I just put a 2" leveling kit on my truck (nothing in the back) and new Toyo Open Country 275/65/20s on my Sierra All Terrain. I just went out to the garage and measured. I don't think it's exact, as it's tricky to eyeball the top of the car and hold the tape measure, but it looks to be about 75" at the highest part.
On another note, I did have to have the installers trim the felt in the wheel wells a little to get the tires not to rub, but I'm glad I went with the 65. The truck looks great and handles very well.