Gordonandpatti, welcome to irv2.
We have towed our 2006 Saturn Vue (also with Bridgestone tires) approximately 12,000 miles and have driven another 12,000 miles. So far (knock on wood), no tire problems. I have only rotated the tires once. I am overdue to have it done again and plan to do so as soon as we stop in one place long enough to get an appointment.
Make sure your tow bar is as level as possible. See the article in the "Towing Issues & Toads" Forum titled Tow Bar Angle and Height Difference
. If the motorhome is significantly higher than the toad there is a chance the up and down motion of the back of the motorhome could be slightly lifting the toad causing the cupping. I am using a 4" drop receiver with my Allegro Bay and Vue, which results in the tow bay being almost perfectly level. Whether or not a drop receiver is required and how much drop is needed will, of course, will vary with the motorhome and toad.
You don't say what year your Vue is or how many miles it has on it, but as others have said there can also be issues with the car itself that can cause the tires to cup.