Interesting points in the replies. I like 28" wheels, tires with sleek pattern and I swear hard pumped tires roll better. New tires are always nice but I have not tought much about the tubes, maybe I should? Neither have I thought much about the inner weave weaken or becomming less bouncy with age. I wear my tires out, thinking it is economical and less waste and I just live with the situation until I get a new pair or I need new for different conditions. Some tires have complex layers of different rubber compounds. I think Schwalbe had a test showing that the harder most durable rubber gives less rolling resistance compared to the softer type giving best grip. Some tires have the same rubber all the way to the kevlar or inner nylon weave, maybe wear affects rolling resistance less then.