Should I expect from a set of road tires? My rear is squared off and I seem to be getting an lot of flats on my front (a run of bad luck?). I searched the forum and saw people throwing out numbers like 6k miles...I asked at my LBS and he said 800-1000 miles (yes, I realize he may just be trying to sell me tires). He also said I could expect my front to last half again as long. Any thoughts?