There is a TSB relating to rerouting the wires to prevent rubbing. If the inner fender well and outer bumper cowl is properly installed, tight and secure it should not rub anywhere else. On the tires, for what it is worth, here are my thoughts.
The tires are the Nitto Terra Grappler 285x60x18. These are excellent tires, and very resistant to thorns and rocks out in the desert. They do well in the snow as well. There are several options on this size, I opt for the extra tread depth version, they will serve you well. It sounds like you will be passing by this area on your trip. You will note the preferred model chosen here has maximum tread depth as well as maximum plies. I also run nitrogen, and do not find I need to worry about airing down.
They do make a narrower one now, if you prefer it. Here is my choice, with part number followed by a couple of other size options.
size model tread depth, diameter rim width max load / psi
LT285/60R18 E123S 200-880 15.6 31.50 11.50 8.0-(8.5)-10.0 3415 @ 80
*255/55R18 109S 200-440 12.7 28.98 10.35 7.0-(8.0)-9.0 2271@50
*255/60R18 112S 201-180 12.7 30.00 10.28 7.0-(7.5)-9.0 2469@50
P265/70R18 114S 201-080 13.1 32.64 10.67 7.0-(8.0)-9.0 2601@35
*275/65R18 120S 200-930 13.5 32.05 11.06 7.5-(8.0)-9.5 3086@50
LT275/65R18 E123R 200-940 15.6 32.01 10.83 7.5-(8.0)-9.0 3415@80
LT275/70R18 E125S 200-910 15.6 33.27 10.94 7.0-(8.0)-8.5 3640@80
*285/60R18 120S 200-410 13.6 31.30 11.5 8.0-(8.5)-10.0 3086@50
LT285/60R18 E123S 200-880 15.6 31.50 11.50 8.0-(8.5)-10.0 3415@80
LT285/65R18 E125R 200-810 16.5 32.52 11.22 8.0-(8.5)-10.0 3640@80
LT tires with a "C" load range have a 6-ply rating. LT tires with a "D" load range have an 8-ply rating.
LT Tires with an "E" load range have a 10-ply rating.
*Indicates Extra Load (XL)
Due to the fact the gallery image sizes here are too small, you can check out a few pictures here. Substitute . for / disco3 / co / uk /gallery/thumbnails.php?album=21898