Bert
those 20000 lb axle weights are "max" weights and as you say we don't come into that class truck. We come in the 10000 GVWR and higher weights that FMCSA title 49 mentions. Look at part 571.3 for definitions of terms for GVWR/GAWR/GCWR [no numbers]. Now we go to the state we are registered in for where those weight numbers come from and how those numbers are inforced in the state the vehicle is registered in.
My state for example, when a weight check is required for a 3500 DRW, first looks at the tires capacities. Those officers know what approx weights a 3500 DRW tires fit in. If someone has installed semi truck 22.5 wheels/tires or 4500 19.5 tires/wheels with those higher capacities on that 3500DRW that throws a red flag. The officer then goes to the truck manufactors axle capacities from the trucks door tag and will use the smaller weight numbers between the two. Let me repeat this again, "this is how my state" enforces commercial or non commercial weights on 10000 GVWR and higher trucks. As my state dot officer says "the same weight regs", pertaining to the trucks door tag/plates, are used for that 3500 DRW when used for DOT legal commercial purposes or non commercial purposes or just hauling a RV or using the truck for farm use or going to Lowes for a load on concrete.
I would talk with your province motor vehicle authorities [2 or more] on how they determine and enforce axle weights/tires capacities/and truck GVWR for your trucks class.
JIM
