16.5 vs 16 vs 15" WHEELS-C20

[frenchy51]

I have a 1971 C20 Custom Camper that needs new tires. It currently has 16.5 wheels on it that I assume are stock(6-bolt). I've been told these are dangerous due to no bead and to switch to 16". In my research, I'm finding it's harder to find used caps etc. for 16" over 15" (like the C10's have). My question is what is the advantage to run 16" wheels on my C20 instead of 15"? Maybe 15" don't come in the 6" bolt pattern??? Merry Christmas and thanks in advance for any insights.