What does the term 'permissible towing mass' mean?
4 Answers
Permissible towing mass refers to the combined weight of the trailer and the cargo being hauled. It is a theoretical value, also known as the 'nominal towing capacity.' The total mass includes both the vehicle and the towed object, meaning the vehicle's weight plus the weight of the towed object, with the towing force applied to this total mass. Therefore, when calculating the total towing mass tonnage, the weight of the towed object should not be considered solely as the nominal towing capacity. Notes on permissible towing mass: 1. Total mass on the driver's license: Refers to the vehicle's curb weight + approved passenger capacity + approved passenger weight (number of passengers in the cabin × average weight of 65 kg per person). 2. Curb weight: The vehicle's own mass. 3. Certified load capacity: The standard mass of cargo the vehicle is designed to carry. 4. Permissible towing mass: Refers to the total mass that a semi-trailer can tow (including the combined mass of the towed vehicle and cargo). It is the sum of the tractor's mass (excluding the driver and fuel), the towed vehicle's mass, and the cargo mass.
The term 'Maximum Permissible Towing Mass' may sound technical, but it simply refers to the maximum weight your vehicle can safely tow. This value is mandated by national compulsory standards and is indicated on the vehicle's nameplate and manual. It includes both the weight of the trailer itself and the total weight of the cargo loaded on it. For example, if you're driving an SUV towing a caravan for a trip, the caravan's own weight plus luggage and water tanks are all factored in. Exceeding this limit is illegal, will definitely fail the annual inspection, and may result in fines if caught by traffic police. It's particularly important to note that there are significant differences between vehicle types - sedans may only handle a few hundred kilograms, while American-style large pickups can manage three to four tons. Always verify your vehicle's towing capacity when purchasing a trailer; otherwise, you risk anything from transmission system wear to serious accidents like axle breakage.
When we bought our pickup truck two years ago, the salesperson emphasized this point. The approved towing capacity, simply put, refers to the vehicle's maximum capability for towing. It's not just about how powerful the engine is—what really matters is whether the chassis, suspension, and braking system can handle the towing force. For example, when towing a yacht, sudden braking creates significant inertia from the trailer. If the factory-installed brakes aren't properly matched, it could easily lead to a rear-end collision. This specification also accounts for the cooling system's load—towing heavy loads with the AC on in summer increases the risk of overheating. Most standard SUVs have an approved towing capacity of around 1-2 tons. Exceeding this limit can cause steering instability, make the towed object invisible in the rearview mirror, and increase the likelihood of scraping the undercarriage during turns.
The permissible towing mass indicates the maximum weight your vehicle can tow. It's stamped on the doorframe nameplate of the front passenger seat, representing the designed towing capacity. This figure includes both the trailer's own weight and its cargo load. For instance, when towing an RV, the combined weight of the trailer itself plus furnishings and water tanks must not exceed this value. Overloading risks frame deformation, premature transmission failure, and creates significant highway hazards. Always weigh your full load before towing.
