A standard curtainsider semi-trailer has internal dimensions of approximately 13.60 m in length, 2.45 m in width and 2.70 m in height. It offers roughly 86–90 m³ of volume, 33 Euro pallets and a net payload of around 24 tonnes. In a mega trailer the internal height rises to 3 metres; in a reefer trailer the internal dimensions are a few centimetres smaller because of the insulation.
Why are internal dimensions read separately from legal external dimensions?
Article 128 of the Turkish Highway Traffic Regulation (Karayolları Trafik Yönetmeliği) limits a vehicle's external dimensions: width 2.55 m (2.60 m for refrigerated bodies), height 4.00 m, and 16.50 m length for a tractor and semi-trailer combination. What matters to the shipper, however, is the inside of the body. Side walls, curtains and stanchions take 7–10 cm off the width. For height, the decisive factor is the deck height above the ground: on a standard trailer the deck is at about 1.20–1.30 m, leaving an internal height of 2.65–2.70 m within the 4 m limit. A mega trailer lowers the deck with small-rim wheels and a low chassis, bringing the internal height close to 3 m.
Internal dimensions by trailer type
| Type | Internal length | Internal width | Internal height | Volume | Euro pallets |
|---|---|---|---|---|---|
| Standard curtainsider | 13.60 m | 2.45–2.48 m | 2.65–2.70 m | 86–90 m³ | 33 |
| Mega | 13.60 m | 2.45–2.48 m | 2.95–3.00 m | approx. 100 m³ | 33 |
| Reefer | 13.30–13.40 m | 2.45–2.47 m | 2.55–2.65 m | 82–87 m³ | 33 |
| Jumbo (truck + drawbar trailer) | 2 × 7.70 m | 2.45 m | approx. 3.00 m | 110–120 m³ | 36–38 |
Values vary by a few centimetres depending on the manufacturer and model. The rear door opening may be lower than the internal height; for tall cargo, the door dimensions should be checked separately. The differences of the mega trailer are explained in the mega trailer entry, and the structure of the refrigerated body in the reefer trailer entry.
What limits the weight capacity?
In Türkiye, the maximum gross weight of a tractor and semi-trailer combination with five or more axles is 40 tonnes. Since the tare weight of the tractor and trailer together is 14–16 tonnes, the net payload comes down to about 24–26 tonnes. Mega and reefer trailers are heavier, so they generally carry one or two tonnes less. Even if the gross weight stays below the limit, the load on a single axle is also limited: 10 tonnes on a single non-driven axle and 11.5 tonnes on a driven axle. A heavy, short load is not simply placed in the middle of the trailer; it is positioned after calculating the axle load distribution.
In the European Union, Directive 96/53/EC generally takes 40 tonnes as the basis; in combined transport it allows 44 tonnes for vehicles carrying a 40-foot ISO container. On international trips, each country's rules are checked separately.
Cargo density determines whether volume or weight fills up first. Dividing a net capacity of 25 tonnes by 90 m³ gives roughly 280 kg/m³. If the cargo's density is below this (furniture, foam packaging, empty bottles), the trailer fills up by volume before weight; if it is above (ceramics, metal, paper reels), the weight limit is reached before the volume is full.
Which trailer for which cargo?
- Palletised general cargo: standard curtainsider; can be side-loaded with a forklift. Typical uses are covered in the curtainsider truck entry.
- Light but bulky cargo (white goods, automotive parts, packaged textiles): mega or jumbo.
- Food and pharmaceuticals: reefer trailer.
- Cargo exceeding legal dimensions: lowbed and special trailers; the limits are in the legal road dimension limits entry.
Common mistakes
- Using the external height instead of the internal height when calculating pallet height.
- Filling the volume without checking the weight limit, especially the axle load.
- Confusing the industrial pallet (1.20 × 1.00 m) with the Euro pallet; a standard trailer holds 26 industrial pallets.
For full truckload shipments, Voltim Global determines the trailer type and loading plan at the quotation stage based on the packing list.