While I respect Bill on satellite info my experience on tags is different. My tags at about 11K lbs have considerable less wear than the duals. It really it doesn't make any difference in my typical driving how much the tag scrubs - consider how often you make a a tight turn - ie several in a CG vs 100's of miles on the road.
Soon I'm going to replace my tag tires and dual tires because both are BadYear original tires installed by Monaco. The fronts with excessive BadYear river edge wear were replace last summer, with 25K miles.
Unfortunately Monaco choose to install BadYear tires and I've moved on.