The old D402 rear tires were usually good for around 9-11k miles, so if we were talking about a D402 maybe the idea that you had gotten what you paid for at 11k miles might have some merit. Since the D407 is a higher priced dual compound tire that is heavily promoted as having a longer (higher mileage) life, however, the statement from H-D is just more of their BS that they use to avoid paying for their screwups.
Actually, the number of miles on the tire doesn't mean chit. The warranty is based on the amount of tread remaining, not the number of miles on the tire. If the tire has 9/32" of tread when new, and is considered totally used up at 1/32", then you have 8/32" of useable tread. Let's say your tire now measures at 3/32". That means that you still have 2/32" of useable tread, which is 25% of the total. My interpretation of that would be that Dunflop or Harley should pick up 25% of the cost of a replacement tire, assuming the original is defective. If anyone assumes that they should get 100% after using up 75% of the tire, they obviously aren't familiar with how tires or batteries are warranted. BTW, if you go to the Dunflop website, you will note that there is no mileage guarantee on those tires. You might find that type of guarantee on automotive tires, but I've never found it on motorcycle tires.
I'm not certain, sem_bunda, what going to another dealer would do for LETS_ROLL. A dealer isn't going to give some guy who didn't buy the bike from him a free tire. The selling dealer, the guy who made the big profit on the bike, would be the guy I would expect to step up and help his customer. First by interceding with the MoCo on his behalf, then by kicking in some cash toward a new tire if the MoCo won't.
Jerry