Hi 3B; The fronts are 5-bolt, as you say, and have the outer ring on them (if the rings were chrome, you could almost mistake them for a Trim Ring). However, the rear 5-holers don't have the separate ring (or at least the outer dual wheels don't; I haven't looked at the inner ones). The truck, unfortunately, is currently located an hour west of here at a garage where it's getting some mechanical work done on it, so I can't go and look closely. The dually rims are spoked, though, if that helps. Also, separate to the rims, the hub that sticks through the centre of the wheel has an 8-bolt plate on it. I know those are not part of the rims, so that probably wasn't much help. Grigg's letting send him a photo, so we'll see what he thinks of the rear wheels.
