On Sunday, September 29, 2019 at 2:37:44 PM UTC-4, Ned Mantei wrote:

Some (many? most?) rims have wear indicators. At least for Mavic XC717
and X719 there are/were tiny holes going partway into the rim. The idea
is that the rim should be replaced when the holes are no longer visible.

None of my rims have those. If I had one around, I'd mike the thickness from
the bottom of the wear indicator to the inside edge of the rim. That should be the assumed minimum safe thickness.

- Frank Krygowski