Hooking up a caravan for a long-awaited holiday often feels like the start of freedom. But for many drivers in Spain, the real journey begins with a calculation: how much weight is trailing behind the car, and is it within safe and legal limits? The answer can mean the difference between a relaxed lead and a stressful, potentially dangerous day on the road.
A commonly used safety benchmark is the “85% rule”: it recommends keeping a caravan’s loaded mass at or below 85% of the towing car’s unladen mass. It is a non-binding rule of thumb, not a Spanish statutory limit, and cannot replace the manufacturer’s towing specifications or the legal checks shown in the vehicle and caravan documents. Stability also depends on load distribution, speed, road gradient and crosswinds. A heavier towing vehicle can generally offer more resistance to trailer-induced movement, but no single ratio guarantees stability.
Keeping the caravan relatively light compared with the car can provide an additional handling margin. If a caravan begins to sway, the combination’s stability depends on several interacting factors, including the vehicle, trailer, coupling, load and driving conditions. Strong crosswinds, passing heavy vehicles and steep gradients can all make handling more demanding, so the 85% guideline should be treated as a planning aid rather than a promise that a vehicle can correct any sway.
Before setting off, drivers should check the car’s technical documentation for its permitted towing capacity, including the limits for braked or unbraked trailers, and confirm that the coupling equipment is approved for the combination. These specifications are separate from the car’s own maximum authorised mass and the authorised mass of the complete car-and-caravan combination. Staying within the manufacturer’s towing limit matters for acceleration, braking, thermal loads and handling; engine power or vehicle size alone cannot establish how much a car may tow.
Spanish driving-licence rules are a separate check. Category B covers cars with a maximum authorised mass of up to 3,500 kg and no more than eight passenger seats besides the driver. The entitlement for a car-and-trailer combination depends on the authorised masses and configuration recorded in both sets of documents; B96 and B+E provide additional entitlements for heavier combinations. The practical test is so not the 85% guideline or the caravan’s empty weight, but the vehicle and trailer documentation together with the driver’s licence category.
Insurance is another distinct requirement. Spanish insurance guidance uses the caravan’s maximum authorised mass (MMA), rather than its empty weight or the load it happens to carry on a particular trip, to determine whether separate compulsory cover is generally required. A caravan or trailer above 750 kg MMA generally needs its own policy; units at or below that threshold fall within the exemption described in Article 2.8.b of the consolidated motor-liability insurance law. A valid policy for the towing car does not by itself establish that a heavier caravan is separately insured, and insurance requirements do not determine whether the combination is within the vehicle’s towing limit or the driver’s licence entitlement.
One common mistake is relying solely on the caravan’s empty weight listed in the paperwork. The loaded figure includes fixed accessories, such as air-conditioning units, manoeuvring aids, awnings and supports, as well as luggage, clothing, dishes and food. Adding at least 200 kg can be a rough planning estimate for extras, but the caravan’s documented MMA remains the legal ceiling, and the actual loaded mass must also stay within the car’s and trailer’s permitted limits. A caravan with an empty mass of 650 kg, for example, may have an MMA of 1,000 kg; the authorised figure, not the empty weight, is relevant to obligations such as the insurance threshold.
Load placement matters even when the overall mass is legal. Heavy items placed high up or toward the rear can aggravate pitching and sway. Secure items so they cannot fall or shift dangerously, distribute weight low and close to the axle, and follow the caravan manufacturer’s loading instructions. The tow-ball load should also remain within the limits specified for both the car and the caravan; any percentage target, including the commonly cited 5% to 7% range, must not override those technical limits.
For those planning long journeys, real-world tests, like the recent highway range comparison of electric SUVs covered by RUSSPAIN, highlight how small technical details can have a big impact on travel safety and comfort.
