Hi Chris,
Bit of a long story. The 18s were on my D3. I had a dual rear Kaymar bar so 285 tyres fitted without isuue on there. They did scrub a little in the guards but not enough to worry me. The biggest issue was the front passenger side where there is a bit of loom running along the chassis. This would be a problem if it either rubbed through or was ripped off. Tombie is correct about it being a problem if dropping to bump stops. Also, was significantly heavier on fuel and the 2.7 was found wanting with the extra gearing and weight (the Toyo R/Ts are a big heavy tyre) meaning it's pick up was a bit lethargic. Having said all that, they actually went well pretty well as far as off road and in the sand goes. Also, they do look pretty cool (which of course is personal opinion) being big wide and chunky.
Sooo, when I sold the 3. I put some other tyres on and kept the 285s as they were only a few 000ks old. They are in the shed. The D4 came with 20"s so I bought a second hand set of Compomotives that came with 265/60 Cooper AT3s with a bit of tread. So the plan is to wear these down and put the 285 on. Spare, I'm guessing will go on roof, or on rear carrier if I have one on by then- which is possible as the 20s have heaps of tread and the coopers are as hard a rock so will take ages to wear

. I'll need to protect the loom in the passenger wheel arch somehow and I have a GOE emergency air up kit (that never, thankfully, got fitted to the D3) to fit.
Now, knowing what I know now. I wouldn't go for 285s. I'd look at either 265/60 or the 265/65 (though this is off the top of my head, here is heaps of info on here about sizes) as they fit better and the 285s don't offer any performance advantages.
Hope this helps.
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