A method of operating a vehicle at different altitudes, the vehicle comprising: an engine; a throttle operator being operable by a driver of the vehicle; a throttle valve regulating airflow to the engine, a throttle valve position of the throttle valve being based at least in part on a throttle operator position of the throttle operator; a continuously variable transmission operatively connected to the engine, the CVT including a driving pulley, a driven pulley, and a belt operatively connecting the driving pulley to the driven pulley; at least one ground engaging member operatively connected to the driven pulley and comprising at least one of: a wheel and a track; a plurality of centrifugal weights operatively connected to the driving pulley for controlling an effective diameter of the driving pulley; a piston operatively connected to the driving pulley for applying a piston force to the driving pulley when actuated and thereby changing the effective diameter of the driving pulley; and a control unit for controlling actuation of the piston and the piston force, the method comprising: controlling the effective diameter of the driving pulley, via the plurality of the centrifugal weights, responsive to a driving pulley speed; determining at least one of an altitude and an atmospheric pressure; determining a driven pulley speed; determining at least one of the throttle operator position and the throttle valve position; selectively actuating the piston based on the at least one of the altitude and the atmospheric pressure to adjust the effective diameter; and controlling the piston force based on: the driven pulley speed; and the at least one of: the throttle operator position and the throttle valve position. an engine; a throttle operator being operable by a driver of the vehicle; a throttle valve regulating airflow to the engine, a throttle valve position of the throttle valve being based at least in part on a throttle operator position of the throttle operator; a continuously variable transmission operatively connected to the engine, the CVT including a driving pulley, a driven pulley, and a belt operatively connecting the driving pulley to the driven pulley; at least one ground engaging member operatively connected to the driven pulley and comprising at least one of: a wheel and a track; a plurality of centrifugal weights operatively connected to the driving pulley for controlling an effective diameter of the driving pulley; a piston operatively connected to the driving pulley for applying a piston force to the driving pulley when actuated and thereby changing the effective diameter of the driving pulley; and a control unit for controlling actuation of the piston and the piston force, the method comprising: controlling the effective diameter of the driving pulley, via the plurality of the centrifugal weights, responsive to a driving pulley speed; determining at least one of an altitude and an atmospheric pressure; determining a driven pulley speed; determining at least one of the throttle operator position and the throttle valve position; selectively actuating the piston based on the at least one of the altitude and the atmospheric pressure to adjust the effective diameter; and controlling the piston force based on: the driven pulley speed; and the at least one of: the throttle operator position and the throttle valve position. controlling the effective diameter of the driving pulley, via the plurality of the centrifugal weights, responsive to a driving pulley speed; determining at least one of an altitude and an atmospheric pressure; determining a driven pulley speed; determining at least one of the throttle operator position and the throttle valve position; selectively actuating the piston based on the at least one of the altitude and the atmospheric pressure to adjust the effective diameter; and controlling the piston force based on: the driven pulley speed; and the at least one of: the throttle operator position and the throttle valve position. the driven pulley speed; and the at least one of: the throttle operator position and the throttle valve position.