This playlist on YouTube shows where all 180 of the Red Rings are located for each Zone.
https://www.youtube.com/playlist?list=PLzW8CnEl03XoVpGJAzs6A...Do not attempt this until you have unlocked all of the wisps (ie until you unlock the Terminal Velocity Zone); many are inaccessible without certain ones being unlocked. You will have to revisit each level once you've unlocked them all.