You may or may not have heard that you can get your tires filled with fancy nitrogen instead of regular air. Your car may even have nitrogen filled tires already (you’ll likely have green valve stem caps)! Should you be filling your tires with nitrogen? Let’s find out.
The air in the atmosphere that we all breathe (and non-electric cars breathe) is made from about 78% nitrogen, 21% oxygen, and 1% of other gases and water vapor. Nitrogen molecules are slightly larger and slightly lighter than air (less than 5% difference for both). Tire service stations all around the country now are offering to fill tires with nitrogen instead of compressed air.
The main benefit to filling with nitrogen is increased tire pressure retention. Tires filled with nitrogen have been shown to lose less pressure over time than plain air by about a third. For example, if your tire was filled with air and lost three PSI over time, an identical nitrogen filled tire should only lose two PSI over the same time period.
The nitrogen filled tires also are filled with “dry nitrogen” which has much less water vapor than plain air. However, air compressors at tire service centers usually have dehumidifiers, which gets rid of much of that moisture. There are other benefits to using nitrogen such as reduced corrosion of wheels and tires due to less moisture, but the gains are generally minuscule.
Getting your tires filled with nitrogen can be costly at $5 to $30 per tire ($20 to $120 for four tires) compared to getting air for free in many places. Maintaining nitrogen filled tires is also more work since filling up your tires at a regular air pump will negate the benefits of getting the nitrogen in the first place, forcing you to take the tire to the shop for topping up, which may incur more expenses. It could also cause you stress if you notice your tire is low and are nowhere near a nitrogen equipped service station requiring you to fill up with air.
There are a few applications where nitrogen is being used regularly. Racing teams use nitrogen due to the more consistent nature of nitrogen vs air (which has slightly varying ratios of nitrogen, air, and other gases). This results in a more consistent tire pressure when up to temperature, which is very important when traveling around 200 miles per hour. Large aircraft and industrial machinery also almost exclusively use nitrogen filled tires.
In general, it is a good idea to check your tire pressures regularly to maintain proper pressure. This will ensure better fuel economy, tire longevity, and most importantly, safer handling in all conditions. Using nitrogen can mean longer safe intervals between checking tires. Luckily for most drivers, all light passenger vehicles manufactured after 2007 are mandated to have some sort of tire pressure monitoring system onboard to alert drivers when their tires do not have the proper pressure, so you won’t have to leave the comfort of your driving chair to check. However, these monitoring systems will not alert you until your tire has lost a significant amount of air.
Q: Can I top of my nitrogen filled tires with air?
A: If your tires need extra tire pressure, air can be added when nitrogen cannot be found. While this will reduce the benefits of filling with nitrogen in the first place, it is safer than driving on under inflated tires.
Q: I need a repair to one of my nitrogen filled tires, what do I do?
A: If your tire is repairable, and the shop doesn’t offer nitrogen fills, there is no need to change what they’re filled with. You should then have the repaired tire purged and filled with nitrogen as soon as possible to ensure consistency between your tires.
Q: Is it worth the cost?
A: If you don’t want to check your tires pressures or hate filling up your tires at gas stations, nitrogen could be worth the price premium to you.