One thing I've often wndered about is why the same tires are used for both the front and rear. When I look at my tires the rear always wears more than the front. The rear tire also drives the bicycle; while the front tire simply rolls. It seems to me that the forces on the the tires are quite different.

Some roll down tests have shown that tires with flexible sidewalls are faster than those with stiffer sidewalls, but does that mean that they are better at driving the bike; that is transmitting power? I wonder whether it might be better to put a tire with a flexible tire on the front wheel,and one with a stiffer sidewall on the rear.