Seems like you could expand on Street's idea and make the diameter adjustable (a couple more cuts to the wheel maybe?)

The $500 tool had a similar design weakness in that you already had to have the type of tire diameter / profile size available. This is great if you're a tire dealer and have a huge stock of different tires in the back but for the do-it-yer-selfer at home, we have to be a little more creative!

Street's suggestion is more practical for the average gearhead at home