[cj847]

Haven't had a chance to remove a tire. Will report back if/when I do.

While we are documenting, I was curious how some 15" will work with disc brakes and other won't. A quick look at the back shows the difference. Hope it shows up in pics.

15" DB wheel (1982 c10) the one with 5 lugs.

15" non DB (assumed to be 1970 or earlier)

As you can see the db maintains approx 13.5" dia all the way to the center. The non disc dia is reduced within an inch of the bead.