I have 2 old Valkyries with a total of over 270,000 miles. After trying Dunlops, Bridgestones, and Metzelers, I settled on Avon 'Tyres'. I've installed dozens of the Avons, and every time the new tire felt much better than the one I just removed. I think tires deteriorate slowly and we hardly notice, until we replace them.

IMO the OEM Bridgestones are a very good tire. My only complaints are they seem skittish on tar strips, and they don't last too long. On my Valkyries I always get over 12,000 miles from a rear Avon, while the Bridgestone I tried only gave me 8,500. On my F6B I'm getting about 10,000 from a rear Bridgestone. When I wear my current tires out I'll be trying some Avons.