The verb "creaked" in the sentence "The big steel wheels creaked a couple times, then started moving" implies a slow, gradual, and somewhat noisy movement. It suggests that the wheels are old or not well-maintained, and as they begin to move, they make a characteristic sound, which is the creaking.
The use of the word "creaked" suits the purpose of the sentence by vividly describing the action of the wheels. It helps create a sensory image for the reader, allowing them to hear and almost feel the wheels' movement. Additionally, the choice of this verb adds to the atmosphere or mood of the scene, potentially conveying a sense of anticipation, as if something important is about to happen, which engages the reader's imagination and curiosity.