Matthew W.wrote a review of Continental Grand Prix 4000 S II Tire - Clincher on September 23, 2019
Familiarity: I've used it several times
1st pair of GP4000s. I've used them for roughly 1k miles now, from mountain climbs and descents to spirited suburban riding on relatively good pavement. These tires roll fast, are light for a training tire, and have held up against most road debris. The front tire punctured at 859 miles, and the rear tire punctured at 936 miles - both due to the infamous goathead thorns. In both cases, the thorns punctured well off the centerline of the tire - possibly bypassing the Vectran Breaker layer? No experience riding in significant wet conditions.
Note: not sure if it is just my experience, but these tires can be an absolute PITA to mount on my Mercury M1 disc alloy rims. Maybe I just need more practice...