Your wheels look good. I can't tell from the pictures, maybe it's an optical illusion. On the rear hubs the plate for the axle shaft is round. It does not have the notches like the front hubs.
On the rear axle shaft plates there are 8 holes. 6 evenly spaces for the bolts that secure the axle shaft to the hub, and 2 threaded holes that usually have a spare bolt secured with a nut. I'm told these were used to pull the axle shafts from the axle.
The cap on the tube was to keep it from getting pulled into the wheel if the tube lost air.