I too had a Metzler Z4 front with a belt separation at 9,450 miles on a 2005 FJR. The tread depth was not near the end, there was a lot left. This separation, unfortunately for me, occured 300 miles from home on the way to the EOM weekend. To prevent the loss of the weekend, I bought a new tire from a local Yamaha dealer. I am now in the process of getting Yamaha to cover the loss. They have not refused yet, they are in the process of getting the defective from the dealer so that they can inspect it for themself. The Yamaha customer service rep told me that if the tire is defective, they would reimburse me for the cost of the new front tire. We'll see how it goes.