Hook47 said: "So now Goodyear is making law? Read the load inflation table, you can increase by 9% with no decrease in speed from the usual 55 MPH. Also, can increase by 16% if you don't go past 45 MPH which is usually the minimum hwy speed. "
No. Goodyear isn't making any law I know about. They (and others) do provide tires that match the ratings that comply with the standards (law) the DOT recognizes in which they specify weight, pressure and speed, each of which is a component of the tires' rating.
By slowing down, one may make some modest increases in weight capacity. One can also add some pressure and carry a bit more. BUT (there's always a BUT) this makes your tires carcass far more susceptible to bruising or breaking from impacts they could otherwise easily absorb. Separations are also more likely from the heat buildup within the tire. Also, I know of no one (thankfully) that drives around impeding trafic at 45 mph down the freeway with grossly overloaded tires/wheels. Even restricting ones' speed to the 55 mph you mention in your post is unlikely over time, at least it is in this part of the country (Nevada. Open roads with speed limits of from 65 to 75 mph for the most part.)
It's possible to mount some tires (implement rated) that are not DOT rated on rims that will fit the hubs on our trucks which can then be used to carry tremendous loads over rough terrain at slow speeds, not to exceed 35 mph. But these tires are of little import to the average RVer or even commercial hauler for that matter.
The tires to which I referred are DOT rated at the weight and pressure I posted, including a speed rating of 75 mph, which is far more in line with what people might actually limit themselves to than some particular percentage of overload at reduced speeds and increased pressures you mention.
I think you might be giving the average person who possesses little actual knowledge of how tires are built and/or rated just enough information to be dangerous to themselves and others. I personally wouldn't advocate exceeding the tires DOT rating. Even exceeding the ST rated tires speed rating of 65 mph on my trailer is spooky to me. Can hardly wait to change them out for some LT rated tires I won't have to worry so much about.
