3 x 7k axle but only 20k GTW???

BurbMan wrote:
It's the tires. A load range E tire has a rating of 3042 lbs @ 80 psi, so the axle is limited to 6084 lbs even though the axle itself is rated at 7k.

So 3 axles is a total of 18,252 plus whatever on the hitch/pin plus a safety margin for loading...side-to-side and front-to-rear, depending on how the rig is loaded will not distribute the load equally over all 6 tires, so if running at max weight it's likely that at least one tire overloaded and one is underloaded.

That would only hold true if the tires are LT tires and not ST. "E" rated ST tires would be rated to 3400 lbs. My toyhauler came with "E" rated ST tires, and the axles were down rated to 6800 lbs. with a GVWR of 18,000 lbs.