cent difference in what engineers call the ‘specific heat’ of air versus the specific heat of nitrogen. What this means is: if those tyres run on air and they jump from 20 degrees C from cold inflation to 40 degrees C after a hot lap, and they start at 32 psi, they’ll finish at 34.184 psi.

If we replace with nitrogen and go again, same heat input but four per cent fewer degrees in temperature rise. So at the end of the lap, 39.2 degrees C, instead of 40. Pressure at the end of the lap will be 34.096 psi. Less than one tenth of a psi pressure difference...

shk292

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#1852508 25-Aug-2017 13:24

6FIEND:

...the principal benefit of using Nitrogen is that the tyre pressure will vary less with temperature changes (compared to regular compressed air).

Important on a racetrack where 1-2psi difference might equate to winning or not... Almost pointless on the road.

So you're saying that Charles's Law applies less to Nitrogen than other gases? Why would that be?

I have a family member who runs a garage and sells this service. He is convinced it works and sells it genuinely because of that. But to me it's as convincing as homeopathy.

Bung

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#1852547 25-Aug-2017 13:40

Ge0rge:
6FIEND:

...the principal benefit of using Nitrogen is that the tyre pressure will vary less with temperature changes (compared to regular compressed air).

Important on a racetrack where 1-2psi difference might equate to winning or not... Almost pointless on the road.

Sorry @6FIEND, they've slipped you some of the Kool-Aid while you weren't looking...

There is something in it due to the water vapour present in locally produced compressed air v's dry nitrogen. That would vary by season.

I think most people are better off using air and checking regularly. I've had less trouble from slow leakage than random nails and TEK screws. Sticking Nitrogen in and thinking it fixed something gives a false sense of security.

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frankv

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#1852549 25-Aug-2017 13:45

Agree with everything everyone above said.

Nitrogen still leaks, but oxygen passes through rubber at about twice the rate. Nitrogen will still leak if your valve is faulty or you have a puncture or whatever. All the benefits sold to the OP are potentially real, but negligible. Most are due to the nitrogen not containing any water. There's no particular reason, apart from that it is pointless, that garages couldn't have water traps on their air compressors.

Another line salespeople may use is that aircraft tyres are filled with nitrogen... that's large aircraft where a set of tyres costs more than my salary, and is partly to reduce flammability, partly to reduce leakage at high altitude where the pressure differential is much greater, and partly to extend the life of the tyre. Light aircraft just use air in their tyres.

Sidestep

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#1852574 25-Aug-2017 14:02

Ge0rge:
"Would I like to pay extra to have my tyres filled with nitrogen?"

What he really meant to say was..

"Would you like to pay extra to have your tires filled with nitrogen?" "otherwise I'll fill them with this moisture laden air that's come past our un-serviced water trap through an oily airline that's run our impact driver"

"and then your TPMS will fail a week from now"

geoffwnz

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#1852605 25-Aug-2017 14:40

Not to mention that they aren't filling said tyres in a vacuum, so whatever air was already sitting in there (1 ATM I'm guessing) when the bead seated will remain in there anyway.

I do race, and I don't bother with Nitrogen filling. Partly because of negligible benefit, partly because CBF, mostly because <Insert Nitrogen scammer of choice here> doesn't tend to have outlets at rally service parks or pit areas that tend to be in paddocks on back roads.

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RunningMan

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#1852606 25-Aug-2017 14:47

If nitrogen doesn't leak but air does, surely the easiest solution is fill up with air, then everything that is non nitrogen will leak out, leaving a nitrogen filled tyre for free

WyleECoyoteNZ

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#1852669 25-Aug-2017 15:14

I found this old Tiff from Fifth Gear clip on the subject.

https://www.youtube.com/watch?v=kmnZ4-EUbIk

Fully, 100% agree with his last comment

Wiggum

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#1852674 25-Aug-2017 15:19

RunningMan:

If nitrogen doesn't leak but air does, surely the easiest solution is fill up with air, then everything that is non nitrogen will leak out, leaving a nitrogen filled tyre for free

You do realize that air is about 80% nitrogen right?

RunningMan

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#1852679 25-Aug-2017 15:26

Wiggum:

You do realize that air is about 80% nitrogen right?

You do realise that once the other 20% leaks out, it's 100% nitrogen right?

Wiggum

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#1852682 25-Aug-2017 15:29

RunningMan:

Wiggum:

You do realize that air is about 80% nitrogen right?

You do realise that once the other 20% leaks out, it's 100% nitrogen right?

Well the 20% oxygen/Co2 is not going to leak out by itself, without taking the nitrogen with it.

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