The Self Inflating Tire is simpler than it sounds, consisting of just two components: a peristaltic pump and a valve that stops over-inflation. Basically, a round tube embedded in the tire's sidewall is compressed at the bottom as the tire rolls, forcing air into the tire. Once it's inflated to the proper pressure the valve — which can be electric or mechanical — shuts off. That's it. Wish you'd thought of it?
The system is notable because it doesn't need an external air compressor or any other hardware. Just by driving around (a mile should be enough to compensate for a month's worth of normal air-loss, according to the company), you'll keep your tires at their ideal pressures. Obviously, keeping your tires at the correct pressure is good for safety, economy and tire wear.
The Self Inflating Tire is currently being developed for production by Coda Development. With the ability to be incorporated either in the tire sidewall or rim, it should prove cheap and easy to produce. Tire inflation may not be the sexiest aspect of car maintenance around, but it's both incredibly important and oft neglected. SIT will be launched at the SAE World Congress in April. [Via SIT]