Tyres, load and payload: weighing your camper before a journey
How to read a tyre sidewall, what the weight terms on the plate mean, and why a trip to a weighbridge tells more than any brochure figure.
By CampingSpirit Editors · August 18, 2026 · 6 min read
Tyres are the only part of a camper that touches the road, and weight is the one number most owners never check. The two are closely linked: an overloaded vehicle runs its tyres hotter, flexes the sidewalls more and brakes later. A short session with a tyre sidewall and a weighbridge answers most of the questions, and costs far less than a failed tyre or a fine at a roadside check.
This article explains how to read the markings, what the weight terms mean in practice and how to check a loaded vehicle. The figures that matter are always those on the vehicle’s own plate and in its handbook; what follows is how to understand them.
Reading the sidewall
A tyre size such as 225/75 R16 is followed by two codes that matter more to a camper than to a car: the load index and the speed symbol. The load index is a number that corresponds to the maximum load the tyre can carry; an index of 91, for example, stands for 615 kg per tyre, and the speed symbol, such as V, stands for a maximum speed. Both apply to tyres that are in good condition, correctly inflated and not overloaded or repaired. The index on each tyre must at least match what the vehicle manufacturer specifies for the axle, and a tyre of the same size with a lower index is not a substitute.
Van-based campers normally use C-marked tyres, such as van tyres. Heavier coachbuilt and low-profile motorhomes are normally fitted with CP-marked tyres, which Michelin describes as designed for heavy motorhomes, with a higher load index and higher pressure and a reinforced carcass. Fitting ordinary car tyres, or replacing CP tyres with a van tyre of similar size, risks exceeding the load rating. If in doubt, the tyre should match the vehicle’s documents, not the tyre shop’s stock.
Age matters as much as tread
Rubber degrades with time even on a vehicle that is hardly used, and campers often stand for months. The production date is moulded into the sidewall after the letters DOT: the last four digits give the week and the year, so 2714 means the 27th week of 2014. Continental advises withdrawing all tyres, spares included, that were produced more than ten years ago, whatever the tread looks like. For caravans, which stand longer and carry heavy fixed loads, advice in the UK trade is often to replace after around six years. Legal tread depth is 1.6 mm in many countries, but braking in the wet deteriorates before that point, and a camper used in winter or in mountains is better served by replacing earlier.
A spare tyre is a tyre like any other. If it has hung under the floor for a decade, it carries the same age problem, and a flat is not a good time to find out. The same goes for tyre repair kits: sealant and compressor are worth checking for expiry date and function before a long trip.
Pressure and monitoring
Pressure is the cheapest safety measure. For CP tyres on a motorhome, Michelin cites a rear-axle pressure of up to 5.5 bar (80 psi), which is far above car values, and recommends checking monthly and before long journeys. Continental suggests a check every two weeks. The correct value is the one in the vehicle handbook or on the placard, set for the actual load and measured with cold tyres. Under-inflation is the typical way a heavily loaded tyre fails.
A tyre pressure monitoring system, either with sensors on the valves or inside the tyres, reports pressure and sometimes temperature to a display in the cab. It is a sound addition for vehicles with twin rear tyres or a trailer, where a slow loss is hard to feel. It supports regular checks with a gauge but does not replace them.
The weight terms in plain language
Several terms appear on the plate and in the papers. Maximum technically permissible laden mass (MTPLM, or GVWR in the United States) is the most the vehicle may weigh when fully loaded. Mass in running order (MRO) is the vehicle as delivered with standard equipment; for motorhomes in the EU it includes a driver counted at 75 kg, a fuel tank at 90 per cent, and a manufacturing tolerance of plus or minus 5 per cent, according to Hymer’s published explanation. Payload is what remains between the two. The EU sets a minimum payload for motorhomes with the formula 10 × (n + L) kg, where n is the number of seats including the driver and L is the vehicle length in metres: for a 6 m motorhome with four seats, 10 × (4 + 6) equals 100 kg. That is a floor for the manufacturer, not a guide for loading a holiday.
Real payload is used quickly. Every passenger beyond the driver counts as 75 kg in the manufacturer’s standard, and then come water, gas, bicycles, a rear carrier, an awning, awning accessories, a generator, tools, food, clothes and, in many vehicles, a second battery or inverter fitted after delivery. Adding them is the only way to know whether a 3,500 kg camper with a few hundred kilograms of user payload will fit the family and the luggage.
Weighbridges and axle loads
Total mass is not the only limit. Each axle has its own permitted load, and a vehicle can be below the total and still above on the rear axle, typically when bicycles, a garage load or a tow-bar carrier push weight behind the axle. A public weighbridge shows both: drive on with the whole vehicle for the total, then weigh the front axle alone to get the rear by subtraction, or use a platform that weighs per axle. Weighbridges are found at farm co-operatives, recycling and building-materials yards, some fuel stops and, in North America, at truck stops with certified scales. Prices are modest and are usually posted.
Weigh the vehicle as it will travel: full water tank if that is how it is driven, gas, passengers, bikes and the usual contents of the lockers. If the result is over, the remedy is either to carry less or, where the manufacturer allows it, to have the plated mass revised. Several countries fine overloading, and an insurer may question a claim if overloading played a part in the accident; the details differ by country, so it is worth reading what applies on the planned route.
A practical check before a trip
Before a long journey, check the production date on all tyres including the spare, set the pressure for the real load with cold tyres, and look at the sidewalls for cracks, cuts and bulges. Write down the total and axle limits from the plate. Weigh the vehicle fully loaded once per season and again after any major change in equipment. Keep the slip from the weighbridge with the vehicle papers, because it shows what was done, and it is cheaper than a new tyre.
