That is a very complicated formula that also has to account for maximum light flux, relative humidity, air circulation, and root temps. Maximizing all those components to the equation would allow/require temps into the upper 80's for full utilization rates.
An experienced grower will recognize the various stress markers when running the system full tilt boogy and adjust the parameters on the fly, but the greatest mode of failure with higher temps is fluffy buds - so approach temp's over 85 with due caution.