From memory, my Grand with 30.5" (245/75/16) tyres had a rear diff height only 15 mm lower than my Patrol with 33" tyres.
Saying that, a Patrols rear diff is twice the size of a Grand's.
With a 3" lift, I don't have too much trouble with height, although I try and stay away from the tracks that have large boulders to avoid under sill damage.
The first day I bought the car I took it offroad and struggled to get over a small dirt mound without scraping - hence the lift and largest legal tyres that I could.
Here's the link to my measurements.
http://www.ausjeepoffroad.com/forum/...ghlight=height