I have just put new tyres on her after 11,600km city riding with the original ones. There was plenty of grip left but the front tyre had developed 2 shallow cracks in the middle, that ran the full circumference of the tyre. The same thing had started to develop on the back tyre as well. I have no idea what caused this?
Anyway, I put on some Bridgestones, and although I have just started bedding them in, already there is a massive improvement in grip. I also checked my brakes whilst at the garage and had to change the rear pad (1st time) but the front is still okay. They told me at the last service that it was just below half way, and probably okay for another 2k km. However, I've done 1100 since and it was really low so changed it no hesitation.