DEARBORN, Mich. — Ford Motor Co. will offer inflatable rear seat belts in more of its vehicles starting next summer.

Ford was the first in the industry to offer the belts, which are now available on the 2011 Ford Explorer SUV. The company plans to offer them on the Ford Flex, a seven-passenger crossover wagon, and two unnamed Lincoln vehicles.

Inflatable seat belts look like regular seat belts but with slightly more padding, since the air bag is sewn into them. When the car is in a severe crash, a balloon-like cushion inflates along the belt from the shoulder to the buckle. The belts help prevent chest injuries by distributing the force of the crash over an area that’s five times larger than a traditional seat belt. They also cushion the neck.

Ford spent a decade designing and testing the belts.