Some of the higher end racing wheels have dual valves for replacing the air with nitrgen at the track. The dual valves make it easier to pump the nitrgen in one valve while forcing the air out the other or so i have been told.

example these are on my sons highly modded A4...Kosi Racing K1 TS



Scott 2000 Contour SVT #1464 Mustang Dyno: 171.6hp/145.3lb Dynojet Dyno: 171.1hp/148.9lb 1989 20th Anniversary Turbo T/A "Indy 500 Pace Car" #1376 of 1550 All Original, 46k with a few mods 2002 F150 SuperCrew