First off I should be better prepared. I screwed up and I know it. I run tubular tires and I'm new to cycling; so let me know how dumb this sounds. I just examined at my rear tire and it looks very bald. I feel it needs to be replace now, but I guess I could race on it. I called the local cycle shop and they do not have the model specific replacement I'm currently using. I have a big (tri) race on sunday. I just replaced my front tire a couple hundred miles ago. I have 3 tires that came with the bike originally that are in good shape. Two are used and 1 is new. should I put the tire i'm comfortable with on the rear and put one of the other tires on the front? Changing the rear tire on my cervelo p3 is a PITA due to the rear dropout position. I figured I put my trusted tire on the rear and reglue it, then put the unknown tire on the front which would be a faster fix if it blows in a race.