Before we dive in - understand this -- we can give you some guidelines to follow, but you will have to make the final call and are ultimately responsible for carrying anything on top of your vehicle.
The Rev Roof Top Tent weights 86 lbs. This is the total of the Rev Tent at 25 lbs, the Rev Ladder at 11 lbs, and the Rev Platform at 50 lbs. (NOTE: It is possible to carry the tent and ladder in the vehicle, thus drastically reducing the weight on the vehicle roof while moving.)
Many factory/OEM cross bars are curved or more or less ornamental and are not suitable for Roof Top Tent use. It is likely you will need to use after market load carrying systems by Yakima, Thule, Rhino Rack, Front Runner, etc.
For transport, it is safe to have a load bar/cross bar, or rack system that is rated for at least 150 lbs of "Moving Weight."
Most roof tops and load carrying systems will also advertise a "Static Weight". This is how much the system can hold when the vehicle is not moving. The theory is, this should be the weight of the Roof Top Tent, plus the weight of the people (and pets!) in the tent. Manufacturers are very conservative with this number! Good news is: The Rev Roof Top Tent is the lightest system out there, so that will help when doing the math.
If you are unsure about what system is the best to mount your Rev Roof Top Tent to, consider searching online and finding forums where other owners with the same vehicle make and model discuss best practices for mounting roof top tents. There is a ton of valuable information out there by people who have done it before you.
If you find out your vehicle isn't suitable for mounting a Rev Roof Top Tent, you still can camp in a Rev Tent on the ground. You can have all the comfort and features of the best Roof Top Tent, but use it at a lower elevation. You can place a Rev Tent on the roof of a vehicle for transport to the camp site and won't even need load bars or a roof rack. Just strap it down using the Rev Straps and Rev Door Hooks. Save $$, save weight, but still camp like a champ!