With my design I could pull five books.
- Switched gears from biggest gear attached to motor and smallest gear attached to wheel to Smallest gear attached to motor and biggest gear attached to wheel. I did this because at first it was built for speed and I changed it so it was built for torque which allowed me to pull more weight
- Attached gear system to back wheels for four wheel drive. I did this because it gave me more power to drive and allowed me to pull more weight.