I actaually had that happen quite badly to a pair of grifo's I had. The front I was able to fix simply with some clear superglue, but the rear proceeded to get worse (considering the lower rolling pressure and strain. I contacted challenge and sent some pictures and they quickly sent out some new ones. I only had one small spot on the new ones where they started doing that again. BUT since i went ahead and aqua sealed those, it seems to be holding it down better. Since they are hand made, it's rather unavoidable. I know. Bummer. I guess thats the downside to some lonely man sitting in a warehouse strapping rubber to cotton.