My mechanic told me why the front tires of my vehicle wore out faster than the back ones. The first reason was that I didn’t rotate them. Who knew? The more interesting reason is that the front tires of a front-wheel drive car do all the work. They strain between the torque of the motor and the resistance of the street. They also bear the pressure from steering the car in one direction or another. In the end resistance to forward motion, and pressure from changing direction wears them out. Church leaders go bald for the same reasons.