I was running Shinkos when I decided to try the Tourances. Shinkos were ok except that I simply could no longer stand the singing. About from 40 mph to 45-50 mph they were so loud I'm guessing folks in the cars beside me could hear my tires. I'm not an opera fan, and wanted that fat lady to quit belting out her high C or whatever note it was. The rear was almost bald and the front had about 8,000 miles on it with more tread depth than the new Tourances start with!! So I just changed out both Shinkos for two new Tourances. The Shinko appears to be a softer rubber compound. Personally, I don't have a problem running a front 705 and a rear Tourance -- but I might ride differently than you. I just chose to replace both at the same time because of the road noise; plus I got a really great deal on the set of new Tourances then. So far, the Tourances are out performing and out lasting the 705s - and I just put my second set on. So on a per mile cost level, the Tourances are a better tire for me than the Shinkos.