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Hi everyone,

What do you all think about filling tires with nitrogen? From what I understand, they don't change pressure much with temperature, etc.

Any opinions?

I did it in my Insight a couple of years ago. I had 60 psi n2 put in and didn't check it for 12 months. It only lost about 3 pounds per tire, but I didn't feel it was worth the cost of $5 per tire and I had to drive 70 miles one way to get it. A local Ford dealer is advertising it now. I called last week and they wanted $65.

$65 in gas would be a better deal IMHO :)

I don't see the big deal. If you can get it for free, it wouldn't hurt to try. But regular air is already 78% nitrogen.

If N2 really leaks out significantly more slowly, then over time we should all end up with tires filled with very close to pure N2 ,since O2 would preferentially leak out.

Save your money.
Charlie

In southwestern Ohio we have a chain of tire shops (Tire Discounters) that have used nitrogen exclusively for the last several years. In our three vehicles we now have notably less changes in psi for short term (daily/weekly) temperature changes and the bigger variations due to seasonal changes.

In aviation N2 has been standard (as opposed to compressed air) for many years due to the reduced moisture content and greater resistance to expansion/contraction. Although the benefits are much less pronounced in automobile operations, the effects are definitely positive, and shouldn't be ignored. Not sure I would pay $20 for all four tires to be "refilled" with N2 for my vehicle since I check air pressure 2-3 times each week, but I'm also feel much better that it is in the cars that my GF and her daughter drive regularly when I'm not in town. I'm also happy we have it for free, and will choose to pay +$20 at Tire Discounters rather than get "cheaper" tires at Walmart.:woot: Since I made it a point to tell the manager at the tire shop this, he has even refilled tires several times with N2 for free after I have had to repair a flat on the road.

One aspect that may appeal to hypermilers - a fill with N2 is approximately 2.5% lighter than with straight compressed air.;)

If N2 really leaks out significantly more slowly, then over time we should all end up with tires filled with very close to pure N2 ,since O2 would preferentially leak out.

Save your money.
Charlie

This has been my argument -- the tire effectively becomes a filter if this is in fact the situation.

May I suggest paying $1 or slightly less for teflon tape for the tire stem threads? It does the same thing for less. ;)

A 78% Nitrogen blend works great for me.

Just about all race teams from amateur to Indy car use nitrogen in their tires because the delivery system, a compressed gas bottle in most cases has no way to create condensation as an air compressor does therefor no moisture in the tire which expands at a rate much faster than air (or nitrogen) and therefor change the tire pressures which are critical in a race tire. Most good compressors have driers on them but can't always eliminate all the moisture. If you tire had a ton of moisture in it I guess it could run the pressure up way to high if you are running near the limit anyway but it would take a lot of moisture to make this kind of difference so overall it's a little hard for me to see the advantage for the average street driver.
Jay

This has been my argument -- the tire effectively becomes a filter if this is in fact the situation.

I posted this in another thread earlier today, but I'll post it here too.

If a tire has pure nitrogen in it, oxygen will "leak" in from the outside. It will do this until the partial pressure of oxygen inside the tire is the same as the partial pressure of oxygen outside of the tire.

The tire does not act as a one way barrier. Just because the tire has a high pressure of nitrogen in it, that will not prevent oxygen from permeating from the outside in. This is just a function of the partial pressure. If there is a barrier, the net change will be that a gas will diffuse/permeate from the side with the higher concentration to the side with the lower concentration.

Of course, this permeation is very slow, so it's not something that will make a big difference for most over a realistic time frame.

HMM, I am still not real sure why the tire would perform any differently with nitrogen or air if the pressure was the same and their was some way to make sure the air was completely dry. It's the moisture that would make them perform differently IMHO.