I dont think i totally understand what you mean by this.
Not exactly true. The tires alone will only net you about 1/2 inch of additional ground clearance so yes you are correct with that statement. However the actual suspension lift is going to give you a few more inches of ground clearance under the belly of the vehicle which matters the most when it comes to off roading. As the belly of the XK is rising due to the larger tires and bigger lift, so is the top of the XK. Basically the top of your Commander will sit approx. 3 inches taller then with your current lift provided your running 33 inch tires with the 4 inch superlift.