Kerb weight is one of the most basic but an important specification of any vehicle, be it a two-wheeler or a four-wheeler. In simple terms, it is nothing but the weight of the vehicle in running condition. The American manufacturers use the term 'Curb Weight' for the purpose.
Manufacturers should take into account the weight of all the standard equipment fitted on the vehicle and consumable items while measuring kerb-weight of the vehicle. This includes items such as engine oil, coolant, brake oil etc. and a completely filled fuel tank. However, it never includes the payload of the vehicle i.e. weight of the passengers and the cargo.
Lack of any standard universal method to calculate kerb weight of vehicles has made this term slightly ambiguous. For instance, some European manufacturers include the weight of driver (assumed to be 75 kg) while calculating kerb weight. This is in contrary to some other manufacturers who omit the weight of the driver from these calculations. Hence, the definition of the kerb-weight varies significantly the world over.
Many manufacturers have set their own standards for calculating kerb weight. Some manufacturers consider that fuel tank is 50% of its total capacity instead of completely filling the tank while some others assume that it should be merely 10% of the capacity.
To overcome these variations, some manufacturers have come up with a solution of mentioning ‘dry weight’ in the vehicle specifications. Dry weight is the weight of the vehicle without any consumables such as oil, fuel. It also does not take into account the payload. Naturally, dry weight of the vehicle is always less than its kerb-weight.
The term kerb-weight is more significant in case of two-wheelers. This is because it gives the idea of how much weight the rider has to balance.