@Simon Dawood I also have a Pajero LWB 2011.
I changed to Yoko AT GO15's (from HT's) last year, and am extremely happy with them - 265/60 R18's. Should have done it sooner. Great even onroad, with a minimum of road noise, and only then, after 110km p/hr. Manufactured in Thailand, Japanese ones not available anymore in the market from what I understood.
I don't have any lift on my Pajero, so some type of limit there. Will defer to @Frederic 's advice and comments. Some in the group have asked me if I've had any issues with the 18inches - none so far. After 34 drives, only one pop-out. I don't ever go lower than 12PSI though.
As @Frederic has mentioned, supply was an issue (with the 18inch) Yokos when I bought them, although did manage to find them at the Yokohama showroom/agency (others had one or two; I was looking for five including the spare) in Al Khabaisi, behind the car showrooms (close to DXB airport). They had literally been manufactured 2 months before my purchase.
Hope this helps...