Just adding my experience with the RT660’s. Ran a set from middle of last year until December without any abnormal wear to speak of and got about 90+ runs out of them with no issues other than loss of grip which is to be expected. I replaced them with another set after being very happy with them and experienced center rib issues on 3 out of 4 tires. One failure occurred after about 6 runs, the other two failed the next day during competition after being swapped front to back. Approximately 14 runs before I have 3 tires that look like they’re falling apart and one that’s wearing normally.
I am running the same pressures as I did with the previous set and cooling them in between runs, the only major change I can speak of is the addition of camber. I have a friend running an almost identical setup and he isn’t having any issues with the RT660’s.
All that being said it’s not the first time I’ve seen them fail and I’m hoping I was just unlucky. I’ll probably run some Rivals at the next event. I don’t want to have to worry about having a ruined set of tires after 1-2 events.