It's probably a bug that we missed as WMD members. Just report it on the official forums.
The things is we use cold tyre pressures in the menu and we know that hot tyre pressures can inflate up to 0.3 bar (i.e. a 4-5 PSI increase). So if you start with 1.7 bar cold, you'll be running at around 2.0 bar when they are at optimum racing temperature.