Stone wheel in a trough (by Vincent Jones, CC-BY-SA)

Wagon wheel (by Richard Sonnen, CC-BY-NC-ND)

Steamroller (by Rog Frost, CC-BY-SA)

Car wheel (by Mr T. in DC, CC-BY-ND)

Bicycle wheel (from Soil-Net, CC-BY-NC-SA)

Bulldozer tread (by John Schilling, CC-BY-NC-ND)

Eggbeater (by Candice Wouters, CC-BY-NC-ND)

Table saw (by Patrick Fitzgerald, CC-BY)

Wheel of Fortune (by Paul Stack, CC-BY-ND)

Ferris wheel (by Josh McGinn, CC-BY-ND)