Tire temperature issue?

The pressure you set them to is the pressure without tire blanket heat. That 80C or so that the tire blankets heat the tire will raise the pressure by about 8 psi (all the tire blankets do is heat the tire so you don't have to do multiple laps getting it up to temperature)...

 

With the lack of dynamic tyre temps on the hud, is tyre pressure a reliable indicator that your tyres are in the right window for optimum grip?

Edit, I suppose there's nothing to stop you massively over inflating stone cold tyres in which case it wouldn't be. But for a reasonably close enough set up, would it be reliable?

 

Yes.

 

Yea, and there is one more good way to see how close you are to optimum grip: after returning to pits look at the graining/blister values (blisters = overheat, graining = too cold). Both are non reversible so if you start without tyre blankets some graining will happen as tyres heat up. Also if there is some blistering on the hardest working tyre and none on the others it means you are roughly in the optimum.

45 is way too high, in completely default setup you should see left side numbers close to 35. It looks like it's either you overdriving the tyres (too much steering probably) or some outstanding bug that would make everyone complain already (so very unlikely).