For your car or bike. No interior threads; the opening is tapered slightly so you should be able to get it to fit on most valve stems. Push it down and screw it on, the valve stem should cut its own threads.
Despite the fact that the measurements of the STL are indeed to proper scale, your printer may make the hole too small due to squeezing of the filament. You may need to scale it up a little bit for proper fit, as was the case with mine.