Stuff the tallest tire possible under the fenders then adjust the gearing to match.
A tall tire gives a longer footprint on the ground. That longer footprint means any single point on the tire is in contact with the ground for a longer period of time compared to a short tire. That point has a better chance of grabbing the ground and pushing you forward.
If you're doing road course etc type of racing then a wide tire is better to handle the side to side cornering. Drag racing is straight line where a tall tire is better.