I have to agree with Scott on the 305/40/22's. I've been doing some research of my own on tire options for when I perform an upgrade myself...and while I was going to stay with 20's and change to 20x10's, I am now looking into going with 22's instead.
The debate now is regarding rim width options...9", 9.5", or 10". I believe I'm going to go with Cooper Zeon LTZ's on my Overland, unless they are not available at time of purchase...then it'll be the Nitto Terra Grapplers as an option, in the same size. Compared to my Hankook's in 275/55/20, I would only lose about 1" of sidewall along radius of tire and put my speedo closer to a correct reading as opposed to now by going up to a 22" rim...which to me is acceptable right now.
As you can see, in the attached pics...the Coopers will fit ok on 22x9's (hence the reason for debate) and I like the look of the tire in general in a 305/40.
(Please excuse the OEM rims in the pics, they were the best pics I could find showing the fit of the tires on a rim.)
I know someone has done a 285/45/22 in an A/T tire (which is over 32" tall), but I don't think anyone has done a 305/40 yet.
Let me know what you think...Enjoy!!