Jay,
Awesome job - just now getting to this post. I too enjoy all of the work by BBQ Eng, and everything else from everybody that is home built.
WHEELS - I see a few questions and suggestions on these, and see that you've rectified your manuverability issue. Here is my suggestion:
Go with solid wheels all the way around. Can't see where you live, but if it's anywhere cold, or hot, the tubes or tires are going to give you nothing but hell. Any local hardware store should have a good supply of 8" to 10" solid rubber wheels. By the looks of it, this baby is going to be part of the family for a good long while, and at some point you are going to have to deal with them.
Again, just a suggestion. I've been fighting my wheelbarrow and lawn tractor tires and opted for solid wheels on all of my torch carts and BBQ's.
Can't wait to see this baby fired up!
Tracey