I had this very problem when I had them on my XR, lovely to begin with and then truly awful on the front end. So much so that when I sold the bike I suggested that the buyer chipped me £300 on the asking price and then go out and buy what he liked to run with.I had this problem on an R1200 RS I fitted them to, and about the same mileage. The centre of the tyre seems to be a harder compound and the shoulder wear quicker. It felt truly awful the way the bike would suddenly tip in. They were the best tyres ever when I first fitted them but I was glad to get rid of them and fitted a pair of Road 5's. I've stuck with them and have now fitted a pair to my F900 xr.