Charles, who are you gonna believe, Wikipedia or your lying eyes?

Here's Mimas at 396 km diameter, not radius, and Miranda at 472 km.

  [Close-up view of Verona Rupes, a 20 km high fault scarp on Miranda, a moon of Uranus.]

Here are the dimensions of some moons of Saturn. Note that even Earth is 12,714 km x 12,756 km with ratio of .997. I added the ratios to this list of moon dimensions.

Tethys	1,072 x 1,056 x 1,052 km = .981
Enceladus	512 x 494 x 490 km = .957
Mimas	418 x 392 x 382 km = .914
Hyperion	370 x 280 x 226 km = .611
Phoebe	230 x 220 x 210 km = .913
Janus	194 x 190 x 154 km = .794
Epimetheus	138 x 110 x 110 km = .797