I noticed some strange damage on my rear tire, where there appear to be diagonally cuts going around the entire wheel. I have no idea what might have caused this damage. I first saw it a few months ago, but didn't think anything of it because I had just replaced my tires with these relatively fancy Panaracer kevlar tires so I figured they should hold up for at least a year.
Anyway, just a few days ago I felt my rear tire bumping and when I looked at it, I could see the tube is starting to bulge out slightly through the cracks in the tire sidewall. The front tire is completely fine, but it's starting to look like I have to replace the back tire.
So my questions are, has anybody else dealt with this issue before? Any ideas what might have caused this damage? Am I indeed correct that the tire needs to be replaced?
First picture has the most severe scarring, the second picture shows how it extends around the entire wheel.