Do you understand the construction of vehicles?

"The roof-crush regulation was finally updated, after many years of deliberation, in 2009. That was the first significant update in 38 years. The mandatory three-year phase-in period starts with vehicles manufactured in September, 2012. This rule change could represent a significant safety improvement, but some safety advocates say the proposal doesn't go far enough.

Background on rollover-resistance standard. The old "roof crush" requirement was promulgated in 1973. That regulation is Federal Motor Vehicle Safety Standard 216. It required automakers to subject a sample of every model to a roof-crush test before it could be sold. In that test a stationary vehicle had a weight pressed against one edge of its roof. The roof had to withstand a force equivalent to 1.5 times the weight of the vehicle, up to a limit of 5,000 pounds, without the plate moving more than 5 inches."


My H3 curb weight is 4700lbs, so what is the roof-crush weight?

 

The roof crush limit if for specifically that, a potential roll over situation. That doesn't mean the roof won't buckle or deflect leading to additional problems. But hey, your Hummer, your choice. Forums are for relating experiences and expressing opinions. The general opinion here is it's not advisable to put loads on the roof that exceed the limits of what the roof rack was designed to carry. BTW, have a mishap and see where the lawsuit goes.

 

Don't worry about me, I have been hauling heavy loads on the roof of my vehicles for over 35yrs. My last roof hauler was a 1998 s-10 blazer that I purchased in 2000, I also loaded as much or more on that roof, which is way beyond "your limits"? I never had a problem, and sold it in 2012 for $6k. Let me know if you need anymore information on the capable weight I have hauled on the roof of my vehicles in the past, I've been driving since the 70's.

 

Believe me, you're the last person I worry about. Manufacturers put out numbers and limits on things because of safety and liability and they realize all types of people with varying degrees of knowledge, expertise and common sense will use their products. And you are correct, they do go conservative because the consumer doesn't always follow their guidelines in the strictest sense. But, that said, keep doing what you're doing if it works for you. I myself would use a pick up truck for loads of that size and weight because they are designed with just that job in mind. You know, the "choose the correct tool for the job" effect. And when I look for information I'll use the manufacturer's information. It's been derived by engineers using design models and supported by physics, not by "Strap it down and let's see how she does." Like the comedian Ron White says "You can't fix stupid."

 

Just because you can or have does not make it safe nor does it make it right.
Another persons safety (other than in your vehicle) is a factor that should be considered too.