Does haveing your tires filled with nitrogen really save gas?

yes just a little

there are no drawbacks, its better for your tires but will not increase your fuel mileage a great deal. what increases your fuel mileage is the proper tire pressure and Nitrogen filled tires have a tendance not to lose inflation as fast because of the larger molecule size.
read these links.
BTW All my cars tires are nitrogen filled.

http://www.nitrogendirect.com/N2Info.htm

http://www.dailyvidette.com/media/paper420/news/2005/10/07/OtherCampus/Nitrogen.Gas.Tires.Increases.Fuel.Efficiency-1013224.shtml

http://www.poynter.org/column.asp?id=2&aid=89747

my tires i think are nitrogen filled..

obviously your going to have to fill them when they need it with nitrogen…

they seem to help gas mileage/ride too

OK, here’s the “lowdown”

Dry nitrogen does not expand or contract with temperature changes.
Therefore, durring cold temperatures your tires will still be at proper operating pressure, and you will get an improvement in gas mileage.

It’s probably worth it if you live somewhere cold. Otherwise it’s a waste of money.

And, no, cars do not come with tires prefilled with nitrogen.

Nitrogen supposedly keeps the tire pressure more constant under changing temperature conditions.

Advantage : you will not need to check your tire pressure as often, and the tires will not be low due to colder weather.

Disadvantage: $25 to put nitrogen in the tires vs $0- $1 to put regular air (which is part nitrogen) in your tires.

My personal opinion is that it is not worth the money to do it!!!