About this detail of the Tiger
The outer end of a Tiger swing arm carried the roadwheel hub on 2 roller bearings. The narrow space between the arm and the hub was a reservoir, filled with lubricating grease for these bearings.
A grease-filling tap was provided in the center of the hub, as shown here. It was angled so that the grease gun could grasp it easily. (The red paint is postwar.)
This is a detail from a German lubrication chart for the Tiger, reminding us to grease each roadwheel hub  .
The tap was built into a hexagonal pipe on the cover of the grease reservoir. (The diagram shows the original wheels of the Tiger, not the later "steel wheels".)
The reservoir cover could be unscrewed. Like most bolts on the tank, it had a sheet-metal tab to prevent it working loose. The tab, shown here, was threaded onto the hexagonal pipe.
This diagram shows the flange that is exposed when an odd-numbered hub is broken down for transport. The tab is holding the reservoir cover within the hub. The notches in the tab align it at intervals of 30 degrees on the cover. There are 4 locating slots in the flange, carefully positioned to divide these intervals into 4 parts. The locking ring therefore needs only 3.75 degrees of slack in either direction so that it can always be locked into one of these slots. A small screw is used to fix it there.
The even-numbered wheel hubs have no flange. Their tab is held in one of 4 notches in the hub itself, and locked in place with a circlip.
When the road wheels are installed, protective covers conceal all of this except for the grease-filling tap. There are different covers on alternate wheel stations because of the interleaving of the wheels; those on the odd-numbered axles are deep cones.(The latest version of this article)