shessh calm down fella!
Diameter of 235/85/16 is 31.7 inches
Diameter of 265/75/16 is 31.6 inches
Body work cutting will be requied for both if you use it for any more than tarmac driving. If you have a 2" lift and extended bump stops you don't need to to do too much, you will need to cut the rear of the rear arches back which is an easy quick job.
The more extreme the off roading you do the more you will need to cut as whem tje axles twist not only will one wheel move backwards, but one wheel will move forwards in certain circumstances - at this point you will catch on the sills so shortened sills and front of rear wheel arches will need to be trimmed. (in the end I had 2" shorter sills and trimmed at least 1" from the entire wheel arch)
Fronts aren't so bad, if yuo have a standard bumper then that will have to have plastic end capps chopped, then as above the sills will need to be trimmed and again an inch or so around the arch depending on extreme of off roading and chunkyness of tyres.
The wider tyres will be the more mods you need to make as they are much more likely to protroud beyond the arch in certain places depending on the off set of the wheels you buy.
You can do it two ways, fit them and see (then wish you hadn't), fit them and see and say damn it to them catching every now and again. Or make all the mods over a weekend or two.
It took me around 3 months of fitting, and trial to see where things caught to work out what to trim and cut. Bit of a shame she caught fire whislt I was making the final mod!
Matthew