Answer: Tom changed the tire.
Step-by-step explanation:
Active voice helps provide a different shift in the grammatical layout of particular sentences. It occurs when the subject of the sentence performs the action expressed by the given verb.
We are given the following sentence: "The tire was changed by Tom."
Using active voice we have to alter the sentence in such a way where it directly states that Tom is the one doing the aspect of changing the tire.
With such alterations, we are left with: Tom changed the tire.