I did the 10" pneumatic also, 2 swivels and 2 fixed.
They worked great but... 'When they went flat' the plastic rims broke! They are junk now.
I'm leaving the cab on the flatted tires until I'm ready to shove it out of the garage and lift the cab off.
This said, I would (if I had it to do over again) use rigid casters. At least when I finished with the dolly, I could disassemble it and still have some good casters for another day. I also made a 2x6 box frame but it doesn't have a plywood top like Tom's.
To get more clearance under the dolly, I would add some 4x4 legs (brace them if needed).
Just my 2 cents.
Jerry
