Late to the game I know, I use this one from SPC. Seems to work pretty well! I think Peter Bergman sells them as well, but he doesn't have them listed on his site.
Doesn't do any good if the hub is aluminum too. Or doesn't protrude through the rim. I like the hub mounted magnetic gauges better, but they don't work on my Duster (aluminum hubs) or my Challenger (hub recessed in the wheel bore).
