I have been running Schwalbe Durano S in size 23 C. The 25c Michelin Optimums are mounted on some HED C2 wheels that I just bought, so I do not know how much can be attributed to the difference in wheels. The new combination gives me the same ride quality as my 35c's on my cross bike. I started the Optimums at a little lower pressure then normal, since the HED wheels are suppose to let you do that for ride quality, but I may need to add some to help with the resistance that I seemed to have. I may at some point put a pair of the Schwalbe's to see if I like them better.