When it’s time to buy new tires, you may be presented with the option of filling those tires with nitrogen instead of the standard, plain old air. Why would you use nitrogen? What are the benefits or differences with using nitrogen vs. air? Let us help you understand more about using nitrogen for tire inflation.
What is Nitrogen?
Nitrogen is an element – atomic number seven on your periodic table – which is one of the most common elements in the universe. In fact, nitrogen makes up around 78 percent of the air we breathe – compared to oxygen at around 21 percent.
Why Do Some Tire Shops Put Nitrogen in Tires?
For tire inflation purposes, the nitrogen offered by some tire dealers is typically around 99 percent pure nitrogen. One perceived benefit of using nitrogen in your tires is that nitrogen should theoretically lead to more consistent tire inflation pressure over time, as nitrogen is slower to escape between the tire’s structure than oxygen. This however doesn’t remove the need to regularly check your air pressure, as both oxygen and nitrogen do permeate the structure of the tire, but you may find less variation over time if consistently using nitrogen.
You might note that auto racing cars will often use nitrogen to fill their racing tires. In racing environments, any fluctuation in tire pressure can have a significant impact in the vehicle’s racing performance. In street driving, small pressure changes may not be immediately noticeable, but even with nitrogen, regular and frequent pressure checks are necessary to ensure your tires are at the correct inflation pressure and have not sustained another leak via a puncture.
Note: The use of nitrogen does not remove the need to regularly check your tire pressures. The use of nitrogen as an inflation method will not adversely affect any applicable Goodyear limited warranties for tires. Nitrogen is not offered as an option at Goodyear company owned retail locations for tire inflation.
What is the Benefit to Using Nitrogen When Filling Your Tires?
Nitrogen molecules — compared to molecules of oxygen — are larger and therefore slower to permeate or diffuse through the structure of the tire. Thus, nitrogen loses pressure less quickly than oxygen by a rate of around 40 percent. This means that, in theory, given static ambient air temperatures, and no punctures, valve misfunctions, or other tire and wheel damage, you may not have to fill your nitrogen-filled tire quite as often.
As underinflated tires can also cause decreased fuel economy, you may see claims that nitrogen will give your car improved fuel efficiency. This claim is tied to the potential of more consistent pressures offered by use of nitrogen for inflation in your tires. An underinflated tire may provide decreased fuel economy. This effect can be mitigated with regular and frequent pressure checks, whether using air or nitrogen for your inflation.
No matter what your tires are filled with, you still should be frequently checking your tire pressure. Goodyear recommends you check your tire pressure at least once a month. Using nitrogen does not eliminate the need to regularly check your tire pressure.
Is it Safe to Mix Nitrogen and Standard Air When Filling Tires?
Simply adding air to a nitrogen-filled tire is acceptable – again, air is mostly nitrogen. However, you’ll immediately lose any benefit of the higher concentration of nitrogen if you fill with regular air. If the trade-off means driving on an underinflated tire, then absolutely fill the tire with regular air to return to correct inflation pressures.
What Do Green Valve Stem Caps Mean?
Green valve stem caps are an identifier that signifies the tire was filled with nitrogen. This can serve as a good reminder for a vehicle on which you’ve just begun to use nitrogen for inflation. If green valve stem caps are noticed on a vehicle, and you haven’t personally taken the step of filling up with Nitrogen, you may want to have a tire shop ensure your next inflation is performed with nitrogen, if that’s an important feature to you.
Why Do Tire Shops Use Nitrogen vs. Regular Air When Filling Tires?
Some tire shops feel that nitrogen is an important feature to provide to their tire buyers. Besides the cost of acquiring the nitrogen, there is more labor involved in filling tires properly with nitrogen. To remove the regular air from a tire and fill it with nitrogen requires a “purging” process where the tire is repeatedly filled with nitrogen to gradually remove as much of the regular air out of the tire as possible.
If you have additional questions, please contact your local tire shop.