Tire Pressure and Nitrogen

[jbr7t]

So I've been running Nitrogen in my cage tires for quite some time. 100 degrees or 10 degrees the pressure doesn't vary. Is anyone using nitrogen on their motorcycle tires?

[dirtrider]

Afternoon James

 

Sure, I have been running around 78% nitrogen since the late 1940's. Acts just like regular air to me.

 

You probably should check you air pressure gauge as it doesn't sound like it's working correctly if it doesn't show any tire air pressure difference between 100°f & 10°f even with nitrogen.

 

[Danny caddyshack Noonan]

Using a custom mixed gas like Dirtrider.

 

The pressure difference you should be seeing is about (313/263)=1.19 or 19% difference assuming no change in tire volume which, isn't exactly correct but, not a bad assumption within about 1psi or so.

[ESokoloff]

Ask Joe.

[Quinn]

Does NASCAR put nitrogen in their tires? There's a lot of tire research going on during races, so I would kinda think that if there was an advantage, they'd be all over it.

 

That said, I'd be afraid to use it in my motorcycle tires; no telling what it would do to the balancing beads that are in there.

 

 

----

 

 

[George Brown]

Afternoon James

 

Sure, I have been running around 78% nitrogen since the late 1940's. Acts just like regular air to me.

 

You probably should check you air pressure gauge as it doesn't sound like it's working correctly if it doesn't show any tire air pressure difference between 100°f & 10°f even with nitrogen.

:D LMAO Me Too!

[RT66Rider]

During my Shifter-Kart racing days, the vast majority of experienced racers ran only 100% nitrogen in their tires.

But for me, air was good enough.

 

Kart tires normally run between 7-12 psi, so maybe heat expansion at lower pressures is a bigger factor. Don't really know.

[dirtrider]

Lots of reasons racers run nitrogen. Some legitimate & others a bit wannabe.

 

On real high speed race tires even 1/4 to 1/2 pound can change the tire's behavior. Then if racing a vehicle at very high speeds you are looking at high tire temperatures so using nitrogen under those conditions makes sense as nitrogen is very dry & even more important extremely predictable from race to race.

 

Then most (professional) race teams have high pressure nitrogen handy to run their power tools so nitrogen makes sense there also.

 

I just can't see the advantage of running nitrogen in street tires as street tires are not responsive to very small pressure changes as well as the variable temperatures & conditions they operate at.

 

My guess is a lot of local racers (even cart racers) use nitrogen as it seems high tec & looks cool to others as well as they perceive it makes their lap times quicker. Maybe even helps if the tires they are using are responsive to 1/4 pound pressure changes.

 

The good news is that using nitrogen won't hurt or harm anything in the tire & in most cases is dryer than wet shop air so if it's free why not use it.

 

Personally my shop air is very dry as I have a large angled free air cooler on the compressor output side so the air is pretty dry at the hose end & moisture has never been an issue at hose outlet.

 

[Selden]

Don't forget the effects of di-hygrogen monoxide on tire pressures....

[ESokoloff]

Don't forget the effects of di-hygrogen monoxide on tire pressures....

 

Had to Google/Wiki that one

[terryofperry]

I'm assuming James was asking a serious question so I'll reply in kind. I'm running Nitrogen because I get it free, have the tank and regulator which makes it easy. I've been using it about 4 years, first in an RT and now in a GSA.

 

The pressures are more stable during the ride and very stable over time. I check them often, at least every ride and rarely add.

 

Nascar uses Nitrogen in their tools as it is moisture free and the tools are more reliable. As others have said, a 1/2 # of pressure can vary the handling greatly at 200 mph. Nitrogen does epand with temperature as the gas laws apply. Just not as much and it is quite easy to chart it vs.temperature.

 

Formula 1 uses air eclusively but not the air coming out of your compressor. It is DRY, no moisture at all, like we use in SCUBA. Moisture in air expands and causes problems, depending on the moisture content. Formula 1 runs Bridgestone exclusively and Bridgestone engineers can calculate moisture free air as well as NASCAR.

 

It is the moisture that is the problem. Fill on a rainy day, more moisture.

 

Oygen molecules are a little smaller than Nitrogen, thus they can more easily permeate out of rubber, but not by much.

 

As stated before, I run it because it is freely available to me.

A setup for the home would cost about $200 with a tank and regulator. It is only about $8 to get the tank filled so no biggie.

 

Air is fine, it is free, works very well and if I had to buy the setup I would need to think about it. If my vehicles were using it from the factory I would invest in the setup for sure as the dealers charge way too much for it and to top off would be a pain to go to the dealer.

 

Ride safely

 

Terry

[Selden]

It is DRY, no moisture at all, like we use in SCUBA. Moisture in air expands and causes problems, depending on the moisture content.

Exactly, which is why I referred to di-hydrogen monoxide. Nitrogen has almost nothing to do with it; you could get just as good results using CO2 if it was totally lacking in water.

 

Helium might be iffy because the molecules are so small. Of the noble gases, Xenon (atomic number 54) would probably be best, as it's inert, and has a relatively large molecule. Even though its atomic number is higher, Radon (86) would probably turn most people off, since it's radioactive.

[TestPilot]

Pure nitrogen has a higher specific heat than air (1.04 to 1.01), so the heat generated in the tire during riding results in a lower temperature change with pure nitgogen and, hence, a lower pressure change.

 

Water vapor actually has a higher specific heat than nitrogen. However, the problems of condensation inside the tire outweigh any theoretical advantages.

[RockBottom]

It is DRY, no moisture at all, like we use in SCUBA. Moisture in air expands and causes problems, depending on the moisture content.

Exactly, which is why I referred to di-hydrogen monoxide. Nitrogen has almost nothing to do with it; you could get just as good results using CO2 if it was totally lacking in water.

 

Helium might be iffy because the molecules are so small. Of the noble gases, Xenon (atomic number 54) would probably be best, as it's inert, and has a relatively large molecule. Even though its atomic number is higher, Radon (86) would probably turn most people off, since it's radioactive.

 

Since air is 0.000114% kryponite that's what I'm using. Just because it's cool.

[bmw_rider]

Using a custom mixed gas like Dirtrider.

 

The pressure difference you should be seeing is about (313/263)=1.19 or 19% difference assuming no change in tire volume which, isn't exactly correct but, not a bad assumption within about 1psi or so.

 

True only if both measurements are taken at the same altitude.

[jbr7t]

Ok, so this post has proven to me that there are a lot of people smarter than myself around here.

 

Yes my statement of the same pressure 100 degrees to 10 degrees was a bit of an exaggeration for literary effect.

 

I do notice changes in the pressure in my motorcycle tires. Some mornings when I leave for work it may be around 30 degrees but coming home it's over 60. Maybe it's just me being paranoid but I can "feel" a difference in the bike's handling.

 

I guess I will have to check into the expense of using 100%nitrogen. On my truck tires I didn't have to pay any fees. When I got my new tires the guy told me about it and that it was better to keep consistent pressure etc. So they filled with nitrogen with the install. I'm sure I paid for it somewhere in there but it wasn't listed as a separate charge.

 

 

[Selden]

I do notice changes in the pressure in my motorcycle tires. Some mornings when I leave for work it may be around 30 degrees but coming home it's over 60. Maybe it's just me being paranoid but I can "feel" a difference in the bike's handling.

Of course you can feel a difference in handling; if there is that much of a temperature change, I would expect the temperature to go up about 2psi at the warmest part of the day. Tire pressures are almost always a compromise, and most people are not willing to check and change pressure several times a day as the ambient temperature goes up and down.

 

The "Ask Joe" link covers the topic more thoroughly than anybody here has. Nitrogen makes a difference, but the cost/benefit just isn't there for everyday use (unless you can get nitrogen for free) in auto or moto applications. Silver conducts electricity better than copper, but silver wire is not cost-effective for most uses.

[Danny caddyshack Noonan]

Helium might be iffy because the molecules are so small.

 

Worse than iffy. It would be flat in an amount of time that I could calculate but, that would obviate the purpose of taking vacation this week.

I have some devices that are helium filled at about 15psi gauge and sealed with an o-ring. They have 0 psi gauge after several years.

[Boffin]

Our own Joe Frickin' Friday has looked at this in some depth, in the way that only an engineer could.

His Nitrogen for Tires: FAQ goes into the science far better than I ever could.

 

Andy

[Redbrick]

Our own Joe Frickin' Friday has looked at this in some depth, in the way that only an engineer could.

His Nitrogen for Tires: FAQ goes into the science far better than I ever could.

 

Andy

 

Wow........More than you ever want to know about the subject.....Really very interesting even though I no comprende parts of it... ......Thanks Boffin for pointing out Joe's F F's dissertation and, of course, thanks to Joe...

I just changed tires on our Camry after about 3 years of use and 44M miles...They were filled with nitrogen and I think only a couple of them required added inflation during that time and used breathable air....Other than that, we got those cool green valve caps too.....

Had the same Michelins put back on and, yes, nitrogen inflated again....Wouldn't have done so if I'd read this thread first......

[jbr7t]

Ok, after reading a good portion of Joe's article I think we need to open up a new section of this board... dumb guys that bought BMW's. I will be the president. I think I will not be waisting my money on Nitrogen.

 

That is one of the things I love about this board, if I have a question there is always someone smart enough to answer it. Thank's Joe. I can imagine that took a great deal of research and time.

[dirtrider]

Afternoon James

 

 

Nothing wrong with nitrogen as it is usually dryer than plain old shop air (especially in hot humid areas)

 

If you can get it for free then why not. You certainly don't want to pay very much for it.

 

 

[Joe Frickin' Friday]

That is one of the things I love about this board, if I have a question there is always someone smart enough to answer it. Thank's Joe. I can imagine that took a great deal of research and time.

 

Glad to help out. Tne nitrogen-in-tires question is a perennial favorite on motorcycle and car discussion boards, but the issue has always been murky and ill-informed. I originally put that material together as a post for BMWST back in 2006, and then turned it into a web site where I could format it better and provide broader access.

 

A short summary of some of the more contentious points:

 

• pressure variation:
  As the plots on my site show, nitrogen and [dry] air pressures vary with temperature in a virtually identical manner; for a temperature increase of 40 degrees F, the difference in pressure rise is only about 0.04 psi. The thing that can make a big difference in pressure-versus-temperature behavior is water, but only if you've got so much in there that you have a substantial amount of condensation in your tires when they're cold; that's not likely to happen unless you're using something like a Slime pump (i.e. a compressor with no storage tank) to fill your tires from empty on a humid day.
   
  
• Leakage:
  Nitrogen does leak out more slowly, but not nearly as slowly as some vendors would have you believe. The difference, according to theory and according to testing by Consumer Reports - is a factor of 1.6. That is, for a given period of time, the pressure loss in an air-filled tire will be about 1.6 times that of a nitrogen-filled tire.
   
  
• Motorsports:
  These guys already have bottles of dry nitrogen lying around for servicing suspension components. It would make sense to use this stuff for all of their other needs anyway (air tools, tire filling, etc.) even if there were no other benefit; an air compressor as part of their pit equipment would be redundant. And if Belle Tire happens to be one of your race team's sponsors, then you'll probably be contractually obligated to talk up the benefits of nitrogen every time there's a microphone in front of you.
   
  
• Trucks, A.K.A. "Articulated Lorries:"
  These tires run at elevated pressures (~100 psi) and get retreaded for extra miles. The reduced leakage rate of N2 is valuable when it takes a trucker a half-hour to check/top off all of his tires, but it also helps extend the life of the underlying tire carcass by reducing long-term oxidation. This is a non-issue for motorcycle tires running at 40 psi and being changed out after just a season or two.
   
  
• Aerospace:
  If you wanted to fill your 747's tires with air, you'd need a special high-pressure compressor to do so since they run around 200 psi, something your home Craftsman air compressor can't achieve. But even if you could, you wouldn't want to, and it's not because of a few grams of condensation potentially throwing a 300-pound tire out of balance: it's about mitigating fire risk. Just as surely as things burn poorly in the rarefied air at Everest high camp, things burn unusually well in 200-psi air. Airliner tires can get pretty hot, and if they're full of air (instead of nitrogen), they'll burn and possibly explode. Yeah, it's happened.

As Dirtrider says, if a nitrogen fill is free, go for it. If they want to charge you for it, save your money.

[jbr7t]

Thanks Joe.. I'm just a simple guy, the abridged version is right my speed!

 

 

[racer7]

Both my science Ph.D. and track experience support not wasting the $ to do nitrogen in street tires. If you get it free or cheap, fine- it won't hurt- but don't expect miracles.

 

Random air compressors are a problem for racers mostly because water is often blown out the end of air hoses. And races tires operate above the sea level boiling temp for water, Not to mention that trackside tire changes might be done while moving new tires around a wet track environment.

Some carry nitrogen for air tools because the tanks are more portable than a shop compressor and where they are allowed, nitrogen rechargeable shocks need a source. So many reasons none of which apply to a street motorcycle or car.

one thing you won't find is racers who think nitrogen makes tires faster but it is most definitely true that 1/2 and even 1/4 psi increments have handling impacts in racing conditions.

 

Permeability of materials to gases is a fun subject and full of unanticipated surprises but air and nitrogen through rubber aren't all that different so not really worth worrying about. One oddity that has bitten many newbie biochemists is the ability of carbon dioxide gas to penetrate common plastics and dissolve in the water inside a container. More than one newbie has stuck a carefully made frozen enzyme prep in a plastic container into something cooled with dry ice for shipping only to discover on arrival that the carbon dioxide has waltzed right through the plastic, dissolved into the ice, and the denatured / precipitated that expensive bit of protein by the resulting pH change. Gas permeability is a subject of significant interest to packaging engineers where preserving items in inert atmospheres or a vacuum and keeping out reactive oxygen or water vapor can greatly change the shelf life of items.

[jviss]

What I'm getting from this is that if you fill with air, and then add air as your tire pressures drop over time, from the mostly non-nitrogen constituents of air leaking out much more quickly than the nitrogen; then, before long, you will have mostly nitrogen in your tires anyway, whether you want it or not.

 

My guess, however, is that for street tires the leaks one most frequently encounters are not from permeability, and are much more sever than the loss of pressure from permeability, even when small. I've put air in the Pirelli Scorpions on my BMW X3 perhaps twice in 30,000 miles. I have TPMS, plus I check them occasionally. I bet I lose more air checking them than any other way.

 

 

[Ken H.]

This subject comes up every once in a while, and I have to blame the whole confusion about the subject squarely on bill padding by tyre service shops made possible by our poor educational system. Anybody who has even a basic knowledge of physics/chemistry (you know, the kind of education we 50+ year olds used to get in Jr. High) would know that for us mere mortals (who don’t drive a formula one race car or a 747); the whole purported benefits of pure nitrogen in tyres is pure blahoey.

 

As several people have already pointed out (but apparently much of the public no longer knows) you ALREADY ARE using 78% nitrogen when you fill you tyres with plain old air.

 

Even if you did spring for the extra cost 100% nitro option at the tyre place (and how would you know if they actually did it anyway?) the first time you added air (yes AIR) to your tyre at wherever, you’re diluting the mixture. Couple of top offs of pressure and you’d be trending right back to a mix.

 

Paying for pure nitrogen in street tires - it’s one of the biggest scams ever cooked up.

 

[lkchris]

Formula 1 runs Bridgestone exclusively ...

 

It was Pirelli exclusively in 2011 and that will continue in 2012.

[terryofperry]

Kent

 

You are correct for this year and next. The excerpt was from a Bridgestone engineer when they had the contract.

 

This is from the F1 site:

 

http://www.formula1.com/inside_f1/understanding_the_sport/5283.html

 

 

"Formula One tyres are normally filled with a special, nitrogen-rich air mixture, designed to minimise variations in tyre pressure with temperature. The mixture also retains the pressure longer than normal air would."

 

Terry

 

 

[Polo]

What I'm getting from this is that if you fill with air, and then add air as your tire pressures drop over time, from the mostly non-nitrogen constituents of air leaking out much more quickly than the nitrogen; then, before long, you will have mostly nitrogen in your tires anyway, whether you want it or not.

 

This sounds so much like Cliff's Buffalo theory. Good one!