Running Nitrogen in Tires

By Clifford Meier
May 14th, 2008

 

Filling tires with nitrogen instead of compressed air is becoming a common practice. Many tire dealers are offering this service, even the discount facilities like Costco and Sam's Club. There has been much information published and many discussions as to the advantage and benefits of using nitrogen.

The reported benefits include the potential for reducing rubber aging. less moisture reducing wheel corrosion, reduced heat, reduced air loss, better fuel mileage, better handling, and better tire wear. Let's not forget, it also offers the repair facility an opportunity to make a little extra money.

The use of nitrogen in  large trucking fleets or the commercial trucking industry are well documented and support these claims. The National Highway Traffic Safety Administration or NHTSA has seen reduced aging, less corrosion, better wear and handling for this application.

We can agree nitrogen will do no harm to tires, so as I see it, this becomes a two fold question. Is there any benefit to filling our low mileage motorcycle tires with nitrogen? And, if there are some advantages, do they justify the additional cost of $10 or more per tire? I didn't know much on the subject so I needed to do some reading. Hopefully this information I've compiled will help  you to clarify its use and answer the above questions. You can then make your own decision.

I have a bias and it's only fair that I let you know where I sit before I tell you where I stand. I'm the guy that can't justify the extra cost versus benefit with synthetic oils. I'll be the first to pay more for added benefit but why pay more for anything when a lesser cost item will do the same job?

One claim is nitrogen prevents deterioration of the tire and corrosion of the wheel. These are of no real benefit for the motorcycle. We're lucky to see 15K miles and as a result we replace our tires frequently. Corrosion may be an issue with steal wheels that rust and flake from the moisture but we are running on cast wheels. The cast wheel will hold a good seat on the tire bead and the moisture will not effect it. The question of moisture inside the tire may have been more significant in the old days. Today, the compressors have filters and a drainage system to keep the moisture to a minimum. In my opinion, these items have no benefit.

Nitrogen is denser than oxygen. This means nitrogen has larger molecules and it won't escape as easily as oxygen does from our tires. This results in a more gradual loss of pressure over time. An interesting point and assumption comes to mind. Compressed air or oxygen is actually 78% nitrogen. So oxygen, leaving the tire before the nitrogen means after a period of time with air loss, you actually have a higher concentration of nitrogen in the tire. Is this possible? Even though nitrogen results in a more gradual loss of pressure over time, it's still a loss and it must be maintained. This may be of some benefit but in my opinion, if it must be maintained anyway it's not worth the additional cost.

Better fuel mileage, better handling, and better tire wear all stem from the gradual loss of air pressure. Properly aired tires will give you better results. If you have no desire to check your tire pressure regularly the nitrogen has some benefit. In my opinion, even with a minimum of maintenance, by checking your tires monthly you can mitigate the benefit of nitrogen and save your money.

Reduced heat in the tire being an advantage to nitrogen also stems from proper inflation. An under inflated tire can't maintain shape, allowing more deflection as the tire rolls therefore building internal heat and increasing pressure. This causes a reduction in fuel economy and reduces the tire's tread life. You will also find a loss of steering precision and cornering stability. I come to the same conclusion, if you have no desire to check your tire pressure regularly the nitrogen has some benefit. In my opinion, with a minimum of maintenance checking your tires regularly you can mitigate the benefit of nitrogen and save your money.

It's time to find out what the experts say so I contacted Dunlop, Metzeler, and Avon with the following email asking their opinion.

My Email:
To Whom it may concern:
I ride the Honda VTX 1800 Retro and not that this has anything to do with the overall question but at least you know what tires I am working with.

I have heard many discussions about the advantage of running nitrogen in tires in place of compressed air. Better handling, better tire wear, no wheel corrosion, limited air loss etc and I'm curious what your thoughts and recommendations are as a tire guru.

Thanks,
Clifford

My response from Dunlop:
Clifford,

Thank you for taking the time to contact us.  The only real advantage to nitrogen use is the fact that it's dry in comparison to compressed air.  In very extreme conditions, the dry inflation gas seems to help reduce pressure rise and (possibly) temperature rise.  We're hard pressed to see the gains on the race track.  We'd suggest that the benefits for road use on motorcycles would be very
difficult to measure.

"Dunlop Tire"
website@dunlopmotorcycle.com
awittmeyer@dunloptire.com   

My response from Metzeler:
Hello

There are many discussions about nitrogen that is for sure. We have found that using it will not prevent air loss around the valve stem, core, and cap. Our studies show that there is no change in handling and at street speeds the temperature of the tire will not change dramatically.

The idea that using this gas will stabilize tire pressures is no substitute for visually checking your pressures and the condition of your tires on a regular basis. We will always say that simple consistent tire care is mandatory to riding safe and using Nitrogen will not change this but we fear that people may be led to believe so. Thanks for the e-mail.

US Metzeler Moto
www.us.metzelermoto.com

My response from Avon:
Dear Sir,
To date we have not seen any damaging effects of running nitrogen in tires in place of compressed air. Nitrogen is very stable so technically there is no expansion or contraction like there is with air which means however much nitrogen you put in your tires it should stay that way. So your tires will stay at the right pressure and you will not be running under or over inflated (assuming you put the right amount of nitrogen in your tires) and this should lead to better tire wear and so on.

The only negative aspects of running nitrogen we have seen to date are:
1) it costs money
2) if for some reason you did lose some nitrogen (leaky valve stem, puncture) and then had to add air if you couldn't locate nitrogen it nullifies the positive effects of running nitrogen. You would have to have the mixed air/nitrogen taken out of your tires and then fresh nitrogen put back in.

So I leave it to you to decide which way works best for you.

Best regards,
Sukoshi Fahey (Ms.)
Avon Tyres Customer Service
c/o Hoppe & Associates, Inc.
PO Box 5112
Lynnwood, WA 98036 USA
1-800-624-7470
Ph 425-771-2115

After reading the response from Avon I decided to send a follow up email.

My Follow up Email to Avon:
Ms Sukoshi, Sorry, one more question. As I understand it, compressed air is already 78% nitrogen. So, if we naturally lose air over time, and assuming oxygen leaks before the nitrogen, don't we eventually end up with nitrogen in the tire anyway?

From my understanding nitrogen also leaks out but at a slower rate or percentage. Is there really an advantage using nitrogen if we need to air the tires anyway?

If my assumption is correct from your comments, simply checking and airing your tires regularly there is no real benefit to running nitrogen, especially when you're adding $10 per wheel to your tire cost. It's not like we get 60 to 100K miles on a motorcycle tire, they have a very short life span with 12 to 15K.

Thanks,
Clifford

My follow up response from Avon:
Dear Cliff,
Good points. I asked our engineer in the UK and this is what he had to say. Basically if you use air you will be fine. Nitrogen will restrict the tyre pressure going more than air will when the tyres
get hot.

Air as we know it is made up from mainly Oxygen and nitrogen.

As most peoples pressure gauges are only accurate to within 2-3 psi anyway, I donít think paying the extra for nitrogen will result in any major benefit.

You could argue that itís the hot pressure that counts and the cold pressure is calculated or set so that when the air inside the tyre has warmed up, it gets to the correct pressure. Nitrogen could restrict this pressure build up and cause the tyres to effectively run slightly under-inflated!

Sukoshi Fahey (Ms.)
Avon Tyres Customer Service
c/o Hoppe & Associates, Inc.
PO Box 5112
Lynnwood, WA 98036 USA
1-800-624-7470
Ph 425-771-2115

I found this follow up email interesting. How accurate is our tire gauge? Nitrogen restricting the pressure build up possibly causing the tires to be slightly under inflated? That's something I never thought of. Thank you Avon for being so candid. And thanks to both Dunlop and Avon for taking the time to respond.

This is a bit off the main subject but it fits with the follow up email from Avon. What is the proper inflation for your tires? You can find the answer by reading my story "Tires - The Overlooked Component" (linked here) Airing tires, riding at highway speed for 20 minutes and checking pressure. If the hot pressure is more than 5 pounds above the cold pressure the tire is under inflated, building heat and adding pressure. If the hot pressure is 5 pounds or less above the cold pressure the tire is properly inflated. If the hot pressure is close to or the same as the cold pressure, the tire is over inflated.

Overall from what I read, my conclusion is since the benefit or difference is so small and nitrogen is difficult to get and more costly, it's not worth the effort or the cost. Bottom line, if you maintain / check your tire pressure, regardless of air or nitrogen you will receive the best results.

As Ms Sukoshi Fahey from Avon said in her first email, "So I leave it to you to decide which way works best for you."

In closing I will share with you a quote from the Avon website. ĒFact: the only things connecting you and your motorcycle to the road are your tyres. And while it's all too easy to ignore your tyres, they can only give you their best if you take a little time to look after them properly." "Look after your tires and they'll look after you."

Until we ride again...