What is the correct tyre pressure for a 205/50/16

Under the lid in the center console, between the front seats, you should find the label with the information relating to the tyre pressures

Look on the tire. The recomended ptessure should be printed on the sidewall. Otherwise, call your Ford dealer. They will know.

I can calculate it with spreadsheet I made, call myself tyre-pressure specialist nowadays.
Depends on tyres maximum load and Pressure needed for that ( AT pressure 6pr 55psi/3.8 bar, 8pr 65psi/4.5bar or 69/70psi/4.75/4.8bar). and maximum speed of tyre given as letter mostly N to R for caravans.

Then from Caravan MPVW ( max permissable Vehicle Weight).
Or better real weight ( overloading is more rule then exeption and unequall load is possible.

But normal car tyres or XL/reinforced/Extraload are sometimes OK if they have enaugh maximum load for MPVW.
Will try to make picture of example.

Depends also on the kind of tyre.
For the maximum load of tyre nex kinds need next pressure , wich is called AT-pressure/maxloadpressure/reference-pressure , for up to maximum speed of tyre or if lower 160km/99m/h. This is not the maximum pressure of tyre.

Normal car tyre /standardload AT 2.5bar/36psi ( exeptions as low as 2.2)
XL/Reinforced/Extraload AT 2.9bar/42psi ( exeptions 2.8 and 3.0)
6PR( plyrating) /C-load AT 3.8bar/55psi EUR ( USA 50psi/3.4bar)
8PR/D-load AT 4.5/4.8 bar/ 65/69/70 psi
From E -load is not often used in Europe.

From this AT pressure you can calculate the needed pressure for lower loads . Made spreadsheet for it in wich I first add 10% to the assumed load before calculating.
Will give example picture

Tire pressure should be written inside the drivers or passengers side door jams or the owners manual...

the link I supplied below with give you the tire pressure specs depending on which model civic you have

http://www.drivegreen.com/ATP-%20honda.htm

hi from uk the light/simbol you dscribe illuminated is the tyre pressures monitoring warning this is indicating that one or more of your tyres is under inflated in other words you need to check and inflate all tyres to correct pressure as indicated/recommended in handbook the light should reset after driving if not ceck h/book tyres info

40psi to ensure good ride quality and good rims

This is depending on the tyre size. Assuming this is a factory set you can check the following.

http://www.thetyrepressuremonitor.com/tyrepressures_renault.html

DEPENDING ON TYPE OF TYRES IT SHOULD BE 2.2BAR LOOK ON THE TYRE PRESSURE IS PRINTED ON THE TYRE