This simple model was built to demonstrate full articulation on a 8 wheel chassis using 68.8x40 balloon tires. The model is not powered but simply tests the geometry required to keep all 8 wheels on the ground at all times. The rear 4 wheels articulate on rocking beams. The front 4 have to articulate in two planes as well as steer. The final result is that the chassis is effectively mounted on only 3 points. Note the correct steering geometry. i.e. the front axle steers more than the second.
These pictures show the extreme limits of the articulation on a test hill.
Note that despite the axles at crazy angles the chassis is virtually level.