Sounds like the Fedex guy took it upon himself to check the signature on file box so he would not have to lug the tires around. I would have asked to see the signature and I would report it to his boss.
“I would have asked to see the signature and I would report it to his boss.”
Have you tried to call FedEx lately and get any customer service? Even talk to a human? Let anyone who has a clue how their own system works when you do talk to a human?
I had items delivered by UPS to a friends house and it satated signature required. The items were delivered whil no one was home.