This was me flipping a tire at Super Sprartan Miami 2014. When flipping a tire, be sure to get low and use your legs not just bend over. Bending forward rather than using power from your lower body can cause strains in your back!
This is a very basic move. the main things to focus on in your form are that A- your heels can go flat on the ground (if they cant, move your feet closer to the wall). also, be sure to lift your knee as if youre going to kick or are doing high knees. the most important part is to keep your hips pushed in toward the wall! i do a couple sets of three (usually 3 sets) and then i do another 2 sets of 8. i usually have to do a few in slow motion first just to get the rhythm and movement correct.