Notes for this project. I started the back of this, but it fell off, which might’ve been a blessing in disguise, as the gauge was quite off. Now it’s off, here are some measurements: 57r and 40s in 4” (1.425 stretch factor)
Ball is 57mm Tall x 77mm Wide. If above stretch factor had been applied, it would be 81mm Tall x 77mm Wide. Much closer to round!