Weights and dimensions, loading and overloading rules
This domain is arithmetic and legality together. Swiss limits are fixed in the VRV/OCR and the vehicle admission rules, and overload is prosecuted - but the exam mostly tests whether you understand that several limits apply at once: total weight, axle load, tyre capacity and the load distribution.
Dimensions
- Width: 2.55 m generally; 2.60 m for insulated or refrigerated bodies meeting the required wall thickness.
- Height: 4.00 m, load included. A load sticking above the body still counts.
- Length: 12 m for a rigid motor vehicle, 18.75 m for an articulated combination or road train on the permitted network.
- Anything wider, longer or heavier needs a special permit and often an escort.
Weights
- Combination maximum 40 t; a two-axle rigid vehicle 18 t, three-axle 26 t, four-axle 32 t; trailers 18 t on two axles, 24 t on three.
- Axle load maximum 10 t, with 11.5 t permitted on driven axles under the conditions set for twin tyres and axle design.
- Payload = permissible total weight minus the empty weight including driver, fuel and equipment. Tyre load indices must cover the axle load as well.
Load distribution
A load placed too far forward overloads the steering axle and makes steering light; too far back it overloads the rear and can exceed the trailer or bogie limit. If you cannot weigh, calculate with moments: share on the rear axle = load × distance from the front axle ÷ wheelbase.
Worked example
A three-axle rigid truck, empty weight 11.5 t, permitted total 26 t, wheelbase 4.5 m. A 12 t load sits with its centre 3.0 m behind the front axle. Rear-axle share = 12 × 3.0 / 4.5 = 8 t; front-axle share = 4 t. If the empty front axle is 5 t and the rear bogie 6.5 t, loaded values are 9 t front and 14.5 t rear - both legal. Move the same load to 1.0 m behind the front axle and the front takes 12 × 3.5 / 4.5 ≈ 9.3 t extra, giving 14.3 t on a 10 t axle: clearly overloaded.
Traps
Thinking 40 t is always allowed regardless of axle count; forgetting that the driver, fuel and equipment reduce payload; ignoring the tyre load index; assuming the 2.60 m width applies to any body; loading until the springs look level rather than calculating.