Native tool · INT.04 Drive · runs on this page
Noseweight & Rack Load
Two questions with the same answer key: how much weight belongs on the towball when the caravan is hitched, and how much rack and bikes the ball can carry when it is not. Enter the limits from the plate and the towbar label.
Noseweight & rack · v1.0
Static vertical load on the ballTrailer and limits
Rack on the ball
Inside the limits you entered
Guideline windows: Caravan and Motorhome Club (5–7 %), US 10–15 % hitch load. The rear-axle line is a lever model, printed with its assumption. Limits are yours to read off the plate.
Why the window, and why the cap
Noseweight is the trailer's vote on stability. A hitch that presses down with 5–7 % of the laden weight keeps the coupling loaded through crosswinds and lorry wash; go lighter and the trailer starts to hunt, go heavier and the car's rear squats, the front goes light and the towbar carries more than it was tested for. The window is guidance from the towing bodies; the cap is law and metal: the car's plated maximum noseweight and the towbar's S-value, whichever is lower.
The US uses a wider window because bumper-hitch trailers and weight-distribution hitches are set up differently. Switch the selector and the tool applies 10–15 % of the loaded trailer weight instead.
Racks on the ball are noseweight too
A towball bike rack is a static vertical load like any hitch, so the rack and the bikes are checked against the same cap. The second question is leverage. Bikes on a rack hang 30–60 cm behind the ball, so on the car's rear axle they act like a heavier load placed at the ball. The tool multiplies the raw load by (1 + overhang ÷ axle-to-ball distance) and prints both figures. Towbar makers rate the S-value at the ball, so the raw figure is the one to compare with the label; the effective figure tells you how much of the car's rear-axle margin the rack is eating.
| Rack + bikes | Raw load on the ball | Rear-axle equivalent (40 cm behind, 110 cm lever) |
|---|---|---|
| 15 kg rack, 2 × 12 kg bikes | 39 kg | 53 kg |
| 15 kg rack, 3 × 12 kg bikes | 51 kg | 70 kg |
| 18 kg rack, 2 × 25 kg e-bikes | 68 kg | 93 kg |
| 18 kg rack, 3 × 25 kg e-bikes | 93 kg | 127 kg |
FAQ
5 to 7 percent of the caravan's actual laden weight, never more than the car's plated maximum noseweight or the towbar's S-value, whichever is lower. A 1 400 kg laden caravan wants 70 to 98 kg on the ball; a car limited to 90 kg narrows that to 70 to 90 kg.
Yes. The rack and everything on it is a static vertical load on the ball, checked against the same limit. A 15 kg rack with three 12 kg bikes puts 51 kg on the ball.
Because the load sits behind the ball, it works on the car's rear axle like a heavier load placed at the ball. With the load 40 cm behind the ball and 110 cm from rear axle to ball, 51 kg acts on the rear axle like about 70 kg. The towbar's rating still uses the raw load.