Nitrogen-Filled Tires & Better Gas Mileage?

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When I bought my tires from Costco, I noticed the caps for the valve stems were a flourescent green and asked about them – it means the tires are filled with Nitrogen. After reading a friend’s blog claiming that nitrogen-filled tires get 0.5 mi/gal better gas mileage and have a longer tire lifespan, I wanted to find some “proof” to these claims. The belief, also pushed by Costco in their tire brochures, is that the larger nitrogen molecules don’t react to temperature changes (better tread life and mileage) and lack moisture (won’t corrode the tire from the inside). It doesn’t affect my decision if these claims can’t be proven because there is a miniscule increased cost for using nitrogen (I can only “fill” my tires at a Costco, most gas stations only have air, but the service is free).

The theory is that the oxygen in the air inside the tire, when heated as a result of driving, can oxidize and rot the inside of the tire over time. A nitrogen filled tire won’t oxidize for obvious reasons, no oxygen. This is all anecdotal though and for most people, I think the tread of the tire wears out before the tire does from internal rot.

As for the nitrogen not reacting to temperature as much as compressed air, it’s probably a bit of snake oil magic going on there. At such low pressures, the nitrogen behaves like an ideal gas (just as oxygen and water vapor) so that means pure nitrogen will act just like regular air. A 0.5 mi/gal improvement in gas mileage is 1.6% improvement (on my car, which gets a little more than 30 mpg) which seems way too much.

It sounds like the “nitrogen is better than air” theory is not entirely true but since it costs me very little (if at all really) I won’t be complaining much about it. As long as you don’t pay for nitrogen, fill it with nitrogen; but if it costs you money, ask for regular air.

{ 167 comments, please add your thoughts now! }

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167 Responses to “Nitrogen-Filled Tires & Better Gas Mileage?”

  1. Grant Burtt says:

    BUT dont go out and fill the family car with it unles you plan to keep the tyres for the next 20 years.

  2. Ron Bowers says:

    Is there a 800 number for service since I have a vehicle with nitrogen in the tires.

  3. Gene says:

    Bought a set of Michelins at CostCo because of the
    sale price. For the next 500 miles, my mileage went up from 23 mpg avg to over 27 mpg avg. When I
    returned to CostCo to have the lug nuts re-torqed
    I mentioned to the manager about my mileage increase that I attributed to the Michelin tires.
    Only then did I find out that the tires were filled with Nitrogen. So… I am a believer.
    The car is a 1999 Mazda Protege with the 1600 cc engine and auto transmission.

    • Keith says:

      Gene: More likely correct inflation pressure and new tires. May also have been your driving habits over those 500 miles. After all, cow magnet users swear they get better mileage, too….


  4. ed says:

    almost 80% of the air we breathe is Nitrogen

  5. LTC Kelly says:

    SSgt DAC, I don’t mean to knit pick, but actually, the way Nitrous Oxide works is by introducing, as you say, lots more Oxygen in the combustion chamber, but the power boost comes from then being able to squirt more gasoline in there in the proper ratio which allows an explosion equal to that of a much larger combustion chamber (engine). All NO kits have the requisite lines and sprayers for the extra gasoline. To run just the extra Oxygen would make the fuel/air ratio so lean it couldn’t run (or if it did it would pop & crack & burn things up).

    But seriously folks, thanks for the laughs (and maybe I should thank our public schools, too). Everyone take a deep breath – what you just breathed in was 78% Nitrogen. Its not toxic, its not explosive, its just air really. And I’m sure Cosco has a machine that extracts that 21% oxygen out of our air and leaves only the Nitrogen. And, unless Cosco sucks your tire into a complete vacuum before filling it, there’s not much more Nitrogen in there after filling than before. What IS in there is marketing.

  6. Anonymous says:

    if my tires require 51 psi of nitrogen and id like to switch it to regular air how many pounds of pressure do i put in. is it the same?

    • N2TYRZ says:

      Use the same psi whatever media you chose and check often at least once a month or before a long trip and dont forget the spare.
      One thing interesting to do is read your tires. Im not the Tire Whisperer but if tread is wearing in the middle more then use a few less ponds and if wearing on the edges use a few psi more to promote even tire wear and rotate every 5-8k if possible. This is providing you dont have an alignment or other problems in suspension.

  7. George says:

    “if my tires require 51 psi of nitrogen and id like to switch it to regular air how many pounds of pressure do i put in. is it the same?”

    It’s a standard formula:

    Multiply the Nitrogen pressure by 7 giving the seventh modal weight.

    Next multiply that modal weight by 11 to get the air-argon equivalence derivitive.

    Multiply the derivitive by 13 which gives the Higgins-Einstein converted mass ratio.

    Finally divide the H-E by 1001 to convert to pounds.

  8. dennis says:

    Sounds like nitrogen would be a good alternative for the RV’s and trailers as those are the tires that dry rot before tread life is reached. I think I’ll try it on my boat trailer tires. They’re dry rotting now and I have a lot of thread left.

    • N2TYRZ says:

      I would wait until you buy a set of new tires before using nitrogen, The rotting is mostly occuring from outside influence and some inside. Nitrogen will not reverse this condition. I would replace tires soon before a failure may happen and destroy your rv or day. How old are your tires?? They say life expentacy is 10 years but in drier climate less.
      A friend of mine has a high dollar fishing boat use nitrogen and his pressure loss is minimal a few pounds in over a year so we top off. I furnish the Nitrogen and he gives me awesome fish and crab so I dont have to buy a boat.
      Nitrogen tires run cooler beacuse its dry and dissipates heat quicker. Cover your tires from sun will help too when stored. I dont sell tires just try and maximize their life when I can.

  9. What is not addressed is what tire pressure is correct for nitrogen filled tires and what about for air? My cars recommended pressures are 32 front 30 rear cold. They expand 3 lbs within 1 to 2 miles. Based on that any savings on fuel would be negligible assuming you put 3 lbs higher pressure when using nitrogen. Otherwise you would have under-inflated tires and would have a significant reduction in fuel economy.

  10. Ray says:

    If tires are filled with nitrogen and high temps cause tires to become overinflated when sitting cold should one decrease the pressure as with regular air or will the tires remain safe for driving without decreasing tire pressure?

    • N2TYRZ says:

      Tire pressure is based on cold tires and should be checked in morning or when have not been driven for 3 hours. Go by the manufacturer sticker on the door plate or wherever located and set tire pressure whether using nitrogen or compressed air. Sidewall tire psi is max for that tire which usually is 20 to 30% higher than car mfg recomends and the same tire maybe used in different vehicles and vary depending on car weight etc.
      Air or nitrogen will increase in pressure as you drive and still be at a safe level. Underinflation usually causes failure instead of over inflation. However a friend had a valve stem blow out on a 100 plus hot day fortunatly when it was setting in his driveway.
      If you have a car with TPMS system it will drive you crazy watching psi flucuate up and down as you drive. I painstaklenly set all mine to 32 psi on a 70º day. As I drive even with nitrogen they increase a few pounds and not all at the same time. As my car sets at work and check the psi the side hit by the sun can be 2 – 5 pounds higher than the other side. As tempreture changes from morning to day the will increase slightly too. So myth busting, Nitrogen is affected by tempreture but may not as much as wet compressed air. Cars with TPMS systems may fail prematurley if exposed to moisture. They say if you take care of TPMS valves life expectancy is 7 years so if exposed to wet compressed air may cause premature failure costing several hundered dollars to replace.
      Sorry for long winded responce but these are my observations.

  11. N2TYRZ says:

    I have used nitrogen our family tires since 2006. Our tires usually exceed the posted life by 10,000 miles or more. I rotate and keep an eye on inflation even using nitrogen which usually requires very little top off over tire life. I have a classic Ford 1956 f100 show truck that put new 3″ whitewall tires on in 9/08. The truck sits most of the time (like the consumer reports test did instead of using daily driven tires for a more accurate comparison) and finally in 7/2010 I decided to top off. The lowest psi was 3# loss and others 2# or less and spare still at 32# after almost 2 years. The whitewall tires are still white with no discolor. I have read that as air permeates through sidewall has some affect of turning whitewalls yellow.
    I have a part time business that I do mostly during summer months is Nitrogen Tire Inflation at car cruises. I bought my own nitrogen tire inflation system and have about 2k invested..Yeah I drank the cool aid but it has paid for itself already and many times do the service for free for safety and feedback. The tire system will purge all 4 tires simultaneously twice then top off to recommended psi automatically in about 10 minutes. Most of the classic cars and motorcycles I have done and followed up on after a year still have same psi. The feedback from customers on how the handling improved is encouraging. I charge 20.00 for 4 tires and 10.00 on a motorcycle and give free top off for life of tire or they can have done at Costco or any other of the 50 plus dealers in the Portland area. The Harley dealer in town who promotes nitrogen charges $23.00, most car dealers charge $40.00 some do for free. Bikers have given almost 100% positive feedbacks on handling improvement. Another person who tracks his daily mileage drives 150 miles a day had an increase of 1.5 mpg. The tires were only about 2 weeks old and match same psi of air to nitrogen used.
    Not all people have seen mile increases but some have exceeded tire life by 10k or more as well. There are some Nitrogen dealers charging as much as 50.00 per vehicle and think is ludicrous. Eventually nitrogen will be a free and a standard in tire inflation. Lance Armstrong and tour d France bikers use in their bikes so must have some merit. Some people spend 4$ or more on a bottle of water of cup of coffee each day which seems excessive too but choice is your own.
    There are many truck fleets online that have done testing and have seen the advantage of nitrogen inflation. One company said a tire failure cost them about $500.00 since using nitrogen failures have ceased and tire life has increased 30%. Wal-Mart has tested and is converting their fleet because of tire life increase and tire failure decrease.
    In conclusion these people are doing real live studies without all the science, windsocks and plumb bobs people use to down play the benefits of nitrogen tire inflation on paper. Proper tire inflation is paramount whether you use air or nitrogen. I will be starting a blog soon of people who have used with feedback positive or not.
    The majority of the classic cars and motorcycles I check are usually underinflated by 10 pounds or more. Motorcycle riders had rode 300 miles on tires with less than 15#psi they should have around 38-40# psi kind of scary. Millions of barrels of fuel are wasted each day due to underinflated tires or tyres in Europe.
    Ok now check your tire psi especially the spare that will be usually severally underinflated.

  12. George says:

    So, is there any science behind this improved handling claim?

    • N2TYRZ says:

      All this science I dont understand…its just my job 5 days a week… Rocket Man…..oh got lost for a moment. Not a scientist myself but all that is done is the purge of wet compressed air or maybe even dry compressed air reducing the oxygen to 5% or less replacing with dry nitrogen. Not sure on the science end just feedback from drivers input.
      However some vehicles that have a smooth ride to begin with not noticed as much versus a harder ride like a motorcycle. Many Corvette owners comment on the improvement. Also a friend has an older STS Cadillac and went for test drive he commented immediatly on going over bumps were softer.
      I believe the best advantage of nitrogen is maintaining pressure over a longer period of time vs regular air for people who dont check their psi often as they should. I dont buy into the hype of more mpg, rotting rims and tires etc and extreme over charging. Semi truck tires are able to be re treaded more times using nitrogen.

  13. complete snake oil!! the air you breath is 78% nitrogen and so is the air pump. checking the psi in your tires is a good practice. I stop at a convenient gas station with easy air access and over inflate my tires slightly on my way home. In the morning I bleed them to my exact pressure preference using a digital +/-1 lbs accuracy gauge. While I’m at it and the engine has not been started I check my oil. No towel or rag needed and cool engine. I also take a moment for coolant level and occasional power steering check. I keep my engine clean so I never get any grease or oil on my fingers. This long time habit and recommended maintenance done without failure, has made any vehicle I’ve had inexpensive to maintain and bulletproof. No slow leaks unnoticed, premature wear of any kind on my absolutely quiet tires and brakes. Best possible fuel economy and no major repairs ever!! That’s a lot of cars and years of ownership.

  14. Dave says:

    I have been running Nitrogen in the tires in my Corvette (Goodyear runflats) now for over two years. Before I started using Nitrogen I was seeing pressure differences of between 6-8lbs of pressure per tire from cold start to running them over 20 miles. The tires on a Corvette are quite wide and thus increase in temperature pretty fast over long stretches of driving. With Nitrogen I am seeing only pressure changes of between 1-2 lbs. I have also noted that in that pressure drop in extended non-use periods has decreased by at least 2-3lbs of pressure. Needless to say when a replacement tire can cost upwards or $300.00 plus-you do everything to maintain, protect and get as much life out of these tires as possible.

  15. UV MIKE says:


  16. Frankie says:

    nitrogen filled tires will be consistant , which will give you better tire wear you dont have to fill them up often if ever. outside temps wont change the tire pressure like air, that’s your benefit, take it or leave it…..omg.!

  17. Andy says:

    I drive a semi truck and am seriously contiplating that transformation from air to nitrogen. I have heard nothing but positive things about nitrogen vs. air. 1. helps in mpg increase, 2. quietness of ride…less noise caused from the tires, 3. IF a blowout occurs, it only blows out the section of the tire that is bad….not exploding the whole tire and throwing rubber and steel belts everywhere which air causes. 4. Not to mention the air pressure stays constant year round…no more weekly air adjustments due to outside temperature changes. Are all these accurate and what else can I expect? Any other advice you can offer.

    • N2TYRZ says:

      There are dozens of articles on line of trucking companies using nitrogen. They have experienced increased tire life, small mpg increase and failures are minimal for running air. They had commemted that a blowout costs approx $500.00 and have decreased using N2. Here is a link of one of many articles. Hope this helps.

    • N2TYRZ says:

      Andy, I put nitrogen in my friends semi in Nov 2009 he usually gets 300 to 330k on driver tires. He has 440k and going to go another 20k before replacing. He usues the same tires and runs a route weekly 6k per trip. He did not bother rotating 1/2 through like he does with air because the tires were wearing so evenly. I and he recomends it.

  18. larry says:

    I have tried nitrogen in my truck tires and my gas mileage has improved 1 to 2 miles per gallon. That is 4.5 to 8.5 %. I do a lot of delivery and sales work, so I am constantly on the road. This results in considerable savings.

    • N2TYRZ says:

      Great testimony, I have converted pound per pound air vs nitrogen with same results from some customers. Not everyone sees a mileage increase but most all have seen better pressure retention. A customer called me yesterday who I N2 filled his corvette tires in mid 2009 needs a top off of a few pounds. He would have to top off every 4-6 months with regular air. He commented on the handling improvement like a suspension tune up for $20.00. I’m a proponent of Nitrogen inflation and have many satisfied customers. I wonder if the scientists, theorists even check their psi. I would encourage them to do a Myth bust and I would supply the N2 for free. The consumer reports test was positive for N2 but should have tested on actual vehicles, not tires sitting outside unloaded.

  19. Goober says:

    Hey, how about this? Fill your tires with regular air to 42.5 lbs/PSI and simply wait until they deflate to the recommended 32 lbs/PSI. If the theory about the Oxygen leaking out before the Nitrogen holds true, you will then have the recommended pressure of relatively pure Nitrogen in your tires without paying extra for it. I can’t believe that this sad old debate continues, nor can I believe that I actually read all the posts. Ha! Who’s the sucker? I guess I am!

  20. Aj says:

    first post 02/02/2009 at 11:04 am !!!!


  21. malordus says:

    Hear is an article about the advantages of using nitrogen in your tires. Some places charge you to switch to nitrogen, Others do not.

    • FDAFL says:

      Earlier this year we bought a 2010 Mercury Grand Marquis off lease. It’s the model with on-board computer. Dealer gave free nitrogen in all tires with first free oil change. So, I decided to go with the free nitrogen when we did oil change today. I checked tire pressure before I left and it was 32lb in each tire. I checked mileage on the way over when we got on the interstate by pushing the reset button for the average mpg. It was 24.8 on average while on the interstate when we got to the dealer some 35 miles away. Did the same thing on the way back. Got on interstate, hit reset, and checked when we left interstate 35 miles the other way, this time with nitrogen in the tires. Mileage was 30.1 mpg. Can anyone explain this? I’ve read all the goofy letters and replies, I have a doctorate, I was a chemistry scholar. No, it wasn’t the 50 mile per hour tailwind on the way back. I’m thinking about changing out the air for nitrogen in my older Grand Marquis. I know it doesn’t seem possible to get this much of an increase in mileage…but figures don’t lie? Right????

      • N2TYRZ says:

        FDAFL, the best mpg increase I ever heard. The best I personaly heard was 2 mpg. I would attribute the oil change may have helped a little too better lubricity engine worked easier changing viscosity etc. What I have read that nitrogen decreases rolling resistance a study done by some scientist. Good that you matched pound for pound as well so extra psi would be ruled out. Many theroist try and down play the benefits of nitrogen inflation but it has merit. I dont agree with over pricing for the service and should be free with new tires like some dealers offer. Costco does it because they self insure tires so less failures due to underinflation works for them and they dont upsell its free. I do a portable Nitrogen inflation business a car cruises with almost 100% positive feedback. Psi maintained a year later, better ride some say with manual steering older cars alot easier matching pound for pound psi. Another, example a friend and his wife are long haul truckers ownwer operator team. They run the same route each week from west coast to east about 6k per trip. They use the same brand tires for years and same loads. I put nitrogen in their tires in Nov 2009. They usually get 300 to 330k per set of driver tires. They are at 440k and going another 20k before changing tires. He checked psi and had not lost any and usually has to rotate 1/2 through a set but the nitrogen set was wearing so even he didnt bother. He wants me to do his new set when he replaces. The only variable was nitrogen inflation vs compressed air. Sorry for babbling on but my experience has been positive with nitrogen the nay sayers down play nitrogen on paper but probably never tried or own a car.

  22. Anonymous says:

    if tires are filled with nitrogen, can you put air in them or are you locked in to nitrogren forever?

  23. Peg says:

    I just bought a C6 Corvette and it had nitrogen filled tires. I got 31.1 mpg on highway, which was very surprising to me. My Ford Escape on gets about 25 mpg.

    And from everything that I have read, you can put air in the nitrogen filled tires if needed and then have them flushed and refilled with nitrogen.

  24. Mardi says:

    I did get nitrogen in my snow tires this past Wednesday when they were being mounted on my rims. Three days later driving on an Interstate, my car’s Rt front tire popped with great noise. I looked at the tire right before we left our relatives and it looked fine, although I realize that you can’t tell what the pressure it by looking. I can’t imagine that the pressure changed much after driving 200 miles, but I may be wrong. I’ll have them inspect the tire tomorrow to see if there is any evidence of a nail, etc. But I did wonder if the tire might have been under inflated. I’m glad my husband has nerves of steel and didn’t panic and got us off the road safely. It, of course, can be entirely coincidental, but still seems strange that it happened so soon after they were mounted. I’ve had a few flats – one with a nail, another when regular tubes had been used in radial tires back in the 60s. But never a blowout like this. I guess ther is always a first time.

  25. Ronda says:

    Thank you all for your comments on nitrogen and air being mixed in the tire. Funny how the dealer never said anything about my tires needing only nitrogen and the difficulty finding nitrogen sources for inflating them. So, since September I have reinflated my tires twice with air. Today the service manager at the dealership informed me of my mistake. If it is a big deal then the Consumer Safety Commission needs to make the tire manufacturers change the size of valve stems so that the hose for air is incompatible with the tire using nitrogen. In the mean time I will continue to use whatever I have to when the low tire pressure light is on because it is probably more dangerous to drive on an underinflated tire than mixing air and nitrogen. Thank you all for your information..

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