WASHINGTON -- If your motorcoach drivers are being taught to try to put out a tire fire with the onboard fire extinguisher, forget it. Its a waste of time.

Thats the word from experts who testified last month at a federal inquiry into a bus fire that killed 23 nursing home patients in Texas a year ago this month.

The blaze was started by an overheated wheel bearing that set fire to a rear tire.

"The five-pound fire extinguisher is essentially useless," said Robert Crescenzo of Lancer Insurance.

Emmett Bevins of Amerex Corporation, the maker of fire-suppression equipment, said tire fires get so hot it takes professional firefighters dressed in full protective gear and armed with powerful hoses to tackle a burning tire.

Fire extinguishers especially the small ones the federal government requires on motorcoaches are completely overmatched, he said.

Even fire suppression equipment that can quickly put our fires in engine compartments, heaters and other parts of most buses are unable to do the job.

"We have tried for the last 10 years, but unfortunately with no success," Bevins told members of the National Transportation Safety Board, which was conducting the hearing.

Instead of trying to extinguish tire fires, Amerex promotes special heat-sensor monitors that can be installed inside wheel bearings. The sensor sends light and sound signals to the driver when the wheel area turns hot and becomes a fire hazard.

"Our current line of thinking is to not let it start in the first place," he said.

Last month, ArvinMeritor, which manufactures axles for over-the-road buses and trucks, announced a new product called Meritor ThermALERT, designed to help detect elevated wheel-end operating temperatures. However, the announcement said the system was only available for new truck trailers.

ArvinMeritor marketing communications department did not respond to repeated inquiries, asking whether there were plans to make the system available to motorcoach manufacturers.

Bus manufacturers currently take special steps to keep tire fires from quickly burning through the fender and spreading to the inside of the bus.

Bob Capstick of Motor Coach Industries maker of the bus involved in the Texas fire said the inner fender between the tire and passenger areas is constructed of stainless and carbon steel. The fire that was the subject of the hearing spread to the outside of the bus and ran up the side, knocking out windows and sending thick smoke inside.

Brian Queiser of Bridgestone/Firestone said tire fires tend to be externally driven. "We tackle it on one front, the recommended use of our products," he said, adding that proper maintenance, care and service of vehicles is important.