The weight being carried by a commercial vehicle is normally subject to strict regulations.
Why?
Weight restrictions apply to trucks in order to reduce wear and tear on roads and bridges and to maintain safety: a heavier truck will take longer to stop in an emergency.
Types of Weight Restriction
Axle Weight: as the weight of a vehicle is loaded to the tyres through the axle, weight restrictions are often applied to weight per axle, or axle weight. The restriction may vary according to the amount of tyres on the axle (that are in contact with the surface) and on the tyre widths. There may be different weight restrictions between front, back and multiple axles (i.e. dual/triple axles). The proximity between axles may also have a bearing on weight restriction calculations.
Tyre Weight: this is similar to axle weight, but with regards to tyres only. The width of the tyre may have a bearing on the restriction that is applied.
Gross Weight: the overall weight of the vehicle + all loadings
Load Weight Distribution
There may also be regulations governing weight distribution of loads
Enforcement
Many regions insist that vehicle tare weights are displayed or can be accessed by officials. This can allow the gross weight to be calculated more easily by weighing the loaded contents and adding this figure to the tare weight.
Many regions have drive-on scales that allow officials to check the gross weight and, where appropriate, the axle/tyre weights.
Penalties for overweight vehicles or unlawful weight distribution vary between regions.
Responsibility
In many jurisdictions the drivers carry sole responsibility for their vehicle’s weight and will carry the full burden of punishment. In other regions, their employer may share or carry the main burden of responsibility.