Originally Posted by DQDick
That's actually one way to tell a good trailer tire. The bombs don't weigh anywhere near that.
There's a good reason for the extra weight. They are steel cased. The majority of ST tires with less load carrying ability are fabric cased - mostly polyester.
Any designated steel cased tire with the same size designation as a like sized fabric cased tire will carry the same load at the same PSI. It's all in the cording sizes and their tensile strength.
Quite often, steel cased tires are regrooveable. If so, that feature will be on the tire sidewall. That feature also adds to a tire's weight but not to it's load carrying ability.
The steel cased tire has a unique failure trait, the "zipper rupture".
"(A Zipper rupture is a circumferential rupture in the mid-sidewall of a steel-corded radial tire. These are particularly dangerous as they are unpredictable and often occur with little or no warning to alert the driver or tire service provider.)"