Hey Roger, glad you taking her offroad. one thing that I might add is you might want to go with smaller rims rather than bigger ones. there are lots of advantages on going for smaller rims.
more tire options
cheap
greatly improve handling off pavement
etc
if you're going for muds and stuff, you shouldn't go for wider tires, you might not get the traction needed. and you would want to air down, so bigger rims=thinner tires makes it harder.
I've also been to Ocotillo and Anza Borrego Badlands before, have you tried Jacumba? that is one nasty trail for stock vehicle, just East of Indian Reservations on Campo.
My first trip also arranged by the dealer to Ocotillo last October I guess...it's all started from that trip
I've seen the tires used for MKIII G4 Challenges but I couldn't confirm the make of it, maybe someone would comfirm this one.
anyway, welcome to the forum.