try Dunlop or Avon for a change
Hi - I like the BT45s but agree with you the rear does not last long - after about 4000 miles the central line gets worn away. As an alternative for my 2nd GPz550 I got a Dunlop GT501, similar price to BT45
which after 4000 miles still has plenty tread left - there is no central groove which is where the BT45 gets worn out, and this is as good handling as the BT45 and even in the wet.
Another choice is Avon Roadrider which is cheaper, handling in the dry as good as the 45 and 501, only a few times when leant over in the wet accelerating it slipped where the other 2 had never had on the same road same conditions but the rear lasts over 6000 miles, and I just adjust my riding in the wet and been fine