wow, only 3500km. you doing alot of burnouts or what. i got 11,000km on the BT012 and im still running on a set of BT014's. with 25,500km on the bike.I liked the BT014 Bridgestone better than Metzlers. However I was getting about 3500 KMs out of the rear and in 1500 very aggressive kms on a multi day ride in an area with lots of twisties I wore out a front tire. Hard trail braking just demolishes them.
To get more kms out of a tire I tried a sport touring tire, and unless you are on the track you will find them very good, they seem to last about twice as long. They make a funny whining noise when leaned over, warm up a little slower,they are more stable in a straight line and take slightly more effort to get started to lean but they remain on track better. I think if you want to get more kms out of your tires donot be scared to try a sport touring tire. I havenot seen many riders who could find the limits of a sport touring tire on the road (if any). The down side is that once they wear down flat on the face you have to put up with feeling the tire move off the flat spot longer because they last longer.