The 300 rear tire is wearing excessively on the left side - upon inspection it seem bulged in the middle.......any ideas - the pressure is set at 40psi
If you let go of the bars while riding which way does the bike drift? Have a buddy ride behind you while rolling down the road and see if your bike is cruising straight up and down. I get this bad on my front tire, but my bike is heavy on the left side so I'm keeping constant right pressure on the bar.
Gotta remember also that the roads are high in the middle most the time so the bike rides on the left of center part all the time. If you pull out of somewhere or take off at stops and throttle it hard on a raised center road, the tire will wear on the left of center anyway no matter what your tire pressure is or if you ride passengers.
... And your wallet might have something to do with it too!!!