New self-inflating tire constantly under pressure

We all know that keeping your tires properly inflated will prolong their tread life, help you burn less fuel and increase your safety. But finding a working air hose when you're away from your garage is like trying to find a working clock in an early-80's Buick.
This is probably what led Coda Development, a Czech Republic company, to invent a new self-inflating tire. Sure, self-inflating tires aren't new, they've been around for years on commercial vehicles and even a few passenger vehicles . But most of those systems use compressed air to keep the tires inflated.

Coda's new system uses a peristaltic pump built into the tire to constantly maintain air pressure. You may have seen a peristaltic pump used in hospitals to deliver intravenous drugs to patients. It's basically a spinning wheel pressed against a liquid-filled tube. As the wheel turns, it pushes the tube's contents through one end and pulls more in the other. In our case, your car's wheel is the wheel and your air-filled tire the tube. A valve ensures that your tire's pressure is always constant. Theoretically, the peristaltic pump is much simpler and therefore more reliable than a compressor-based system. It's also potentially lighter, cheaper and doesn't require a power source. Sounds like a darn smart idea to us. Coda plans to display its system at the 2008 SAE World Congress in Detroit on April 14th through the 17th, so we'll see if it makes a splash there with auto industry engineers.

[Source: Coda]


SIT - the Self Inflating Tire system is a new invention of CODA DEVELOPMENT s.r.o., a company based in Prague, Czech Republic. The patented SIT solution offers a major advance in solving tire pressure concerns.

In the USA, 27% of passenger cars and 32% of light trucks and SUVs have at least one tire under-pressured by more than 25%. Under-inflated tires negatively impact safety, fuel economy and tire longevity. It is estimated that maintaining proper tire pressure would save the U.S. upwards of 1.24 billion gallons of fuel annually by improving gas mileage. In turn, this would eliminate about 250 lbs. of carbon dioxide emissions per vehicle every year.

The SIT System delivers key benefits. Besides benefiting drivers through elimination of unpopular pressure checks and dirty-handed inflating of tires, it helps to address the serious drawbacks of incorrect tire pressure. These include higher fuel consumption, shorter tire life, and accidents caused by under inflated tires. Plus it's a simple, inexpensive solution designed to be manufacturer friendly. Production costs for incorporating this component will increase only marginally compared to regular tires, while the surplus benefits the technology provides are significant.

SIT is an integral tire feature that uses atmospheric air to inflate the tire automatically when a vehicle is put in motion, compensating for natural loss of pressure and ensuring maintenance-free, constant tire pressure over the lifetime of the tire.

The SIT System is based on proven, highly reliable peristaltic pump principles. It integrates a tube chamber into the tire wall. As the tire turns against the road this chamber acts as a peristaltic pump, forcing more air into the tire until it reaches its desired pressure. Then a managing valve automatically stops further inflation. This simple solution ensures that all tires operate at optimal pressure at all times. Driving less than 1 mile compensates for typical leakage of 1 to 3% per month.

In comparison, currently available inflation systems use externally stored containers of compressed air or external compressors, resulting in higher costs, weight and more elaborate assembly. Plus, the containers ultimately have limited capacity and are not maintenance-free. SIT is a tire-integrated, self-operating component that uses atmospheric air to compensate for lost pressure as needed. SIT provides the most effective and inexpensive tire pressure control, while also being the most convenient solution for the end user - the driver. As a result of this development, people can drive their vehicles with complete peace of mind.

CODA DEVELOPMENT s.r.o. plans to develop the SIT System further into a proven production model in joint cooperation with established partners from the automotive and tire industries. In the coming months CODA DEVELOPMENT s.r.o. will initiate talks with potential partners in order to identify those best suited for introducing this new technology to the market.

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