Hello Keith,
when I bought our Amethyst in 2010 it changed lanes every time a truck drove past us. It was nerve wracking keeping her in the lane.
Steer tires were 11R22.5.........totally undersized for front load but specs plate behind drivers seat stated they were correct!!
We installed 295/ 80 R22.5's and new shocks. Josams did not find any mechanical issues .
She has now gone nearly 40,000 miles and steers like a dream.
Dont need a steering stabilizer.