Starting on a Dropmember frame soon, need advice

[ibanezer]

Hi all,

I have a '68 LWB C20 and plan on the following:

-Porterbuilt Dropmember - front and rear(already have both kits) - weld in notches for the rear
-Drop spindles of some sort(do not have yet)
-73-87 upper and lower arms and brake components
-Plan to run 22" smoothie wheels, "Delmo specials"/Mobsteel, etc.

I should be getting my frame set up in the next month or so. My question right now is in regards to tire size. I'm not sure what size tire I should run once I do eventually buy the 22" wheels. I'm looking at throwing some 15" truck rally's on it, just for the purpose of setting the 4-link up and to get it rolling.

To sum this up, when I do get 22's for the truck, what size tire should I run? Also, what size tire should I put on a 15" wheel for now to set my 4-link up right?

Thanks