Roof type, Fixed point:
Roof bars spacing does vary. If you have fixing points, it will be pre-determined where your roof racks will be positioned on the roof of the vehicle.
Roof types, Raised, Flush and T-track slots:
When it comes to these fitment types you can position the bars almost anywhere on the rails. Positioning the bars approximately 70cm apart is considered ideal when fitting accessories such as pods and bike carriers. Keep in mind that when mounting longer accessories you'll need to fit the bars far enough forward so the accessory doesn't foul on the tailgate (If applicable).
Roof type, Plain roof:
The bars attach to a plain roof using vehicle-specific clamps that secure around the door frame. The bars will typically be mounted 70cm apart, it is, however, very important to check the installation instructions to see exactly where the manufacturer recommends the bars to be mounted. The instructions for mounting are usually supplied with the fitting kit.