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My delivery dealer says my tires are filled with nitrogen...put on green caps....does everyone have nitrogen?
You can save money by filling your tires with N78. N78 is available almost everywhere and is comparable with N100 if your tire valve caps are green. If you have a compressor at home, you can make as much N78 as you like and fill all your tires and you can make points with your neighbors by giving away free N78. If you are going to drive your new Ascent at top speed for long periods or you have a large airplane, 100% Nitrogen is the way to go. At high altitudes, water can freeze in the tires and any oxygen in aircraft tires at high pressures increases the chances of auto-ignition in the event of overheated tires. All braked wheels on aircraft should be inflated with Nitrogen.

Filling car tires with Nitrogen is a scam, that is unless it is free. The only benefit to conventional car tires is the slower rate of pressure loss that takes a year or two to detect; it does not eliminate your responsibility for checking tire pressures at regular intervals. I would suggest that 100% Nitrogen has about the same benefit as filling your tires with 100% Helium. You can save a few grams of unsprung weight, one of the factors that go into the design of suspension systems. In either instance, there is no practical benefit. That being said, you can fill your tires with a special trace gas mix of Nitrogen and Helium or Argon. Using that mass spectrometer or gas chromatograph you got kicking around in your garage, you can locate the leak in that problematic tire. If you don't have that setup, you can fill your tires with air and apply bubble soap with a squirt bottle.

Okay, enough of the BS, here is a real life situation. I have a neighbor that got new tires fitted at Costco. One day she asked me about the 'Check Engine' light. I went over with my OBD tester and found that a camshaft sensor was acting up. After reseting the light, the problem did not reoccur. However, I did notice that the tires looked a little low, sometimes hard to see on regular radial tires. She told me that she had not had time to go back to the Costco tire center to get them checked. What the ****? How many people out there have nitrogen filled tires and are concerned about adding air? I will admit that I got a new set of Michelins on a car at Costco and I actually started to think twice about adding air to the tires after they put those stupid green caps on the valves stems. Filling tires with Nitrogen is VooDoo. People that sell that sort of crap should be ashamed of themselves.
 

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Well, I actually had a good experience with using N2 to fill my tires. I had some issues with the bead on the OEM Yokohamas on my 2009 Legacy, and using compressed air (lol, N78) would actually leak rather quickly. No leaking with the N2 fill. My guess is that the actual "size" of the N2 molecule is larger than whatever the compressed air molecule was, and thus didn't leak, even when it was cold out. Otherwise I would have one tire that liked to stabilize around 28-29 PSI when it needed 33.

I agree though with the individual TPMS sensor displays, this should be a no-brainer.

People, check your tire pressures COLD, and if you're in the garage overnight, convert the values when you check them (read the manual on how to convert to standard temperature).... if you're driving anywhere and you see it's 38 psi - DON'T let the air out to bring it down to 33. You have to check it cold.
 

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Well, I actually had a good experience with using N2 to fill my tires. I had some issues with the bead on the OEM Yokohamas on my 2009 Legacy, and using compressed air (lol, N78) would actually leak rather quickly. No leaking with the N2 fill. My guess is that the actual "size" of the N2 molecule is larger than whatever the compressed air molecule was, and thus didn't leak, even when it was cold out. Otherwise I would have one tire that liked to stabilize around 28-29 PSI when it needed 33.

I agree though with the individual TPMS sensor displays, this should be a no-brainer.

People, check your tire pressures COLD, and if you're in the garage overnight, convert the values when you check them (read the manual on how to convert to standard temperature).... if you're driving anywhere and you see it's 38 psi - DON'T let the air out to bring it down to 33. You have to check it cold.
The air we breath is already 80% nitrogen.
 

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How many people out there have nitrogen filled tires and are concerned about adding air? I will admit that I got a new set of Michelins on a car at Costco and I actually started to think twice about adding air to the tires after they put those stupid green caps on the valves stems. Filling tires with Nitrogen is VooDoo. People that sell that sort of crap should be ashamed of themselves.
We put it in, and it's free Nitrogen for life. But I also specifically tell my customers that if your tire is low - just add air. It's not going to hurt anything. And when you come back in for your next regular service, tell our guys and they'll put Nitrogen back in, no issues.

I do see a difference here in Oklahoma, with the drastic temperature changes we get. That 20% difference doesn't seem like much, but when it's going from 80 degrees to 30 and then back to 90 two days later ... the line at the 7-11 compressor gets long. Also, let's face it - something a lot of people don't realize is the age of the average Subaru customer is 55 years old. Which, to make that the AVERAGE, means we sell a LOT of cars to people who are in their 70's and 80's. The guys who remember when they could work on cars, but now can't be bothered because it's too much trouble.
 

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The air we breath is already 80% nitrogen.
To be accurate: By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide and a bunch of other stuff. Concerning ourselves with just Nitrogen and Oxygen; the latter has a slightly higher molecular weight, but the Oxygen molecular size is just a tiny bit (emphasis on tiny) smaller. Both are diatomic molecules and the molecular shape is slightly cylindrical. That's not all. There is the kinetic diameter and a host of other traits that can affect the rate of permeability of the gases through the polymer chains of the tire rubber. Oxygen does in fact diffuse 3 to 4 times faster, but it is only about 1/5th of the volume of the tire and the rate of diffusion is so slight. I would submit this premise for your consideration: Let's say you started out with consumer grade atmospheric air in your tires. Leakage past the tire bead, valve and valve stem and any punctures is negligible, then over time Oxygen molecules will permeate out leaving behind Nitrogen in a higher percentage. As you add air to maintain tire pressure, the percentage of Oxygen by volume will decrease incrementally. This option costs nothing and is more environmentally responsible. What is the Carbon footprint for producing Nitrogen in liquid or compressed gas states? It takes energy to produce Nitrogen. Less energy is needed to run a compressor to pump air. Even less if you use a manual pump, you just have to eat enough veggie burgers for energy. Big Macs are out because beef production is antithetical to the climate change argument. Nitrogen is therefore contrary to the Subaru PZEV philosophy. I still maintain that there is not enough benefit for nitrogen filled tires and any perceived advantage is dubious. There is only one thing that I can think of where using Nitrogen is a benefit. Compressed Nitrogen is anhydrous. That is, dry... no H2O. Many underground telephone cables are pressurized to keep out water. When dry air from telephone company central office compressor/dryers or remote dryers has been interrupted, a cylinder of compressed Nitrogen is used with a regulator to provide pressure temporarily. Nitrogen is inert and won't support oxidation or combustion. Atmospheric air contains a small percentage of water vapor. Water vapor will condense in the tank and lines of an ordinary air compressor. The water that collects in the tank is bled off periodically, but some water vapor makes its way through the delivery line and into your tires. An inline oil/water separator and dryer minimizes this problem. Ever try to fill your tires from a remote air station that is fed from a compressor in a remote location during winter and no air comes out? Lines are frozen. Don't go back when it thaws; go somewhere else. I always check the air to see if any water comes out first. One time I inadvertently pumped nearly a pint of water in my boat trailer tires. Unless you have a dryer or a desiccant canister on you compressor, Nitrogen from a bottle is the only way you can ensure that the inside of your wheels are dry.
 

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Interesting. Never heard that before.
Remember, they want to SELL tires. I would say the PSI on the inside of the door is the way to go. Its actually a myth that higher psi contributes to better mileage. And it definitely makes for a [email protected] ride.
Usually but not always. For instance, those of us who used the Yokohama Geolander AT-S tires had to overfill by as much as 5 psi otherwise they were mushy, wallowed and dropped 2-4 mpg more than the expected 1 mpg hit.

But those are big, meaty all terrains that take a lot more pressure than the OEMs did.

But on stock tires or similar replacements, yep, follow the sticker.
 

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Although, personally, I usually go by the max psi on the tire. I do about 80% in the summer and 90% in the winter. These particular tires are max 50 psi, so the 41 psi on all my tires is right at 80%, so I left it.
The car manufacturer sets the psi based on contact patch vs vehicle weight and tire type. Running over inflated does three things ride Quality is not great, handling performance is degraded due to less tire contact and you get uneven wear down the middle of the tire.

If your heavily loaded and or towing bumping the rear tires 3-4 psi over factory pressure is actually suggested and recommended. Primarily to retain even wear and proper tire contact.

40+ psi on stock tires is goofy. Only flat landers with strait grid roads would do that. Around here we have twisty canyon roads and yes 40psi results in exceptionally lousy cornering.
 

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Ok so any of you goof balls familiar with the Miata track circuit? One of the most competitive auto racing you can ever watch. All running gear must be stock. Only mods are removal of the interior for racing seats, roll bar and racing slicks.

On really hot track days the guys who happen to have strait nitrogen to set their tire pressure see very very slight advantage in stable tire pressure vs strait air guys see pressure variations around the track that very very slightly impact their lap times due to impact on cornering grip as tires heat up and psi increases.

Nitrogen in passenger cars especially a 8 passenger 5000lb tow rated wagon will do nothing but make you feel warm and fuzzy thinking your special.

I was in CO 6 yrs ago and this old guy pulls into the parking slot next to me nearly flat tires. I tell him hey you need to air up your tires or your going to get a flat. He waves at me and says I only use nitrogen and haven’t had time to go to the shop with nitrogen. ?

No joke that night I spot him on the side of the road with two flats just destroyed tires. I ended up giving him a ride back to the very same shopping center so he could call a friend.

Ya can’t fix stupid.
 

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Tire pressures set to 33 per tire pressure gauge. Onboard TPMS system concurs. Recent road trip at highway speeds, TPMS would flash and then go steady on. Tire pressure had risen to 37 Psi. Seems tpms also has 4 psi over from what they are cold perhaps?
 

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Nitrogen in passenger cars especially a 8 passenger 5000lb tow rated wagon will do nothing but make you feel warm and fuzzy thinking your special.
I would have to disagree with you on this, granted I do feel warm and fuzzy from using Nitrogen :tango_face_wink: Our family has had Nitrogen in several of our past vehicles, including a few +/-5000 c/suvs. In MN, we see significant changes in temps over the year, ranging from -20 to 98. The Nitrogen keeps a fairly consistent pressure over the varying temps. As noted, proper tire pressure is important for several reasons, mainly safety.

On our 3/4 ton diesel that we do a fair amount of towing with, we use air and monitor the tire pressures closely. The reason for air in the truck is because we adjust the rear tire pressure often. Add air when hauling or towing a fair amount of weight, remove the air when not to get a slightly better ride. This vehicle is owned through a business and when hooked to a trailer qualifies for DOT requirements, so at that time, all tires must be inflated to factory recommendation in the event of a DOT inspection.

Long story short, I do believe strongly that there are applications where Nitrogen is beneficial, so I would not recommend writing it off all together. On our new vehicle purchases, we actually take the car in and have the air dropped out and filled with Nitrogen within the first week. I believe due to the consistent pressure over the course of the year, we achieve better wear on our tires.
 

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You do know 78.09% of regular air is nitrogen right?

If your tire already had air in it and you put 100% nitrogen in it assuming you actually knew you had 100% nitrogen to start with. Your not going to have 100% Nitrogen in your tires. Meaning your probably only getting to 85-90% nitrogen in a tire.

If 10-15 % more nitrogen is “safer” than 78% then the vehicle or tires have some very serious safety issues.
 

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@Carl Abrams So when discussing pricing on my Ascent that just arrived the Finance guy mentioned charge for Nitrogen.

Once they are filled with Nitrogen is this an ongoing cost potentially for the life of the tire?

I have never had tires with Nitrogen so I am not sure if this is legit or as some have said just a way to upsell I believe this is prob a $99.00 charge based off of the sheet I have when we placed the pre order . I did not commit it is hard coded on the form and there is an option to check off if you want it.
 

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@Carl Abrams So when discussing pricing on my Ascent that just arrived the Finance guy mentioned charge for Nitrogen.

Once they are filled with Nitrogen is this an ongoing cost potentially for the life of the tire?

I have never had tires with Nitrogen so I am not sure if this is legit or as some have said just a way to upsell I believe this is prob a $99.00 charge based off of the sheet I have when we placed the pre order . I did not commit it is hard coded on the form and there is an option to check off if you want it.
Costco will fill them with Nitrogen for nothing. Regardless of what you put into them, you should rarely ever have to add more unless you have a leak.

In my case, even if I cared, I wouldn't get nitrogen because I air down for the beach regularly and have to fill with regular air when I leave.
 

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Costco will fill them with Nitrogen for nothing. Regardless of what you put into them, you should rarely ever have to add more unless you have a leak.

In my case, even if I cared, I wouldn't get nitrogen because I air down for the beach regularly and have to fill with regular air when I leave.
Thanks Robert...We do belong to Costco.

So I guess it comes down to wether or not it provides any benefit here in New England
 

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Thanks Robert...We do belong to Costco.

So I guess it comes down to wether or not it provides any benefit here in New England
Regular tire rotation and proper inflation is FAAAAR more important on a Subaru than filling it with nitrogen or outside air. One should easily get well over the tires' ratings with regular rotation.

I easily beat other Subie owners by 20,000-30,000 miles with regular rotation and proper inflation. My all terrains easily coast past 50,000 miles with plenty of tread left on them, and I use my car off road and on the beach very regularly.
 

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Regular tire rotation and proper inflation is FAAAAR more important on a Subaru than filling it with nitrogen or outside air. One should easily get well over the tires' ratings with regular rotation.

I easily beat other Subie owners by 20,000-30,000 miles with regular rotation and proper inflation. My all terrains easily coast past 50,000 miles with plenty of tread left on them, and I use my car off road and on the beach very regularly.
I agree with you...This would be a dealer add correct? This is not something SOA or SNE would do correct?
 

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I agree with you...This would be a dealer add correct? This is not something SOA or SNE would do correct?
Which? I'm not sure I understand.

I just rotate on the SoA schedule (matches oil changes, every 6,000 miles on the Ascent - at most, every 7,500 miles on older vehicles, like the early Gen 4 Outbacks).

As for the all terrains, there's none that fit the stock rims, so, the dealers won't offer any. :sad: I ran all terrains on my Outback (two sets) for a total of 100,000 miles. Still on the 2nd set, and the first set was changed because a massive pothole dimpled a side wall. Many miles still left on the 2nd.
 

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Which? I'm not sure I understand.

I just rotate on the SoA schedule (matches oil changes, every 6,000 miles on the Ascent - at most, every 7,500 miles on older vehicles, like the early Gen 4 Outbacks).

As for the all terrains, there's none that fit the stock rims, so, the dealers won't offer any. :sad: I ran all terrains on my Outback (two sets) for a total of 100,000 miles. Still on the 2nd set, and the first set was changed because a massive pothole dimpled a side wall. Many miles still left on the 2nd.
Sorry...I was referring to the tires being filled with the Nitrogen. The dealer would be the one doing this correct?? I think they are will charge $99.00 as it it an option on the Purchase Order
 

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Sorry...I was referring to the tires being filled with the Nitrogen. The dealer would be the one doing this correct?? I think they are will charge $99.00 as it it an option on the Purchase Order
Yes, some dealers are pushing that. The charge seems to be different at all of them. Numerous repair shops and service centers push it, most charge something, with prices varying all over the place. Costco being free, some places being $5 a tire. Others being very high like the $99 quote from the Subie dealership (some even higher).
 
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