Have you ever noticed cars with mysterious green valve stem caps on their tires? If you have, you may wonder why some people choose to use them. Don’t worry — a lot of people have the same question, and many people give the wrong answer when trying to explain the phenomenon. The first thing you need to know is that green valve stem caps are not a fashion choice. Sure, green is a great color, and it’s probably many people’s favorite, but that doesn’t matter. 

In reality, green valve stem caps indicate that the tires are filled with nitrogen instead of standard air. People do this for a variety of reasons, including the potential to lose a tiny bit less air pressure over time, resulting in things like mild improvements to fuel economy and tire life. However, those improvements are minimal, and filling your tires with nitrogen does cost a bit of extra cash. So, if you’re running regular air in your tires, don’t feel like you need to rush out and switch to a different gas.

That said, if you do prefer to fill your tires with nitrogen, you may be wondering about the best place to get it. Depending on your area, you probably have more options than you realize. Costco is a popular choice, and we’ll cover its tire nitrogen service shortly. However, we’ll also discuss a few other locations that commonly keep nitrogen on hand and the services they offer. Finally, as a former professional auto repair technician and a lifelong gearhead, I’ll go into a little more detail explaining why people use nitrogen in their tires and whether it’s worth it. Let’s dive in and check it out.

Most people are familiar with Costco. The big-box store is famous for its attractive membership options, and it’s also a great place to find deals on car parts and accessories. If you’re a regular Costco shopper or know someone who is, you might already be aware of the fact that the store provides automotive services like tire rotations and replacements. However, what you may not know is that Costco also provides nitrogen for tires — and in many cases, you don’t even have to pay extra for it.

That’s right — according to the Costco website, the company will automatically inflate your tires with nitrogen instead of regular air. It’s part of Costco’s commitment to customer service, and the company claims that it’s an advantage of visiting one of its locations for all your tire needs. While Costco will fill your tires with nitrogen when you pay for a tire service, you may not be able to find self-serve nitrogen at all Costco locations. 

The company’s website does state that self-serve tire-inflation pumps are available at each Costco gas station. However, it does not clarify whether these pumps contain both nitrogen and regular oxygen or simply one or the other. That said, many members report having access to self-serve nitrogen pumps at their local Costco locations, so the box store is definitely worth checking if you’re looking for a quick and potentially free way to fill your tires with nitrogen.

If there isn’t a Costco location in your area, and you really want to fill your tires with nitrogen, don’t despair. You probably still have access to quite a few options. The best way to find these places is to simply open your favorite web browser and search for shops in your local area that offer nitrogen for tires. Searching your town or city name as one keyword together with something like “nitrogen for tires” will most likely yield a ton of results within driving distance, including some places that you may not even know exist.

Some of the most common options you’re likely to encounter during your search are tire and lube shops. Depending on the location, national chains like Big-O-Tires, Discount Tire, and Tire Discounters may provide nitrogen services. Outside of national chains and franchises, your local area probably has dozens or more independently-owned tire stores and mechanic’s shops that offer nitrogen. 

As mentioned, the best way to find these places is a quick Google search. Alternatively, you can check your local phone book or simply drive around until you find a shop with nitrogen. That said, to save time, gas, and energy, it’s best to call these shops ahead of time to find out whether they provide nitrogen gas and ask how much they charge for the service.

If you’ve made it this far, you may be wondering why some people choose to fill their tires with nitrogen and whether it’s worth the extra cost. We mentioned that filling your tires with nitrogen can come with a few benefits. The primary reason why people use nitrogen in their tires is to prevent tire pressure loss over time. Tires are made from rubber, and rubber is porous. That means that, over time, your tires will lose a small amount of air, even if they don’t have a hole or a leak. That pressure loss is pretty small and usually around one to two psi per month, but it’s still inconvenient, and many people dislike making trips to the air pump. 

Furthermore, inconsistent tire pressure can reduce your fuel mileage and the life of your tires. Some people choose to combat that issue by using nitrogen instead of regular air. Nitrogen molecules are slightly larger than air molecules, which makes it more difficult for them to slip through the pores in your tires. However, the difference in pressure loss between the two gasses is minimal, and you’ll most likely have to pay a fee to drain the normal air from your tires and refill them with nitrogen.

All that said, is it worth it to pay extra or travel farther to fill your tires with nitrogen? For most people, the answer is no. Filling your tires with nitrogen probably won’t make a noticeable difference in your driving experience. You may see slight improvements to your fuel economy and tire life over extremely long periods. However, those aren’t things that most people will notice, and for average drivers, those slight improvements aren’t worth the added expense that comes with using nitrogen in their tires.