In the Tyre Flipping obstacle you'll have to flip a tractor tyre.
It won’t be so heavy but you have to know how to tip over it correctly, doing it fast and avoiding to hurt yourself.
A classic error is trying to lift them up only with the arm strength.
You have to crouch down near the tyre, grasp them with the hands, lean and lift the tyre only with the legs strength. Like a rugby player in a scrum.
Remember, you must push, not pull.