This is the best scale tutorial on the internet at this time. Thanks for your work in showing it.

You should measure at middle of rim edge to opposite middle of rim edge. The 20 inch measurement is the inner wire embedded in rubber also the rim edge is slightly more than 20 inches so it stays on the rim after being inflated. It would throw off accuracy by quite a bit. Sorry I got technical but if it mattered..... well , have a great morning.

Neat,simple and clear Keep up

Great explanation. Thanks!

Thank you for making this video!

Great video!