When several vehicle conditions appear together, decide whether each one independently prohibits operation before combining the results.
Classify the condition before judging it
Use three checks: is the condition safety-critical, is the equipment required for this vehicle class, and does the measurement cross the limit? Brakes, steering, wheel retention, tyres, visibility, required lights, restraints and prescribed emergency equipment have direct operating rules. A rough-running engine or failed convenience indicator may need repair without creating an operating ban. Equipment provided by the design must remain present and serviceable.
| Condition family | How to test it |
|---|---|
| Brakes and steering | Reject leaks, failed pressure information, loose fixed parts, excessive free play, or a failed required assist |
| Tyres and wheels | Check the threshold for the vehicle class, exposed cord, approved size and load, every wheel fastener, and matching construction on one axle |
| Visibility and restraint | Required wipers, demisters, glazing, mirrors, seat belts, head restraints, and the driver's seat mechanism must do their safety job |
| Lights and reflectors | Check function, cleanliness, prescribed mode, and orientation colour rather than treating every installed lamp as a defect |
| Class-specific equipment | Ask whether the vehicle is a car, truck, solo motorcycle, motorcycle with sidecar, bus, or heavy bus before requiring kits, extinguishers, warning devices, or wheel chocks |
| General symptoms | Do not promote an engine symptom, optional accessory, or ordinary cabin feature into an operating prohibition without a defined safety rule |
Threshold wording is exact: a value equal to the minimum is not below it. Passenger-car and car-trailer tread is barred below 1.6 mm, bus tread below 2 mm, and motorcycle tread below 0.8 mm. Colour is positional: front reflectors are white, rear reflectors are red, and reversing lamps are white. Permitted front lights may be white, yellow or orange, and rear indicators may be red or orange; white rear turn signals are a defect. Judge each neighbouring condition separately.
Official-exam nuances
- On the official exam, the accepted answer for the motorcycle with side attachment, 0.6 mm tread, missing medical kit and present passenger grip is all listed cases.
- On the official exam, the accepted answer for the bus with one wheel chock and one fire extinguisher is both cases, even though the general two-chock rule applies only above five tonnes.
- On the official exam, the accepted answer for 1.4 mm passenger-car tread together with yellow front reflectors is the yellow reflectors, although the general tread rule also rejects 1.4 mm.
Common mistakes
- Combining conditions before judging them. One permitted lamp or harmless symptom makes an all-cases conclusion too broad.
- Treating an exact minimum as a failure. The word below matters, and the threshold changes with vehicle class.
- Judging colour without position or device. First identify lamp versus reflector and front versus rear.
- Turning every maintenance complaint into an operating ban. A fuel-level display, entertainment device or ordinary cabin light is not a required road-safety system.
- Calling design-required equipment optional. Belts, head restraints, guards, latches, wipers and seat adjustment must work when the vehicle was built to have them.
- Checking tyres one at a time. Tyres can be individually serviceable yet form an unsafe axle pair because their construction, tread pattern, retread status or seasonal type differs.
Try it
The operation of vehicles is prohibited if:
- There are unforeseen displacements of the steering control details and joints or the threaded connections are not stretched.
- There is no fire extinguisher in the truck.
- In both cases.
The operation of vehicles is prohibited if:
- Car trailer tires have a residual tread pattern height of less than 1.6 mm.
- The rear of the vehicle is equipped with orange-colored turn signals.
- In both cases.
The operation of vehicles is prohibited if:
- Exterior lighting devices and reflectors are dirty
- The front and rear protective devices are dirty
- In both cases.