No, the weight is not an issue. You have to remember, it was designed by Chrysler for Chrysler. The back door and spare tire setup was designed all along to be able to use this Mopar rack. It is interchangeable amongst rear tire mounted Jeeps, so it is a design requirement that the backdoor be strong enough to support both the weight of the tire and bikes.
Its pretty cool how it is set up. It has a turnbolt that reeeeeeeeeally cinches it down inside the bracket, and you have holes so you can put a lock on it to keep would be criminals away. You don't have to worry about it coming loose, it wont. Probably at least 5 inches of that bolt is inside the wheel holder bracket. Also, it comes with a J shaped peice of steel that surround the top cinch bolt, passes through the top plate steel, and down through so that you can padlock it. No one has a chance at getting at your bikes, because you are talking about something that is cinched down and locked to the vehicle, and the bikes are cinched down and padlocked through plated steel. Very secure.
Chrysler designed it to hold two bikes with a max weight of around 50 lbs each, for a total of about 100lbs for bikes. It is secure, smart, cool looking, and it is OEM so why risk someone else's good idea?
EDIT Forgot something. Most bike racks are metal on metal, such as inside the hitch, or on top of a metal rack, etc. This provides no shock or vibration support and will rattle your bikes to death. Just average road travel beats the hell out of them, because there is no mechanism to isolate your bikes from the road. My friends Saab Thule mount vibrated his CF bike so bad his handgrips came loose.
THIS mount, however, solves that completely. See how the center of the rack is tight in the middle of the wheel, but the actual weight bearing structures are braced against, and supported by, the sidewall of the tire? It is exactly the same as an air suspension on a big rig. Any vibration is absorbed by the tire, making this a nearly vibration and rattle free ride, and also preventing you from stripping the installation bolt, because the tire will give slightly with pressure!!!!
Ingenious design. Almost as if Germans had something to do with it.
