A wheel structure contains: a body and a rubber loop. The body is one piece formed and includes an arcuate face surrounding around an outer surface thereof, a peripheral groove defined around an outer rim of the arcuate face to fit with the rubber loop, a peripheral face defined around a peripheral side of the body, a first slot arranged around a left side of the peripheral face, and a second slot formed around a right side of the peripheral face, wherein the first slot and the second slot retain with the rubber loop.