The first half of the mileage was two up and the second half was two up but fully loaded with camping gear. Tyre pressures were correct and the stated bike carrying capacity wasn't exceeded.
I appreciate you say the pressures were correct at the time but what pressures did you have ? Was they at the Suzuki recommend pressures or Michelin's ?
Looking at the picture you provide the tyre looks to me like it's been ridden under inflated.
Under inflation results in alot of extra heat and the outer edges of the tyre wearing prematurely.
When you add two up fully loaded weights to the equation you get accelerated wear.
The recommended pressures are a guide and not exact as different tyres require different pressures.
If you had say a Bridgestone on the rear you would need less psi than a Michelin because of the makeup of the tyre , Bridgestone being alot heavier and harder especially in the side walls however , Michelin's are made alot softer and require more PSI.
Just to give you and example I have a small Honda CB500F with PR4s fitted , 160/60/17 rear and 120/70/17 front . The bike is very light, I ride solo but keep the pressures at 42psi rear and 38psi front.
To be honest Michelin should state their tyres need harder pressures.
