GTW: What it means and why it matters
GTW (Gross Train Weight) is the maximum combined weight of your tow car plus your caravan or trailer, fully loaded. It is set by the car manufacturer and must not be exceeded.
GTW is one of three critical weight checks for safe towing (alongside the 85% rule and the braked towing limit). It represents the total weight of the "train". Car plus trailer. That the vehicle is designed to handle. GTW is particularly important because it can be the limiting factor even when both the 85% rule and the towing limit pass. For example, a car with a 3,500kg towing limit but a 5,000kg GTW could be limited by GTW if the car itself is heavy. GTW is listed in the car's handbook and on the VIN plate.
Why this matters
Exceeding GTW overloads the car's drivetrain, brakes, and structure. It is illegal, voids your insurance, and is a common MOT failure point for tow cars.
Common misunderstandings
- GTW is not the same as braked towing limit. GTW includes the weight of the car itself
- A car might pass the 85% rule but still fail the GTW check
- GTW is set by the car manufacturer, not the caravan manufacturer
- GTW is not the same as GVW or MAM. GVW and MAM cover the vehicle alone, GTW covers vehicle plus trailer
Example
A tow car with a kerbweight of 2,100kg, a braked towing limit of 2,500kg and a GTW of 4,400kg can legally pull a caravan up to 2,300kg MTPLM. 2,100kg car plus 2,300kg caravan equals 4,400kg, exactly the GTW. A heavier caravan would fail the GTW check even if it sits under the 2,500kg towing limit.
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Frequently Asked Questions
Check the VIN plate (usually inside the driver's door frame), your car's handbook, or use our free towing capacity checker by entering your registration number.
You are overloading the vehicle. Insurance is invalidated, you risk prosecution, and the car's brakes and drivetrain may not cope safely.