Steering wheel diameter?

I love my Steering Concepts 18" "big rig" steering wheel, but I was unable to answer a question whether it's bigger than the original wheel (?)
Anybody willing to measure, I'd be grateful!

The stock wheel on my 69 is 17"

AZ Don does your van have power steering? I read through a lot of your build thread and it is impressive work, cant remember if you have power steering or not. Wondering how much of a difference that big steering wheel made as far as easier steering effort. (I do have power steering on my frankenstein 4x4 but it has a 13" wheel and is still pretty hard to turn at low speed/sitting still)

My van DOES NOT have power steering, however, the cross-steer setup that I built to get rid of the bump-steer includes a bell-crank with one of it's two arms longer than the other so that the steering ratio is slower than stock (slightly more turns on the wheel)....
I never ran the van with the stock steering or steering wheel, so I can't really give a comparison....
It drives nice though and corners like a go-kart as expected, being that I lowered the front several inches and added two leafs per side and a 1" stabilizer bar ( and air shocks)
Rear is a 323 posi wearing four shocks....

Sounds really cool Don! Yours handles the exact opposite of mine... I still have the factory 17" wheel which should bolt up to my new column so I will give it a shot