AFTER MONTHS OF BACKING AND HAULING, the Firestone Tire & Rubber Co. finally signed an agreement this week to recall and replace millions of its tires that failed to meet federal safety standards. And the tens of thousands of motorists who have been confused and angered by delays in getting safe replacements should be pleased to learn that moments after the signing, National Highway Traffic Safety Administrator Joan Claybrook reported that the federal government plans to fine Firestone up to $800,000.

Certainly sanctions are in order. Firestone should have moved a lot faster on so serious a safety matter. The possible fine stems from new allegations that Firestone violated tire-safety standards in 1976, when its "500" model tire failed government safety tests. Firestone responded then by claiming that it had received a "bad batch" of tires and succeeded in convincing the government that a limited recall of 400,000 tires would take care of things. But now, according to the safety administration, it's been learned that the problems extended to all of Firestone's 500s -- which the company had continued to sell. Administrator Claybrook says Firestone delayed "to save as much money as possible and because of a very serious concern about being defrauded by junk dealers bringing in old tires."

During these delays, and without discussing it with negotiators for the government in the case, Firestone added to public confusion by telling dealers that any tire worn down to a certain point would not be covered by the recall. Under this week's agreement, virtually bald tires covered by the recall will be replaced, provided they are still on the motorist's vehicle. Up until now, even motorists with not-so-worn tires have gone to downtown Washington Firestone dealers and have been told to wait until February or March for an appointment to trade in their tires -- and never mind the risk of a blowout in the meantime.

Any manufacturer may accidentally produce an item that fails to meet federal safety standards -- and consumers can understand such an honest mistake. They can be all the more forgiving when there are diligent efforts to recall such products. But when an estimated 13 million tires that have failed to meet safety standards are rolling along the nation's highways, an enormous number of lives are in danger -- and swift corrective action is absolutely essential. That is the significance of the government's persistence in this case.