What is the payload of a vehicle - and how do I calculate it?

How to calculate the payload of a vehicle (with example)

Payload capacity table

What happens if you overload your car?

Being aware of your car’s payload will help ensure that you stay safe and legally compliant whilst carrying cargo and passengers. Driving an overloaded car carries serious risks:

Safety Risks

• The additional weight will increase stopping times, meaning the vehicle is less responsive in emergency situations.
• It will also increase the strain on your tyres – and the risk of tyre failure.
• Steering will be more difficult, especially if the weight isn’t evenly distributed.
• If the boot or passenger cabin are overloaded with luggage, visibility may be compromised.
• If your car is in an accident and deemed to be overloaded, your insurance may be invalidated.

Long-term damage

Exceeding the recommended payload may damage your car, hinder its performance and stability - and compromise its towing capacity.

Continuously overloading your vehicle can lead to excess wear and tear – and may also damage the frame, which can cause wheel misalignment and steering issues.

Legal consequences

• If a police officer pulls you over and deems your car to be overloaded, you could receive a £300 fine and up to three penalty points on your driving licence.
• If your overloaded car presents a safety threat to you and/or other road users, you could face a fine of up to £5,000.
• If the offence goes to court, you may also face a driving ban – or in some cases, a prison sentence.

Can you increase payload capacity?

Yes, it is technically possible to increase a car’s payload capacity by modifying the vehicle. Any changes that reduce the car’s weight may increase its payload capacity, for example:

• Swapping heavier steel wheels for alloy alternatives.
• Removing any unnecessary seats and the spare wheel.
• Removing optional equipment and aftermarket extras such as stereo systems.

Any modifications to your vehicle should be carried out by an experienced mechanic.

Limitations to consider

From a legal perspective, you may still be subject to your vehicle’s factory payload limit.It’s important to remember that the manufacturer’s payload limit often represents the ‘best case scenario’ and loading close to this limit may put a strain on your vehicle.

If you want a significantly larger payload, the most economical solution may be to sell your car and upgrade to a larger vehicle.

What is a chassis?

Whilst the terms ‘chassis’ and ‘frame’ are often used interchangeably in an automotive context, the chassis is technically the load-bearing part of a car’s frame, whereas the remainder of the frame is the structural body (or skeleton frame of the vehicle).

Chassis design and payload

• The choice of chassis material (e.g. steel, aluminium or composite materials) can influence payload capacity.
• Stronger materials such as steel may allow for a higher payload capacity, but this may come at the cost of a higher overall vehicle weight.
• Chassis configuration varies from vehicle to vehicle – and this design choice may also have an impact on payload capacity.
• The suspension system and the chassis work together to absorb impact. A well-designed suspension system can help the chassis maintain integrity whilst under strain.
• The distance between the front and rear axles (or the wheelbase length) affects the distribution of weight. A longer wheelbase may improve stability and load distribution.

Different car chassis designs

Ladder frame chassis

A ladder frame (or body-on-frame) chassis is commonly used for SUVs and pickup trucks. It comprises two parallel longitudinal (or ladder) rails spanning the length of the vehicle and is connected by cross members.

Ladder frame chassis are stronger than other varieties, providing higher payloads and towing capacities.

Monocoque chassis

A monocoque (also known as ‘unibody’ or unitary construction) chassis combines the body and chassis into a singular structure. The seat, suspension, transmission, engine and body panels are all connected to the chassis.

Monocoque chassis are often used for hatchbacks and sedans. The simple, lightweight construction helps to provide a good level of fuel economy. However, monocoque chassis are stiff and unsuitable for off roading. Repairs can also be expensive and complicated.

Backbone chassis

A backbone chassis comprises an inflexible ladder-like framework that forms the vehicle’s core. This style of chassis is strong, durable and ideal for heavy-duty applications. Therefore, backbone chassis are often used for trucks, buses and other large vehicles.

Due to their rigid construction, a backbone chassis can help to improve a vehicle’s stability. However, they are heavier than other chassis types (such as the monocoque style) and this extra weight can increase fuel consumption and reduce payload capacity.

When travelling in a vehicle with a backbone chassis, you may also notice that the ride is slightly harsher than in those with more flexible chassis designs.

Tubular chassis

Tubular chassis are constructed from a series of tubelike pipes that form a three-dimensional cage structure. This type of chassis is often used for race cars, as it provides a good level of protection and a favourable rigidity-to-weight ratio (making cars strong but lightweight).

However, designing a tubular chassis is a complex process and they can’t be mass produced. A tubular chassis also elevates the door, making it more difficult to access the cabin - and they are unsuitable for passenger cars.