nickag wrote:
I'm waiting on a Yakima Fulltilt 4 to arrive at my local retailer. The Fulltilt slides into the 50mm hitch, some of the DIY install hitches will only take a towball mount rack. Be aware that if you're installing a DIY type hitch they may have a load rating that limits them to two bikes. The reason I went for a professional hitch install is that it is load rated for four bikes. Make sure you get a hitch that is sufficient for the load you're intending to carry.
Some of this makes no sense.
There are some style of hitches for passenger cars that are not a receiver hitch, which would be the square type. These sometimes have a built in little pedestal that does only take a ball. This has nothing to do with DIY or not. This may be a common one to DIY since it often does not require modifications to the bumper cover, that is all, no other reason. On this type of hitch a "towball" mount as you keep calling it would be a fairly permanent install of hte bike rack as they are designed to be bolted to the hitch or bumper on a truck/suv (which makes no functional sense).
The load rating of a hitch is usually the tongue weight and has nothing to do with the hitch itself but the towing vehicle. If your vehicle has a 2000lbs tow rating in the US the tongue weight limit would be 200lbs. If that same exact car had a version (different engine brakes transmission etc) with a tow rating of 3000lbs that same hitch hardware would fit and the weight limit would be 300lbs. There are classes of hitches that may restrict tongue weight and towing capacity but not at the level we are discussing here. Paying someone to install it is fine, however it doesn't require professional installation in order for the higher capacity to be obtained that has only to do with your level of confidence doing the actual work.
What you would want to find out is not the tongue weight for your vehicle but the actual rating of the hitch. If it can pull 2000lbs of trailer it is going to be able to hold 4 bikes.. think about it. (yes some of the forces are different directions)
However something to think about is the GVWR of the vehicle itself. Most passenger cars have about 800-1000lbs at most headroom over their curb weight. If you've got leather, sunroof etc your headroom on that is even smaller. So if you have 4 bikes on the back, the rack, the hitch (say 30lbs), gear and 4 people you have now most likely blown right over the gvwr of your vehicle and your concerns should not be whether your hitch can hold the weight of 4 bikes (it can) but can you stop and turn properly. Even if you are under your GVWR you may be overweight on your rear axle limit, you've now given your sedan the least desired handling property of a 911, and none of the good ones.