All the maximum loading ratings mentioned for our platforms are dynamic loads; this is the maximum weight that can be carried while the vehicle is moving on a sealed road. If you check the instructions for a particular platform, leg set, or mounting system you can see the maximum dynamic weight. You'll also need to check the roof loading limit for your car (check the owner's manual) as they may be different. Adhere to the lower weight.
Static (parked) load ratings are relevant if, for example, you are carrying a roof tent. If you check with your vehicle manufacturer they should be able to confirm the static weight limit. Products like the Backbone, Ruggedline, and Ridge Mount will generally mention these in the instructions.
More information on load ratings can be found here: