Two of the most popular light trucks used by fleets – the Ford F-150 and the Dodge Ram – received poor safety ratings in a study released today by the Insurance Institute for Highway Safety (IIHS).

The institute characterized the safety performance of the Ford F-150 (seen being tested in both photos) and Dodge Ram in 40-mph tests as poor. In the case of the F-150, the institute said it's about as "bad as it gets."

Ford said today other test results have shown the F-150 to be "outstanding," with a high level of safety. DaimlerChrysler, maker of the Dodge Ram, issued a release saying no single test reflects a vehicle's "real-world safety."

James Vondale, director of Fords' automotive safety office, echoed DaimlerChrysler’s claim. He called the frontal offset test “an extremely severe high-speed test that does not often occur in real-world situations.”

“The F-150 exhibited major collapse of the occupant compartment in the offset test,” said Brian O'Neill, IIHS president. “As a result of this collapse, the dummy's movement wasn't well controlled.”

O’Neill said high-injury measures were recorded on the dummy's head and neck. He added that the airbag deployed late in the crash, which contributed to the high injury measures.

"This was a very poor performer," O'Neill said.

Public relations-wise, the timing of the study could not be worse for Ford. The F-150 is one of the Ford vehicles that came equipped with the now-controversial Firestone Wilderness AT tires. Ford recalled 13-million vehicles, including Explorer SUVs and Ranger light trucks, two weeks ago because it said those tires are unsafe.

Bridgestone/Firestone Inc. requested last week that the National Highway Traffic Safety Administration begin an investigation into the safety of certain models of the Ford Explorer.

The two other light trucks tested by IIHS fared much better.

The Toyota Tundra got a good overall rating, along with a good rating for five of six sub-categories. It received a marginal rating only for the chance of an injury to a driver's right foot.

The GMC Sierra 1500 and its twin Chevrolet Silverado 1500 received a marginal rating overall, with a good rating for its prevention of different types of injuries, but poor ratings for the cab's structural integrity as well as how well the airbag, seat belts and other restraints restricted movement by a crash dummy during the test.

The institute is a private organization funded by auto insurers. The institute's crash-worthiness evaluations consist of three performance measurements: occupant compartment intrusion, injury measurements of a dummy in the driver seat, and analysis of how well the vehicle restraint system controlled dummy movement.