Originally Posted by Eric F

A tubeless fail experience...

4 miles into my ride last Sunday morning, I hit something that slashed the sidewall of my rear Conti GP50KTL. It went flat pretty quickly. I pulled the wheel off the bike, and tried rolling the tire around on its side to get sealant to the site of the cut, and hit it with a small shot of CO2. Nope - it wouldn't seal. I pried the bead off to pop in a tube without an issue, and noticed that there wasn't any liquid sealant left in the tire, despite a recent 20ml top-off. I spent about 15 minutes trying to get the nut on the tubeless stem to budge, and it just wouldn't. When I reached my limit for how much pain I would tolerate in my fingertips trying to turn that nut, I called an Uber for a ride home.

Inspecting the tire the next day, I found a pretty clean 1/2" long cut perpendicular to the bead. I reassembled the tire with a fresh load of sealant, but it just wouldn't seal. I pulled it apart again, and threw the tire in the trash. Maybe I could have patched the tire from the inside, or booted it and run a tube, but I choose to just get a new tire.

This wasn't really a failure of the tire. I wouldn't expect that a tubed tire to have survived the same slice, either. It was a failure of the tubeless system...or my lack of carrying pliers (not something I've ever carried)...or me ignorantly tightening the valve stem nut too tight.

This is the second time I've had a sidewall slash issue cause a flat with the GP5KTL. Maybe it's time to try a different tire.