The loaded tires will add as much as 123lbs per sideaccording to the manual (my
BX1500 shares the same manual) depending on concentration of Calcium.
I'd use either anti freeze or Rimguard (even heavier than Calcium) The big advantage is that it's so low that it keeps your center of gravity down compared to weight elsewhere.
It will help keep the uphill tire on the ground when you try doing things you shouldn't, but sometimes have no choice, like carrying loads in the FEL going down hill, then turning while still on the hill.
When using the FEL the ballast box should also be used. I usually fill my rear tires within a couple days of getting a new tractor. The tires affect more of the side to side stability while the Ballast affects more of the front to rear stability.
I don't have a loader on my BX, but on my
L3010 I would rate the loader as somewhere between vicious and flat out TFD (too f'n dangerous) without tires loaded or ballast, with tires loaded and no ballast I would call it a little touchy with heavy loads. With both, a little kid could run it with supervision.