[TheMan]

It sounds like the weight thing might be the trick, if your bed is empty.
Put 3 bales, or about 600 lbs over the rear axle and let me know if that did the trick.
Sidebar story. I once pulled up to a muddy construction site with about 1,000 lbs of hardware in my bed, drove right up to the storage shed, just like it was dry pavement. Unloaded the Dodge and couldn't move!
Had to tie a tractor onto my front bumper and the two of us barely made it out.
Weight properly distributed can work wonders.

...and now you know why VCI is important.