I had diff lock engaged, in low ratio.
When i slowly got to the tipping point, with opposing front and rear wheels in the air, it stopped moving forwards. i revved the engine so the two wheels started to spin more and more but the brakes don't seem to kick in to force the drive to two wheels that were in contact with the ground.
Am planning to replace the tires but not sure whether to go for 235 or 265....probably BFG AT or Cooper ST