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Taking the car on holiday: weight limits, roof box, bikes and trailer

How to load a family car, roof box and bike rack. An overview of weight limits, towbar nose weight and the rules for towing a trailer.

October 27, 2026

Taking the car on holiday: weight limits, roof box, bikes and trailer

Key takeaways

The car's load includes passengers, luggage and accessories. A roof box or a bike rack doesn't increase the car's payload; it only adds its own weight.
The maximum roof load includes the roof bars, the empty box and its contents. The load ratings of the roof bars and the box itself also apply.
With a towbar-mounted bike rack, the weight of the rack is deducted from the permitted nose weight. Only the difference is left for the bikes.
The limit for a braked trailer is shown in the registration certificate under O.1, for an unbraked trailer under O.2. The limits for the car, the combination and the nose weight on the tow ball apply at the same time.
A roof box increases drag: in ADAC measurements at 130 km/h, fuel consumption rose by around 18% on average.

A holiday by car tests a family car more thoroughly than a year of everyday driving. On top of the passengers and luggage come bikes, sports kit or a trailer, and a roomy car can easily become an overloaded one. When choosing a used car, it is therefore worth looking beyond the boot at the payload, the options for fitting accessories and the towing figures. They show whether the car can carry the family's kit safely or whether some of it will have to stay at home.

Taking the car on holiday: weight first, then storage space

A big boot shows where to put things, not how much the car may carry. Even an estate or SUV with plenty of room can reach its weight limit before the last free corner is filled. How to compare the boot itself is explained in the article on boot space.

The vehicle documents state the maximum authorised mass and the unladen or kerb weight. The payload is the difference between them:

Payload = maximum authorised mass − unladen weight of the car.

With the kerb weight, it matters what it already includes, above all whether the driver is counted. If so, the driver isn't counted again in the total. Higher trim levels and retrofitted accessories increase a used car's actual weight compared with the brochure figure, which leaves less for the load.

The family total includes:

passengers (except those already included in the weight figure you are using);
luggage, food, drinks and sports kit;
roof bars, the box and its contents;
the bike rack, including the bikes;
when towing, the trailer's nose weight on the tow ball.

Water, drinks and sports equipment add the most weight without anyone noticing. Moving luggage from the boot to a roof box doesn't reduce the total; on the contrary, the box and roof bars are added to it.

Why the figure for the same model isn't enough

Weights and space vary with the engine, drivetrain and equipment, even within the same model. Škoda quotes a 640-litre boot for the pre-facelift Octavia Combi IV (from 2019), while the iV plug-in hybrid has only 490 litres because of its battery, which also adds to the unladen weight. The petrol and hybrid versions of the Hyundai Tucson NX4 (from 2020) differ in a similar way. So don't carry figures over from one version to another. Nor does an SUV's taller body mean a higher payload.

Anyone who regularly travels with a full car and heavy kit should look for a used car with a margin in its payload. You can't add it after purchase with a bigger box or stronger roof bars. Roomy models are compared in the articles on the best estate car and the family SUV with a big boot.

How to load the car so it stays stable

Heavy items go at the bottom and as close as possible to the rear seatbacks. Lighter, bulky kit can go higher up or in the roof box. The centre of gravity then rises less, and the heavy load won't shift forward under hard braking.

Secure luggage and rigid items to the lashing eyes in the boot, especially if there is free space around them. A roller load cover won't hold the load in place. If you load above the seatbacks, the car needs a dog guard or a dividing net.

Besides the total weight, the limits for each axle apply too. A heavy load at the back of the boot, a rear-mounted rack and the nose weight from a trailer can overload the rear axle even if the overall limit isn't exceeded. The surest answer comes from weighing the loaded car, ideally axle by axle.

What tyre pressures to use

For a fully loaded car, set the pressure the manufacturer specifies for full load. You will find the figures on a label in the door frame or on the fuel filler flap and in the owner's manual. They can differ for the front and rear axles and for different tyre sizes.

Pressures are set with the tyres cold. The number on the sidewall is the tyre's maximum, not a recommendation for the car. Higher pressure doesn't increase the car's payload and won't fix an overloaded axle.

Roof box: how much it can carry and how it affects driving

Light, bulky items belong in a roof box: clothes, sleeping bags, some of the sports kit. Leave heavy suitcases and supplies of drinks low down in the car.

When loading, several limits apply at once:

Part of the set-up	What counts towards its load
Car roof	The roof bars, the empty box and everything inside
Roof bars	The box and its contents, within the load rating given by the roof bar manufacturer
Roof box	The load inside the box, within its load rating
Whole car	The entire roof set-up with its load, together with everything else in the car

The box's load rating is therefore not the same as the maximum roof load. The weight of the roof bars and the empty box is first deducted from the roof limit. Only the difference is left for the load, and even that may be lower because of the load rating of the box or roof bars.

The roof bars must match the way they attach to the specific car: raised roof rails, flush rails and a plain roof each use a different system. Before buying accessories, one compatibility check against the exact model, body style and year of manufacture is enough.

How fast to drive with a roof box

The upper limit is set by the lowest speed allowed by the manufacturer of the box or the roof bars – and, of course, by traffic regulations. There is no universal limit for all boxes. Crosswinds, rain or a fully loaded car call for slower driving even below this limit.

In ADAC measurements, a roof box increased fuel consumption at 130 km/h by around 18% on average. For a specific car, it depends on the shape of the body and the box and on your driving style. On a long journey, easing off saves fuel; after the holiday, so does taking off the box and roof bars.

Items inside the box belong under the tie-down straps. The lock keeps the lid shut; it doesn't secure the load.

Bike rack for the car: roof, towbar or tailgate?

The choice of rack depends on the weight of the bikes, what the car can take and how often you carry bikes. For e-bikes, the load rating of the whole set-up matters more than the number of places in the rack's name.

Rack position	Practical advantage	Main limitation
On the roof	The bikes don't stop the tailgate from opening	Lifting bikes up high, roof load, greater vehicle height and drag
On the towbar	Easier loading of heavier bikes	Nose weight on the tow ball, the rack's load rating and the rear axle load
On the tailgate	No towbar needed	The rack must fit the specific body style; limited access to the boot

How many bikes can a towbar-mounted rack carry

The permitted nose weight of both the car and the towbar applies; the lower of the two values counts. The rack and all the bikes must fit within it.

Weight of the bikes ≤ permitted nose weight − weight of the empty rack.

The rack's total load rating and the rating for each position must also be respected. A rack with three places often can't carry three heavy e-bikes; the weight runs out before the holders do.

If the bike manufacturer allows the battery to be removed, doing so lightens the load on the rack. Store the battery in the car and secure it; it still counts towards the car's load.

A tailgate rack needs mounting points approved for the specific body style. A spoiler, the glass or the shape of the tailgate edge limit its use. Being able to hook on all the straps doesn't mean the rack is right for the car.

Towbar and trailer: which weights apply at the same time

For a trailer, a powerful engine and a tow ball behind the bumper are not enough. The registration certificate contains these figures:

Figure	Meaning
O.1	Maximum permissible mass of a braked trailer
O.2	Maximum permissible mass of an unbraked trailer
Maximum authorised mass of the car	The limit for the loaded car, including the nose weight from the trailer
Maximum authorised mass of the combination	The limit for the car and trailer together
Permitted nose weight	The limit for the load on the tow ball

All limits must be met at the same time. A fully loaded car therefore often can't tow a trailer of the maximum weight given under O.1, because it would exceed the combination limit. That limit isn't simply the sum of the car's and the trailer's maximum weights.

The load in the trailer belongs low down, over the axle, according to the trailer manufacturer's instructions. Moving heavy items right to the back to lighten the tow ball is a mistake: the combination then becomes more prone to snaking. The nose weight should be within the specified range, not as low as possible. For mountain trips with a trailer, a car with four-wheel drive also comes in handy; see the article on the 4x4 family car.

Fixed, detachable or retractable towbar?

The design mainly changes how you use it. The permitted trailer weight is determined by the figures for the car and the towbar.

Design	What it means in practice
Fixed	The tow ball stays permanently behind the car
Detachable	The neck with the tow ball is removed after use
Retractable	Once unlocked, the tow ball swings away under the bumper

On a used car with a towbar, check the mounting, corrosion, play, the locking mechanism and the electrical socket. On a detachable version, also check that the key is available and the neck locks properly.

Can a towbar be retrofitted?

Yes, if that version of the car allows it. Besides the mechanical part, it involves the wiring, on newer cars often electronic coding and, depending on the rules of the country of registration, an entry in the vehicle documents. That adds to the work and the time at the workshop.

Some versions of cars must not tow a trailer at all, or only with a low limit, even though a tow ball for a bike rack can be fitted. Anyone who needs a trailer regularly should choose a used car with a factory-fitted towbar and suitable figures under O.1 and O.2. On Carvago, you can search for such cars among offers from dealers across Europe, so the choice doesn't end with a handful of local listings.

What to watch out for before you set off

The most common mistakes share the same root: each accessory looks sensible on its own, but together they add up to more than the car can handle.

A roof box as a cure for overloading: it adds space, not payload, and weighs something itself.
Number of holders instead of load rating: the bikes fit on the rack, but it can't take their weight.
Towing capacity confused with nose weight: a high trailer limit doesn't tell you how much a rack with bikes may weigh.
An overloaded rear axle: a heavy boot and a rear-mounted rack use up its limit before the overall one.
Loose items in the cabin: under hard braking, they fly towards the occupants.

A short checklist

Add up the passengers, luggage and accessories, including the accessories' own weight.
Compare the total with the limits for the car, axles, roof, racks and any trailer.
Secure the load and tighten the accessories according to the instructions.
Set the tyre pressures for full load.
Check that the lights and number plate are visible, as well as the lighting on the rack or trailer.

Carvago: a used car chosen with the holiday load in mind

When a car is regularly going to carry the family, bikes and a trailer, payload, towbar and roof rails should be part of the choice from the start. Carvago has the widest selection of used cars, roughly a million cars from dealers in several European countries. Finding a specific version with the engine and equipment you need is therefore much easier than in local listings.

Every car is inspected by a technician before sale as part of CarAudit™, with up to 270 checkpoints: technical components, diagnostics, a test drive and the available information on the car's history. The customer knows the result before deciding to buy, and Carvago guarantees the condition stated in the CarAudit™ certificate.

Once the purchase is approved, Carvago uses a power of attorney to handle the paperwork, including registering the car in the customer's country, and delivers it to the customer's door. The family doesn't have to deal with transport or paperwork and can drive off straight away – even straight on holiday.

FAQ

How do I find out whether the car will fit into a garage with a roof box or bikes on top?

After fitting the accessories and loading the bikes, measure the height from the ground to the highest point of the set-up. Write the figure on a note within the driver's line of sight. A height restriction at an entrance applies to the whole set-up, not just the car.

Can a bike rack affect the parking sensors and opening the boot?

Yes. The bikes intrude into the camera's field of view and the area monitored by the sensors. Even a tilting rack may not allow the tailgate to open fully on every body style, so when choosing a rack, allow for the space the tailgate needs to swing.

Do I need to adjust the headlights when fully loaded?

Yes, if the car doesn't have automatic headlight levelling. A fully loaded boot raises the front of the car, and the headlights then dazzle oncoming drivers. Set the manual control to the position the owner's manual gives for full occupancy and load.

Is there anything extra to consider for an electric car or plug-in hybrid?

The battery increases the unladen weight, so there is often less left for passengers and luggage than in the petrol version of the same model. Some electric versions have a low trailer limit or aren't approved for towing at all. A roof box also increases electricity consumption and therefore shortens the range between charges.

Can I go through an automatic car wash with a rack or roof box fitted?

Neither a roof box nor a bike rack belongs in an automatic car wash. The brushes can catch them and damage both their mountings and the car.