Trailer Valuation: The Vehicle Category Determines the Scope

With scarcely any asset class does a single entry determine the scope of inspection as far as it does with trailers. The permissible gross weight determines the vehicle category, and the vehicle category determines which braking system is prescribed, at what interval the periodic technical inspection falls due and which components must be present at all. An expert who establishes the category only at the end of the inspection may not have looked at half the relevant items.

The classification follows Article 4 of Regulation (EU) 2018/858 on the approval and market surveillance of motor vehicles and their trailers. Category O1 covers trailers with a permissible gross weight of no more than 0.75 tonnes, category O2 those over 0.75 up to 3.5 tonnes, category O3 those over 3.5 up to 10 tonnes and category O4 those over 10 tonnes.

What is notable about these limits is that the same thresholds recur elsewhere in German law. The inspection intervals of Annex VIII to the StVZO and the braking provisions of § 41 StVZO work with the same weight values. In practice this means that determining the category from the registration certificate is not a formality but the switch that sets the entire further scope of inspection.

The trailer capture profile carries the weights as a field group of their own and names the source for each field. The permissible gross weight appears in part I of the registration certificate in field F.1, the unladen weight in field G. The payload is not an independent entry but the difference between the two. Nose weight and permissible axle load appear on the manufacturer's type plate.

This statement of source is not a bureaucratic detail. A trailer whose type plate is missing, illegible or visibly fitted after the fact is a different valuation case from one with complete marking, irrespective of its visible condition. Where the type plate is missing, nose weight and axle load cannot be established at the vehicle; that belongs recorded as a finding and not supplemented from a catalogue.

• Take permissible gross weight and unladen weight from part I of the registration certificate, fields F.1 and G
• Show the payload as a difference, not as an independently established entry
• Read nose weight and permissible axle load from the type plate and document the plate's condition along with them
• Capture the number of axles and the axle assembly, the latter from the manufacturer's marking on the assembly

Reconciling paperwork against vehicle is particularly productive at this point. A subsequently altered chassis, a replaced axle or a converted body shift the weights without the paperwork necessarily reflecting it. Where paperwork and vehicle diverge, the divergence is the finding.

The capture profile distinguishes the braking system as unbraked, overrun brake, air brake, air brake with ABS and air brake with EBS. Which of these versions is permissible follows from § 41 StVZO and again depends on weight.

Under § 41 paragraph 11, single-axle trailers and two-axle trailers with an axle spacing below one metre need no brake of their own if the combination achieves the prescribed deceleration and the trailer's axle load exceeds neither half the unladen weight of the towing vehicle nor 0.75 tonnes. The overrun brake is tied to weight limits by § 41 paragraph 10; on trailers up to 3.5 tonnes it is permissible if the brake acts on all wheels. § 41 paragraph 9 further requires that a trailer separating from the towing vehicle brings itself automatically to a stop, and does so on an incline and a decline of 18 per cent.

For the survey this yields concrete inspection points that the profile carries individually: the condition of the braking system, the condition of brake cables and linkage in the grades in order, needs adjustment, corroded and defective, the wear of the coupling against its wear limit, and the presence and condition of the breakaway cable or breakaway brake. The breakaway cable in particular is frequently overlooked during inspection, although it is the practical implementation of the requirement in § 41 paragraph 9.

Many trailers carry a 100 km/h plate. For the valuation it matters that this approval is not permanently attached to the vehicle but to conditions that must be met at the time of the particular journey. One of them is directly verifiable at the vehicle and expires silently.

§ 3 of the Ninth Regulation on Exemptions from the Provisions of the Road Traffic Regulations provides that the trailer's tyres must, at the time of the particular journey and recognisable from the embossed date of manufacture, be younger than six years and marked with at least speed category L, that is 120 kilometres per hour. A trailer with a valid plate and eight-year-old tyres no longer meets the requirement, without anything about the plate having changed.

The remaining conditions appear in § 1 of the same regulation and tie the trailer's permissible gross weight to the unladen weight of the towing vehicle by a factor depending on equipment: 0.3 for all trailers without a brake and for braked trailers without hydraulic shock absorbers, 0.8 for caravans with a rigid body and hydraulic shock absorbers, and 1.1 for other trailers with hydraulic shock absorbers. § 4 of the regulation additionally addresses the nose weight of the combination, for which the lower of the two permissible values applies in every case.

• Read the date code of all tyres and capture them individually, not only the least favourable tyre
• Check the speed category of the tyres against the requirement of category L
• Establish whether hydraulic shock absorbers are present, since the permissible weight factor depends on it
• Carry the finding on the 100 km/h condition as a finding and not as legal advice

On a trailer the body is the part that most directly determines utility value and at the same time wears fastest. Here the profile carries side boards by material and condition, tarpaulin and bows, the load floor by material and condition, the lashing points and the internal dimensions of the load area in millimetres.

With the floor, distinguishing the material is particularly worthwhile. Phenolic plywood, a timber floor, an aluminium or a steel floor age differently and are repaired differently. A load floor of phenolic plywood that has broken through or is swelling is a different finding from a distorted aluminium plate, and both are something other than a corroded steel surface.

To be separated from the load area is the load-bearing substance. Corrosion on the frame is carried by the profile in the same three grades as on a motor vehicle: none, surface rust, rusted through. Added to this is the condition of the drawbar and front frame as a field of its own. A rusted-through frame or a deformed drawbar are not body defects but findings on a load-bearing component, and they stand in a different relationship to value than a torn tarpaulin.

• Switch through the lighting system completely and distinguish single failures from several failures
• Capture the electrical connector by design, seven, thirteen or fifteen pin, and check the condition of the contacts
• Check underrun protection for presence and damage, where required for the category
• Check the jockey wheel and support legs for function, not only for presence

The trailer profile closes with the same valuation fields carried by the other asset classes: an indicator for frame or accident damage, the overall condition grade and the value fields. Here too the grade is derived from the individual findings and not awarded in advance.

Damage to the frame is the finding with the greatest leverage here, because it concerns the load-bearing structure and does not lend itself to assessment of repair by visual inspection. Where it is established, it shifts the grade irrespective of how well maintained the body appears. Conversely, a sound frame does not carry a good grade if the braking system and lighting show defects.

The value fields differ by purpose: market value and current value for the valuation report and for pre-purchase advice, replacement value for the valuation and damage report, diminished value for the damage report. Which value is required follows from the engagement and belongs clarified at the outset. A report that mixes the terms is open to challenge even where the figure is plausible in the result. We have set out the delimitation between the value concepts in more detail using the example of residual value.

Trailers are often operated over long periods and with changing towing vehicles, and their valuation is questioned correspondingly late. What carries the findings then is not their length but the binding of every statement to a named source: registration certificate, type plate, measuring instrument or visual inspection. The profile records this source per field; in the report it must remain visible.

Three points are, from experience, particularly in need of explanation when questions arise later: the origin of the weights where the type plate was missing; the finding on the 100 km/h condition, because it hangs on a date that keeps moving; and the delimitation between a body defect and damage to the load-bearing structure. An expert who addresses these three points expressly in the report answers the most frequent queries before they are put. The underlying principle is the same as for any other report: no value without a source.

DIAVAG is a software platform for experts and carries a dedicated capture profile for trailers, semi-trailers and container chassis with the field groups trailer data, weights and axles, brake and coupling, body and load area, and technology and condition. The platform employs no experts of its own and produces no reports. Which findings are established and how they are to be appraised is decided by the expert who signs the document.