Less Pressure Fluctuation: Here in the high deserts of Arizona, we can see a 60 degree change in temperature between early morning and late afternoon hours. During a single day, air-filled tires change change by 10 PSI or more, making many tires dangerously under-inflated and over-inflated in a single day. By contrast, nitrogen filled tires change by only 2% per ten degrees, keeping them within the safety zone at all times. Pressure and condensation issues due to elevation changes are also reduced, which is why all commercial aircraft now use nitrogen in their tires.
Better Pressure Retention: Bleeding oxygen slowly through the rubber (and sometimes nozzle), air-filled tires lose 1.5 pounds of pressure or more each month. By contrast, nitrogen-filled tires lose two-thirds less air each month. This is particularly important as new lubricants have been developed which increase the amount of time between service visits, thereby decreasing the number of times per year that tire pressure is tested by a mechanic.
Increased Fuel Economy: Proper tire pressure optimizes the balance between grip of the tire on the road and rolling resistance. Over-inflated tires lose grip during acceleration, wasting fuel, and under-inflated tires have too much resistance, increasing the fuel needed to maintain your speed.
Improved Handling and Performance: On my Saturn SKY, I noticed better handling immediately after putting nitrogen in the tires, and it made sense to me why all NASCAR cars now have nitrogen in their tires. Each tire has a recommended "contact patch" which is where the tire should meet the road. Over-inflated tires have a decreased patch, and tend to lose grip in the corners, and under-inflated tires have a larger patch which increases wear and tends to put excess stress on the sidewalls. Also, the fluctuating temperatures of Arizona causes the rubber to stretch and shrink daily, eventually leading to loss of elasticity of the rubber. In our shop here in Phoenix, we see a lot of tires that are stiff as a board having completely lost their elasticity (sometimes called dry rot, but more accurately attributed to temperature changes rather than dryness).
Extended Tire Wear and Life: One major new tire retailer who installed nitrogen generators in 500 stores found a 30% reduction in tire warrantly claims among those vehicles who opted for nitrogen. Often, we can tell how many miles a car has on it by looking at the tires, but those tires that use nitrogen often fool us, because they are the most likely tires to achieve or even exceed their manufacturer's warranty mileage.
Better for the Environment: Nitrogen-filled tires improves fuel efficiency, reduces toxic emissions, and reduces tire wear and landfill space, making nitrogen better for your pocketbook AND the environment.
Longer-term Stability: Living in snow-bird country, we have a number of customers who leave their vehicles in the garage for months without use. And, with the addition of our Saturn SKY, we now have a number of local customers who are driving their Saturn's either only on the weekends or sometimes just a few months out of the year. For those who tend to store vehicles, condensation is the big enemy. With air-filled tires, water vapor in the air slowly condenses and settles on the bottom of the tire, eventually and irreversably seeping into the rubber. That is why on trailers, you sometimes see large chunks of rubber break away from the tire, because of rubber or steel belt deterioration caused by water seepage. Use of Nitrogen, on the other hand, eliminates water vapor from the inside of the tire, and you can reliably store a vehicle for many months without deleterious affect on the tires.
The Future: The question I get most often is, why don't all Saturns come with Nitrogen from the factory? The answer is that someday they probably will, because safety and environment is such important issues for us as a company. Over time, many Saturn retailers are following our lead and are installing nitrogen generating devices in their shop. It is sort of a chicken-and-egg thing, with more nitrogen infrastructure needed before we can make nitrogen the defacto standard in tires. However, in the past few years, nitrogen generating equipment costs have fallen sharply, and we expect that someday, everyone will be at least offering nitrogen as an alternative.
Another question we are asked is, "can you mix air and nitrogen?" And the answer is, "yes." Air is 78% nitrogen, which is a non-combustable gas (unlike pure oxygen). Nitrogen-generating plants simply extract nitrogen (and remove oxygen) from air. Therefore, although we are trying to get as much purity of nitrogen as possible, if you find yourself at a quickie-mart and need to top off your tires with a couple pounds of pressure, you should do so, because you are adding 78% nitrogen, and this will have limited negative affect on your tires. If you have a flat on a trip and need to completely fill a tire with air, however, we recommend that you also fill the matching tire with air, so that both tires perform the same as the temperature changes and pressure fluctuates with air.
