My race wheels don’t have 2 valve stems to “do it right” or I would use it. But only for my race wheels. My AutoX tires gain heat very quickly (as they are designed to) and pick up 2-4psi per lap for the first few laps, then level off as the heat levels out (I use a water sprayer as necessary to prevent over-heating). With nitrogen I could waste a lot less time between runs dropping my air pressures back down, and would have a more consitent tire from start to finish of any given lap (since, in effect for the first few laps the tires are as much as 4psi different by the end of a lap).
For road course I think it’d be even nicer since I can’t exactly get out and adjust my pressures between laps. It usually take a session or two to establish the proper cold temperature to give me the hot temp I want for my session. It changes based on track surface, tire I’m using, weather condition etc. I know I have a baseline of about 5-6psi lower than what I want to run. But it’d be nice to narrow that.
You don’t need to create a vacuum if you have 2 valve stems. You pull both valve cores and only hook the nitro up to one. As long as you’re willing to waste a little nitrogen free-flowing it for a while, you will flush all of the atmosphere out of the wheel/tire with the pressurized nitrogen.
-TJ