Nitrogen inflation of car tires

[AlephZero]

A local garage has big advertizements featuring "free nitrogen inflation of all new tires fitted, as used in Formula I motorsport for the past 20 years".

My cynicism assumes this is snake oil so far as normal road tires are concerned - can anybody confirm or deny this?

It reminds me of a cycle racing team (possibly apocryphal) that used helium-filled bike tires to save weight...

 

[brewnog]

We had this discussion a few years back, try a search. My opinion (and, I believe, the conclusion of the discussion) was that any benefits are so negligible that you wouldn't notice them.

 

[FredGarvin]

It's a load of hogwash. You are right in that aspect for sure. There is only 1, count it, 1 benefit to Nitrogen: The diffusion rate of nitrogen through the rubber is slower than with compressed air. That is the only thing I will grant.

There are, however, a lot of things also claimed that simply are not true or misleading:

- Better gas mileage. Not true if you keep your tires inflated properly. The slower diffusion means you may not have to fill your tires quite as frequently to keep them at the proper pressure. Nitrogen, however, is not the direct link to better gas mileage. Keeping your tires properly inflated is.

- Longer lasting tires. See the argument about keeping your tires properly inflated.

- Longer lasting tires due to oxidation. It is true that the rubber in the tires will not oxidize in a pure nitrogen environment. The problem arises in that even if you do fill up with nitrogen, the majority of the surface area of the tire is exposed to atmosphere.

- Use it because NASA/Military use it. This one cracks me up because there is a down to Earth reason why. When you are servicing an aircraft, one of the things you usually have to do is to make sure that hydraulic system accumulators have the proper pre-charge. That pre-charge is high pressure nitrogen. Now, you also have to make sure your tires are filled properly. Do you think it makes sense to lug around another bottle of high pressure air or simply use the nitrogen, which makes up 78% of air anyways. It's a convenience factor. Combine that also with the fact that nitrogen has an extremely low dew point from a controlled source, so you don't have to worry about water freezing at altitude. Not exactly a worry for your car tires.

This whole thing is a marketing gimmick. Around these parts, they say you can "nitronize" your tires. It's a marketing ploy that has everything packaged in techie wrappings to make it look better.

 

[Danger]

I stand corrected, and have deleted my previous post.

 

[FredGarvin]

I stand corrected, and have deleted my previous post.

Why? I didn't get a chance to read your link!

 

[Danger]

It was to a site run by the 'Get Nitrogen Institute' or something of that nature. Apparently it's a commercial enterprise, which I didn't realize at first, and so contains the 'advantages' that have been debunked here.

 

[AlephZero]

To be fair, the advert didn't actually claim any specific technical advantages (which seemed strange, if there were any) - just the idea that if motorsport does it, it must be good.

As you say, end of discussion!

 

[russ_watters]

I stand corrected, and have deleted my previous post.

I still get to see it!

 

[Danger]

Yes, well... have fun with that.

 

[FredGarvin]

In all fairness, go ahead and repost it. I didn't get a chance to see it and I would like to see it. The local vendors here are even worse in that they don't even understand the proposed benefits. They simply parrot what they have been told to. So if there is anything that has some substance to it, I'd be interested to read it.

 

[turbo]

At the local Tire Warehouse, there is a rotating "warning" light inside a green dome mounted on the ceiling over the cash registers with a sign that says "nitrogen inflation under way" or something to that effect, presumably to get suckers to ask about it so the salesmen can sell them on the "service". What a crock!

 

[AlephZero]

In all fairness, go ahead and repost it. I didn't get a chance to see it and I would like to see it. The local vendors here are even worse in that they don't even understand the proposed benefits. They simply parrot what they have been told to. So if there is anything that has some substance to it, I'd be interested to read it.

This is a link to the nitrogen system the UK garage was using. http://www.uniflate.com/
There's nothing much there except what you said already.

 

[russ_watters]

In all fairness, go ahead and repost it. I didn't get a chance to see it and I would like to see it. The local vendors here are even worse in that they don't even understand the proposed benefits. They simply parrot what they have been told to. So if there is anything that has some substance to it, I'd be interested to read it.

He gave the name, but in any case, as such sites go, it wasn't that bad. They do mention pretty much everything you said, but the primary thing they emphasized was the leak rate -- though at 1.5psi/month, I'm sure it was exaggerated.

 

[Danger]

In all fairness, go ahead and repost it. I didn't get a chance to see it and I would like to see it.

Okay, for whatever it's worth, here you go.
http://www.getnitrogen.org/"

 

[AlephZero]

the primary thing they emphasized was the leak rate -- though at 1.5psi/month, I'm sure it was exaggerated.

I've convinced myself the biggest cause of pressure loss is the gas you lose every time you check the pressure.

I once tested that theory by inflating the spare tire to 30psi and not touching it for 12 months. The pressure at the end of that time was ... 30psi.

 

[Danger]

That's not an entirely scientific test, though. A spare is not subjected to the same conditions as a tire in use.

 

[mgb_phys]

It's a convenience factor.

Interesting, I assumed it was a fire risk thing. I noticed that the tires on a WW2 bomber at an airshow had "nitrogen inflation only" printed on them.

The problem with your car tire tests is that you didn't use properly aligned nitrogen in the right and left tires - it's obvious that speaker cable salesman have got new jobs!

 

[Homer Simpson]

Don't forget to get your headlight fluid topped up.

 

[FredGarvin]

Interesting, I assumed it was a fire risk thing. I noticed that the tires on a WW2 bomber at an airshow had "nitrogen inflation only" printed on them.

A bomber...full of bombs...wings full of fuel...ammunition out the wazoo...but don't worry. If we catch on fire, the tires are filled with nitrogen.

 

[mgb_phys]

A bomber... If we catch on fire, the tires are filled with nitrogen.

You've never had to deal with safety people then?
Laser guided bombs that not only have to be eye safe but eye-safe if viewed with binolculars for instance!

 

[NoTime]

You've never had to deal with safety people then?
Laser guided bombs that not only have to be eye safe but eye-safe if viewed with binolculars for instance!

You wouldn't want to blind the people you are trying to blow up.
Obviously, the safety people realize that half the fun is in having them see it coming.

 

[FredGarvin]

You've never had to deal with safety people then?
Laser guided bombs that not only have to be eye safe but eye-safe if viewed with binolculars for instance!

You always have safety people. I was just joking around. Your bomber example is exactly the kind of thinking that makes us make fun of safety "experts." It's a flying gas can with high explosives, but don't you dare forget to fill the tires with N2. That could be a real fire hazard.

 

[Q_Goest]

Your bomber example is exactly the kind of thinking that makes us make fun of safety "experts." It's a flying gas can with high explosives, but don't you dare forget to fill the tires with N2. That could be a real fire hazard.

So true – thanks for the laugh. I remember a tech sergeant that worked on B-52’s in the Air Force telling me they had to sand off all the rust on the bombs and repaint them on a regular basis because it was against the Geneva Convention to drop rusty bombs – the shrapnel might give someone tetanus.

 

[FredGarvin]

So true – thanks for the laugh. I remember a tech sergeant that worked on B-52’s in the Air Force telling me they had to sand off all the rust on the bombs and repaint them on a regular basis because it was against the Geneva Convention to drop rusty bombs – the shrapnel might give someone tetanus.

You are joking...right? That's beautiful.

 

[Danger]

I just thought of something here. Would the use of nitrogen affect the generation of static electricity by the tires in motion?

 

[FredGarvin]

Aircraft I have seen had small grounding straps that usually drag off the landing gear. I don't think static is a function of the N2. Why don't you do a quick experiment Danger? Fill your car tires with N2 and then rub them on your sweater. If your car sticks, the N2 doesn't help.

 

[Danger]

Reminds me of a girl in a fuzzy sweater that I saw stuck to the ceiling at an office party a few years ago...

 

[FredGarvin]

That's a strange party...

 

[Danger]

She was a strange girl.
Anyhow, the reason that I asked about the static has nothing to do with safety; it's just curiosity. As I understand it, most of it is built up by friction between the tire and the air inside it rather than the road. Since nitrogen is a lot drier than regular air, I wondered if there would be a noticeable difference.

 

[FredGarvin]

She was a strange girl.
Anyhow, the reason that I asked about the static has nothing to do with safety; it's just curiosity. As I understand it, most of it is built up by friction between the tire and the air inside it rather than the road. Since nitrogen is a lot drier than regular air, I wondered if there would be a noticeable difference.

I would "think" that the static would be a function of the rubber hitting the road. I really do not know for sure. Perhaps someone else would know...

 

[Danger]

I could very well be wrong about that. It's just something that was lurking the in back of my brain.

 

[turbo]

I may be off base, here, but don't aircraft accumulate static charges just from moving through the air? Nothing to do with tires, etc, but the movement of air along the hull. They made a big deal about that in Hunt for the Red October, and Tom Clancy is usually a stickler for details.

 

[Danger]

Yeah, they do. Cars as well. There's just something about tire air that I must have heard or read somewhere a long time ago. I really have no idea where I got that idea.

 

[FredGarvin]

I may be off base, here, but don't aircraft accumulate static charges just from moving through the air? Nothing to do with tires, etc, but the movement of air along the hull. They made a big deal about that in Hunt for the Red October, and Tom Clancy is usually a stickler for details.

Indeed they do. If you get a chance to really look through an aircraft, you'll see tons of grounding straps on a lot of components, even control surfaces.

Helicopters also generate tremendous static build up.

 

[mgb_phys]

Helicopters also generate tremendous static build up.

The bit in Hunt ... is pretty accurate, one of the things you learn on a air-sea resuce course is never to grab hold of a basket being lowered by a helicopter, let the grounding straps touch the boat first.

I assumed that especially for WW2 era prop driven planes flying at lower altitudes through weather the static build up was bad and there was a risk of sparks when the wheels touched and so having them filled with an inflammable gas was a 'theoretical' safety feature.

 

[FredGarvin]

The bit in Hunt ... is pretty accurate, one of the things you learn on a air-sea resuce course is never to grab hold of a basket being lowered by a helicopter, let the grounding straps touch the boat first.

I assumed that especially for WW2 era prop driven planes flying at lower altitudes through weather the static build up was bad and there was a risk of sparks when the wheels touched and so having them filled with an inflammable gas was a 'theoretical' safety feature.

We would laugh a lot because every once in a while there would be someone who would be hooking up our external loads who would not use or improperly use their grounding straps. Most of the time it was a natural tendency of the person on the ground to think that they could grab one of the hooks and pull the helicopter over to where they were to make the hook up easier and faster.

Such pretty blue arcs...