Converting the Steyr 12M18 Ex-Military
Every number you need before the first cut: load area dimensions, weights and axle loads — plus the calculation nobody else makes: what actually remains for the conversion after the legally required remaining payload.
For the conversion
4,991 kg
Payload minus the legally required remaining payload with 2 seats.
Usable interior width
240 cm
After 25 mm of insulation and panelling per side.
Height above the floor
205 cm
After a 50 mm floor build-up.
Weights and axle loads
The legally required remaining payload is (seats − 1) × 75 kg + 10 kg × (seats + vehicle length in metres), under DIN EN 1646-2 and Regulation (EU) 1230/2012.
Dimensions
The load area width applies at its widest point. Between the wheel arches it is considerably narrower — anyone planning a crosswise bed there usually builds it over the arches.
What fits inside
Sleeping crosswise works up to roughly 235 cm in height — calculated with 5 cm added for pillows and movement.
Lengthwise, length is not the hurdle: 440 cm of usable length is enough for any height. What matters here is what is left over — at 1.85 m tall that is 255 cm behind the bed for kitchen, bathroom and storage.
People up to roughly 203 cm can stand upright.
What matters with this vehicle
Between the kerb weight (6,350 kg) and the gross vehicle weight (11,500 kg) there are 5,150 kg. With two seats you must keep 159 kg of that free for people and luggage — leaving 4,991 kg for insulation, furniture, equipment and water. With four seats it is only 4,821 kg.
The permitted axle loads add up to 11,800 kg, which is 300 kg more than the gross vehicle weight. So you cannot use both axles to the full — the gross weight is reached first.
The smaller reserve is on the front axle: empty it sits at 3,800 kg, 4,600 kg are permitted. That leaves 800 kg — and those go faster than the 5,150 kg of total payload suggest, because heavy furniture rarely sits in the middle.
The shell alone costs weight: roof, side walls and rear doors add up to around 38.6 m². With 19 mm Armaflex that is about 44 kg, before a single piece of furniture is in the vehicle.
From data sheet to floor plan
In the app you draw bed, kitchen and bathroom to scale into exactly this vehicle — including wheel arches, sliding door and roof taper. Weight, axle loads and centre of gravity are calculated while you plan.
Open the app in your browserCarry on with these numbers
All calculators are free and need no account — the Steyr 12M18 Ex-Military is already stored there as a vehicle.
Frequently asked questions
How much payload does the Steyr 12M18 Ex-Military have?
Between the kerb weight (6,350 kg) and the gross vehicle weight (11,500 kg) there are 5,150 kg. Part of that has to stay free for people and luggage, as the standard requires.
How much weight is left for the conversion?
With two seats 4,991 kg, with four only 4,821 kg — the payload minus the legally required remaining payload under DIN EN 1646-2.
Does a crosswise bed fit in the Steyr 12M18 Ex-Military?
Yes, sleeping crosswise works up to roughly 235 cm in height. Calculated above the wheel arches, after insulation and panelling.
Can you stand up in the Steyr 12M18 Ex-Military?
Yes, up to roughly 203 cm in height. Above the finished floor 205 cm remain.
Further reading
The values come from the vehicle catalogue in the VanLogic app: manufacturer data sheets and the ADAC vehicle catalogue, merged for the common model years of a series. Kerb weights vary by several dozen kilos depending on equipment, and uprating changes both gross weight and axle loads. What counts is your registration document.