Hi, I know you said it is stock, but does it have a lift at all?
Even a two inch lift can affect tyre wear.
Go to a good alignment shop and have them do a castor sweep on the front end.
This will tell you if you need castor correction bushes fitted to the front radius arms.
I have had this done to my two Patrols so far and the difference is very noticable.
Even a sagged suspension wil affect tyre wear in the same manner.
Well worth doing IMHO.

Cheers