Load distribution plans for trucks: where to put the weight

A load distribution plan is a layout showing where each item of cargo sits along a truck’s deck, worked out so that no individual axle exceeds its legal limit. It is produced before anything is loaded, and it exists because where the weight sits matters just as much as how much of it there is.

The concept comes from German road transport, where it is called a Lastverteilungsplan, but the underlying calculation is the same everywhere. This guide covers why position drives axle loads, what the 60/40 rule actually means, a worked example using real numbers from our truck axle load calculator, and how kingpin load works on an articulated unit.

Why cargo position, not total weight, decides axle loads

A truck can be comfortably under its gross weight limit and still have an illegal axle, because gross weight and axle load are two different measurements. Gross vehicle weight is a single total. Axle load is how that total is shared out across the axles, and the sharing is decided by geometry: how far each item sits from each axle.

Think of the deck as a beam resting on supports. An item placed exactly halfway between two axles puts half its weight on each. Move that same item so it sits directly over one axle and that axle now carries all of it. Nothing about the cargo changed, only its position, and the axle reading moved by 100%. Multiply that across twenty pallets and it is easy to load a perfectly legal payload into an illegal configuration.

The full derivation of the lever calculation, along with the EU and US limit tables and what an overload costs, is in our companion guide to calculating truck axle load distribution. This page is about the decision that comes before it: where to put things.

The 60/40 rule, and why it is not the test

The 60/40 rule puts roughly 60% of the cargo weight in the front half of the trailer and 40% in the rear half. It exists because the failure mode it guards against is overwhelmingly the common one: loading from the tail forward, which piles everything onto the trailer bogie.

It is a good starting point and a bad finishing point. The rule says nothing about how the weight is spread within each half, so two loads can both pass it while one is legal and the other is not. The worked example below contains exactly that case: two arrangements that both put two thirds of the payload in the front half of the deck, one of which has an axle 16% over its limit.

Worked example: the same 24 tonnes, three different positions

Take a standard 5-axle articulated semi with an unladen weight of 15,000 kg, carrying 24,000 kg of payload as three 8,000 kg blocks. Total weight is 39,000 kg against a 40,000 kg EU gross limit, so every arrangement below is legal on gross weight. Only the positions change, measured in metres from the front of the cargo deck.

All figures in kilograms, EU limits under Directive 96/53/EC. Red values are over the limit. Reproduce these exactly in our truck axle load calculator by selecting the 5-axle semi with a 15,000 kg unladen weight.

Loading from the tail: 201% of the limit

With all three blocks in the last third of the deck, the rear trailer axle carries 20,125 kg against a 10,000 kg limit. That is not a marginal overload, it is double, and the steer axle is down at 2,419 kg, which makes the vehicle light at the front and harder to steer and brake. The gross weight reading of 39,000 kg says nothing is wrong.

Shifting the block forward: still illegal

Moving the whole group forward by six metres fixes the rear axle and breaks the one in front of it. Trailer axle 1 now reads 11,550 kg against a 10,000 kg limit, 16% over. Two thirds of the payload now sits in the front half of the deck, so this arrangement passes the 60/40 rule and is still illegal. The weight moved, but it stayed bunched.

Spreading it along the deck: legal with room to spare

Separating the same three blocks so they sit at 3.0, 6.5 and 10.0 metres brings every axle inside its limit, with the worst axle at 85% of capacity. The payload is identical, the vehicle is identical, and the only thing that changed is that the weight is no longer concentrated in one place. This is the result a load distribution plan is trying to find.

Kingpin and fifth-wheel load on an articulated unit

On an articulated combination the trailer’s weight does not go straight to the ground: part of it is transferred to the tractor through the kingpin, which sits in the fifth-wheel coupling on the tractor’s chassis. The trailer behaves as a beam supported at two points, the kingpin at the front and the trailer bogie at the rear, so the split follows the same lever logic as everything else on this page.

Cargo loaded towards the nose of the trailer pushes weight onto the kingpin, and from there onto the tractor’s drive axles. Cargo loaded towards the tail loads the trailer bogie instead. This is why moving a pallet forward can overload a drive axle that is nowhere near it, and it is the mechanism behind the standard fix of sliding the fifth wheel or the trailer bogie: neither moves the cargo, both move the support point.

One honest limitation to be aware of: our calculator models the whole vehicle as a single beam across all five axles rather than modelling the kingpin transfer as a separate stage. That is accurate enough to catch an obviously illegal arrangement before the truck leaves the yard, which is what a distribution plan is for, but it is an engineering approximation rather than a certified axle weight. Treat the output as a planning figure and weigh the vehicle if you are close to a limit.

How to fix a distribution problem without removing cargo

Spread the weight along the deck rather than shifting it as a block, because moving a bunched load usually just hands the overload to the next axle along, exactly as the middle column of the table shows. Start by identifying which axle is over, then move the heaviest items away from it in both directions rather than all in one.

Keep the heaviest items between the axle groups rather than at either end of the deck. Weight at the extreme tail is carried almost entirely by the rear trailer axle, and weight ahead of the steer axle is carried almost entirely by the steer axle, so both ends of the deck are the least forgiving places to put anything dense.

If no arrangement brings every axle inside its limit, the payload genuinely exceeds what that vehicle can carry and something has to come off or move to a second vehicle. That is a real answer, and finding it in the planning stage is considerably cheaper than finding it at a weighbridge.

Check the plan before the truck is loaded

A distribution plan is only useful if it is produced before loading starts, which means the calculation has to be quick enough to run a few times while you try arrangements. Our free truck axle load calculator takes a list of items with weights and positions and returns the load on every axle against EU or US limits, so you can test a layout in seconds. If you are quoting the job as well as planning it, the loading metre calculator works out the floor space the same cargo occupies.