This is exactly how my tires wear on my 883 L sportster. I had the front one replaced on warranty by HD, then put two more new ones on later that summer as the back one was showing thread. Then I put another new set on the following summer but a different kind. Got a nail in the rear and had to replace that one, now I see that both tires are showing uneven wear again and I've only had them on for 5 months with very little riding. It is impossible to put a harder tire on as none fit and these soft performance tires are not standing up. Really disappointed in HD and that they have made it impossible to switch to a different tire. Getting expensive. My air pressure has been checked regularly and I do not ride crazy.
If your rear tire looks like the one I took off my BMW R1100RT a few years ago, it was caused by driving on crowned roads at highway speeds for long periods of time
measure from the swing arm pivots to the axle centers when adjusting your belt tension .This will center the wheel and reasonably align it .
make sure your shocks are in good shape and not too stiff as this will cause cupping or wavy wear .
lastly ,if you ride 5000 , 7500 , 10,000 miles on roads that are graded to drain to the shoulder , you will see more wear on the left side .
The wheel was not torqued down correctly. So it is not running true down the road. Put it up on stands if you can to get the wheel of the ground. Pit it in gear and run it and see if it looks like it is running straight to you.
wrong pressure / out of balance / skidding
