I was reading an article about synchronizing clocks on the rim of a rotating disc with a central, inertial clock. I was wondering how is this possible or have I misinterpreted something. Clocks on the rim tick slower than the central clock because they move relative to the center, so I don't understand how can the rim clocks agree with the central clock on notion of simultaneity? Long story short, even in non-inertial frames, do clocks ticking at different rates always disagree on simultaneity? That at least seems normal to me. If the time on the rim clocks ticks slower relative to the proper time of the central clock, I don't understand how can the rim clocks adopt the simultaneity where the rim clocks tick slower, that seems like a contradiction. Can anybody explain what is really meant by 'synchronizing rim clocks with the central clock'?