The Wheel is an item acquired in Bugmuck.
The Wheel was a part of the boiler system located at the heart of the Volcano. When the Volcano erupted, the Wheel was among the debris. Tinker needed the Wheel to complete his rocket, and asked the Hero to retrieve it for him, along with other parts. The Wheel was found in the Bugmuck, in the Coleoptera's nest. The hero killed the bug and retrieved the Wheel successfully.