I am a retired engineer. Yes, most products are designed with a "safety margin". But, it is just that, a "safety margin". It is not intended to be used up in normal usage. It is intended to extend the useful life of the product and to provide for unforeseen/emergency situations. You may get by for years exceeding a products ratings, but when an emergency does arise,it may well fail from the abuse. If your insurance company learns you were using a hitch beyond its limit, and it fails in an accident, you can bet they are not going to pay. Myself, I am a firm believer in the 80% rule.