Flipping tires is a good way to rip your bicep. You are lifting with bend arms ballistically.
If you’re using mostly your arms, specifically biceps, you’re doing it wrong.
Coach you're are way off base with this from a kinesiology stand point. Lifting a tire with bent arms is dangerous. Show me a video of someone keeping their arms straight lifting a tire. Everyone has bent arms at some point during the lift applying force. Your hips and legs can over power your bicep and rip it.