Classical diagnosing methods of wheeled tractor defects apply state mapping by measured diagnostic parameters of different symptoms: operation's efficiency, thermal state, vibrations, leak proof etc. This elaboration takes a mixed approach, connecting rule knowledge with phenomena knowledge about wheeled tractor defects, achieved from analytic (model), simulations and exploitations tests. Correctness is recognized, i.e. relationships and connections between the occurring phenomena in destruction process of wheeled tractors, to which we can assign features of stability, significance and...