How about another option - at the track I compare cold and hot tire pressures for determining optimum pressure. I'm looking for 10% increase. Too little increase means too much cold tire pressure. Too much increase means underinflated cold tire pressure.
I've never tried that experiment with a street tire, but it might be able to give you an indication of the sweet spot, based on the same principles - an over inflated tire doesn't reach optimum temperature, whereas an under inflated tire overheats.
"Bueller, you're an island of sense in a sea of bullshit" - swimmer