What is centre of gravity in truck loading?

The centre of gravity (CoG) of a loaded truck is the single point through which the combined weight of the vehicle and all cargo effectively acts. It exists in three dimensions: longitudinal (front-to-rear, which determines how weight is split between drive and trailer axles), lateral (left-to-right, which determines tyre load balance and lateral stability), and vertical (height above ground, which determines rollover resistance). Controlling all three axes is essential for legal axle compliance, load safety, and vehicle handling. The CoG of the cargo alone is calculated as a weighted average of each item's position and weight — load planning software automates this calculation.

How does cargo position affect axle loads?

Axle load distribution follows the lever rule: weight is shared between the kingpin (front support point) and the bogie (rear support point) in inverse proportion to their distances from the cargo CoG. Cargo placed close to the kingpin transfers more weight to the kingpin; cargo close to the bogie transfers more to the bogie. For a 13.62 m trailer with cargo CoG at 5 m from the front: 5/13.62 = 37% of cargo weight goes to the bogie, 63% to the kingpin. Shift the CoG to 8 m and it reverses: 59% bogie, 41% kingpin. This is why heavy cargo near the front can overload the kingpin even if total GVW is within the limit.

What is the CTU Code and does it apply to road transport?

The CTU Code (Code of Practice for Packing of Cargo Transport Units) is a joint document published by IMO, ILO, and UNECE in 2014. It provides guidelines for safely packing and securing cargo in containers, swap bodies, and trailers. For road transport, the CTU Code is directly applicable to any unit that also moves by sea or rail — i.e., most international freight. For purely domestic road transport, national regulations (e.g. EU EN 12195 series, German VDI 2700) govern cargo securing, but the CoG principles in the CTU Code are considered best practice regardless. Many major shippers require CTU Code compliance in their supply chain contracts.

How do I calculate lateral CoG balance when pallets have different weights?

Lateral CoG is the left-right weighted average of your cargo. For a standard curtainsider loaded 2 pallets wide: if the left column totals 12,000 kg and the right column totals 11,000 kg, the lateral CoG is offset from centre by (12,000 − 11,000) ÷ 23,000 × (trailer width ÷ 2). For a 2.48 m interior, this is 1,000/23,000 × 1.24 = 54 mm — just over the 50 mm typical limit. Practical fix: move the heaviest pallet from the heavy side to the light side, or split a heavy pallet's row with a lighter one. Load planning software calculates this automatically from pallet weights.

What happens if the cargo CoG is too high?

A high centre of gravity reduces the truck's rollover threshold — the lateral acceleration at which the truck begins to tip. Modern trucks have Electronic Stability Control (ESC/ESP) that intervenes at 0.3–0.4 g lateral acceleration, but a heavily top-loaded trailer can tip before ESC can react. High CoG also increases the risk of cargo shift during braking and cornering, which can itself cause loss of vehicle control. Practically: always load heavy items on the floor first, lighter items on top. Never load machinery or dense cargo (metal parts, stone, liquids) on top of standard pallet cargo. For loads where high CoG is unavoidable (e.g. tall machinery), reduce speed on ramps and corners and consider a low-loader trailer.

Load Stability Guide

Centre of Gravity in Truck Loading

Where you place cargo determines how weight distributes across axles, how the truck handles in corners, and whether the load is legally compliant with CTU Code requirements.

Longitudinal CoG

Affects axle loads

Lateral CoG

< 50 mm off centre

Vertical CoG

Affects rollover risk

CTU Code

IMO / ILO / UNECE

CoG Position & Axle Load Simulator

Drag the cargo block to see how longitudinal CoG position shifts weight between kingpin and bogie

FRONT (kingpin) REAR (bogie)

Cargo CoG — 4.8 m FRONT (kingpin)

Kingpin load 15,500 kg

limit 12,000 kg OVER LIMIT

Bogie load 10,500 kg

limit 21,000 kg OK

CoG Planning Guide

How to control CoG in truck loading

Follow this sequence when planning a load — getting CoG right prevents axle overloads, reduces tyre wear, improves fuel economy, and keeps you compliant with CTU Code and EN 12195.

Step 1

Understand the three CoG axes

Every load has a centre of gravity in three dimensions. Longitudinal CoG (front to rear): determines how weight is split between the kingpin (5th wheel) and the trailer bogie. Shift cargo forward and kingpin load rises; shift rearward and bogie load rises. Lateral CoG (left to right): must be within 50–100 mm of the trailer centreline in most EU regulations — asymmetric lateral loading causes tyre overload on one side and handling instability. Vertical CoG (height): a higher CoG raises rollover risk in corners and emergency manoeuvres. All three must be considered together.

Step 2

Calculate the longitudinal CoG of your cargo

For a single pallet or item, the CoG is typically at the geometric centre. For mixed loads, calculate a weighted average: CoG position = (Weight₁ × Distance₁ + Weight₂ × Distance₂ + …) ÷ Total weight. Distances are measured from the front of the loading floor (kingpin end). For example: 10,000 kg at 2 m and 10,000 kg at 10 m gives a combined CoG at (10,000×2 + 10,000×10) ÷ 20,000 = 6 m from the front. This position then determines the axle load split via the lever rule.

Step 3

Place the heaviest cargo low and centred laterally

Heavy items should always go on the floor, not on top of lighter cargo. Low CoG reduces rollover risk in cornering — a fully loaded curtainsider with a high CoG (e.g. stacked metal coils) has a rollover threshold as low as 0.35 g lateral acceleration, versus 0.5 g for a well-loaded trailer. Laterally, keep the CoG within 50 mm of the centreline. On a curtainsider with EUR pallets, alternate pallet orientations if pallet weights differ. For loose cargo, split it evenly across both sides of the trailer.

Step 4

Use the lever rule to check axle loads from CoG position

Once you know the cargo CoG position along the trailer, axle loads follow the lever rule. For a trailer of length L, with cargo CoG at distance d from the kingpin: Bogie load fraction = d ÷ L; Kingpin load fraction = 1 − (d ÷ L). Add the vehicle tare distribution to get total axle loads. EU limits: kingpin max 12,000 kg, bogie max 21,000 kg. If your cargo CoG is at 40% of trailer length, 40% of cargo weight goes to the bogie and 60% to the kingpin — check both against their limits before loading.

Step 5

Verify compliance with CTU Code and EN 12195

The CTU Code (IMO/ILO/UNECE) requires that the load's CoG be documented for all cargo transport units. For road transport in the EU, EN 12195-1 governs lashing and securing calculations — it accounts for CoG height when calculating required lashing forces. Higher CoG requires stronger or more numerous lashings to resist the same forward/rearward/lateral forces. For heavy, dense, or awkward cargo, document the CoG position on the loading plan and attach it to the CMR waybill.

Step 6

Validate with a weighbridge or axle pad scales

Calculations give you a good estimate, but real-world CoG validation requires weighing. Drive the loaded vehicle onto a weighbridge and request individual axle group weights — most modern truck weighbridges print per-axle weights. Alternatively, use portable axle pad scales at the loading bay. If axle loads are outside the expected range, the cargo CoG is not where you calculated — check for shifted cargo or unequal pallet weights. For high-value or legally sensitive loads, a pre-departure axle check is industry best practice.

CoG Regulations

CoG rules and limits at a glance

Based on CTU Code (IMO/ILO/UNECE 2014), EN 12195-1:2010, and EC Directive 96/53. Consult national regulations for route-specific requirements.

Lateral CoG tolerance

≤ 50 mm

From trailer centreline

Kingpin load limit

12,000 kg

EU standard 5th wheel

Trailer bogie limit

21,000 kg

Dual axle, ≥ 1.3 m spacing

CTU Code

Required

For international cargo moves

Lateral CoG asymmetry

Max 50–100 mm off-centre

Most EU regulations and the CTU Code require the cargo CoG to be within 50 mm of the trailer's longitudinal centreline. Exceeding this creates unequal tyre loading: a 100 mm lateral offset in a 24,000 kg load adds approximately 200–400 kg extra load to one side's tyres, accelerating wear and reducing margin to tyre load ratings. For curtainsiders with odd pallet counts, place the odd pallet in the centre and alternate heavier/lighter pallets across each row.

Vertical CoG and rollover

Keep CoG as low as possible

The rollover threshold of a loaded truck is directly related to the height of the combined vehicle + cargo CoG. A standard curtainsider loaded with pallets at 1.5 m CoG height has a rollover threshold of ~0.45 g. The same trailer with heavy cargo stacked high at 2.5 m CoG height may have a threshold as low as 0.3 g — easily exceeded in emergency lane changes or motorway on-ramps. Always load heavy items on the floor and lighter items on top. Never stack dense cargo (machinery, metal parts) on standard pallets without checking floor load limits.

CTU Code documentation

Mandatory for international moves

The IMO/ILO/UNECE CTU Code requires the packer of a cargo transport unit to produce a packing certificate stating that the cargo has been properly stowed and secured, with reference to the CoG position. For road-only domestic transport, national regulations may be less strict, but the CTU Code applies to any unit entering an international port or crossing an international border. Non-compliance can result in detention of the unit at port and liability for any cargo damage or road incident attributable to improper loading.

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