The tracking device on the front of the terrain is designed to push the front wheel slightly off center. This would be used when there is an uneven weight distribution, if the stroller is being used on uneven terrain, or if one of the tires is running low on air pressure (causing a lean or counter-steer) on a stroller that pushes it to one side or the other.

The tracking device is very easy to adjust to your desired position. With the wheel in a locked position, loosen the front axle with the two tri lock knobs on each side of the wheel. The tracking device is a lever located between the tri lock knob and the front wheel fork. Once the axle is loose, this lever can be pushed in either direction to cause the front wheels position within the front fork to angle slightly to your desired direction. When the wheel is where you like to fix it into place, hold the lever in place while you simply re tighten the tri lock knobs on each side again to lock the wheel in place once again.