physics
posted by bubble .
An automobile tire is rated to last for 60,000 miles. To an order of magnitude, through how many revolutions will it turn? I don't know what circumference i should use for 1 rev

According to
http://www.ajdesigner.com/fl_tire/tire.php
the circumference of a typical automobile tire (205 60SR15) is 2.0 meters.
Convert 30,000 miles to meters (by multiplying by 1609 meters/mile) and divided it by 2 meters per revolution.