Posted a similar tread as my 6 tires show wear on the outside...so I thought.
https://www.irv2.com/forums/f258/cla...ar-648657.html
BUT.... as NXR posted above...I looked at good pictures of my tires new and sure enough the tread slits don't go to the edges of the outermost thread.
Take another look if your rear tires look the same and are the same tire.
The old adage is true....start with the most simple explanation...in this case it is probably "nothing is wrong...don't over worry". Plus it shows much internet advice should be taken with caution and double checked before heading off in the wrong direction.