Nitrogen in Tires

My last Hybrid was a 2005 Honda Civic Hybrid

It was one of the best cars I ever owned (tied with my Subaru Outback). I switched to the 2010 Prius because I liked the technology

My Honda, with nitrogen filled tires used to get an average 50 MPG. I determined nitrogen gave me about 2 more MPG

I did not have the Toyota dealer put nitrogen in the tires because I felt his prices were to steep, and he wanted to include the nitrogen with a package I was not interested in getting

I have a little over 1,000 miles on my new Prius, and am getting about 55 MPG

Plan on having the tires filled with nitrogen tomorrow and am anxious to see the difference in mileage

Any predictions?

No difference.

Nitrogen in passenger car tires doesn't hurt anything, but it doesn't help either. This topic has been extensively discussed many times on PC. Give it a search if you want the gory details.

Tom

No difference. There are so many things that affect MPG, it is practically impossible to determine that a 2 MPG swing was due to just one factor, unless you're doing detailed testing like bwilson.

The primary benefit for mileage is that nitrogen is much less affected by tire temp. changes. Constant proper inflation is good.

Thirty years in the commercial aircraft field, ALL our aircraft tires were filled with nitrogen.

Nitrogen is affected by temperature in exactly the same way as all ideal gases. It is a common misconception that nitrogen is somehow immune from the Ideal Gas Law, but it is not and behaves almost identically to normal dry air.

There are good reasons that nitrogen is used in the tires of commercial aircraft. None of them apply to passenger cars:

1) Nitrogen is easy to transport onto the ramp as a cooled liquid.

2) Nitrogen gas expanded from liquid nitrogen is inherently dry. Commercial aircraft flying at altitude are subjected to extremely cold temperatures. At these temperatures, moisture inside the tires can condense and freeze, leading to server imbalance when landing.

3) Commercial aircraft tires are subjected to extreme conditions during landing. Nitrogen does not support combustion in the event of a tire fire.

Tom

...not to mention that air is 78% Nitrogen.

W/O Nitrogen - 55 mpg

W/ Nitrogen - 55.000000000000000000001 mpg *
















* Your mileage may vary. :madgrin:

...and at no extra charge...

Tom

Air is mostly nitrogen anyway. Now if you put helium in there I might understand it. The "lift" from the tires wanting to float should make the car "lighter".

How about uranium hexafluoride for better traction?

Tom

Just during the winter months, you don't want to hurt FE in the summer.

Can I get that at Amazon.com? :madgrin:

Never mind the nitrogen crap. Give me my name back!!


Oh oh. I just looked at your profile and you are 2 years older than I am. Never mind.

I have nitriogen in our Michelin Energy Saver AS tires from Costco. Nitrogen molecules have less tendency to leak out of a tire than normal air pressured tires because the Nitrogen molecules are bigger.

At least that is what Costco Tire Techs told me.

Alfon

At least Costco doesn't charge extra for it.

Not at Amazon.com but you might try United Nuclear.

I am an international super secret agent. If people shoot at my car and I end up ditching it underwater, I can breath the air in my tire, stay down, and avoid getting killed - just like James Bond did in one of his movies. In the same scenerio, you will surely have to come up for air, and get shot. I will live another day to gamble in Monte Carlo with supermodels. The Costco Tire Tech guy knows nothing of the demands of a super agent. My life is just too exciting for nitrogen.

This is another reason to inflate tires to higher pressure than the door placard. It keeps this emergency air supply available to greater depths.

The molecules aren't "leaking" out in the traditional sense. They are permeating through the rubber (microscopic pores in between the spaghetti network of polymer chains). Oxygen permeates faster then Nitrogen through rubber.

I predict no noticeable difference unless you typically go several months between refilling your tires (basically not refilling them unless you see an obvious visual loss of tire pressure).

There is a misconception between the cause and effect here. The type of gas or gas mixture that is in the tire has no direct impact on MPG. None. It's the pressure that will have an impact on MPG. Take 2 sets of tires, one filled with pure N2, the other filled with air, both intially at the same pressure. Both cars will initially have the same exact MPG, all other factors being equal. Over a really long time (months), the O2 in the air-filled tires will permeate out through the rubber faster than the N2 in both sets of tires. The air-filled tires will thus lose their pressure slightly faster, resulting in a small drop in MPG over a long time (not right away).

If you check and refill your air pressure once or twice a month, you will never notice a difference in MPG.

I usually check my pressure once a month, and notice only about a 2 psi drop in pressure using air. And that's not enough to make much of a difference in MPG. I'll keep my tires filled with 80% nitrogen, thank you.