How Far Can A Roof Box Overhang

How Far Can A Roof Box Overhang?: Safety First!


If you’re in the market for a new roof box or in the process of changing cars then you might be wondering how far a roof cargo box can overhang? While most people are probably thinking about the overhang at the front of their vehicle it is actually the rear of the vehicle where you probably need to pay more attention.

If you’re driving some form of hatchback or SUV then you need to position your roof cargo box so that it doesn’t affect your ability to open the rear hatch. If you do decide to purchase a box that will overhang at the rear then you’re just going to have to avoid accessing your vehicle via the rear hatch while the cargo box is in place. For most people, this is likely to be a dealbreaker.

Some overhang (of the roof) at the front shouldn’t cause too many problems as you are unlikely to be affected by it once you’re in the vehicle. Obviously, you probably shouldn’t install an 84-inch long box on a Mini!

How Much Is Too Much?

To an extent, it comes down to commonsense. You don’t want to be installing a box that overhangs beyond the dimensions of your car for example.

You want to avoid creating any issues with stability. Follow any manufacturer guidelines regarding the positioning both of the box and any contents. Many boxes will probably suggest that you should allocate the load within the cargo box to 25%/50%/25% spread between the two roof bars that it is attached to.

You should try to select a box that is appropriately sized for your vehicle. Don’t just buy the largest possible box. Think about what you’re actually going to carry in the box and base your purchasing decision on that.

Rear Overhang

If you’re driving a saloon or coupe then rear overhang would become less of an issue as it’s unlikely to affect your ability to access your trunk. Although in the case of the coupe is any form of roof storage a great idea?

If you own a hatchback or SUV then you’re going to have to buy a box that you can position where it won’t interfere with the rear door. Positioning it a little more forward may cause the box to protrude over the windshield but most people find that box isn’t visible when you’re sitting in the front seats anyway so it doesn’t become a major problem. Depending on your vehicle you may need to allow quite a bit of room at the rear of your roof to allow for a fully opened rear hatch.

Size Matters

You should try to purchase a box with the size appropriate to the vehicle you will be fitting it to. Obviously, if you have a large SUV such as a Ford Expedition or Audi Q7 then you can go to town and get a large storage box. On the other hand, if you’re driving a Honda Civic then you should restrict yourself to smaller options. You will find some limits in the owner’s manual regarding the weight that the roof is able to support.

Make sure to stick within that limit and don’t forget that the weight of the rack and box is included in the total. The storage box will also have a load capacity specified by the manufacturer and you need to make sure you don’t exceed that limit to avoid damage to your roof cargo box.

Legal Issues

You shouldn’t assume that fitting some storage to your car that overhangs is actually going to be legal. Different countries and even different states could have widely differing rules regarding any legal overhang limit.

According to legalbeagle if a load overhangs the front by more than 3 feet, the rear by 4 feet or the side by 4 inches then you need to mark the overhang with warning flags and lights for driving after dark.

These rules are different to the UK where a variety of different measures might need to be employed depending on the amount of overhang.

So to be on the safe side try to avoid purchasing a box that is going to overhang the front, rear or sides of your car.

Audi with roof box overhanging windshield
Audi SUV with roof box overhanging windshield

Stability And Safety

Your first consideration really should be the safety of yourself and other road users so don’t purchase an inappropriately sized box or overload one that is the correct size!

Take care to follow the manufacturer’s recommendations on how to attach the vehicle to your car. Make sure to stow your contents appropriately following any guidelines for weight distribution. This is particularly true for a heavy load. Try to tie down the items in the box to make sure they aren’t moving around while in transit.

Do you want your belongings strewn across the highway because you failed to follow the advice of the manufacturer?

How Far Can A Roof Box Overhang: Summary

A small amount of overhang shouldn’t be too detrimental, however, make sure to follow the instructions both from the manufacturer of your vehicle and your roof box. Don’t forget to check with your local authorities to make sure you aren’t in breach of any regulations.

Or take the simpler option and purchase a cargo box that doesn’t overhang and therefore should give you fewer headaches. This will allow you to concentrate on enjoying your road journey rather than worrying about the load on your vehicle’s roof. 

Similar Posts