Published 8 November 2026 · OFM4x4.co.uk

A rack's advertised capacity is only one part of a loaded roof calculation. The vehicle roof limit, mounting kit and weight of the rack itself also count.

The quick answer

Use the lowest applicable limit for the vehicle, feet, bars, platform and accessory mounts. Subtract the mass of every fitted item before deciding how much cargo can be carried.


Find all the limits

Read the vehicle handbook and the rack system's application instructions for the exact roof type. Dynamic road use and parked static loads can have different meanings. A high platform rating cannot override a lower vehicle limit.


Count the hardware

Include bars, feet, platform, awning brackets, tent mounts and permanently carried tools in the roof total. A roof box's empty mass is part of the calculation. Do not count only the luggage placed inside it.


Place loads intelligently

Follow the mounting positions, crossbar spacing and distribution instructions. Long items need an approved restraint method and must not obscure lights or project dangerously. A heavy item high on the roof changes handling even within the limit.


Review after use

Inspect clamps and fasteners to the rack maker's interval, especially after rough surfaces. Look for movement, damage to rails and rubbing at contact points. Reweigh a changed setup instead of relying on an old calculation.


Specification checklist

Before ordering or booking work, have these details ready: Vehicle roof rating, rack and mount part numbers, accessory masses and intended cargo mass.


Frequently asked questions

Is a rack's static figure my driving limit?

No. Use the applicable dynamic limit for travel and the vehicle maker's instructions.

For an application check, contact OFM4x4.co.uk with the vehicle and component details above. Confirm the current fitting instructions for the exact product before work starts.

Technical reference: www.thule.com. The relevant product manual takes priority over general guidance.