i run two steel (531 and 022) road bikes, two butted aluminum, and two CF bikes, aged 3 to 35 years old, some with carbon forks some with steel. all have 23 or 25's on them most are Vittoria Cora Evos. PSI is about 80 on all of them. they ride a little different, but all in all it's masked by various road conditions and how hard i'm pushing. i treat them equally as far as mileage is concerned. i do avoid the CF's when touring though.