Axle's Hill

Zack comes upon Axle who is struggling to drive up a hill with a large flag that he made. Axle's tires aren't very good at gripping the dirt. Zack's tires are very grippy but he doesn't have enough power to climb the hill with Axle's big flag. They call the strongest Zerby they know, Rex. But Rex can't climb the hill either, because he's a heavy truck and even all his power isn't enough to make it up the hill. Sandy the bulldozer comes by and the Zerbies learn that not only are Bulldozers super powerful, but the caterpillar treads grip the dirt even better than wheels. Sandy not only carries the flag to the top of the hill, but tows up Axle, Zack and Rex as well.