I got a sidewall blowout on a GP4000 25mm-wide at 1400 mi. Otherwise, the 4000S 23's seem to be flat-immune to about 2400ish mi, keep an eye on the wear dimples, and either replace when they look near-obliterated, or wait til you get a couple close-in-time punctures. I've ridden Vittorias, Specialized, Panaracers that come to mind, these contis are nice tires, to me. YMMV.