What is the ideal tire pressure for 225 70 R16 studded winter tires?

the ideal tire pressure is usually printed on the side wall of the tire

Comment from Asker:
But the standard tire size for my vehicle (2006 Ford Escape XLT 4x4 Automatic) is 235 70 R16, which I changed to 225 70 R16. Since the tire size is slightly different than the standard one, I think it may be lower than the printed recommended pressure in car's door (not on the side wall of the tire, because this one shows the max pressure but not the recommended pressure).