Freightliner Cascadia Steer Axle Over 12000 lbs

They'll go more by what the tires are rated for than the steer axle, just don't exceed the tire rating and you should be good.

 

As Northern Mechanic rightly stated, it is all leverage. Just because a truck leaves the factory with x specifcation doesn't mean it is legal or prudent to operate it that way. The manufacturer cannot possibly know all the ways that truck will be used.
If it is a 12,000 # axle, I would not load it much higher than that. Typically the tires are matched to the axle rating, hence 6175#'s x 2= 12,350#'s. That is the number that would be best not to exceed. You can put up to 20k on a single axle, IF your axle and tires are rated for it.
Even a 5th wheel firmly bolted to the frame with no slide capability can be adjusted by unbolting it and moving it in the needed direction.

 

The ISX is heavier in the front. its easy fixable issue. take off bolts and move 5 wheel's rails about 6-10 inch back on truck frame. May need additional hole drilled on truck frame.

 

Exactly. There are no guarentees that the manufacturer or the company/dealer that rigged up the truck did it correctly.

 

I have a 2012 cascadia with dd15 I have same problem it's partially a design flaw check your steer axle springs and bushings they wear quickly and lower rear air suspension a little they set it at 2 5/8 from factory but it should be at 2 3/8 I don't have a sliding 5th wheel either looking to add one but really check your front springs mine started to look like a recurve bow instead of a curve bow honestly Frieghtliner should put a recall for the fix but of course they won't but they will charge u 700$ per spring when u need new ones