Nitrogen in Bike Tyres?

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#1525993 4-Apr-2016 20:01

Athlonite:
the only thing I found using Nitrogen in my car was the tyres were a little quieter on the road and lasted a little longer before I needed to replace them (+15000K's) so for me it was worth it

Just checking if this is a serious statement? If so, can you think of any other factors you could attribute these results to?

gregmcc

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#1526007 4-Apr-2016 20:18

The whole nitrogen in your tyres is a big con. The people who swear by seem to be easily conned

frankv

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#1526016 4-Apr-2016 20:42

From http://www.getnitrogen.org/pdf/graham.pdf

O2 "permeates" approximately 3-4 times faster than does N2 through a typical rubber, as is used in tires, primarily because O2 has a slightly smaller effective molecular size than does N2.

So the benefit of pure nitrogen would be about 5% reduction in permeation rate, replacing 20% oxygen with something that leaks about 1/4 the amount. But, as before, each time you top up your tyre, you'll automatically be increasing the nitrogen proportion, since a bigger proportion of the oxygen will permeate through the rubber. But it will increase about half the speed compared to my previous calculation.

This doesn't come anywhere near Jase2985's 37% difference (3.5psi vs 2.2psi). Probably other molecules (i.e. water (which is probably smaller than oxygen), and argon at about 1% each in air) also permeate out, but it still doesn't add up. Maybe there's things like condensation of water at lower temperatures, which would lower the pressure (but only 1% at most). Dunno.

JWR

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#1526025 4-Apr-2016 21:23

frankv:

From http://www.getnitrogen.org/pdf/graham.pdf

O2 "permeates" approximately 3-4 times faster than does N2 through a typical rubber, as is used in tires, primarily because O2 has a slightly smaller effective molecular size than does N2.

So the benefit of pure nitrogen would be about 5% reduction in permeation rate, replacing 20% oxygen with something that leaks about 1/4 the amount. But, as before, each time you top up your tyre, you'll automatically be increasing the nitrogen proportion, since a bigger proportion of the oxygen will permeate through the rubber. But it will increase about half the speed compared to my previous calculation.

This doesn't come anywhere near Jase2985's 37% difference (3.5psi vs 2.2psi). Probably other molecules (i.e. water (which is probably smaller than oxygen), and argon at about 1% each in air) also permeate out, but it still doesn't add up. Maybe there's things like condensation of water at lower temperatures, which would lower the pressure (but only 1% at most). Dunno.

I'll accept that...

But, there is also this... "Most modern tubeless tires are constructed with a virtually impermeable butyl rubber liner..."

Source... Airtight synthetic rubber liner

Also, I found out another reason why Formula One teams might use Nitrogen in tyres.

They have a lot of of it around.

Compressed Nitrogen is used to drive the mechanical ratchets and other power tools.

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#1526033 4-Apr-2016 21:35

1. Unless your tyre was completely devoid of air and filled with pure nitrogen you are just putting something into ... Mostly air.

2. How do you know that you are putting pure nitrogen into your mostly air filled tyre? Any certification standards?

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#1526126 5-Apr-2016 07:05

JWR:

But, there is also this... "Most modern tubeless tires are constructed with a virtually impermeable butyl rubber liner..."

Source... Airtight synthetic rubber liner

And goes on to say

"Check your tires' air pressure monthly, as some air loss occurs over time."

I guess when they say "virtually impermeable" they mean "only slightly permeable". lol

Also, I found out another reason why Formula One teams might use Nitrogen in tyres.

They have a lot of of it around.

Compressed Nitrogen is used to drive the mechanical ratchets and other power tools.

I suspect that the F1 ratchets, etc are powered by compressed nitrogen rather than air is to avoid rusting the interior of their expensive tools with water from the air. And maybe to avoid any possibility of ice forming in the lines and jamming things up. When a race costs you $10M, it's worth spending a few dollars to avoid any possible problem.

Large aircraft tyres are also filled with nitrogen... I think to reduce the fire risk.

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#1526159 5-Apr-2016 08:25

To be any use at all the tire shop would first use a tire purging system after initial inflation to dry & evacuate before the nitrogen fill.

The only real benefit to Nitrogen filling is that the shop isn't filling your tires with the terrible moisture laden spray that comes out of many of their inflators.

A decent shop will have an air dryer system after their compressor. A lot of smaller places don't, or don't service the systems they have.

Think of your TPMS senders being permanently wet, the sealing surfaces of your rims corroding.

RileyB

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#1526173 5-Apr-2016 08:55

I thought the reason for using Nitrogen in tyres was only relevant to racing, and was for one of two reasons:

1, The increase in pressure from the tyre heating up is more predictable

2, It has less moisture in it then just using a normal air compressor, however you could get the effect by using a moisture trap on your air compressor

Maybe you would be better to look at your tyres/tubes/valves? I bought a new bike a few months before Christmas (~6 months old?) and reading the pressure hot (after coming back from riding), have never had more then 0.5 PSI difference in reading, and have never had to top up the tyres.

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#1526175 5-Apr-2016 09:02

I view nitrogen in tyres the same as extended warranties on electronics - the only product is 'pure profit' for the seller.

Now there's a thought, maybe tyre retailers could start selling extended warranties for nitrogen filled tyres?

BTR

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#1526192 5-Apr-2016 09:35

I was hoping the OP was asking about push bikes. Because using Nitrogen on a push would;t be a waste of time at all...

MikeAqua

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#1526229 5-Apr-2016 11:10

Nitrogen molecules by themselves aggregate.

That's (mostly) why pure N leaks through rubber slower than 0.8N air.

freitasm:

Air is already almost 80% Nitrogen...

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#1526237 5-Apr-2016 11:23

I am talking about my mountain (push) bike. Every time I go to use it (2 to 3 times a month the tyres have deflated) ... checked for leaks etc and none are apparent. I've never owned bike that didn't need regular topping up. The rubber is thin so I guess that's to be expected.

I have a tandem trailer. I put nitrogen in the tyres in one axle and air in the other two (same 8-pr tyres installed on same day).

After >18 months and a tyre rotation (back tyres carry slightly more load), the N filled tyres are within a couple of PSI of their original pressure. The air tyres have had a couple of 5 - 10 psi top ups.

I got the air replaced with nitrogen last week for free. I've never had to pay 'extra' for nitrogen when buying tyres.

Mike

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#1526238 5-Apr-2016 11:23

John Cadogan pretty much sums up the nitrogen ripoff:

MikeAqua

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#1526259 5-Apr-2016 11:39

Have it in all our cars and trailers and would never go back to air.

At $0.00 per tyre it's hardly a rip off.

So does anyone actually have a suggestion as to how to get pure nitrogen into bike tyres?

Mike

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#1526266 5-Apr-2016 11:46

MikeAqua:

Have it in all our cars and trailers and would never go back to air.

At $0.00 per tyre it's hardly a rip off.

So does anyone actually have a suggestion as to how to get pure nitrogen into bike tyres?

Have your bike on the rack next time you're in getting your car tyres done. Ask the chap nicely :-)

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