Four 2009 full-sized pickups got low marks in side-impact crash tests by the Insurance Institute for Highway Safety, a research group for auto insurers.

Crash protection is 'poor' in crew-cab versions of the Chevrolet Silverado and Nissan Titan without side-impact airbags, according to test results the institute released on Wednesday.

The Dodge Ram with standard side-impact airbags got only a 'marginal' rating, the institute said. The Titan with optional side airbags also was rated marginal. The Silverado with optional side airbags still was rated poor, the institute added.

The Silverado results also apply to its sibling, the GMC Sierra, the institute said.

The institute's four rating categories are good, acceptable, marginal and poor.

Although pickups are touted as workhorses, the side-impact crash protection in the tested models is 'wimpy at best,' the institute said in a statement.

Three pickups tested earlier got 'good' scores in side-impact crash tests, which simulate being struck by another pickup or SUV moving at 31 mph. Those models getting good side-impact scores were the Honda Ridgeline, Ford F-150 and Toyota Tundra, all with side-impact airbags.

All of the full-sized pickups tested got good scores in frontal-impact crashes, conducted at 40 mph.

But pickups, which have advantages of size, weight and height, also should do a good job of protecting occupants in side crashes, said David Zuby, the institute's senior vice president. He contended the Silverado, Titan and Ram 'still miss the mark.'