Technical Information

No more spreadsheets! We combine sensible defaults with your inputs, to present complex technical calculations in a simple graphical way.

Axle Weight Distribution

Calculate the distribution of mass over front and rear axles of the truck, trailer axles and trailer hitch. Calculated masses are compared to manufacturer ratings, Road Traffic Act regulations, and user-defined limits. Issues are flagged by colour-coded indicators.

Setting truck dimensions in the TruckScience Axle Weight Calculator

Calculate after-frame, front and rear overhang, overall length, width and height dimensions, cab to body clearance, frontal area and many more. Relevant dimensions are checked against Road Traffic Act regulations and user-defined limits. Issues are flagged by colour-coded indicators. Know what will fit before you proceed with the build.

Maximum Payload

The amount of payload that can be legally carried on your truck is influenced by the chassis spec, body mass and position, as well as the placement of all of the ancillary equipment on the vehicle. Experiment with dimensions and placement of components to realise the full payload potential of the truck, while complying with axle mass limits, overall length, etc.

Center of Gravity

Overall vertical centre of gravity is auto-calculated by combining the mass and centre of gravity of the truck, the body, and each additional item of equipment. Calculating the overall vertical centre of gravity of a truck is vital to assessing its stability. The program also calculates the Static Rollover Angle, that is, the angle to which the truck could be tilted before the centre of gravity is brought directly over the roll point.

Turning Circle

Turning Circle, or Turning Radius, is a measurement of the smallest circle in which the truck can make a 360° turn. The wall-to-wall turning circle includes the space required for the vehicle front overhang, while the curb-to-curb turning radius assumes that the truck can overhang the curb to turn in a smaller circle. The Turning Ability of the chassis may be specified using Inner Steering Angle, Curb to Curb Radius or Wall to Wall Radius.

The Performance Feature in the TruckScience Axle Weight Calculator. Specifying the route a truck will travel, payload to be loaded and offloaded at each waypoint, average speed, and external factors such as wind conditions, and simulate fuel consumption under these conditions. Predicting fuel consumption for transport operators.

The program uses data from manufacturers, as well as proven algorithms, to calculate the performance of any vehicle, over any route, with any load. Specify the route your truck will travel, payload to be loaded and offloaded at each waypoint, average speed, and external factors such as wind conditions, and simulate fuel consumption under these conditions. Predicting fuel consumption is vital for transport operators to understand the viability of a contract.

The Total Cost of Ownership feature in the TruckScience Axle Weight Calculator. Including finance, maintenance, fuel, toll fees, driver wages and other running costs. Sliders to examine how changes in fuel price, interest rates, etc.,

Total Cost of Ownership is calculated based on fixed and variable costs, including finance, maintenance, fuel, toll fees, driver wages and other running costs. Use simple sliders to examine how changes in fuel price, interest rates, etc., will affect the bottom line, and compare how competitor vehicles stack up under actual operating conditions.

Wide Range of Combinations

From Class 1 right up to Class 8 trucks, with infinite possibilities for bodies and equipment, and pulling up to 2 trailers behind.

Chassis Types

Choose to do a weight study for a chassis cab, or ‘rigid’ – single or twin steer -, semi truck, pickup truck or van. The program supports trucks with up to 6 axles – 2 on the front and 4 on the rear, with available axle layouts including 4×2, 4×4, 6×2, 6×4, 6×6, 8×2, 8×4, 8×6, 10×4 and 12×4. Both European-style ‘cab-over’ and US-style ‘conventional cab’ trucks are supported.

Truck Bodies

Add a body to carry payload. Choose from service bodies, box or van bodies, tautliners, dropsides, flatdecks, timber bodies, livestock carriers, tipper bodies, rollbacks, beavertail bodies, tanks, compactors, hooklift bins, or import your own. The possibilities are infinite.

Add Equipment Axle Weight Calculator

As with bodies, the program supports any and all types of equipment or accessory. Pre-defined categories include cranes, fridges, tail lifts, 5th wheels, hitches, hooklifts, bullbars, aerokits, aerial platforms, fairings, toolboxes, outriggers and rear bumpers. There is a catch-all ‘Other’ category into which you can import any equipment of your choice.


When a body has been added to the chassis, the maximum water-level (or evenly-distributed) load that can be legally carrried by the current configuration is automatically calculated. This can be overridden with a user-defined water-level load. Alternatively, multiple separate payload items may be positioned on the load deck. All technical information is re-calculated on the fly, as the load’s position, mass, volume or centre of gravity changes.

Lift Axles

Adding axles increases the load-carrying capacity of a truck. You can add pusher or tag axles to your truck, and define them as being liftable or not. Override the weight, Gross Axle Weight Rating (GAWR) and the Bridge or regulation limit for the lift axle. Axle weights can be calculated based on the lift axle being in the raised or dropped position. The number of tyres on the axle and tyre width are taken into account when calculating the footprint of the tyres, and this in turn is used to determine regulation limits against which the design will be verified.

Add Trailers Axle Weight Calculator

Add up to 2 trailers, with up to 4 axles on each. Choose from Semi-trailer, Drawbar trailer, Pup trailer, and Interlink combinations. Axle masses are calculated for all axles or axle groups, as well as for the hitch, where applicable. 5th Wheel offset and Front Overhang are all configurable, and all technical information is re-calculated with each change.

Library of Product Specs

Save time searching for masses and dimensions, and use realistic graphics to bring your proposals to the next level.

OEM specs in Axle Weight Calculator

TruckScience is backed by a library of product specs, which include general arrangement drawings, masses, dimensions, centre of gravity and ratings. Specs for new trucks, bodies, equipment and payload are added to the library on request. OEMs may choose to distribute product information to all users, or to only approved dealers and distributors.

Editable Templates in Axle Weight Calculator

Generic templates are provided for all common bodies, equipment and payload items, which can be used to experiment with theoretical dimensions, masses and centre of gravity positions. These are useful if you have not yet settled on a particular product, but wish to determine the spec of a potential product for your configuration. These may also be used as substitutes when a product spec is not yet available in the product library.

Import Drawings In Axle Weight Calculator

Import drawings of bodies, equipment and payload items, to build up your library of product specs. Save these specs to your own Personal library, your Team library, your approved Distributor library, or publish them to all users.

Compare competitor specs side-by-side to identify advantages and handle objections. See how their gross vehicle mass, engine capacity or driveline measure up, and many more.

Compliance Checks

Knowing that your configuration is safe, legal and efficient is not just about compliance. It’s about peace of mind.

Regulations available in Axle Weight Calculator

The South African Road Traffic Act defines the maximum mass of a truck, depending on number of axles, axle spacing, the tyre footprint of those axles, etc. In addition, there are limits to vehicle length, rear overhang, etc. As you work, your configuration is being checked for compliance with the Act, and any issues are flagged.

Axle Weight Calculator

Chassis manufacturers define Gross Vehicle Mass (GVM) ratings, Gross Axle Mass ratings, and Gross Combination Mass (GCM) ratings. These are the maximum allowable masses for the vehicle and its axles, as stipulated by the OEM. As you are adding or making changes to components, your configuration is automatically checked against these ratings.

Organisation Standards in the Axle Weight Calculator

You can define your organisation’s internal standards for mass distribution, dimensions and vehicle stability. For example, the minimum percentage of gross mass that must be carried on the front axles, the maximum rear overhang as a percentage of wheelbase, or the maximum height of the overall COG. These compliance checks are in addition to the checks against manufacturer ratings and regulations.

Graphical PDF Reports

They say that a picture paints a thousand words. We say a picture catches misunderstandings early in the process, and helps get the sale.

The reports include a sign-off area, for you and the customer. Obtaining sign-off ensures that all stakeholders are informed and in agreement about the proposed design, and helps to prevent misunderstandings that could cause problems down the line.

Customizable info in the Axle Weight Calculator

Users can add custom text to the reports. This can be used for a company-wide disclaimer, or job-specific notes regarding current lead times, etc. In addition, certain ‘Favourite Measurements’ can be highlighted on reports, and these can be toggled on and off, depending on the intended audience.

Collaborate with
other users

Great things happen when clever people work together to come up with the best solution.

Share Calculations in the Axle Weight Calculator

In addition to the reports that can be shared in PDF format, live calculations can be shared with other users. Sharing calculations in this way allows multiple users to collaborate on a configuration, suggest improvements or experiment with different layouts. Calculations can be shared in read-only or edit mode.

Team Library in the Axle Weight Calculator

When you add a body, or an item of equipment or payload, either by importing a drawing, or by using a generic template, you can save it to your Team library, so that your colleagues can reuse it in future.

Distributor Library in the Axle Weight Calculator

Body and equipment manufacturers can make product specs available to approved distributors through a ‘Distributor Library’. Product specs are added to the library by uploading drawings in DXF format, and providing masses and dimensions for these products. Manufacturers control their own Distributor Library, including what is added to it, and who has access to the information.

Vehicle Prototyping in the Axle Weight Calculator

Manufacturers can experiment with different vehicle configurations before releasing a vehicle to the market. This allows Product Managers to define a spec that is optimised for local conditions.

Multiple Teams in the Axle Weight Calculator

Define multiple teams on one subscription, each with their own logo, distinct custom text on reports, and separate Team Library.

Usage Stats in the Axle Weight Calculator

Get detailed statistics on your company-wide usage, to ensure your organisation is getting value from your subscription. Usage reports include the most recent login and frequency of use for each of your users.

Intuitive Interface

Our design team are driven by the desire to give you an interface that is simple, intuitive and consistent.

Drag and Drop Function in the Axle Weight Calculator

To move bodies, equipment or payload around on the truck, simply drag & drop the components. As things are repositioned, all technical information is re-calculated, compliance is re-checked and maximum payload is re-calculated in real-time. Drag items around, to examine the point at which an axle becomes overloaded, or to watch the maximum payload rise or fall.

Interactive Drawing in the Axle Weight Calculator

The drawing is interactive. Click the WB dimension to extend the wheelbase, the rear of the chassis to edit the rear overhang, the body to edit the body mass, or the crane to edit the crane COG … No more searching around in menus to find where to change a value!

Color-Coding in the Axle Weight Calculator

As you work, your configuration is checked against what we call the ‘3 pillars of compliance’ – Manufacturer Ratings, Regulations and Organisation Standards. Compliance is confirmed by green colour-coding. Overloading issues or problems with dimensions are flagged in red.

Multiple Views in the Axle Weight Calculator

The default view is simple and uncluttered. You can however examine detailed views of mass distribution for the truck, fuel and crew, or the trailer. You can review centre of gravity points for individual components, and see overall centre of gravity. You can examine detailed mass information for axle groups, or see a bird’s-eye view of the turning radius of your configuration. You can also switch between side and top views, to help with lateral positioning of equipment and payload.