Been running Bridgestone Spitfires virtually since I got this bike. Averaging solo 20,000k's front & rear with very good grip plus audible warning (low pitched howling) that you're getting near the limit. With trailer & pillion aboard. rear dropped to about 16,000k's but front remained about the same. Good all round tyres with pretty good wet weather capabilities at a very good price. Last pair I bought cost $210 the pair fitted and balanced from MTM Motorcycles Brisbane.
Note: rear is 16" in my case.