I found some good information on max motor currents for various SK3 motors. Apparently they are produced by SunRay, an OEM in China. Some guys on a RC forum dug this up. These numbers look a LOT more sensible than the ones provided by HobbyKing. For example, you’d think that a 200 Kv 6374 would be able to handle roughly twice the current as a 200 Kv 6354, given that the 6374’s stator is about twice the length of the one in the 6354. But Hobby King lists the SK3 6374 200 Kv at 80A, and most 6354 200 Kv motors are listed as 70A. But if you look at the table below for “60-size motors,” the 6374 200 Kv (listed as a 5035 195 Kv) is rated to 75A, while a 6354 260 Kv (listed as a 5020 225 Kv) is rated to 45A.
You have to convert the listed sizes to our typical naming convention, since the spec sheets refer to the motors by their stator dimensions, i.e. 6374 = 5035, 6354 = 5020, and 5045 is probably either 4020 or 4025.
Check out how max motor current is higher for motors that have higher Kv windings, confirming the idea that you always want to pick the highest Kv you can subject to erpm limits, and your ability to fit more extreme gear-ratios on your board.
Since max rated current is basically the only important spec when it comes torque, having reasonable ratings based on a actual tests is incredibly insightful.