You can buy nitrogen gas and put it in tires, as it is becoming a popular alternative to replacing regular air in your tires. It gives many benefits, such as fuel economy and better temperature control. You can buy it in places like Costco, tire dealers, and car dealerships. Another option is places that sell welding gases, as they too sometimes will also sell nitrogen. There is also a website, Get Nitrogen Institute, that lets you put in your zip code and it will show you a listing and a map to see what nitrogen providers are in your area. Nitrogen is somewhat expensive. In some places charging around $30 to fill up your tires.