Hey, Sheldon. Thanks for stopping by. "or the fabric shows through the rubber." My experience is that the rubber becoming absent occurs at about the same time. I must have melded our experiences. A mindless meld, perhaps. My apologies. Seems pretty close to me, though. You don't mention front or rear, so I'm guessing this advice applies to either.
Less rubber to deform equates to less rolling resistance, also in my experience. Experiment: Take two brand new tires, mount them on the bike, ride'm. Take two 'experienced' same brand tires, ride'm, and let me know what you think. I say the 'seasoned veterans' roll better.
Lastly, assuming one puts a 'seasoned' rear tire on the front, and a newbie on the rear, one would tend to purchase fewer tires in the long term. Perhaps your experience is that front and rear tires wear at the same rate, but I don't think you'll back that horse.
Again, thanks for the reply/riposte. Rarely have I found anything you've written to be contentious, or inaccurate, or a waste of time to read. I value your input, and have read MANY of your articles and humorous essays. I'm still hoping a FasterCard application will appear in my mailbox...
PS: I still wipe my tires...and I'm pretty sure I get fewer flats because of that silly habit.
Bill "Somewhat Full of Crap" Kipper, aka Starclimber
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Coach Bill