I took my Metzeler Roadtec 02 off my PP last night and replaced them with Angel GT2. I couldn't believe how thin the rear was in the middle of the tyre, it can be pushed in with no force at all, they are down to the wear indicators admittedly. It shows how good tyre manufacture is that sharp stones don't just go straight through when they worn, or lucky. Both front and rear on wear indicators, done approx 4200 miles on them. Very good grip wet and dry, but they wore in a strange way across the front tyre, perhaps the weight of the bike, or the tyre design, or me, but felt really odd when going into corners for about the last 1000 miles. Won't have them again.
Front tyres often wear on the outer edges due to road camber. When the wear is quite high, this can lead to a strange sensation when leaning over.
I’ve just changed the tyres on my 899 both Pirelli and just on the wear limits, the rear as you say was also really thin in the middle and when I was stacking them up ready to fly tip I noticed a sharp stone had actually punctured it so I guess they can push through. The Bridgestones are just as thin in the middle when I change them as well.
Flytip Mine get a second life on the farm, work really well with rat poison, raise off the ground a bit, poison inside the tyre, put a slab on top, rats think its great as they can feed on the yummy poison in a fairly dark, hidden place. They aren't too fussy about tyre brand!
