You're probably not going to like this answer, but I think the truth is that you really won't know until you mount them. I just picked up a set of 265-60-18's and had to trim the cladding just as much as those with 285-60-18's. You have to remember that these vehicles were hand built so they're not all EXACTLY the same.

As someone who really is averse to cutting ANYTHING if possible, I will tell you that the trimming required for slightly larger tires really isn't bad at all. It was super easy to do in the driveway with a Dremel, and only another OCD VX owner would ever know that it had been done.