We get a lot of questions about tent mounting and roof rack systems for roof top tents. There are frequent discussions on expedition and off-highway travel websites on this subject as well. A full discussion of this subject will develop over time, and there are several variables to consider when selecting a rack system for your tent.
Many late model vehicles are equipped with factory side rails and crossbars. The side rails are quite strong, but the factory crossbars are more cosmetic than structural. For this reason, we suggest that the factory crossbars be removed, and a stronger bar system put in place.
In the photo above, the factory side rails on this Toyota 4runner support Thule 450 Crossroads clamps that secure a pair of Thule load bars. The hardware on the Maggiolina fits into a pair of recessed steel channels in the bottom of the tent, and the U bolts and mounting plates secure everything to the crossbars. This is a strong and reliable mounting set-up.