So thought I would post an update, felt like a longboat but finally collected my truck mid December and am pretty happy with it. I took it straight to put on the Cooper ST Maxx 275 65 R18 and immediately found scrubbing on the front mud flaps, which I expected. I removed the mud flaps that night and appears with out road test that it was ok. However I found that at the right angle going over something as small as a cross over into a fuel station that they scrubbed on the plastic inner guard, not alot but enough to be a problem.
So, I looked into a few things, without having too much experience playing around with larger tyres etc, and found some quite ups on adjusting the castor to allow more clearance between tyre and wheel arch area. So, I decided to take it to a wheel alignment "specialist in BNE to seek the appropriate advice about doing this. They put it up on the machine and advised that due to the lift kit they were unable to adjust the castor forward anymore than it was as there was not enough adjustment in the standard upper control arms to allow the wheel to be aligned once castor adjusted forward, therefore no resolving my issue.
I then spoke to the tyre shop who recommended the tyre size and advised that it shouldn't be a problem and booked to go see them, I also spoke to service manager at the dealership and he offered to take a look irrespective of me having put the tyres on the vehicle after delivery.
So it went into Toyota first and they managed to adjust the castor forward from approx. 1 deg as it was currently set at to 1.5 deg which didn't sound like much to me, but provided a significant amount of clearance. Maybe 20mm or there abouts.
I also took it back to the tyre shop (the one who recommended the tyre size but did not actually sell or fit the tyres) and they had a look at what Toyota had done and agreed with what was done, and said that in fact there might be a little more adjustment available if I needed it, although Toyota mentioned that they had adjusted to within Toyota specifications for castor adjustment, which I was happy with.
So, only one more thing to do, give it some sort of test. I took it out last week, nothing extreme, but enough to give it a go, and glad to say that at this stage appears that no scrubbing at all, still have the mud flaps off, and don't think there is enough clearance to put them back on, but I haven't tried yet either. Few pics below of test, didn't get too many, had a little one in the back seat so didn't have too much time to play.