I has to do with keeping tire pressures more stable during temperature changes. If they are offering it at no charge, I would go ahead and have them do it. Most places charge for nitrogen fills... I've seen $10-15/tire, which then in my mind is not worth it. You should be checking your tire pressures regularly anyway.

 

That's good info. Thanks. I was hoping it would make the car lighter. Ha!

 

Facts and Myths About Nitrogen Inflated Tires - Make Driving Fun with Performance Tires & Wheels | Tire Rack

 

^^^ That Tire Rack link is very good for consumer applications.

I'll add another bit. The racers use pure Nitrogen because it is guaranteed to have no water vapor (humidity). As the temperature of the tire changes during a race, the water vapor inside has a significant effect on how the tire pressure changes. So filling a tire from a typical air compressor means the tire gets the about the same humidity inside. Sourcing from a Nitrogen bottle eliminates that variable.

Many large industrial facilities have dryers included in their air compressors or as separate units after the compressor. These are not easily portable (fit into a race trailer for example). However, a Nitrogen bottle is relatively easy to store in the race car trailer.

 

More good info. Thanks for sharing.

 

exactly as stated above^^ When we do a burn out the tires will increase in pressure about 1 to 2 pnds and with nitrogen it has been the same. Same as sitting in the stagging lane in the hot sun. Not a big deal for some street cars but I'm at the edge of getting a good pass and 1 to 2 pnds fluctuation can be the difference form hooking or spinning.

 

This is easy to figure out. Atmosphere is 78% nitrogen. The primary difference in expansion or consistency in pressure really all comes down to moisture content, not the gas.

Dry air is immeasurably different than nitrogen, but air is actually slightly more temperature stable for pressure. Dry air has a gas constant of 286.9, and dry nitrogen 296.8. Water vapor has a gas constant of 461.5

In order of stability:
Dry air 286.9
Dry nitrogen 296.8
Water vapor 461.5

The real worry is how humid the air or nitrogen in the tire is. If there is a great deal of humidity, pressure could be noticeably less stable. My tractor tires are a real problem on hot days, because they are 3/4 full of water for weight.

I fill my race air tank and rear tires with air from a dryer in my shop air system, not that it matters much. The pressure still changes with temperature even with dry air, so I still watch it. I have the dryer for air for radio transmission lines. I bottle my own dry air, instead of buying gas.