I asked Bill Burke for his input on the subject:
"Yeah, pretty much what I thought! They are rated as lifting eyes so the safety factor is good with the Working Load Limit and Proof testing rating.
They are popular with rover folks for some reason. The fastener on your bumper uses a "split" lock washer which will open up after some time and the nut will need to be checked frequently. I suggest you get a "crimp" nut and remove the split washer.
I also suggest you look at the flat washer - although the bumper looks substantial - unless it is 1/4" or so the small surface area the nut and washer encompass looks to me like a larger surface area (backing plate or larger width washer) would be prudent.
Secondly: the fastener looks to be course thread and I suggest a fine thread since it is the threads that actually bear the brunt of the force for any load.
Again, these aren't really rated for dynamic loads but have a rating good enough to handle vehicle recovery with a 6000gvw vehicle. They are designed for static loads - as in crane and over head lifting operations.
I have had many discussions with bumper makers that install these.....much to my aggravation on their reluctance to offer a complete safe package for those "eyes!" I have seen them stress the metal on the bumper, strip threads on the fastener.
The ones you have are fine for most light recoverys. With time you will want to inspect frequently - or change over the fastener and backing plate.
Bill"