This was from a Lexus blog https://blog.lexus.co.uk/lexus-is-tyre-pressure-and-size-guide/
Pressure
16-inch wheels (SE): The front tyres should be inflated to 36 psi, but this can be increased to 39 psi in the interests of economy at speeds of 100mph or less.
The rear tyres should be inflated to 36 psi, unless five passengers are on board and speeds exceed 100mph. You may choose to increase inflation levels for rear tyres to 39 psi to increase economy. This is only advisable at speeds below 100mph.
Was just curious if it made a difference. I've left it as 36 PSI for now.