With many people wanting to add bike racks, toolboxes, and storage to the back of their motorhome or caravan, it’s important to know your vehicle dimension and rear overhang rules.
Dimensions must not be your only consideration. The weight of whatever you are adding can unbalance or overload your vehicle and affect its handling, so know your weights before you go!
Light rigid motor vehicles include cars, utes, 4WDs, small buses and small trucks (e.g., motorhome). The following dimensions apply.
Rear overhang (ROH) is 60% of the wheelbase or 3.7 meters, whichever is the lesser, measured from the rear overhang line.
Any object permanently fitted to a vehicle (e.g., bullbar, winch, toolbox) is considered part of the vehicle and must be included within the applicable dimension limits.
Dimension limits for trailers are divided into three categories: pig trailer, dog trailer and semi-trailer. Dog trailers aren’t used as RVs.
A pig trailer is a trailer that only has one axle group near the middle of the goods carrying surface. E.g., Caravan, camper trailer, box trailer.
Drawbar length (DBL) is measured from the centre of the axle group to the centre of the drawbar coupling pivot point with the drawbar level and must not be more than 8.5 meters.
Rear overhang (ROH) shall be no more than the length of the front load carrying area or body, ahead of the rear overhang line, or 3.7 metres, whichever is the lesser.
A semi-trailer a trailer with a single axle or axle group towards the rear, with a means of attachment to a prime mover that would result in some of the load being imposed on the prime mover. (e.g., fifth wheeler).
Rear overhang (ROH) shall be no more than 60% of the distance between the centreline of the ‘fifth wheel’ king pin and the line from which the rear overhang is measured, or 3.7 metres, whichever is the lesser.
Once again, it must be noted that rear overhang includes any equipment fitted to the rear.
Get the latest on RV road safety
