"Filling pure Nitrogen into a tire isn't easy since you have to get all the air and moisture out. Most race teams with single valve stem wheels have to fill a wheel and then purge it three times to get it close to pure Nitrogen. That can get costly. Some wheel manufacturers like Enkie make a dual valve stem wheel like the NT03+M where one valve is use to fill with Nitrogen, while the other valve is for simultaneously purging the air. It might have been better if they placed the stems 180 degrees from each other for better purging instead of adjacently."