Jamieson, Fausset and Brown on Ezekiel 1:18

18. rings--that is, felloes or circumferences of the wheels.

eyes--The multiplicity of eyes here in the wheels, and Eze 10:12, in the cherubim themselves, symbolizes the plenitude of intelligent life, the eye being the window through which "the spirit of the living creatures" in the wheels (Eze 1:20) looks forth (compare Zec 4:10). As the wheels signify the providence of God, so the eyes imply that He sees all the circumstances of each case, and does nothing by blind impulse.