Originally Posted by ChrisSlicks

The real reason that cars come with Summer tires is car reviews. People like to bench race cars on specs, and the car with the stickiest tire can win a test especially braking, slalom, and skid pad. That is the reason cars like the WRX STi made the switch because they were falling behind their competitors. Basically if one car in the class switches to Summer tires the rest are forced to follow else they risk losing a comparison test.

As for the tires that came on the car, I didn't really care as I pulled them off right away and sold them and then bought what I wanted.