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Tire Pressure

Old 1/4/15, 09:45 AM
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Tire Pressure

I like to keep my tires aired up so the roll better. Now that I have my new Mustang I noticed the pressure at delivery was 30 psi cold. My fuel economy instinct is to run them at 38-40 cold.

What do you guys run yours at normally?
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Old 1/4/15, 04:50 PM
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Originally Posted by MuddyLX View Post
I like to keep my tires aired up so the roll better. Now that I have my new Mustang I noticed the pressure at delivery was 30 psi cold. My fuel economy instinct is to run them at 38-40 cold.

What do you guys run yours at normally?
I ran mine at 40... as I do with all my vehicles. Tire guys will tell us we're stupid, but my experience is better fuel economy and much longer tread life.
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Old 1/4/15, 05:31 PM
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My thoughts too. I rarely plan to do much that would need grip. I'm happier when I can coast for a mile and at 30psi you can really feel the drag when you toss it in neutral.
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Old 1/6/15, 10:58 AM
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My 2015 was delivered with a Nitro fill vs "normal" air...and at 33f and 32r. I didn't request nitro, but the car was delivered with it ($99.00 dealer "option") and I normally ran 35f and 32 rear on my 2012 GT.
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Old 1/6/15, 01:20 PM
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Originally Posted by Music man in Pcola View Post
My 2015 was delivered with a Nitro fill vs "normal" air...and at 33f and 32r. I didn't request nitro, but the car was delivered with it ($99.00 dealer "option") and I normally ran 35f and 32 rear on my 2012 GT.
Regardless of what tire pressure you run, (tire pressure is tire pressure) nitro fill is a crock of crap strictly designed to put money in the dealers pocket. I have nitro in 3 vehicles, supposedly smoother ride, more stable in temperature changes etc etc...bull crap. Every time the temperature makes a major change the TPMS light comes on forcing you back to the dealer for a "nitro" top off...hmmmm, exactly what the dealer wants. The opportunity to do their "free 48 (or whatever) point inspection" and sell you oil changes, tires, brakes, shocks, alignment, cabin filters, air filters and on and on.

I hope you didn't pay a cent for that scam...
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Old 1/6/15, 09:26 PM
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I added compressed air from my garage compressor. Now it weighs all of 0 ounces more and the ride is noticeably the same.
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Old 1/6/15, 11:20 PM
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Originally Posted by elkk View Post
Regardless of what tire pressure you run, (tire pressure is tire pressure) nitro fill is a crock of crap strictly designed to put money in the dealers pocket. I have nitro in 3 vehicles, supposedly smoother ride, more stable in temperature changes etc etc...bull crap. Every time the temperature makes a major change the TPMS light comes on forcing you back to the dealer for a "nitro" top off...hmmmm, exactly what the dealer wants. The opportunity to do their "free 48 (or whatever) point inspection" and sell you oil changes, tires, brakes, shocks, alignment, cabin filters, air filters and on and on. I hope you didn't pay a cent for that scam...
Honestly id have to disagree with that. My dad got his 05 tacoma nitro filles back in 2008 and hes only been back twice to get topped off. Its held through 6 years of bipolar south texas weather
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Old 1/8/15, 08:28 PM
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When I first got my car and started driving the car felt like it was all over the road...riding on marbles. The tires were inflated to 47 PSI.... rode like crap, was noisy at high way speeds and handled like crap. After I lowered the pressure to 35 it was all bueno from there!!
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Old 1/8/15, 09:02 PM
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Originally Posted by CCTking View Post
Honestly id have to disagree with that. My dad got his 05 tacoma nitro filles back in 2008 and hes only been back twice to get topped off. Its held through 6 years of bipolar south texas weather
Well all three of my cars with Nitro have their TPMS dash lights this morning at 4 degrees. Bipolar south Texas weather? HA! Visit St. Louis for some major temp changes.
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Old 1/8/15, 10:53 PM
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For my 2011, I think OEM is 35f 35r. I've had no issues, regular 'air', no nitro stuff.
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Old 1/9/15, 07:40 AM
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Nitrogen content in air is approximately 78%. Oxygen is approximately 21% and everything else makes up approximately 1%. A little research shows that O2 is slightly smaller than N2. It permeates rubber more readily than N2. This would indicate that pure N2 could be a better gas for your tires than straight air. The report I read was written by a Dr. that works for a company that sells gasses. Hmm, maybe they want to sell more Nitrogen. Maybe they are correct and 21% of the gas in your tire will escape more readily than the rest.


I believe that if any benefit is to be had from Nitrogen, it would be that the gas remains in the tire, not that it maintains pressure at various temperatures. The laws that govern gas expansion apply to all gasses, and even if the increased molecule size and viscosity of Nitrogen caused it to maintain pressure better, it will still fluctuate with temperature changes.


Having said that, I don't care to test it or put Nitrogen in my tires. I can keep a compressor in my garage and maintain my tire pressure. How economical would it be for me to obtain and maintain a Nitrogen tank? I'm pretty sure I'd laugh at the cost involved. I'm not going to put myself at the mercy of a dealer. What do I do on vacation? Is the amount of time required to take my car to a dealer and get a Nitrogen fill worth it? What amount of airing up my tires is worth Nitrogen assuming it works as described above?


Different things matter to different people. That why we don't all have exactly the same car configured exactly the same way. Those that it matters to will do it. Those that aren't sure need to weigh potential benefits and determine what would make it worth doing.


I've never felt burdened by putting air in my tires. It is a potential solution to a problem I don't have.
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Old 1/9/15, 09:31 AM
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Originally Posted by LinckG View Post
Nitrogen content in air is approximately 78%. Oxygen is approximately 21% and everything else makes up approximately 1%. A little research shows that O2 is slightly smaller than N2. It permeates rubber more readily than N2. This would indicate that pure N2 could be a better gas for your tires than straight air. The report I read was written by a Dr. that works for a company that sells gasses. Hmm, maybe they want to sell more Nitrogen. Maybe they are correct and 21% of the gas in your tire will escape more readily than the rest. I believe that if any benefit is to be had from Nitrogen, it would be that the gas remains in the tire, not that it maintains pressure at various temperatures. The laws that govern gas expansion apply to all gasses, and even if the increased molecule size and viscosity of Nitrogen caused it to maintain pressure better, it will still fluctuate with temperature changes. Having said that, I don't care to test it or put Nitrogen in my tires. I can keep a compressor in my garage and maintain my tire pressure. How economical would it be for me to obtain and maintain a Nitrogen tank? I'm pretty sure I'd laugh at the cost involved. I'm not going to put myself at the mercy of a dealer. What do I do on vacation? Is the amount of time required to take my car to a dealer and get a Nitrogen fill worth it? What amount of airing up my tires is worth Nitrogen assuming it works as described above? Different things matter to different people. That why we don't all have exactly the same car configured exactly the same way. Those that it matters to will do it. Those that aren't sure need to weigh potential benefits and determine what would make it worth doing. I've never felt burdened by putting air in my tires. It is a potential solution to a problem I don't have.
I agree with your conclusion however I always thought that it was the moisture content of the air in tires that was the main cause of pressure fluctuation, not the size of the gas itself.
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Old 1/9/15, 09:43 AM
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Originally Posted by wannabe View Post
I ran mine at 40... as I do with all my vehicles. Tire guys will tell us we're stupid, but my experience is better fuel economy and much longer tread life.
If you run high pressures like 40 you will see more tire wear.
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Old 1/9/15, 11:10 AM
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Nitrogen fill really has no impact. It sounds good - i.e. smaller molecules might not escape as quickly, but not much data to support. The key is to check your pressure regularly, and don't wait for the light to come on. You're already 8.75 psi low at that point (TPMS regulation FMVSS138 says 25% below original placard, but FoMoCo actually turns it on 1 psi sooner so about 8psi) so not waiting is better for mileage. Once a month is recommended in the owner's manual. (And don't forget to take a peek at your spare too!!)
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Old 1/25/19, 07:16 AM
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Originally Posted by 2011gt5.0 View Post
If you run high pressures like 40 you will see more tire wear.
I agree! At least the center of the tire would wear quicker than the outside tread.
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Old 1/25/19, 07:18 AM
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Old thread I know! So how much does it matter if you add reg compressed air to your nitrogen filled tires? Tire pressure should be the same whether you are using compressed air or the nitrogen? Both should be at 32 or what ever the door sticker states? correct?
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Old 1/25/19, 08:02 AM
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I'm running a 78% nitrogen mixture in my tires.
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Old 1/25/19, 12:00 PM
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Originally Posted by SpectreH View Post
I'm running a 78% nitrogen mixture in my tires.
Is that the correct percentage for winter air? How long does it take to flush your tires with summer air?
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Old 1/25/19, 12:55 PM
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Originally Posted by Sarge View Post
Is that the correct percentage for winter air? How long does it take to flush your tires with summer air?
The quickest way I found was to use water to flush the old air out. You have to add a second valve stem tho.
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Old 1/25/19, 12:58 PM
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Yea and No sheet. After I posed here I continued my search and found all sort of entertaining threads on this subject. I think the best one was from like 2008. LOL
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