16.5's are not much good in most mudding folks minds, they don't have the inner lip, or bead as some call it, and if aired down can fold over and come off the rim very easily. Used to be a lot of larger tires were manufactured for 16.5 rims as more of a standard than a 16 or 17+, but now days that isn't the case. 16.5's are becoming obsolete (not to mention unwanted) in the offroad world, and making way for 17's as more of a standard (for 8 lug) or larger.
I remember ten years ago when I got into wheelin, if you wanted a larger 36" plus tire you had to have a 15" rim or a 16.5, something to fit a 16" was rare. Now it's harder and harder to find something to fit a 16.5 wheel.
Guess it all depends on what you are going to do with them.