Surprised it took the 3rd page before someone said something about Dual Compound tires. While I dont have the time or patience to find even more photos to support my argument, I will share my experience.

On 3 different motorcycles inside of the last 10 years, all of my front tires have had what looks like a flat angle on each side of the center compound. And I think that it may have been 3 different manufacturers, but no completely sure. The Triumph Sprint (standard/sport tour) had dual compound. It wore dunlop roadsmarts, and the suzuki c50 had metzlers. Dont remember whats stock on our bike. But all 3 have done the same on the front tire.

Dont know if this helps or not.