Court did a review, so you can take a look at that.
We found they did fine--they are individually bungied to the rack--they aren't just clattering. There is a cross-bar that isn't evident in my photo, and each has its own built-in place to put each lower wheel.
Wheels/rims did fine hanging from the rack. We did not have any interest in driving 75-80mph with bikes on a rack--we stuck to speed limits and highways/roads had good quality pavement.
As for stress on the hitch, this rack requires a class III hitch. Class III is a minimum of 500 pounds. Ours is rated even higher than that.
We liked how visible the bikes are from in the car. You CANNOT drive into a garage with this rack attached.
As for how low the bikes hang (clearance from the ground), we had no difficulties with a very steep driveway at the rental house on our vacation. Our car required the extension piece, which we ordered with the rack. There are instructions on how to determine if one's car needs the extension piece.
We are satisfied with the rack. It does take us two people to load, but we bought it for vacations when we take all four bikes. Otherwise, we don't need a rack to hold all of our bikes--we do most recreational riding from home, or with just two of us at a time.