What C Rate is 16ohm cell?

16ohm or milliohm (correct me here)...
My IR tester shows that a brand new 25R (8C) is 7, a brand new LG M26 (3.9C) is 28 and I have unknown cells that are about 1.8Ah and 16 ohm(/milliohm) and wanted to know the C rate by their IR.

It's milliohm.

I never fully trust what my tester says about the resistance anyways. I discharge the Cell at different Currents and monitor the temp.

You probably have a ACIR tester which isn't useful for determining c-rate and as mentioned probably isn't even that accurate to begin with.

25R does about 10C even with some aging but gets warm.