This product neatly falls nicely into the category of "Why didn't I think of that." This conceptual design comes way of John Wrightson. The tire cap has a small LCD screen that will display the current tire pressure with a push of the button. Now if only Wrightson could figure out a way for the caps to know what the recommended pressure is for said tires. Smart idea, but would definitely suck when the caps are lost—which is likely to happen.
Tire Pressure Check [Yanko]