On my visit to the Costco Tire center last fall with the minivan I needed two new winter tires. I was forced to have the new tires on the back rather than the front because some tire company is showing videos of the usual best tires on the front arrangement causing accidents on a test track with a wet surface on a curve. These constraints will result in us buying more tires in the future. When the fronts wear more you can't just move them to the back anymore.
My MH tires had to be replaced due to age before any serious wear was apparent so perhaps this isn't an issue for us.