23K on the stock F1's here myself. Hoping to get through this one last summer...maybe 30k out of them. I don't know if I'll make it though! :) They are already starting to spin quite a bit more than they used to, but checking the tread they still have some left. Not sure what I want for next tires, but the super sports are #1 on the list right now. Checking to see if I want to get something that's closer to an R compound and trade of longevity of the tire for more grip.