As pictured here, nitrogen has larger molecules than hydrogen or oxygen. In theory, this makes it less likely to escape through the semi-permeable tire liner, causing the tire to lose less air over the same time period as regular air. Nitrogen is a “drier” gas, and while it is still impacted by the ideal gas law, the lack of water vapor creates more stable expansion and contraction of air pressure due to temperature changes. Because it is nitrogen in your tires and not oxygen, corrosion or oxidation is less likely to build up on your wheel finish or your TPMS sensors.
Regular "compressed" air is actually made up of 78% nitrogen. To achieve the benefits of nitrogen, the concentration has to be at or higher than 93%. To reach this level of concentration, tires often have to be purged multiple times. If your nitrogen-filled tires are low on pressure and nitrogen is unavailable, it’s perfectly safe to fill them with regular air. However, to continually maintain these benefits, the tire will later have to be purged and refilled with nitrogen.
Regardless of how stable nitrogen is in theory, your tires will still lose air pressure over time. While some places will fill your tires with nitrogen for free, many places do not. This means you may end up paying more money for air that will still need to be checked frequently.
How do I know if my tires have nitrogen in them now?
The most common way to determine if your tires have compressed air or nitrogen is by the color of your tires valve cap.
- Nitrogen typically have a green colored valve cap or a N2 emblem.
- Regular air typically has the more traditional black or chrome colored valve cap.
Rather than spending extra money to have your tires serviced with nitrogen, we recommend using regular air and checking your tire air pressure once a month. Checking your air pressure regularly will eliminate the worry of under-inflation, which is one of the primary benefits attributed to nitrogen-inflated tires.
Stop by your local Discount Tire for a free air check and we'll get you take care of!