Axle Load Calculator
Works out how a load splits between the axles from where it sits, and checks each axle against its plated rating. It is the calculation behind why rear overhang loads are a problem.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
rear load from a mass = mass × distance behind front axle ÷ wheelbase front load from a mass = mass − rear load axle total = kerb share + load share
The vehicle is a beam on two supports, so a load splits between the axles by the lever rule — moments about one axle. A load exactly over the rear axle goes entirely to it; one behind the rear axle puts more than its own weight there and takes the difference off the front.
What to watch out for
Where this matters:
- Towball and rear carriers. A load behind the rear axle levers weight off the front. 150 kg on a towball 1 m behind a 3 m wheelbase puts 200 kg on the rear axle and lifts 50 off the front.
- Vans and pickups. Loading to the back of the bed rather than over the axle is how a vehicle under its GVWR still exceeds its rear axle rating.
- Light steering is the symptom. If the front feels vague with a load on, the front axle has been unloaded — move the load forward.
Axle ratings are on the plate alongside the GVWR, and both apply.
Frequently Asked Questions
How do I calculate axle weight distribution?
Take moments about the front axle: the rear axle carries the load times its distance behind the front axle divided by the wheelbase, and the front carries the rest. Add each to the kerb weight’s share.
Why does a load behind the rear axle overload it?
Because it acts as a lever. A load 400 mm behind the rear axle on a 3 m wheelbase puts 113% of its weight on the rear axle and lifts 13% off the front — the front axle is the pivot.
Can I be under GVWR but over an axle rating?
Easily. GVWR is the total; each axle has its own limit. A van loaded at the back can be 300 kg under GVWR and 200 kg over on the rear axle, and both limits are enforced.