Encore Puzzler August 29, 1998: Playing Chicken

This guy is driving a truck that weighs 2 tons, and in the truck, he has a thousand pounds worth of chickens. He's driving along, and he sees a sign that says the bridge ahead has a 5000 pound limit. Afraid that he has too many pounds, he doesn't know what to do. He gets out and starts to beat on the truck so that the chickens will fly. Does this work? Why or why not?

[ Car Talk Puzzler ]