Free tool
Overloading check: axle and vehicle mass
Enter the masses from the weighbridge and the permissible limits from your documents. See how far each axle, axle unit and the whole vehicle is over or under, before a traffic officer does.
Mass check
Enter an actual and a permissible mass for at least one axle, or the permissible total, to see the result.
A planning aid, not legal advice. A weighbridge reading by an authorised officer is what counts.
How to check a truck for overloading
A heavy vehicle is overloaded if any single axle, any axle unit (a tandem or tridem group) or the vehicle as a whole weighs more than it is permitted to. Each of those is checked separately, so a truck can be legal in total and still be overloaded on one axle. The check is simple arithmetic once you have two sets of numbers: what the vehicle actually weighs, and what it is allowed to weigh.
1. Get the actual masses
Weigh the loaded vehicle on a weighbridge that reports each axle or axle unit, or use on-board scales if they are fitted and calibrated. Record every axle reading and the total. If you only have a total from a single-deck weighbridge, you can check the GVM or GCM but not the axles.
2. Find the permissible masses
The licence disc and registration certificate show the vehicle's tare (unladen mass) and its gross vehicle mass. The manufacturer's information plate gives the rated axle, vehicle and combination masses. The National Road Traffic Regulations set legal limits: regulations 234 to 237 deal with the permissible maximum axle, axle unit, vehicle and combination masses, regulation 238 with the load on tyres, and regulations 240 and 241 with what roads and bridges may carry. In broad terms, the figure that applies is the lowest of the limits relevant to your vehicle. If you are unsure, ask the manufacturer or your provincial traffic authority, and check the current regulations rather than an old summary.
3. Compare and fix before departure
Enter both sets of figures in the tool. Anything over 100% of its limit is an overload. If the total is fine but an axle is over, the load is badly distributed: move it towards the lighter axles or spread it more evenly. If the total is over, part of the load has to come off.
Tolerance is not a loading allowance
Enforcement practice may include a small tolerance before a charge is laid, to allow for weighing variation. It does not change the legal limit, and loading to the limit plus a tolerance is planning to be overloaded. This tool deliberately applies no tolerance: the permissible mass you enter is the line.
Why it matters
- Fines and prosecution for the driver and the operator, and the vehicle can be held until the load is corrected.
- Faster wear on brakes, tyres, suspension and chassis, and longer stopping distances.
- Road damage, which is why axle loads are controlled so closely.
- Possible problems with insurance claims and with RTMS or customer audits.
Making it routine
Overloading is usually a process failure rather than a single bad decision. Record the tare and permissible masses of every vehicle once, check planned payloads before loading, and keep weighbridge tickets against each trip. A system that holds those figures per vehicle can warn the loader before the truck leaves, rather than after it is weighed.
Worked example
Legal in total, overloaded on one unit
The permissible masses below are hypothetical figures for illustration only. They are not legal limits for any vehicle.
| Steering axle: 6,800 kg of 7,000 kg | 97.1% (-2.9%) |
|---|---|
| Drive axle unit: 16,900 kg of 16,000 kg | 105.6% (+5.6%) |
| Trailer axle unit: 19,600 kg of 21,000 kg | 93.3% (-6.7%) |
| Total: 43,300 kg of 44,000 kg | 98.4% (-1.6%) |
The combination is 700 kg under its permissible total, yet the drive axle unit is 900 kg over its permissible mass. The vehicle is overloaded. Because the steering axle and trailer unit have spare capacity, moving part of the load away from the drive unit can bring every row within its limit without removing anything.
FAQ
Frequently asked questions
Where do I find the permissible mass for my truck?
Start with the vehicle documents: the licence disc and registration certificate record the tare and the gross vehicle mass, and the manufacturer's information plate gives the rated axle and combination masses. The legal limits for axles, axle units, vehicles and combinations are in regulations 234 to 243 of the National Road Traffic Regulations. The permissible figure is the lowest of the limits that apply to your vehicle.
Can a truck be overloaded on one axle but legal in total?
Yes. A load placed too far forward or back can push one axle or axle unit over its limit while the total stays within the GVM or GCM. That is still an overload. Moving or spreading the load usually fixes it without taking anything off.
Is there a tolerance before a truck counts as overloaded?
Enforcement practice can allow a small tolerance before a charge is laid, but it is an enforcement matter, not an extra legal allowance, and it should never be part of a loading plan. This tool does not apply any tolerance because we could not verify a figure from an official source. Load to the permissible mass.
What happens if a truck is overloaded?
In general terms, an overloaded vehicle can be stopped at a weighbridge, the driver and operator can face fines or prosecution, and the vehicle may have to be offloaded or the load redistributed before it continues. Overloading also damages roads, wears brakes, tyres and suspension faster, and can affect insurance cover. Check the current rules with the authorities for exact consequences.
What is the difference between GVM and GCM?
GVM (gross vehicle mass) is the maximum the vehicle itself may weigh with its load. GCM (gross combination mass) is the maximum for a truck and its trailer or trailers together. Check a rigid truck against GVM and a combination against GCM.
Does this tool replace a weighbridge?
No. It checks the numbers you enter. Use a calibrated weighbridge or on-board scale for the actual masses, and take the limits from your vehicle documents and the regulations.
Sources
- National Road Traffic Regulations, 2000 (GN R225 of 17 March 2000), regulations 234 to 245: table of contents as reproduced by Acts OnlineUsed only for regulation numbers and titles. An official consolidated copy (gov.za / Department of Transport) could not be fetched on 29 October 2026, so no limits or tolerances are hard-coded: every limit is your input.
- National Road Traffic Regulations, 2000 on the Southern African Legal Information Institute (lawlibrary.org.za)The site notes that some amendments may not yet be applied. Check the Government Gazette for the current text.
- Department of TransportFor current regulations and amendments.
Stop overloads before the truck leaves the yard
T-ERP holds the GVM and axle limits in each vehicle profile, alerts when a freight order exceeds its load limit and stores weighbridge records against the order. A 30-minute consultation shows you how.