By Julie Steenhuysen

CHICAGO (Reuters) - An experimental tire can sense damage and warn drivers of a potential flat, U.S. researchers said on Tuesday, offering the latest advance in "smart" car technology.

Manufacturers already make tires that can warn drivers when tire pressure is too low but researchers at Purdue University in West Lafayette, Indiana, have found a way to make the whole tire into a type of sensor.

"What we have is a multilayer of different materials on the entire tire with different electrical properties. That allows us to then measure anywhere in the tire," said Gary Krutz, director of Purdue's Electrohydraulic Center and a professor of agricultural and biological engineering.

The system can detect problems like cuts, punctures, manufacturing defects, imbalance, degradation and improper mounting.

Krutz and a team at Purdue developed a sensing system that can pick up distinct electrical signals in the tire layers, detecting changes that could lead to a flat or reduce wear, such as uneven air pressure.

"The whole thing is like a doughnut," Krutz said in a telephone interview. "If you poke it anywhere, like with a nail, we can tell you where it is at and that you poked it."

The tires are made of specially selected rubber and Krutz said the technology draws on the properties of the materials themselves, something that has not been done before in tires.

A special chip inside the tire would probe the different layers and quickly relay safety information to the driver.

"We're talking less than a second," he said. "If the tire starts coming apart like on truck treads, it will give you a warning a long time in advance."

Krutz got the idea from his daughter, a heavy equipment engineer who had defective tires that needed to be replaced after only 10,000 miles.

His team had already made a hydraulic hose that would warn of failure and was working on the technology for use in orthopedic devices to detect wear and tear on artificial hips and knees.

"We thought it might work on rubber and lo and behold, it did," Krutz said.

So far, the Purdue lab has built 24 tires. Krutz plans to patent the technology and license it to manufacturers. He said the most likely first use would be in race cars, where the cost of a flat is high.

"You are blowing up million-dollar vehicles," he said.

He said the technology would cost manufacturers about $1 per tire, translating into something like $50 per tire for consumers.

(Editing by Maggie Fox and Bill Trott)
© Copyright 2007 Reuters.