Tracking wheel sizes

I have noticed recently that many teams with tracking wheels have smaller wheels than their standard drivetrain wheels. They also have a hinge. Is there a reason for smaller tracking wheels? Ex 4 inch powered and 3.25 inch tracking

Most teams like using smaller wheels because they take up less space and are also more precise than larger wheels.

The reason for a hinge is so the wheels maintain contact with the ground at all times and do not slip