An expert-system for diagnosing rough ride problems in heavy trucks has been developed and can be used on a personal computer. The system operates on two levels of knowledge data base: shallow - acquired from truck service experts with well developed intuition, and causal (deep) obtained eg. from a multiprobe vibration analysis system or from any system testing the mechanical behaviour of a truck. The presented expert system, Ride Expert (RE), is able to clearly identify the causes of a truck rough ride in some cases or reduce the cause search space in more complex cases. Virtues and drawbacks of the developed system are presented.