New York Codes, Rules and Regulations
Title 15 - Department of Motor Vehicles
Chapter I - REGULATIONS OF THE COMMISSIONER
Subchapter D - Equipment
Part 58 - Rear-view Mirrors And Rear Object Detection Devices
Section 58.6 - Requirements for multipurpose passenger vehicles, trucks, and buses with gvwr of more than 10,000 pounds

Each multipurpose passenger vehicle, truck, and bus with a GVWR of more than 10,000 pounds shall have outside mirrors of unit magnification, each with not less than 50 square inches of reflective surface, installed with stable supports on both sides of the vehicle. The mirrors shall be located so as to provide the driver a view to the rear along both sides of the vehicle and shall be adjustable in both the horizontal and vertical directions to view the rearward scene.