Towing Weight Calculator
Calculate your vehicle’s safe towing capacity with the 85% rule
What is Towing Capacity?
Towing capacity refers to the maximum weight your vehicle can safely pull behind it. This includes the weight of the trailer or caravan plus any load it carries. Exceeding your vehicle’s towing capacity can result in dangerous driving conditions, vehicle damage, and legal penalties.
The 85% Rule
The 85% rule is a widely accepted safety guideline stating that novice towers should not tow more than 85% of their vehicle’s kerb weight. This rule provides a safety margin for inexperienced drivers and helps prevent dangerous situations like trailer sway or loss of control.
Legal Requirements
In the UK, the maximum weight you can tow is 3,500kg without requiring a special licence. Your vehicle must be type-approved for towing, and the combination must not exceed your vehicle’s gross train weight (GTW).
Safety Considerations
Always check your vehicle’s handbook for the manufacturer’s maximum towing capacity. Consider factors like trailer brakes, nose weight distribution, and driving conditions when planning your towing setup.
Finding Your Kerb Weight
Your vehicle’s kerb weight can be found in the owner’s manual, on the V5C registration document, or on a plate inside the driver’s door frame. This is your vehicle’s weight with fluids but without passengers or cargo.
Trailer Classifications
Trailers under 750kg don’t require brakes, whilst heavier trailers must have their own braking system. The maximum trailer length is 7 metres, and width cannot exceed 2.55 metres.
Towing Capacity Guidelines by Experience
| Experience Level | Percentage of Kerb Weight | Description |
|---|---|---|
| Novice/Beginner | 85% | Recommended for first-time towers and occasional use |
| Some Experience | 90% | For drivers with moderate towing experience |
| Experienced | 95% | For confident drivers with extensive towing experience |
| Expert/Maximum | 100% | Maximum legal limit – requires extensive experience |
How to Calculate Towing Capacity
The basic formula is: Kerb Weight × Experience Percentage = Maximum Towing Weight
For example, if your car weighs 1,800kg and you’re a novice driver:
1,800kg × 0.85 = 1,530kg maximum towing weight
Additional Factors to Consider
Gross Train Weight (GTW): This is the combined maximum weight of your loaded vehicle and trailer. Never exceed this figure, even if the trailer weight seems acceptable.
Nose Weight: This is the downward force the trailer exerts on your vehicle’s towbar. Typically, this should be 5-7% of the trailer’s weight, with most cars having a maximum nose weight limit of 50-100kg.
Payload Considerations: Remember that passengers, luggage, and fuel in your vehicle reduce the available towing capacity, as they contribute to the total weight.
Common Towing Mistakes to Avoid
Never exceed your vehicle’s maximum towing capacity, even if the trailer seems stable. Always ensure your trailer has working lights, brakes (if required), and proper coupling. Check tyre pressures on both vehicle and trailer before each trip, and adjust your driving style for the increased stopping distance and reduced acceleration.
When Professional Advice is Needed
If you’re unsure about any aspect of towing, consult with a qualified trailer specialist or your vehicle manufacturer. They can provide specific advice about your vehicle’s capabilities and recommend appropriate towing equipment for your needs.