A bar that will support 150lbs on a car traveling down the road, will support many times that weight in absence of any acceleration. Yes, it will be fine. I have seen plenty of RTT's on factory roof racks without issue. The longitudinal rails will hold thousands of pounds, the limiting factor is the relative strength of the cross bars and how much they flex while you are up there. They may bounce a bit if you get rowdy in the tent but they wont break.
Auto manufacturers restrictions about weight on the roof is more centered around center of gravity and rollover concerns than it is around the strength of the roof rails and cross bars.
Auto manufacturers restrictions about weight on the roof is more centered around center of gravity and rollover concerns than it is around the strength of the roof rails and cross bars.
