My tires timed out well before they wore out too. I think that my 2001 tires have about 20,000 miles on them, and one reason I am not camping anymore is I can not afford the replacement tires.
What I did when the price of gas was closer to $1.20 per gallon is move the right rear tires to the front, and keep them in the same direction. So inside became right front, and outside rear became left front. By the time they reached 6 years old, I replaced both front tires with the ones that are still on there, and I never rotated them again.
Fred.