Yes, conservatively, I would agree with that. You might be able to squeeze more, but it just depends. There seems to be some minor variation between individual trucks too. I was originally going to go with bigger tires, and when I saw the stock setup with the level, I thought it looks great as-is. Plus, unlike on the 20's and 18's, the factory tires on the 22's are larger (285 vs 275) and really nice. They are also an AT tire, not a regular tire, so unless you plan to go mudding (unlikely with 22's and a Denali) I don't think a change of tires is needed.
BTW, you should look up the piping mod and do it to your truck. Some blue piping would look sick that that blue exterior. I did the grey piping on mine and it looks amazing.