How can I extrude all faces evenly and scale faces inwards separately? How can I extrude all of these faces on the rim of this cylinder, and then further be able to scale both edges of the newly formed face inwards?

I am trying to make a part of a wheel to a Tiger H1 Heavy Tank, similar to this part here: 

I have already figured out how to extrude all faces evenly, however I'm stuck on how to scale the edges for all of them inwards. The problem is, I can't simply just select all of the edges and scale them, because that turns out very wonky looking!

Here is what I have as of now:
i  to inset, i to toggle individual, Alt + S to move along normal