The only 5.5" x 16" two piece Land Rover wheels I know of were a little found option for civilian Rovers and used on MOD Rovers. Looks like this.
The largest tire you can really mount on them is 7.50x16 (because of the 5.5" rim width) and they are very heavy. Aside from the just plain heavy wheel, you need a tire flap and inner tube which add even more weight. They are a bear to balance.