Reading their advice, a track Clio (let's say 1100kg ish) would be in the lower range of their 'heavy' category (1000kg - 1400kg). Their advice is then to go for 28-40psi hot.
Cold temperatures are almost irrelevant because you don't know the starting temperature or ambient conditions, so I would always target the hot temperature.
Simplifying it and assuming a linear relationship between the range of weights and pressures that Toyo suggest:
1000kg to 1400kg = 400kg range
28psi to 40psi = 12psi range
Therefore for every 100kg, there is a 3psi difference.
Using that assumption, an 1100kg Clio should be targeting 31psi hot as a baseline, then adjust to suit driving style and handling preference.
Stick a 100kg driver in there (that's generous
)and a full tank of fuel you're up at 1250kg ish? Therefore using this linear relationship you're looking at approx. 32-33psi?
Any thoughts?