This is especilly so on early vehicles up to 7A Model Year. 
The steering rack is set up different for the rim size - internally.
I remember when we received the first batch of Sports as you could option up for 20's. But could only do so from factory otherwise you would hate the drive as you would feel every bump & the steering wheel would transmit alot of NVH quite badly to the driver & at idle you would feel the diesel harshness.
Being like when having a TD5 with shot engine mounts.
LR then decided to fit the rack to all vehicles.
As i have only just found out the rack in the new 3.0ltrs have this "new" rack standard, but the 2.7ltrs "might not".
 
Hope this clarifies a few things

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