I go with the vehicle’s pressure recommendation for PSI. As you said, the info on the tire is the maximum of which the tires is safely capable, not the optimum. I do experiment on my cars to get it right. On my motorcycle I go with the bike numbers.
Should work the same for a bike. Overinflated, it will wear in the middle, underinflated it will wear on the outside edges. I’ve been doing it thaat way since the late 70’s, works perfect. I just watch tire wear. Adjust accordingly.
I have no idea what the sticker on my car says. Tires say 35psi, with the PTCruiser I’m in now, 30psi seems to work great. Jeep Cherokee I had before liked 28 a lot better.