In a word, yes. 225/40-18 tyres will fit on a Primera P11/Infiniti…
In a word, yes. 225/40-18 tyres will fit on a Primera P11/Infiniti G20 but with some provisos.
You need to have the correct offset and you need to accept some alterations to the fenders depending on the tire you are using.
I am using Kumho V70A 225/40-18. These tires have the text book definition of a “square shoulder” ie the corner on the edge of the tyre is square. 225 cross section includes all of the tread. The tread is just as wide as the rest of the tyre, the sidewalls do not bulge out. At all.