Sabrina,
How do you want to use your truck . . . is it a fun driver or a restoration? I *believe* that the 16s were referenced in the threads because the original rims on many of the trucks in question were 16s.
I would think about the availability and cost of getting the 16s. I have them on both of my trucks, and a full set of radials for my 54 3100 was just quoted at about $475 (US).
I've also got 16" bias tires on my '63 C20, and they still run close to $100 (US) per tire. I won't drive it in snow or on wet roads, though, because of the bias tires.
You can go either route - switching to the 15s or going with 16s. Because I feel weird/unsafe driving my big '63 on bias tires in rain and snow, I wanted to go with radials on our '54. I assumed that I wouldn't be able to get radials for the original rims, so I was planning to switch to 15" rims. Thanks to Woogeroo and the Stovebolt Page, I learned that I could keep my original rims AND find radials to fit.
It all comes down to how you want to use your truck and how much you want to spend on tires. The 15s are generally much cheaper and much easier to find, but I just liked the look of the big stock tires. If you have access to 15s and the price is right, there is nothing wrong with putting on a set of 15s. Have fun with your project,
