[Slydria]

Generally, I find 4-7ft to be the acceptable range for most characters. If you want to go over or under, there should be a reason for it. (I.e. for instance a genetic disorder like dwarfism).

Mechanations are a little more free from this range since you can generally make them out of sturdier stuff, of course this is still within reason.

It's also fair to assume hardier races like say Lupines or Hyattrs would be on average taller, so a bit of hand waving is fine in some cases.

However, when you get to the extreme ranges (under 2ft assuming this isn't a young child or over 9ft) that's when I feel you're getting far too carried away, even if you have an excuse.

In the example you gave, that would be put down (though this is the first I'm hearing about a 13ft character). I mean seriously, armor adding 5ft? That's not armor, those are like stilts.