Info needed: 9.00-16 tube stem size?

[rob love]

When I checked with my tire shop, it turns out a valve assembly that you vulcanize onto a tube will cost more than the complete tube. I was hoping to modify the available valve off center tubes to valve on center. The thought of $50 innertubes ended that. I think we paid about $16 a tube (USD) for the ones from Doberman. While I am by no means afraid to patch inner tubes, and do frequently when the leak is obvious, it is the slow leaks that take up too much of my time.