Originally Posted by
ThermionicScott
Rear wheels propel the bike forward by friction between the tire and ground. Just because you don't feel your rear tire slipping on the ground doesn't mean that the rubber isn't being scraped away by drive forces. That's why rear tires tend to square off and wear out faster than fronts, and lots of climbing accelerates the effect. Seems reasonable to intuit that applying more power (especially suddenly rather than smoothly) would lead to quicker wear.
The more rapid wear on a rear tire is due to the fact that it supports most of the total system mass. And when climbing, even more weight is shifted to the rear wheel. By the same token,
chas58 's claim that the rear tire on his tandem wears twice as fast due to 2x power is likely incorrect; it wears faster because it is carrying much more weight.