Five years ago, Public Citizen, a consumer group with a strong interest in auto safety, was blasting Ford Motor Co. and Bridgestone/Firestone Inc. for creating a deadly combination of defective tires and sport-utility vehicles that ended up taking 271 lives in accidents.

Flash forward to the beginning of this month. Public Citizen, along with Bridgestone, three other tire companies and a trade group representing the tire industry took regulators at the National Highway Traffic Safety Administration to court asking for a tougher tire-pressure monitoring rule. This is the kind of intervention that may have prevented the accidents and the recall of millions of tires that suffered from underinflation and tread separation.

The rule is mandated under the Transportation Recall Enhancement, Accountability, and Documentation (TREAD) Act that Congress passed in the aftermath of the Firestone debacle, with the support of Public Citizen and other safety groups. It called for, among other things, more stringent reporting and documentation of vehicle and tire problems with NHTSA.

Vehicle manufacturers will have to start complying with the rule to install a system on one or more of the vehicle's tires to warn when they are 25 percent or more below the recommended tire pressure. The phase-in of the new technology starts in October and would cover all new vehicles after Aug. 31, 2007.

Public Citizen and Bridgestone may look like strange regulatory bedfellows but they are of one mind that the latest rule issued by NHTSA in April has deficiencies. "No permanent enemies; no permanent friends in Washington," explained Joan Claybrook, president of Public Citizen.

The concern of the group filing the challenge is that the rule will not cover replacement tires and spares, and a warning light to signal low tire pressure will not activate soon enough, so tires may be dangerously underinflated by the time drivers are alerted.

Public Citizen also sued the agency in 2002 when NHTSA issued its first final rule to provide for the systems. It won that case, and the rule just issued reflects the changes the court ordered.

Rae Tyson, spokesman for NHTSA, said the agency could not comment on the rule because of the pending litigation.

The Rubber Manufacturers Association, which represents the major tiremakers, is not part of the case, but it has consistently opposed both versions of the rule. "They re-did the rule and they didn't get it right," said Donald Shea, president of RMA.

One area of contention in that the new rule centers on how long it takes for a warning light to signal a problem. If a tire drops too far below the recommended pressure, a yellow warning light would have to go off within 20 minutes of travel within speeds of 30 to 60 mph. Originally, NHTSA proposed 10 minutes; the tiremakers asked for a warning after five minutes.

"If it's already low, 25 percent could be a significantly underinflated tire," Shea said. Automakers and NHTSA said setting the level too low will pester motorists and cause them to ignore the light.

"It's set up for failure," Claybrook said of the rule. "There are a whole series of things to make this not serve consumers."

"We all have issues," said Steven Akey, vice president of government affairs for Bridgestone Americas Holding Inc. "We think there are a lot of flaws in the rule. The rule is not strong enough."

Tire companies want the strongest possible rule to limit the likelihood that tires will be blamed as defective in accidents, according to a tire industry trade group.

The RMA and groups such as Public Citizen want the warning light to be much more sensitive to underinflation, especially when a vehicle is fully loaded.

The way the rule is now written, tire pressure would have to dip 25 percent below the recommended fill to trip the system. Shea said automakers commonly set the recommended tire pressure below what the tiremaker recommends (this was a problem with the Ford Explorers) to give owners a smoother ride.

Claybrook said city drivers might never be warned because of stop-and-go driving at low speeds, a concern dismissed by the automakers, who said the speed limitation was only for testing purposes.

Replacement tire provisions in the rule also have caused trouble. They provide for a malfunction warning light to go off if a system does not work with replacement tires.

The original final rule called for automakers to certify that the monitoring systems would work with all replacement tires, a requirement the car companies said was "impracticable."

"There was tremendous noncompliance jeopardy for us," said Robert Strassburger, vice president of vehicle safety for the Alliance of Automobile Manufacturers. He said there are about 240 million replacement tires sold annually and typically two to three sets of replacement tires are bought by car owners.

Strassburger said there are several kinds of specialty replacement tires, and tires that might be developed in the future, that will not work with the systems.

All of these issues have added up to one of NHTSA's most contentious rulemakings and charges by Public Citizen that the agency has weakened the rule.

Interestingly, the very first proposal that NHTSA sent to the Office of Management and Budget for review in 2001 may have been just the ticket because it allowed flexibility in what kinds of monitoring systems automakers could use. But John Graham, head of the regulatory arm of OMB, sent the proposal back to the agency, telling it to concentrate on a less expensive monitoring system tied to the brakes. In trying to please the regulatory overseers at OMB, NHTSA came up with a final rule that landed it in court in 2002.

The delays have disappointed Rep. Edward J. Markey (D-Mass.), who introduced the amendment calling for the systems within two years of a final rulemaking -- a deadline long past. He said he hoped the litigation would "reach a timely conclusion so that this feature can be installed in new cars . . . as soon as possible."