Advice on hanging gymnastic rings in garage rafters?
Thanks for the contribution from others in answers and comments. At the suggestion of @DMoore, I'm going to answer my own question. 

After the feedback here and reading more, I've made the decision to not try to tackle this project and will be searching for other means to hang rings (a high wall mounted pull up bar or a tall squat rack) since I'm not comfortable enough in either my knowledge or skills and don't want to unnecessarily or dangerously weaken my rafters.

Thanks again for everyone's feedback and help.