Rim depth vs Tire Width

Hi All,
I am having a hard time getting a clear picture about what the min/max tire width for my rims would be (18 x 9). Is is all just dependent on the tire manufacturer? A lot of the online graphs suggest a max width of 265 for 9 inch rims, but I have seen on several threads that those tires would be too skinny.
I currently have 275/65/18 Wrangler Duratracs on my truck and need new tires.
I'm looking at the BFG KO2s. My local tire shop has 275/70/18, but the manufacturer site says max width for that is 8.5, although the guys at the shop don't seemed concerned.
On the other hand, I was considering 265/70/18 and per the manufacturer site, max width for that would be 9 inches.
What say all you tire/wheel guru's out there?
Many thanks in advance for the advice!!!

 

275/70/18 on 18x9 wheel. These tires are only spec'd up to an 8.5" wheel per the manufacturer. I wouldn't hesitate to go a half inch over spec.

 

I personally never like the tire to be less than 2” wider than the wheel. I.e. 10” wide 7-8” wheel, 11” wide 8-9” wide wheel. That will always insure you have good tire bead pressure on the rim. Has worked well for over the years.

 

We always like to recommend sticking to the tire manufacturer's recommended specs. They must have solid safety reasons to provide the range that they do for each given size.