How to know how much weight a Trailer/Truck can handle w/o damage

every load i haul is over 80k my truck is single frame mostly hwy specs. but its got a pusher axle added and i pull 3 axle trailers, i can be as heavy as 105,500 lbs legally at times, its not going to break the truck, but it does add wear and tear, my repair costs per mile would seem high compared to a truck that never goes over 80k.

 

I thought I mentioned this, but I didn't. We had permits to run the loads I carried.

My 'yard' was an open mine with a haul road and a backhoe to load us. There was no scale on site. There were no DOT scales to my destination. It would of been difficult to load over the permitted weights.anyways
The owners decided that they were happy with anything between 93-96k on the pushout trailer I pulled.