So I went and did the thing I probably should've done 7 years ago and actually mapped out all of the ringboosts you get for a ring. Since the positions don't normally change between rings, you can just create a heatmap and show it in-game, which is what I've done.
This allows to quickly get a visual reference for where you need to be to activate good ringboosts. It also finally clears up where exactly good ringboosts are and aren't.
I've written a Lua script that lets you overlay the heatmap over any ring of your choice. You can check it out
here (GitHub link).
This is the current heatmap. Black shows high-value negative ring boosts, white shows high-value positive ringboosts. Red shows ringboosts that are above the speed cap of 48 / -48. You can clearly see the radial pattern. You could still extend it further to the sides if you wanted.
Here is the raw data. (CSV format, About 5 MiB, currently)