On the XL-7s (which are basically just the extended version) with the Rocky Road coil spacers you can run a 235/75/16 (29.1) with no problems.
With the Calmini 2.5 you fit a 245/75/16 (= to 31x9.5) with minor modifications to the front wheel well. Just bending over the pinch weld at the floor pan and trimming a little plastic inside at the front.
I am currently working on getting 32s under my rig (265/75/16) I have the Calmini 2.5 and I will be installing the Rocky Road 2" body lift and replacing the bumpers with hi-clearance steel bumpers, OME struts, etc...
You can follow it in the XL-7 group. Plus I will be writing up some "how-tos" soon. Most should translate pretty good to the GV as well as I have a 2001 model and they really are closer to each other than say the '05 models.