For a given model, the turning radius is set for the different trim levels by the stops, and the determining factor is the tire diameter. They take the widest tire package available for a given trim level, and all vehicles for said level will get the same width stop (rack limiter) no matter what wheel is actually selected for the vehicle.
The limiters can be removed and altered. Don't alter them so much that the tires will rub, or shops will give you a hard time installing tires.
