I see you are comparing two different tires, Continental 4000 2 and Continental 4000 S so maybe the mileage could be different. I used to use Continental 4000 S 23mm and found I got 3500 miles out of a rear tyre and when I fitted a new tyre it went on the front and I then moved front to rear and I then got an additional 2000 miles out of the old front tyre before it was worn out on the rear wheel. But I found the side walls on them prone to getting ripped too easy so I changed to Maxxis Re-Fuse 23mm which are a lot cheaper and just as fast as the Conti's. I still get 3500 out of a rear but the big difference is only one puncture now in over 5000 miles. For PBP, I fitted 25mm Maxiss Re-Fuse to eliminate any time lost fixing punctures and a bit more comfort.