On smooth level ground.
1. Open your tie rod jam nuts.
2. Visually center the Rack, then measure until it's 4 1/8" from the rack edge to the center of the bolt on both sides.
3. String rear and front wheels at the center of the hub. When the string hits the front and rear of the tire without adjustment, it's straight.
4. Now reconfirm your rack measurement.
5. Now set toe.