DETROIT — U.S. auto safety regulators are allowing General Motors to delay a large recall of potentially defective air bags, giving the company time to prove that the devices are safe and to possibly avoid a huge financial hit.

The unusual move by the National Highway Traffic Safety Administration buys time for GM to do long-term tests of Takata air bag inflators in older trucks and SUVs including its top-selling vehicle, the Chevrolet Silverado pickup.

GM reluctantly agreed to recall 2.5 million vehicles in May to replace Takata front-passenger inflators. The company said at the time its inflators are unique and safer than those linked to 11 deaths in the U.S. and as many as 16 worldwide.

The company petitioned for the delay last week and the government agreed Monday. The decision delays the recall until Aug. 31, 2017. If GM can prove that the inflators are safe by that time, the recall could be canceled.

The recall also covers the GMC Sierra pickup and many popular full-size SUVs from the 2007 to 2011 model years. Some of the trucks are older than the minimum six years that it takes for Takata inflators to deteriorate and become risky. But GM contends its tests show they are safe for at least 31/2 more years.

The testing could help GM fend off several recalls totaling 6.8 million trucks and SUVS with the same inflators that ultimately could cost the company $870 million, according to a GM filing with securities regulators. Another batch of recalls is slated to start Dec. 31. The delay also pushes the decision into the administration of President-elect Donald Trump, who has said he wants to get rid of unnecessary regulations.

GM said the timing of its filings was motivated by upcoming NHTSA deadlines. “Any other conclusion is just speculation,” it said in a statement.

One auto safety advocate called the decision a backroom deal and questioned whether it would keep people safe.

Takata uses ammonium nitrate to create a small explosion to inflate air bags in a crash. Tests show the chemical can deteriorate when exposed to prolonged high temperatures and airborne moisture. That can make it burn too fast, blowing apart a metal canister and flinging shrapnel into drivers and passengers.

In its petition seeking the delay, GM said 52,000 air bags in its trucks and SUVs have inflated in crashes, and none has ruptured. The company also said Takata has tested 1,475 GM inflators and all worked as designed.

GM also said its inflators have bigger vents than the defective Takata inflators, and stronger steel end caps. It also says its trucks have solar-absorbing glass that holds down cabin temperatures, keeping inflators cooler.

NHTSA's decision will delay the recall by about two months. GM has said it will take until June of 2017 to design and manufacture replacement inflators. GM will continue engineering and will be ready if NHTSA decides the recall should happen.