Nitrogen In Tires

[JoeMc]

I have been running nitrogen in the tires on my cages for over a year now and find the plus is true - no pressure fluctuation due to ambient temperature. Is there any reason to NOT run nitrogen in bike tires?

 

(I did do a search on "nitrogen" and did not find this as a previous question. Please excuse me if it is - and point me in the right direction.)

[Heck]

No reason not to.....in fact, you run 78% Nitrogen in your tires anyway....this is the percentage of nitrogen in good ol' air. More gimmick than not to accentuate the "service" you get at your tire dealer...

[Dave in Doodah]

Since air is already about 4/5ths nitrogen, I am not sure I can the cost/hassle justification to go with pure nitrogen...?

 

Although we all have different levels of anal-ness that we take our maintenance to...

[Dave in Doodah]

Heck - you beat me to it!

[Dave in Doodah]

That said, I am looking forward to someone busting out the ideal gas law and putting on a show for us...

 

Lessee... pv=nrt?

[David]

http://home.comcast.net/~prestondrake/N2_for_tires_FAQ.htm

[Joe Frickin' Friday]

I have been running nitrogen in the tires on my cages for over a year now and find the plus is true - no pressure fluctuation due to ambient temperature. Is there any reason to NOT run nitrogen in bike tires?

 

(I did do a search on "nitrogen" and did not find this as a previous question. Please excuse me if it is - and point me in the right direction.)

 

Air and nitrogen respond to temperature changes virtually identically: whichever gas is used, on a 40-psi tire, you'll need to see the temperature change by about 10 degrees (F) before you'll notice a 1-psi change in pressure - and you'll need a pretty good gauge to reliably measure that 1-psi change.

 

See plot at bottom of this post, taken from my "Nitrogen for Tires FAQ". For full context, see the first question in the FAQ.

 

As to running N2 in bike tires...no reason not to, unless they're charging you for it.

[Joe Frickin' Friday]

(I did do a search on "nitrogen" and did not find this as a previous question. Please excuse me if it is - and point me in the right direction.)

 

How did you do your search? I put in "nitrogen" as a search term (click "Search" at the top of this page, type nitrogen, hit enter) and got 11 pages of results.

[Unhofliche_Gesundheit]

for me nitrogen is about ambient temp not tire temp change from cold to hot on any given ride. so i'm not very impressed with that graph.

we had some very nice days say 80F ambient in sept and some very cold days in november (say to -15F ambient.

 

that is 100 degree change - your chart only shows 55 spread.

at the wider spread - assuming some real world humidity - the difference is more important. (it fact we could calculate it but i supposed to be working for the boss man..)

as i understand it nitrogen is airplane technology- where the temp changes are even more extreme on any given day (not over months).

 

bottom line - if you really cant push your self to check your bike tires when the temperature changes nitrogen might be of help - certainly a lot of cage drivers are lazy and helps them. also if nitrogen is free go for it. if not free- maybe you need to push your self into checking your air more often (like once a week) - which i think you are supposed to be doing anyway cause so much is riding on your tires

 

 

[Joe Frickin' Friday]

for me nitrogen is about ambient temp not tire temp change from cold to hot on any given ride. so i'm not very impressed with that graph.

we had some very nice days say 80F ambient in sept and some very cold days in november (say to -15F ambient.

 

that is 100 degree change - your chart only shows 55 spread.

at the wider spread - assuming some real world humidity - the difference is more important. (it fact we could calculate it but i supposed to be working for the boss man..)

 

Check question #1 in the FAQ: there's another plot that ranges from 10F to 170F. Even with humidity, the differences at very low temperatures are negligible, a fraction of a psi.

 

as i understand it nitrogen is airplane technology- where the temp changes are even more extreme on any given day (not over months).

 

Check question #5 in the FAQ. Nitrogen use in aircraft tires has nothing to do with pressure-versus-temperature issues (since it doesn't make a difference in this regard); it's a fire safety thing.

 

bottom line - if you really cant push your self to check your bike tires when the temperature changes nitrogen might be of help - certainly a lot of cage drivers are lazy and helps them.

 

It helps lazy folks cope with leakage (nitrogen does leak out a bit more slowly than air), but it doesn't help them cope with ambient temperature changes.

 

[Unhofliche_Gesundheit]

thanks Mitch - sorry i don't have time to read the links - appreciate being set right. so based on the new knowledge that is safety not performance driven and the performance is the same i gotta agree with you would be crazy to pay for nitrogen in this application. cheers.

[Dave in Doodah]

We all check our tire pressures, right, and tweak as necessary? Is the issue here to avoid adding a few psi in the wintertime, or is it to minimize the affects of the temp change based on the tire warming up during a particular ride?

 

U_G - Your argument may have some merit if you are comparing summer to winter ambient conditions. But not so much if you are just looking at pressure change in the first 15 minutes of one ride. In this case, I don’t see ambient air temp/humidity having much to do with this at all. I agree that a warmed up tire's temperature could pressumably fall off this chart, but reasonable extrapolation tells me that air is air, and nitrogen is air; as far as real world pressure changes go…. Either way, when it comes to summer vs winter, it seems to me you will be adding a few psi in the winter whether you are running air or nitrogen. moot point.

[Dave in Doodah]

It helps lazy folks cope with leakage (nitrogen does leak out a bit more slowly than air), but it doesn't help them cope with ambient temperature changes.

 

Maybe the faster leaking gas is the offending 22% non-nitrogen stuff in the air... let it leak long enough and you've got yourself some pure nitrogen in those tires...

[Unhofliche_Gesundheit]

re: "As to running N2 in bike tires...no reason not to, unless they're charging you for it."

 

i have an even better idea - ...instead of N2,if you have to pay anyway, use N02 - then you have something to suck on when your bwm leaves you stranded (say with final drive failure) out in the middle of nowhere -with no way to 'self-medicate'.

 

use 'multicolor' cap rather than green (see it's a well thought out implementation!).

[JoeMc]

The issue I was inquiring about is the effect on the tire pressure while riding (i.e.; performance & safety). Many articles seem to support up to a 10% increase in tire pressure as a tire heats. My non-scientific background (and research) indicates nitrogen is inert and is not affected by increased heat/cool. Therefore, the tire temp/pressure in the garage before a ride is the same if measured 100 miles down the road in the middle of the summer months.

 

I had to prove this to myself by checking the pressure in cage tires.

 

Dave, do you ever watch "House" on the tube? (rhetorical) Look in a mirror and recite his favorite expression to yourself.

[JoeMc]

Got one reasonable answer. Thanks, Dave. Sorry I missed it in the FAQ.

[Dave in Doodah]

JoeMc - My son loves the show, but I have not seen it...

 

Is it "We're missing something?"

[Dave in Doodah]

JoeMc - not to beat a dead horse or to give TMI, but an inert gas is not unaffected by temperature. The term 'inert' refers to some gases being relatively non-reactive with other substances due to the molecules having a full complement of electrons in their outer shells. Open spots in this valence shell makes molecules more willing to try and 'share' electrons with other molecules and be reactive...

 

Ugh... 5 years of college and this is what I have to show for it...

[Boffin]

The issue I was inquiring about is the effect on the tire pressure while riding (i.e.; performance & safety). Many articles seem to support up to a 10% increase in tire pressure as a tire heats. My non-scientific background (and research) indicates nitrogen is inert and is not affected by increased heat/cool. Therefore, the tire temp/pressure in the garage before a ride is the same if measured 100 miles down the road in the middle of the summer months.

 

I had to prove this to myself by checking the pressure in cage tires.

 

Dave, do you ever watch "House" on the tube? (rhetorical) Look in a mirror and recite his favorite expression to yourself.

 

Nitrogen is a mostly inert diatomic gas. All that that means is that the gas does not react with other chemicals. It does not absolve it from the laws of physics - especially not the ideal gas law.

 

At a constant volume if you increase a gas' temperature you increase its pressure, it's not just a good idea, it the law.

 

Andy

 

 

[Koop]

All gases expand/contract with heat or lack of heat. Look up Boyle's Law.

 

We use nitrogen in our race bikes because it is dry. The moisture in the tires contributes to pressure rise with heat. We want our pressure rise to be constant and predictable, so we use nitrogen. I'm also told that nitrogen molecules are larger than oxygen and other elements in air, therefore their is less leakage as well.

[Koop]

Also, I have nitrogen in the tires of My Touareg and my Wife's Audi. I can see the pressure rise as the tire warms up driving down the freeway via the tire pressure monitoring system.

[JoeMc]

Thanks for all the responses. I'm so glad I qualified myself in the beginning of this thread as "... non-scientific..." It is great to know there are those of you out there who can fill the void for folks like me.

[Joe Frickin' Friday]

We use nitrogen in our race bikes because it is dry. The moisture in the tires contributes to pressure rise with heat. We want our pressure rise to be constant and predictable, so we use nitrogen.

 

How sensitive are your bikes to tire pressure? Unless you're filling from a tankless compressor on a very humid (>50%) day, the difference between air and nitrogen (at operating temp) will be about 1/3 of a psi. Can your tire gauges measure that when filling/checking, and can you feel a difference of 1/3 psi on the track?

 

If you get even a smidge of water-based tire lube in there when you are mounting the tire (a quarter-gram, a single fat droplet will do it), then there will be no difference in pressure. (RU-Glyde has soap and ethylene glycol, but is mostly water.)

[Joe Frickin' Friday]

Thanks for all the responses. I'm so glad I qualified myself in the beginning of this thread as "... non-scientific..." It is great to know there are those of you out there who can fill the void for folks like me.

 

Joe, that's one of the very cool things about a board like this: we're all here because of BMW bikes, but we all pursue different careers. There are cops, firefighters, lawyers, engineers, accountants, carpenters, restaurateurs, musicians, doctors, space shuttle pilots (no joke), machinists, and tatoo artists on board here - all happy to share their expertise when called upon, and sometimes even when not called upon.

[RPG]

I don't and you certainly don't need to.

 

Good 'ol air works fine, which is about 80% N anyway. If you check your tires regularly (and tire pressure), there's little point in going pure N, unless it's free.

 

Some tire shops in the metro Detroit area tout it as the next greatest thing (and charge extra for those who think they gotta have it). "Let the Consumer beware"

 

RPG

[Koop]

We use nitrogen in our race bikes because it is dry. The moisture in the tires contributes to pressure rise with heat. We want our pressure rise to be constant and predictable, so we use nitrogen.

 

How sensitive are your bikes to tire pressure? Unless you're filling from a tankless compressor on a very humid (>50%) day, the difference between air and nitrogen (at operating temp) will be about 1/3 of a psi. Can your tire gauges measure that when filling/checking, and can you feel a difference of 1/3 psi on the track?

 

If you get even a smidge of water-based tire lube in there when you are mounting the tire (a quarter-gram, a single fat droplet will do it), then there will be no difference in pressure. (RU-Glyde has soap and ethylene glycol, but is mostly water.)

 

0.5 psi can make a difference. We've been running Dunlop NTEC slicks, pressure is very important. Usually baseline is 21 psi cold, 23 psi hot (might vary with compound changes). When the track temperature varies much (such as last weekend when we only had 70f surface temps) we'll adjust in 0.5 to 1.0 psi increments. And yes, we use very precise gauges.

[outpost22]

In reading this thread, one really knows that they're on a BMW forum. What a bunch of freakin' nerds

[g_frey]

Yes, but smart nerds.

[OlGeezer]

That said, I am looking forward to someone busting out the ideal gas law and putting on a show for us...

 

Lessee... pv=nrt?

 

The common mistake in using the ideal gas law is forgetting to use absolute temperature. That makes the different between 50F and 70F much less significant.

[OlGeezer]

We use nitrogen in our race bikes because it is dry. The moisture in the tires contributes to pressure rise with heat. We want our pressure rise to be constant and predictable, so we use nitrogen.

 

How sensitive are your bikes to tire pressure? Unless you're filling from a tankless compressor on a very humid (>50%) day, the difference between air and nitrogen (at operating temp) will be about 1/3 of a psi. Can your tire gauges measure that when filling/checking, and can you feel a difference of 1/3 psi on the track?

 

If you get even a smidge of water-based tire lube in there when you are mounting the tire (a quarter-gram, a single fat droplet will do it), then there will be no difference in pressure. (RU-Glyde has soap and ethylene glycol, but is mostly water.)

 

Mitch- isn't the difference between air and nitrogen more significant at elevated temperatures, like 150F?

[wacokid]

I've read that GP teams use nitrogen. That's probably the level of riding skill it takes before the difference in air vs. nitrogen matters.

 

I've always been skeptical of street riders who talk about big differences in traction due to brand, tire model, pressure, etc. Maybe I ride too slow, but I've found that as long I as have adequate tread depth for dispersing water and pressure somewhere in the recommended range according the manual, one tire is usually as good as the next.

[T__]

wacokid, most race teams use nitrogen.. I even used nitrogen in my off road race trucks..

 

Nitrogen usually assures no moisture in the tire filling process & tire filling equipment so there is predictability in every tire fill,, but more importantly (at least to my off road set up) was I had heavily compressed nitrogen to run the air guns & other air lifts & such so why not use it to fill the tires also.. No reason to carry both compressed air & compressed nitrogen..

 

Twisty

 

[Koop]

We use nitrogen in our race bikes because it is dry. The moisture in the tires contributes to pressure rise with heat. We want our pressure rise to be constant and predictable, so we use nitrogen.

 

How sensitive are your bikes to tire pressure? Unless you're filling from a tankless compressor on a very humid (>50%) day, the difference between air and nitrogen (at operating temp) will be about 1/3 of a psi. Can your tire gauges measure that when filling/checking, and can you feel a difference of 1/3 psi on the track?

 

If you get even a smidge of water-based tire lube in there when you are mounting the tire (a quarter-gram, a single fat droplet will do it), then there will be no difference in pressure. (RU-Glyde has soap and ethylene glycol, but is mostly water.)

 

Mitch- isn't the difference between air and nitrogen more significant at elevated temperatures, like 150F?

 

BTW - Race rubber runs at a surface temp > 160f, anything less than that and you risk cold tearing.

 

Sportbike tires typically exceed 130f.

 

I don't know what temperature the BT 020's on my RT run, I'll have to check sometime.

[OlGeezer]

I don't know what temperature the BT 020's on my RT run, I'll have to check sometime.

 

I've gotten mine up to 150F once, but that's about it.

 

After all, I'm an OlGeezer.

[Joe Frickin' Friday]

Mitch- isn't the difference between air and nitrogen more significant at elevated temperatures, like 150F?

 

Nope. Just checked: start at 70 degrees, 40 psi, and go up to 250 degrees, the difference between nitrogen and air is only 0.02 psi.

[MAT2CHI]

I go down to the local jail on Monday morning before they empty out the DUI breath analyzer and have them put that air into my portable air tank. Then I take the portable tank home and use it to air up my tires. The alcohol that's mixed in with the air makes it lighter, and it also keeps the inside of my tubes clean.

 

[dmixon]

In Aviation all aircraft tires must be serviced with nitrogen, for several reasons. very little moisture, which is more critical in aircraft due to temp. changes from field elevation at say 50 degrees to 40K feet in altitude maybe -50 degrees F, Leak rate is less then compressed air, although all aircraft tire manuf. recommend you check tire pressures daily, they also have a built in weep holes on the side wall for expansion and they do leak alittle bit. Then you have corrosion issues with Alum. and magnisume wheels. So i guess there are benifits I never use nitrogen in my bikes tires and i have access to it, I guess i am not that annel, I just check them every week.

[flyingreg]

... so i'm not very impressed with that graph.

we had some very nice days say 80F ambient in sept and some very cold days in november (say to -15F ambient.

 

...bottom line - if you really cant push your self to check your bike tires when the temperature changes nitrogen might be of help - ...

You know, if I go and air my tires at 80F and then find myself going for a ride in -15F, I think there will be more important things for me to be checking beside my tire pressures. I think this issue is all about hot air anyway...................

[John Ranalletta]

Consumer Reports conducted a long term leak down test with car tires. See results here.

[chrisd]

 

 

Joe, that's one of the very cool things about a board like this: we're all here because of BMW bikes, but we all pursue different careers. There are cops, firefighters, lawyers, engineers, accountants, carpenters, restaurateurs, musicians, doctors, space shuttle pilots (no joke), machinists, and tatoo artists on board here - all happy to share their expertise when called upon, and sometimes even when not called upon.

 

That needs to be incorporated into the homepage blurb. Really sums up the site.

[wacokid]

wacokid, most race teams use nitrogen.. I even used nitrogen in my off road race trucks..

 

Nitrogen usually assures no moisture in the tire filling process & tire filling equipment so there is predictability in every tire fill,, but more importantly (at least to my off road set up) was I had heavily compressed nitrogen to run the air guns & other air lifts & such so why not use it to fill the tires also.. No reason to carry both compressed air & compressed nitrogen..

 

Twisty

 

Why don't you just get an air compressor with a good dryer?

[Joe Frickin' Friday]

Why don't you just get an air compressor with a good dryer?

 

Don't even need a dryer. If you're using a compressor with a holding tank, this wrings most of the moisture out of the air; that's why you have to drain the condensate out of those tanks periodically. I can't find my raw data file right now, but looking at the plots in my FAQ, the difference between tires filled with dry air, dry nitrogen, and air from a compressor as described above is less than a tenth of a psi, even at 150F.

 

As has been pointed out though, race teams will have bottles of nitrogen on hand for servicing suspension components, so it doesn't make a whole lot of sense to have a separate compressor; might as well just use the nitrogen for both.

[Dave in Doodah]

That said, I am looking forward to someone busting out the ideal gas law and putting on a show for us...

 

Lessee... pv=nrt?

 

The common mistake in using the ideal gas law is forgetting to use absolute temperature. That makes the different between 50F and 70F much less significant.

 

Touche, Ol Geezer... I got my engineering degree in '86 and am still not an ol geezer (yet). But I totally forgot this 'minor' detail... You are one Smart Ol Geezer...!